Duration: 10/01/2003 to 09/30/2009

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Statement of Issues

Objective 1. Improvement of commercial cow-calf performance in the Southern region of the United States has been due to breed complementary and exploitation of heterosis for calf performance and cow reproductive and maternal traits. Heterosis expressed by crosses of non-Bos indicus tropically adapted breeds with traditional breeds has not been determined in the U.S.such information is needed by producers in the Southern region in order to make the most appropriate choice of breeds to use in crossbreeding programs.


Objective 2. The Southern region of the U.S. produces a large amount of forage that is utilized in cow-calf production. Environmental challenges in this region such as hot, humid weather and a wide variety of parasites have made Brahman crossbred cattle popular. Several breeds have been established in the U.S. based on Brahman-Bos taurus crossbred bases (i.e. Santa Gertrudis, Beefmaster, Brangus, Simbrah, etc.). Other tropically adapted breeds originating in different parts of the world have been evaluated in the U.S. (i.e. Sahiwal, Indu-Brazil, Gir, Nellore, Senepol, Tuli, Boran), and several have just recently been imported (Romosinuano, Bonsmara, Mashona). Knowledge about these tropically adapted breeds is still quite limited compared to more established breeds. Production information is needed on growth, carcass and reproduction characteristics of these tropically adapted breeds, as well as estimates of heterosis, so that cow-calf producers in the Southern region can make informed breeding decisions to profitably produce cattle under their environmental challenges and still produce desirable end-products for consumers.


Objective 3. The Southern region of the U. S. accounts for approximately 42% of the nations beef cows, the majority of which are supported by intensive forage production. Intensive forage utilization in combination with the physical environment (rainfall, humidity, ambient temperature) provides optimum conditions to maintain endoparasite populations that adversely affect cattle performance (Williams and Loyacano, 2001). Research in this region has primarily focused on identifying genetic types that reproduce and grow well under these environmental challenges. However, the genetic types that perform well in this environment tend to be those that provide the most challenge behaviorally (easily excitable, nervous) when restrained for routine management practices. The adverse affects of less desirable temperament on growth rate, meat quality and animal welfare are well documented. Therefore, additional research is needed to determine the genetic variation that exist for internal parasite resistance and for temperament differences.


Objective 4. Economically relevant traits in beef cattle are primarily quantitative in nature. Recent developments in selection tools offer the opportunity to utilize Quantitative trait loci (QTL) data in improvement programs; however, very little is currently known about the importance of QTL x environment interactions. The current selection tools utilize quantitative genetic theories that assume the expression of relevant genes is independent of parent of origin. Recent studies have demonstrated that parent-of-origin effects may have importance for many livestock traits.


Justification:


Objective 1. Efficient cow-calf production in the Southern region is dependent on heat tolerance and parasite resistance in the cows and calves produced in this region. Brahman and Brahman-derivative cattle have successfully met this need and consequently, most cows and calves in the Southern region have some level of Brahman inheritance. Interest in non-Brahman tropically adapted breeds is emerging in the Southern region because of economic discrimination against Brahman and Brahman-derivative genetic types, particularly feeder and slaughter cattle. However, little is known about the performance of non-Brahman tropically adapted genetic types, particularly as crossbred cows and calves, nor is there sufficient information on the performance of the calves as stockers and feeders in the Southern Great Plains and High Plains regions. Consequently, there is a need to estimate direct breed and maternal additive genetic effects and heterosis for cows and calves resulting from crosses of non-Brahman tropically adapted breeds bred to British, Continental, and American (including Brahman) breeds in specific production environments.


Objective 2. The 13 states in the Southern region (AL, AR, FL, GA, KY, LA, MS, OK, NC, SC, TN, TX, VA) account for 14 million beef cows (42.3% of the nations beef cow inventory) and 406,200 producers (48.9% of the nations cow-calf producers) (USDA, 2002). In addition, the cooperating state of Nebraska accounts for 1.9 million beef cows and 23,000 cow-calf producers. It is important to characterize breeds that have potential to improve productivity in regions that have substantial environmental challenges. It is also necessary to characterize heterosis levels between these breeds so that informed breeding and production decisions can be made to increase profitability for cow-calf producers.


Objective 3. Internal parasites are one of the most economically important constraints in raising livestock (Wells, 1999). Unfortunately, the climatic conditions in the Southern region and the demand for year-round forage makes it difficult, even with rotational grazing, to have sufficient time between grazing bouts to break the life cycle of nematodes that are prevalent in the area. Traditionally, beef cattle management in the Southern region has involved anthelmintic treatment for internal parasite control. Continued dependence on chemical control could lead to resistant parasite populations. Additionally, dependence on chemical control has contributed to consumer aversion to drugs and drug residues in food, and the interest by cattle producers and environmentalists for reduced levels of drug residues in the environment (Donald, 1994; Stear and Murry, 1994; Frisch et al., 2000). The producer concerns about the evolution of resistant parasites, public concerns about residues in food and the environment, and the expense of chemical control could all be minimized if resistance to parasites was achieved.


The 1994 National Non-Fed Beef Quality Audit showed that bruises on cattle cost the beef industry $3.91/animal marketed and $30 million annually (Grandin, 1995). Data show that cattle with excitable temperament ratings produced a higher incidence of borderline dark cutter carcasses than cattle with calm temperament ratings (Voisinet et al., 1997a). Studies on temperament of cattle indicate that lower growth rate and reduced meat quality are associated with greater reactivity of animals during handling as indicated by their chute score (Voisinet et al., 1997a, 1997b). Studies to determine the amount of stress on farm animals during routine handling often have shown variable results and are difficult to interpret as related to animal welfare. It is important to breed animals with a calm disposition to reduce stress and to improve both productivity and welfare. Increasing public concern about animal welfare is a major reason why major restaurant companies and supermarkets are auditing handling and stunning practices in the United States and abroad (Grandin, 1997). Genetics also affects an animals response to stress. However, over-selection for docility may have detrimental effects on economically important traits, such as maternal ability (Grandin, 1997). Therefore, before engaging in a selection program to improve temperament, further research is needed to evaluate the genetic variation for temperament and the potential relationship between reactivity to handling and other traits such as productivity and maternal ability (Grignard et al., 2001).


Objective 4. Using phenotypes and pedigrees animal breeders have developed statistical tools that have contributed to significant changes in the characteristics and performance of the worlds beef cattle populations. These changes have enhanced gross performance and efficiency of beef production resulting in a more stable, relatively inexpensive protein supply.


Previous multi-state beef cattle research projects (S-10, S-243, and S-277) have been successful in leveraging resources from several locations. However, in hindsight technological advances in DNA research have not been utilized because DNA samples from animal populations were not collected and stored. The current proposal would establish protocols for establishment of a DNA bank that could be used in studies for parent-of-origin effects and QTL x environment interactions. Objectives 1, 2, and 3 outline numerous variables that can be measured or evaluated with benefits derived from their analysis. Objective 4 seeks to extend the benefits to take advantage of emerging technologies by preservation of DNA obtained from animals used in the other three objectives.

Related, Current and Previous Work

Objective 1. The Romosinuano breed is native to Colombia and derives its name from its origin in the Sinu river region (sinuano) of northern Colombia and its polled (romo) character (Rouse, 1977). Romosinuanos are noted for longevity, docile temperament, adaptation to tropical stressors, and their combining ability with Bos indicus cattle (Primo, 1990; Derr et al., 1995; Martinez-Correal, 1995). Reproductive efficiency, the most economically important production trait in cattle, is reported to be high in Romosinuano, even under harsh tropical conditions. Data collected in Colombia (de Alba, 1987) and Costa Rica (Casas and Tewolde, 1991) indicated that Romosinuano breeding was associated with shorter calving intervals. These data and data reported by Molina et al., 1982 indicated that as the proportion of Romosinuano breeding increased, the percentage of cows that calved tended to increase. Because of this and other desirable traits (heat tolerance, disease resistance, gentle temperament, good carcass quality), the Romosinuano breed has the potential of being an extremely valuable genetic resource for utilization in the Southern region.


Bonsmara is a composite breed native to South Africa, comprised of 5/8 Afrikaner and 3/16 Hereford and 3/16 Shorthorn. (Porter, 1991) This composite was developed in response to the need for a productive breed adapted to hotter conditions of South Africa, and is noted for growth, fertility, and functional efficiency. The utility of the Bonsmara is evidenced by their popularity in South Africa, with Bonsmara numbers exceeding numbers of other breeds in the country.


When diverse breeds are crossed, such as Bos indicus x Bos taurus or diverse Bos taurus x Bos taurus breeds heterosis is exhibited. A modified expression of heterosis can even be observed when crossing inbred or highly selected lines within a given breed (MacNeil et al., 1989). This heterosis can be accounted for, in at least most cases, by the increased heterozygosity resulting from different alleles at many loci that are approaching fixation in the respective breeds. Thus to capture the advantages of heterosis, purebred seedstock must be maintained to support crossbreeding systems (Koger et al., 1973a, b).


Breed effects and heterosis for important beef production traits have widely studied among breeds of cattle used in U.S. beef production. It is accepted that for almost all traits, Brahman-Bos taurus crossbreds express about 1/3 greater heterosis than Bos taurus crossbreds (Franke, 1980). Long (1980) provided a comprehensive summary of breed group means, heterosis estimates, and differences between F1 calves produced by reciprocal crosses for birth and weaning weight, calf survival at birth and survival to weaning, percentage of cows having difficulty when calving, and preweaning average daily gain. Wyatt and Franke (1986) combined data from beef cattle studies across the Southern region and reported heterosis estimates and breed additive and maternal effects for birth and weaning weight and average daily gain for many breeds and breed combinations. Results of this study are widely used to predict crossbred performance.


There is limited information on levels of heterosis in crosses of tropically adapted breeds, or in Bos taurus crosses when one of the two Bos taurus breeds is tropically adapted. There are Bos taurus sources of tropically adapted germ plasm in the world that possess unique attributes that could be exploited in other warm regions. Like most beef cattle breeds, including Brahman, the potential usefulness for these breeds will be in crossbreeding systems (Franke, 1997; Thrift, 1997). Recent evidence from studies conducted between Senepol, Hereford, and their reciprocal crosses indicated that significant levels of heterosis were observed for preweaning growth traits of F1 calves and postweaning feedlot performance of F1 steers, but heterosis levels were less than those reported for Bos indicus-Bos taurus crosses (Chase et al., 1998). Results of a Colombian project, reported by Elzo, et al., 1998, suggested that crossing Romosinuano with Brahman or with Brahman-Romosinuano cows would be advantageous to producers.


There are many estimates of heterosis in the literature for preweaning cattle traits. Reported estimates for birth weight ranged from 0 to 10.8% (Long, 1980; Wyatt and Franke, 1986; Comerford et al., 1987), with the majority of estimates less than 3% (less than 2 kg). Cartwright et al. (1964) and Roberson et al. (1986) reported large heterosis for birth weight, and large sex and reciprocal F1 differences for birth weights of Brahman-Hereford crosses. The work of Thallman et al. (1992) extended this knowledge to other Brahman-Bos taurus crosses and suggested that these effects may be the result of causes other than dominance. Cartwright et al. (1964) reported 6.1% heterosis for calf vigor at birth. Estimates of heterosis for calving difficulty were summarized by Long (1980) and ranged from 1.3% to 56%. Estimates of heterosis for weaning weight (or related traits, e.g., 200-day weight, etc.) have ranged from less than 5% for British crosses (Gregory et al., 1965; Comerford et al., 1987) to much higher estimates of 16 to 21% (6 to 30 kg) for Brahman and some Continental crosses (Cartwright et al., 1964; Peacock et al., 1978; Long, 1980; Comerford et al., 1987).


Long (1980) listed estimates of heterosis from the literature for postweaning weight and gain of steers; most estimates ranged from 3 to 10% (25.2 to 43 kg). Comerford et al. (1988) reported an estimate of 9.8% (0.09 kg per day) for feedlot average daily gain. Chase et al. (1998) reported heterosis estimates for postweaning weight and gain of less than 15% (most less than 10%) in Senepol-Hereford crosses. Heterosis was not important for carcass quality, yield, and palatability traits; expressed heterosis for several important carcass traits was less than 10% across several studies (Long, 1980). Chase et al. (1998) reported low heterosis estimates (less than 5% for most traits) for carcass traits in Senepol-Hereford crosses.


Objective 2. Several research projects in the U.S. have compared the productivity of Brahman crossbred cattle to Bos taurus breeds for calf size and growth (Notter et al., 1978; Franke, 1980; McElhenney et al., 1985; Williamson and Humes, 1985) and maternal productivity (Turner et al., 1968; Peacock et al., 1977; Franke, 1980; Roberson et al., 1986; Green et al., 1991) with the general consensus that F1 Brahman-Bos taurus cattle are very productive under a wide variety of environmental conditions. However, few studies have compared Brahman crossbred cattle to other tropically adapted breeds under U.S. production conditions.


In regard to calf size, Paschal et al. (1995) reported that F1 Brahman-sired calves were substantially heavier at weaning than Indu-Brazil sired calves and marginally heavier than Nellore- and Gir-sired calves. In additional comparisons of F1 calves produced by tropically adapted sire breeds, Brahman-sired calves were heavier at birth and weaning than Boran- (Herring et al., 1996; Cundiff et al., 1999), Tuli- (Herring et al., 1996; Cundiff et al., 1999; Chase et al., 2000) and Senepol-sired calves (Chase et al., 2000).


In regard to cow productivity, Cundiff et al. (1984) reported that F1 Brahman-sired cows had lower percent calf crop weaned and heavier birth weight calves compared to F1 Sahiwal-sired cows. Weaning weights of calves were heavier from the F1 Brahman-sired cows compared to those from the F1 Sahiwal sired cows, and the weight of the Brahman-sired cows was 75 kg heavier than the Sahiwal-sired cows as six-year-olds (Cundiff et al., 1984). Riley et al. (2001a) reported that F1 Nellore- and Gir-sired cows were superior for reproductive performance and calf survival compared to F1 Indu-Brazil-sired cows. Furthermore, F1 Nellore-sired cows had better postpartum udder conformation and longevity compared to F1 Brahman (red and gray)-, Indu-Brazil- and Gir-sired cows (Riley et al., 2001b). Cundiff et al. (1999) and Ducoing-Watty (2002) found F1 Tuli- and Boran-sired cows could be viable alternatives to F1 Brahman-sired cows in regard to reproductive performance, calf weaning weight and cow size. Forbes et al. (1998) reported similar forage intake, digesta dynamics and grazing behavior in Tuli- and Brahman-sired heifers. With a high energy finishing diet, Ferrell and Jenkins (1998) found that Boran- and Tuli-sired steers had lower ad libitum feed intake than Brahman-sired steers. Hammond et al. (1996) reported heat tolerance in F1 Tuli-Angus, Senepol-Angus and Brahman-Angus to be similar to that in purebred Senepol and Brahman.


Objective 3. Parasite Resistance: Studies on cattle resistance to nematodes are limited, although it is now recognized that predisposition to heavy parasitism is genetic in origin, and that in general, individuals that harbor few parasites are probably genetically resistant and those with heavy burdens are less resistant (Gasbarre et al., 1990; Kloosterman et al., 1992). Fecal parasite egg counts are not normally distributed, and a small percentage of an infected herd is normally responsible for the majority of parasite transmission (Gasbarre et al., 1990). Regardless of the mechanisms which mediate resistance, the ability to access the relative genetic merit of breeding stock with respect to transmitting higher parasite resistance will be of economic benefit to the cattle industry. The accuracy of producing breeding values among candidates for selection depends upon the degree to which the genetic composition of the host dictates the observed phenotype (Leighton et al., 1989). Given the omnipresent economic detriment of parasitism, and the need to identify non-chemical means of parasite control, it is important to find a compromise between performance in productivity traits and resistance to parasitic disease (Donald, 1994).


Resistance can be regarded as the ability of an animal, genetically transmitted, to combat the establishment of an infection. Some indigenous breeds exhibit genetically transmitted resistance indicating that selection can provide resistant strains. This is a slow process and the strains have to be continuously subjected to selection to maintain adequate productivity (Snijders et al., 1980). Evidence from cattle studies is sufficient to demonstrate the potential for significant sire effects on progeny resistance to nematode parasites (Seifert, 1977; Stear et al., 1984; Barlow and Piper, 1985; Esdale et al., 1986; Leighton et al., 1989). In the U.S., Leighton et al. (1989) demonstrated that the number of nematode eggs found in feces of calves during their first grazing season was significantly related to the calf's sire.


Studies on cattle in tropical areas have indicated a significant correlation between fecal EPG values and total worm numbers (Bryan and Kerr, 1988). Kloosterman et al. (1978) reported an association between host genetics and resistance to Cooperia spp. in cattle. Genetic correlations between growth traits with worm and fly burdens were significant (MacKinnon et al., 1991; Seifert, 1977) but low (MacKinnon et al., 1991). A high fertility line showed higher fecal egg counts than a low fertility line resulting in a negative correlation between cow fertility and resistance to worms (MacKinnon et al., 1990). An antagonistic relationship between weight gains of cattle and worm burdens, as measured by fecal egg count, has also been found, from which it is concluded that selection for growth performance can lead to reduced resistance to worms (MacKinnon, 1991). Therefore, it is possible that this could reduce the emphasis placed on wide spread selection for resistance to internal parasites (Kloosterman et al., 1992).


Most heritability estimates for EPG levels ranges from 0.3 to 0.4, which suggests that genetic improvement for parasite resistance by selection based on genetic merit is possible in most ruminants (Sonstegard and Gasbarre, 2001). An option to anthelmintics is to identify and utilize resistance genes present in bovine germplasm to reduce parasite transmission. Advances in molecular genetics should offer opportunities for identifying genetic markers for parasite resistance, which would hasten progress in selecting for resistance; however, research in this area is in its infancy (Vercruysse and Dorny, 1999). If genetic control is determined to be by a single gene or if control is polygenic but moderately heritable, then selection could produce significant genetic change (Leighton et al., 1989). Genetic resistance is the ultimate in sustainable parasite control, particularly for resource-limited farmers (Donald, 1994). Instead of selection, efforts have been directed towards controlling the sources of infection by hygienic cultural and chemical methods (Johansson and Rendel, 1968). Many of the concerns about drug resistant parasites, residues in food and the environment, and the cost of control could be addressed through use of cattle that were inherently resistant to parasites (Frisch et al., 2000). Early work (Whitlock, 1955) have shown that by selective breeding, we may be able to create populations of cattle resistant to some internal parasites.


Temperament: There are differences in temperament both between and within cattle breeds (Stricklin et al. 1980; Tulloh, 1961; Le Neindre et al. 1995). In European Continental-cross cattle, certain individuals became extremely agitated every time they were handled in a squeeze chute while others were always calm (Grandin, 1992). Certain genetic lines of European-Continental cross cattle are more excitable than British breeds (Grandin et al., 1994; Stricklin et al., 1980). Brahman and Brahman-cross cattle are more excitable and harder to handle than English breeds (Grandin, 1989); however, Hohenboken (1987) found that Brahmans handled gently have the potential to be extremely docile. Numerical chute scores are a common method used to measure the reaction of cattle to restraint. Numerous scoring systems for behavior and docility have been used in the past to determine temperament scores (Fordyce et al., 1988; Grandin et al, 1994, 1992; Tulloh, 1961; Dickson, 1967) and appear repeatable. The heritability of beef cattle response to handling is generally moderate to high (Burrow, 1997). Therefore, within a breed it may be possible to select animals that are more docile and better adapted to specific management conditions (Le Neindre et al., 1996). A comprehensive literature search revealed heritability estimates from 0.40 to 0.53 (Shrode and Hammack, 1971; Stricklin et al., 1980; O'Blesness et al., 1960; Dickson et al., 1970; Le Neindre et al., 1995) indicating that temperament is a heritable trait that may affect the animal?s reaction to handling. Ranchers and dairymen have learned from practical experience that calves from certain sires are more nervous and/or excitable (Grandin and Deesing, 1998). However, over-selection for docility may have detrimental effects on economically important traits, such as maternal ability (Grandin, 1997). Additional research is needed to explore the genetic variation for temperament under the environmental conditions and production systems of the Southern region.


Objective 4. In the past 15 years numerous studies have been designed to exploit individual quantitative trait loci (QTL). These studies have resulted in new investigations to elucidate gene expression and the complex relationships between the genome, proteome and organism. The potential for these new methods to further impact efficiency of production is great. The use of marker information techniques may have their greatest impact for traits that have been more difficult to improve in the past, such as disease resistance and meat quality. Before the use of QTL analyses can be exploited for beef improvement, two areas need further clarification: imprinted gene effects and importance of QTL x environment interactions. Imprinting describes those genes for which the transcriptional activity is dependent on the parent-of-origin of the allele. Young and Fairburn (2000) stated imprinted genes are often only expressed in a tissue-specific or a developmental stage-specific manner.

Allen (1969) reported, but did not explain a maternal grandsire effect for production of PMSG. In a latter report, Allen et al. (1993) described the effects of fetal genotype and uterine environment on placental development. These authors reported that parental gene imprinting influenced the production of eCG. Recently, there have been several reports on the identification of imprinted genes with major effects on muscle mass, fat deposition, birth weight, and weaning weight in cattle (Engellandt and Tier, 2002; Imumorin et al., 2001; Imumorin et al., 2000) and pigs (Nezer et al. 1999; DeVries et al., 1994; Wilken et al. 1992).

Marker assisted selection has been shown in simulation studies to offer great potential (Marshall et al., 2002). However, the importance of QTL x environmental interactions have not been resolved. Wang et al. (1999) reported statistical approaches to mapping QTLs with epistatic effects and QTL x environmental interactions. One example that is proving difficult to resolve is the STAR gene effects for marbling in cattle, the effect of which is not uniform in different management schemes. There are likely other examples that have not yet been detected because to date the data sets analyzed are from single locations with limited observations. Evaluation of "gene" effects across different environments can best be achieved through collaboration of several research units, such as a multi-state research project. The efforts in other species should also be used for guidance as effects of environment on genetic variation and response are measured (Bubliy and Loeschcke, 2002; Bubliy et al., 2000)

There are several experimental designs that might be employed. It is however important to note that a critical component of the designs is that only segregating families ( i.e. at least one parent must be heterozygous) contribute useful information. Du et al. (2002) summarized that heterozygosity "is affected by a number of factors, including number of genes, allelic frequencies and effects at all loci, recombination fractions among the genes, linkage disequilibrium, and mating system". Knott et al. (1996) described methods for multiple marker mapping of QTLs in half-sib populations. Measurement of effects for single genes affecting meat quality in F2 individuals of a two breed cross was described by Janss et al. (1997). Mapping QTLs for binary traits in backcross and F2 populations was described by Visscher et al. (1996), and Alfonso and Haley (1998) reported on the power of different F2 schemes for QTL detection in livestock.

A CRIS search revealed no similar research projects involving heterosis of tropically adapted beef breeds and/or characterization of tropically adapted beef breeds in the U.S. The CRIS search did reveal several projects dealing with parasite control but none dealt with parasitism via underlying genetic variation. Therefore, objectives of the new multi-state proposal do not duplicate any research currently underway. The objective on DNA markers is no doubt a worthy topic. A CRIS search revealed several projects dealing with molecular markers in all phases of livestock production. The present proposal deals with simply developing a DNA bank to complement the data that will be collected throughout this study. Analysis of the DNA at a latter time, or as part of another multi-state research project, is recommended.

Objectives

1. Determine heterosis effects in crosses representing two or more diverse, tropically adapted beef breeds
   
2. Characterize diverse, tropically adapted beef breeds in subtropical and temperate areas of the United States
   
3. Determine genetic variation in temperament and parasite resistance in beef cattle and their association with economically important traits
   
4. Establish a DNA bank to utilize molecular markers to validate traits of economic importance
   
5. 
   

Methods

Objective 1 The Subtropical Agricultural Research Station (STARS), Brooksville, FL will estimate breed direct and maternal additive effects and heterosis in crosses of Brahman, the predominant U.S. tropically adapted breed, and the Romosinuano, a tropically adapted Bos taurus breed from South America. The Grazinglands Research Laboratory (GRL) El Reno, OK will estimate direct and maternal breed effects and heterosis in crosses of Brangus, a predominant Brahman composite, and Bonsmara, a tropically-adapted Africander composite from South Africa. Calves will be evaluated for preweaning performance and postweaning stocker performance. Steer calves will be evaluated for feedlot performance and carcass merit. Females will be retained to evaluate cow productivity. Data within location will be analyzed using the MIXED procedures of SAS. Linear models will include effects of sire breed, sire nested in sire breed (random), dam breed, sire breed x dam breed, age of dam, calf sex, year, and appropriate interactions among fixed effects in the models. Contrasts will be constructed from least squares means to estimate breed direct and maternal effects, heterosis, and any reciprocal cross effects. Dr. David Riley (STARS) and Dr. Mike Brown (GRL) will be responsible for defining the format for collection, accumulation, editing, statistical analysis of the data, and publication of the results. Objective 2. Several cooperating locations have produced, or are in the process of producing, cattle of at least two tropically adapted breeds where the performance of the crossbred cattle will be evaluated. At the USDA Meat Animal Research Center in Clay Center, NE, calves have been produced by breeding Brangus, Beefmaster, Romosinuano, Bonsmara, Angus and Hereford sires to Bos taurus cows. All the male calves produced will have size, growth, feedlot, and carcass data collected. The heifer calves will be kept for breeding purposes to evaluate cow productivity. One-half of the females sired by Brangus, Beefmaster, Romosinuano and Bonsmara will be relocated at weaning to Louisiana (Baton Rouge) so that genotype x environment interactions for cow production traits can be evaluated. Approximately 50 females by each sire breed will be evaluated at each location. Females will be exposed to MARC III bulls for the first calf and to Charolais bulls for subsequent calves. Steer calves produced from 5, 6, and 7-year-old cows will be fed post-weaning and carcass data collected for analysis. In Texas, F1 cows have been produced by Tuli, Boran and Brahman sires and Angus and Hereford dams at the TAMU McGregor Station. These cows are being kept to monitor lifetime cow productivity. Additionally at McGregor are F1 Brahman-Angus and Nellore-Angus and Angus-Brahman-Hereford-Nellore (25% each)crossbred cows and contemporary purebred Angus, Brahman, Hereford and Nellore herds. At the TAMU Uvalde Station, cows have been produced from Angus, Senepol, Tuli, and Brahman sires. Additionally at Uvalde, Angus and Bonsmara sires have been used to produce F1 calves, and the females will be retained to evaluate cow productivity. At the USDA Sub-tropical Agricultural Research Station (STARS) in Brooksville, FL, there are F1 calves being produced from Angus, Brahman and Romosinuano parents in a diallel breeding arrangement. Male calves will be evaluated for calf size and growth, feedlot performance, and carcass traits. The females produced will be kept for breeding purposes to evaluate cow productivity. Additionally, Mashona and Angus sires will be used to produce the first calves from the heifers produced at STARS. At the USDA Grazinglands Research Laboratory, El Reno, OK, Brangus cows have been bred to Charolais, Gelbvieh, Hereford, Romosinuano, Bonsmara, and Brangus sires. Calves will be evaluated for preweaning performance and postweaning stocker performance. Steer calves will be evaluated for feedlot performance and carcass merit. Females will be retained to evaluate cow productivity. In South Carolina, Angus, Bonsmara and Simmental sires have been bred to Angus, Simmental and Simmental-Angus crossbred dams; male calves will be evaluated for feedlot and carcass characteristics and the females retained to evaluate cow productivity. Additionally, there will be a small herd of purebred Bonsmara females maintained. As the U.S. beef cattle industry moves towards value-based marketing of animals based on carcass quality and yield traits, it will become increasingly important that breeding systems and breed comparisons be evaluated based upon the economic considerations of cow-calf production, calf growth/development after weaning, and marketing offspring based on carcass characteristics. Cow productivity will be evaluated at the various locations by analyzing calf crop born, calf survival, calf crop weaned, cow weight, cow survival and calf birth weight and weaning weight. Dr. Jim Sanders and Dr. Andy Herring (Texas A&M) will be responsible for defining the format for collection, accumulation, editing, statistical analysis of the data, and publication of the results. Objective 3. Seven stations, including Arkansas (Fayetteville), Louisiana (Baton Rouge, Homer and Iberia), Texas (McGregor, Uvalde, and College Station) Florida (ARS-USDA, Brooksville), South Carolina (Clemson), Georgia (Tifton), and Kentucky (Lexington) will record fecal egg (nematode) counts and/or chute temperament for cattle representative of various breeds of cattle. The Angus breed will be common among the participating stations and should provide the genetic ties across location for data analysis. In the parasite studies, productivity traits (monthly body weights/gains and body condition scores) will be recorded. Spring born calves will be utilized for the internal parasite component of the study. Birth date, birth weight, and sire and dam of each calf will be recorded. All participating stations will use either no growth implants or the same implants (and timing). Weaning dates and weights will be recorded. At weaning, fecal nematode egg and coproculture infective larvae counts will be determined, and each calf will be treated with fenbendazole at the rate of 10 mg kg-1 body weight. Fecal egg counts, coproculture larvae counts and animal weights will be taken every 45 days until the first of July (last sampling) of the next year. The above design will provide an opportunity to look at apparent resistance to Ostertagia, Cooperia, Trichestrongulus, Oesophagostomum, and Haemonchus genera nematodes, the most important helminth cattle parasites. Spring- and fall-born calves will be utilized for the temperament study. Breed, birth date and weight, and sire and dam of each calf will be recorded. Temperament differences will be recorded using the following chute behavior scoring system described by Grandin et al., (1994): 1) calm, stands still, no movement; 2) slightly restless; 3) restless, shaking the chute; 4) vigorously shaking the chute; and 5) a berserk frenzy. Temperament scores will be recored at 120 d, 205 d (weaning), 365 d (yearling), 420 d (prebreeding), 480 d (postbreeding) and 720 d (weaning of first calf) for the females and 120 d, 205 d (weaning), 365 d (yearling) for the males. At each location scoring will be conducted by the same individual or by three individuals. Animals will be scored prior to routine practice i.e. injections, and prior to squeezing of the chute. Postweaning internal parasite and chute score observations will be obtained on four (4) calf crops from each location. Both data sets will be analyzed using PROC MIXED in SAS/STAT (2002). Because sires are not available with EPDs for temperament and/or parasite resistance, estimation of genetic variance will be partitioned using a nested ANOVA with sire nested within breed nested within location. The mathematical model will include terms for an overall mean, location, cow breed, year, cow age, calf age, and error and the above nested terms. Simple correlations will be obtained for fecal egg counts and chute behavior scores with productivity traits. In situations where genetic ties exist, an animal model will be utilized to estimate heritability for fecal egg count and chute behavior scores, and phenotypic and genetic correlations among fecal egg counts and chute behavior scores and productivity traits. Dr. A.H. Brown (Arkansas) will be responsible for defining the format for collection, accumulation, editing, statistical analysis of the data, and publication of the results. Objective 4. Objective 4. DNA studies require large numbers of observations and sophisticated statistical analyses to detect small effects. However, these studies also offer a greater potential for extramural funding relative to traditional animal breeding studies. In order to develop a program in beef cattle genetics and biotechnology that shares resources from numerous state or federal research efforts a uniform set of procedures will be established. The mating designs and data collection protocols can be set by objectives 1, 2 and 3 and then each contributing research unit can participate in objective 4 through storage of DNA. Opportunities for DNA analyses may be limited by mating designs for objective 1. Genetic background and heterozygosity which will be found in animals contributing to objective 2 may be beneficial for examination of interactions of QTL x genetic background (Weller, 2001). It is expected that the most useful set of DNA samples will be associated with objective 3. The DNA collection can be accomplished with only a small amount of additional time and equipment. Participants in the multi-state research effort for objectives 1, 2, and 3 can also participate in objective 4 by agreeing to preserve DNA collected from animals involved in the other objectives. Each participant will agree to collect whole blood from parents and offspring throughout the project. If semen is used for A.I. then additional straws can be saved where blood would not be available. The preference would be for each state to extract and save only the DNA but it is recognized that not all states will have this ability. It will be important that replicated samples of the DNA be stored in two locations to help insure against accidental loss. Furthermore, several states have agreed to utilize common sires across locations that will be selected due to unique combinations of EPDs or other characteristics that have the potential for creating heterozygosity in the offspring. Dr. Jerome Baker (Georgia) will be responsible for defining the format for collection, accumulation, editing, statistical analysis of the data, and publication of the results.

Measurement of Progress and Results

Outputs

• Data from proposed studies will be published in peer review journal publications/regional experiment station bulletins
• Results will also be available in CSREES annual reports and through the development of a home page for this project.
• Peer-reviewed journal publications should lead to the development of some extension publications as well

Outcomes or Projected Impacts

• <b>Objective 1.</b> Heterosis and direct and maternal breed effects will be estimated, and these estimates will be used to facilitate genetic choices among breeds for efficient production systems. It is anticipated that this new knowledge will lead to improved management practices and decision-making.
• <b>Objective 2.</b> Data will allow comparisons among females sired by alternative subtropically adapted sires to the Brahman F1 female. It is expected that several of the alternative F1 cow groups will be superior, and that some will be inferior, to the Brahman F1 female for different traits. Of major importance in all these objectives is information on reproductive performance of the cow.
• <b>Objective 3.</b> Data should lead to improved efficiency of beef production in the Southern region through more effective management of available beef cattle genetic resources. Variation between and within breed should lead to the development of improved breeding methods under environmental conditions of the Southern region. Genetic parameter estimates could aid in genetic prediction of breeding value for parasite resistance/susceptibility and temperament. Results should provide the basis for development of breeding programs based on these results.
• <b>Objective 4.</b> Often in the past when research studies are completed a question that is frequently asked is "why wasnt that trait measured ?" It is possible to fill in the blank with any number of traits. In the case of the multi-state project S-277, it could be asked why DNA samples were not collected on the many animals that were involved across the states. There were numerous genetic ties across environments with the same characters measured in these various environments. This type of data would be a good candidate for studies of QTL x environment interactions and also effects of imprinted gene effects. Therefore, the expected outcome of objective four will be to have DNA samples available for future explorations. It is impossible to know today what types of technology may be available for DNA analysis in 3-5 years, but with adequate preparation the technology can be utilized with a little advanced planning.

Milestones

(2004): Forward the first years data to the coordinators of each objective

(2006): Coordinator for each objective should have an abstract(s) prepared for presentation at a professional meeting (state, regional, or national)

(2007): Coordinator for each objective should prepare a rough draft(s) of journal articles

(2008): Coordinator for each objective should submit journal article(s) for peer review

(0):0

Projected Participation

View Appendix E: Participation

Outreach Plan

Results will be presented at local, state, regional, and national scientific and professional meetings and published in scientific journals and extension publications for use by animal geneticists, extension personnel, and industry personnel. These results should be of interest to breed associations, beef improvement federation, and extension personnel conducting adult and youth educational programs at county, state, and regional levels.

Organization/Governance

A regional Technical Committee is to include a regional Administrative Advisor (nonvoting); a CSREES consulting representative (nonvoting); a technical representative of each participating State Experiment Station appointed by the respective director; a technical representative of each cooperating USDA location, named by the head of the respective USDA location, and a technical representative of each participating non-land grant university; a regional project coordinator for each objective, and other nonvoting consultants as seen appropriate. Each SAES, USDA-ARS, and non-land grant university participant will have one voting member.


An Executive Committee, to be composed of the regional Administrative Advisor and three elected officers from the Technical Committee: the Chair, the Chair-elect and the Secretary , shall have the authority to act on behalf of the Technical Committee. The officers shall be elected each year at the annual meeting.


The Chair of the Technical Committee, with approval of the regional Administrative Advisor, shall call meetings of the Technical Committee annually, and more frequently if deemed necessary, for the progress of the project. The Chair shall likewise call interim meetings of the Executive Committee if necessary. The Chair of the Technical Committee will be responsible for preparing a consolidated report (SAES 422) summarizing progress in the project each year. This report will be approved by the regional Administrative Advisor and an appropriate number of copies shall be transmitted to CSREES and each cooperating station.


The Technical Committee shall coordinate the planning and work of the project. Changes in contributions by participating stations will be submitted to the Technical Committee for review. After consideration of the suggestions made by the Technical Committee and appropriate revision, the contributing project shall be offered by the station to the Technical Committee for approval at the next annual meeting. If approval is needed prior to the annual meeting, the Executive Committee is authorized to act for the Technical Committee. If approved by the Technical Committee, each station will prepare an addendum to the procedures section of the regional project outline covering the proposed work. The addendum will be signed by the Director of the petitioning station and the regional Administrative Advisor. The addendum will then be forwarded to CSREES with the appropriate forms. If approved by CSREES, the addendum will be made a part of the project outline.

Literature Cited

Alfonso, L., and C. S. Haley. 1998. Power of different F2 schemes for QTL detection in livestock. J. Anim. Sci. 66: 1-8.

Allen, W. R. 1969. Factors influencing pregnant mare serum gonadotrophin production. Nature 223: 64-66.

Allen, W. R., J. A. Skidmore, F. Stewart, and D. F. Antczak. 1993. Effects of fetal genotype and uterine environment on placental development in equids. J. Repro. and Fert. 97: 55-60.

Barlow, R. and L. R. Piper. 1985. Genetic analyses of nematode egg counts in Hereford and crossbred Hereford cattle in the subtropics of New South Wales. Livestock Production Science 12:79  84.


Bryan, R. P. and J. D. Kerr. 1988. The grazing behavior of cattle in relation to the sampling of infective nematode larvae on pasture. Vet. Parasitol. 30:73  82.

Bubliy, O. A., A. G. Imasheva, and V. Loeschcke. 2000. Half-sib analysis of three morphological traits in Drosophila melanogaster under poor nutrition. Hereditas 133: 59-63.

Bubliy, O. A., and V. Loeschcke. 2002. Effect of low stressful temperature on genetic variation of five quantitative traits in Drosophila melanogaster. Heredity 89: 70-75.

Burrow, H. M. 1997. Measurements of temperament and their relationships with performance traits of beef cattle. Anim. Breeding Abstracts 65:477  495.

Cartwright, T. C., G. F. Ellis, Jr., W. E. Kruse, and E. K. Crouch. 1964. Hybrid vigor in Brahman-Hereford crosses. Tech. Monogr. 1. Tex. Agric. Exp. Sta. College Station.

Casas, E. C. and A. Tewolde. 1991. Genetic parameters for reproduction related traits in Romosinuano cattle under humid tropical environments. J. Anim. Sci. 69(Suppl. 1):207.

Chase, C. C., Jr., A. C. Hammond and T. A. Olson. 2000. Effect of tropically adapted sire breeds on preweaning growth of F1 Angus calves and reproductive performance of their Angus dams. J. Anim. Sci. 78:1111-1116.

Chase, C. C., Jr., T. A. Olson, A. C. Hammond, M. A. Menchaca, R. L. West, D. D. Johnson, and W. T. Butts, Jr. 1998. Preweaning growth traits for Senepol, Hereford, and reciprocal crossbred calves and feedlot performance and carcass characteristics of steers. J. Anim. Sci. 76:2967-2975.

Comerford, J. W., J. K. Bertrand, L. L. Benyshek, and M. H. Johnson. 1987. Reproductive rates, birth weight, calving ease and 24-h calf survival in a four-breed diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle. J. Anim. Sci. 64:65-76.

Comerford, J. W., J. K. Bertrand, L. L. Benyshek, and M. H. Johnson. 1988. Evaluation of performance characteristics in a diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle. I. Growth, hip height, and pelvic size. J. Anim. Sci. 66:293?305.

Cundiff et al. 1984. Germ Plasm Evaluation Program Progress Report No. 11. USDA-ARS, Clay Center, NE.

Cundiff, L. V., K. E. Gregory, T. L. Wheeler, S. D. Shackelford, M. Koohmararie, H. C. Freetly and D. D. Lunstra. 1999. Preliminary results from Cycle V of the cattle germplasm evaluation program at the Roman L. Hruska U.S. Meat Animal Research Center. Germplasm Evaluation Program Progress Report No. 18, June 1999. USDA-ARS, Clay Center, NE.

de Alba, J. 1987. Criollo cattle of Latin America. In: J. Hodges (ed.) Animal Genetic Resources: Strategies for Improved Use and Conservation, pp. 19-43. Animal Production and Health Paper 66, Food and Agriculture Organization (F.A.O.) of the United Nations, Rome.

Derr, J. N., S. K. Davis, J. L. Estrada, J. E. Ossa, M. Westhusin, J. Piedrahita, and L. G. Adams. 1995. Genetic characterization and conservation of Colombian criollo cattle. In: R. D. Crawford, E. E. Lister, and J. T. Buckley (ed.) Conservation of Domestic Animal Genetic Resources, pp 307-313. Rare Breeds International, Warwickshire, England.

DeVries, A.G., R. Kerr, B. Tier, T. Long, and T. H. E. Meuwissen. 1994. Gametic imprinting effects on rate and composition of pig growth. Theor. Appl. Genet. 88(8): 1037-1042.

Dickson, D. P. 1967. A study of social dominance, temperament, and learning ability in dairy cattle. Diss. Abstr. 28:402B.

Dickson, D. P., G. R. Berr, L. P. Johnson, and D. A. Wiekert. 1970. Social dominance and temperament in dairy cows. J. Dairy Sci. 53:904.

Donald, A. D. 1994. Parasites, animal production, and sustainable development. Vet. Parasitol. 54:27-47

Du, F. X., S. K. DeNise, and B. W. Woodward. 2002. Heterozygosity for genes influencing a quantitative trait. J. Anim. Sci. 80: 1478-1488.

Ducoing-Watty, A. E. 2002. Evaluation of F1 cows sired by Brahman, Boran and Tuli for reproductive and maternal performance. Ph.D. Dissertation. Texas A&M University, College Station.

Elzo, M. A., C. Manrique, G. Ossa, and O. Acosta. 1998. Additive and nonadditive genetic variability for growth traits in the Turipana Romosinuano-Zebu multibreed herd. J. Anim. Sci. 76:1539-1549.

Engellandt, T., and B. Tier. 2002. Genetic variances due to imprinted genes in cattle. J. Anim. Breeding and Genetics 119 (3): 154-165.

Esdale, C. R., R. D. Leutton, P. K. ORourke, and R. H. Rudder. 1986. The effects of sire selection for helminth egg count on progeny helminth egg counts and live weight. Proceeding of the Australian Society for Animal Production 16:199  202.

Ferrell, C.L. and T.G. Jenkins. 1998. Body composition and energy utilization by steers of diverse genotypes fed a high-concentrate diet during the finishing period: II. Angus, Boran, Brahman, Hereford, and Tuli sires. J. Anim. Sci. 76:647-657

Forbes, T.D.A., F.M. Rouguette Jr., and J.W. Holloway. 1998. Comparisons among Tuli-, Brahman-, and Angus-sired heifers: Intake, digesta kinetics, and grazing behavior. J. Anim. Sci. 76:220-227.

Fordyce, G., R. M. Dodt, and J. R. Wythes. 1988. Cattle temperament in extensive herds in northern Queensland. Aust. J. Exp. Agric. 28:683.

Franke, D. E. 1980. Breed and heterosis effects of American Zebu cattle. J. Anim. Sci. 50:1206-1214.

Franke, D. E. 1997. Postweaning performance and carcass merit of F1 steers sired by Brahman and alternative subtropically adapted breeds. J. Anim. Sci. 75:2604-2608.

Frisch, J. E., C. J. ONeill, and M. J. Kelly. 2000. Using genetics to control cattle parasites  the Rockhampton experience. International Journal for Parasitology 30:253-264.


Gasbarre, L. C., E. A. Leighton, and C. J. Davier. 1990. Genetic control of immunity to gastrointestinal nematodes of cattle. Vet. Parasitol. 37:257  272.


Grandin, T. 1989. Behavioral principles of livestock handling. The Prof. Anim. Scientist. December 1989. pg 1-11.

Grandin, T. 1992. Behavioral agitation during handling is persistent over time. Appl. Anim. Behav. Sci. 36:1.

Grandin, T., K. G. Odde, D. N. Schutz, and L. M. Beherns. 1994. The reluctance of cattle to change a learned choice may confound preference tests. Appl. Anim. Behav. Sci. 39:21.

Grandin, T. 1995. Bruise levels on fed and non-fed cattle. Proceedings Livestock Conservation Institute. pg 193-201.

Grandin, T. 1997. Assessment of stress during handling and transport. J. Anim. Sci. 75:249  257.

Grandin, T. and M. Deesing. 1998. Genetics and Behavior of Domestic Animals. In: T Grandin (ed.) Genetics and Behavior of Domestic Animals. pp 113  144. Academic Press, San Diego, CA.

Green, R. D., L. V. Cundiff and G. E. Dickerson. 1991. Life-cycle biological efficiency of Bos indicus x Bos taurus and Bos taurus crossbred cow-calf production to weaning. J. Anim. Sci. 69:3544-3563.

Gregory, K. E., L. A. Swiger, R. M. Koch, L. J. Sumption, W. W. Rowden, and J. E. Ingalls. 1965. Heterosis in preweaning traits of beef cattle. J. Anim. Sci. 24:21-28.

Grignard, L, X. Boivin, A. Boissy, and P. Le Neindre. 2001. Do beef cattle react consistently to different handling situations? Applied Anim. Behav. Sci. 71:263  276.

Hammond, A. C., T. A. Olson, C. C. Chase, Jr., E. J. Bowers, R. D. Randel, C. N. Murphy, D. W. Vogt and A. Tewolde. 1996. Heat tolerance in two tropically adapted Bos taurus breeds, Senepol and Romosinuano, compared with Brahman, Angus, and Hereford cattle in Florida. J. Anim. Sci. 74:295-303.

Herring, A. D., J. O. Sanders, R. E. Knutson, and D. K. Lunt. 1996. Evaluation of F1 calves sired by Brahman, Boran, and Tuli bulls for birth, growth, size, and carcass characteristics. J. Anim. Sci. 74:955-964.

Hohenboken, W. D. 1987. Behavorial genetics. Vet. Clin, North Am. Food Anim. Prac. 3:217  229.

Imumorin, I. G., S. K. Davis, J. O. Sanders, and J. F. Taylor. 2000. Reciprocal differences in Bos taurus x Bos indicus cross calves: Statistical search for imprinted regions in the bovine genome. J. Anim. Sci. 78 ( Suppl 2 ): 19.

Imumorin, I. G., D. J., de Koning, S. K. Davis, J. O. Sanders, J. A. M. Arendonk, and J. F. Taylor. 2001. Identification of imprinted QTL in the bovine genome. Proc. XIth Intl. Conf. on Plant & Anim. Genomes. (http://www.intl-pag.org/pag/9/abstracts/P5j_04.html).


Janss, L. L. G., J. A. M. Van Arendonk, and E. W. Brascamp. 1997. Bayesian statistical analyses for presence of single genes affecting meat quality traits in a crossed pig population. Genetics 145: 395-408.

Johansson, I. And J. Rendel. 1968. Genetics and Animal Breeding. W. H. Freeman and Company, San Francisco, CA.

Kloosterman, A., G. A. A. Albers, and R. vanden Brink. 1978. Genetic variation among calves in resistance to nematode parasites. Vet. Parasitol. 4:353  368.

Kloosterman, A., H. K. Parmantier, and H. W. Ploeger. 1992. Breeding cattle and sheep for resistance to gastrointestinal nematodes. Parasitol. Today 8:330 - 335.

Knott, S. A., J. M. Elsen, and C. S. Haley. 1996. Methods for multiple-marker mapping of quantitative trait loci in half-sib populations. Theor. Appl. Genet. 93: 71-80.

Koger, M. 1973a. Alternative procedures for crossbreeding. In: M. Koger, T. J. Cunha, and A. C. Warnick (ed.) Crossbreeding Beef Cattle, Series II. Univ. Florida Press, Gainesville. pp 448-453.

Koger, M. 1973b. Summary. In: M. Koger, T. J. Cunha, and A. C. Warnick (ed.) Crossbreeding Beef Cattle, Series II. Univ. Florida Press, Gainesville. pp 434-447.

Le Neindre, P., G. Trillet, J. Sapa, P. Menissier, J. N. Bonnet, and J. M. Chupin. 1995. Individual differences in docility of Limousin cattle. J. Anim. Sci. 73:2249.

Le Neindre, P., X. Boivin, and A. Boissy. 1996. Handling of extensively kept animals. Appl. Anim. Behav. Sci. 49:73  81.

Leighton, E. A., K. D. Murrall, and L. C. Gasburre. 1989. Evidence for genetic control of nematode egg shedding rates in calves. J. Parasitol. 75(4):498  504.


Long, C. R. 1980. Crossbreeding for beef production: Experimental results. J. Anim. Sci. 51:1197-1223.

MacKinnon, M. J., D. J. S. Hetzel, N. J. Cobert, R. P. Bryan and R. Dixon. 1990. Correlated responses to selection for cow fertility in a tropical beef herd. Livestock Prod. Sci. 27:105  122.

MacKinnon, M., J., K. Meyer, and D. J. S. Hatzel. 1991. Genetic variation and covariation for growth, parasite resistance and heat tolerance in tropical cattle. Livestock Production Sci. 27:105  122.

MacNeil, M. D, D. D. Dearborn, L. V. Cundiff, C. A. Dinkel, and K. E. Gregory. 1989. Effects of inbreeding and heterosis in Hereford females on fertility, calf survival and preweaning growth. J. Anim. Sci. 67:895-901.

Marshall, K., J. Henshall, and J. H. J. van der Werf. 2002. Response from marker-assisted selection when various proportions of animals are marker typed: a multiple trait simulation study relevant to the sheepmeat industry. Anim. Sci. 74: 223-232.

Martinez-Correal, G. 1995. The Colombian criollo breeds. In: R. D. Crawford, E. E. Lister, and J. T. Buckley (ed.) Conservation of Domestic Animal Genetic Resources, pp. 161-166. Rare Breeds International, Warwickshire, England.

McElhenney, W. H., C. R. Long, J. F. Baker and T. C. Cartwright. 1985. Production characters of first generation cows of a five-breed diallele: Reproduction of young cows and preweaning performance of inter se calves. J. Anim. Sci. 61:55-65.

Molina, R., O. Deaton, and H. Muqoz. 1982. Production potential of the Romosinuano and its use in crossbreeding for beef. Trop. Anim. Prod. 7:257-261.

Nezer, C., L. Moreau, B. Brouwers, W. Coppieters, J. Detilleux, R. Hanset, L. Karim, A. Kvasz, P. Leroy, and M. Georges. 1999. An imprinted QTL with major effect on muscle mass and fat deposition maps to the IGF2 locus in pigs. Nature Genetics 21: 155-156.

Notter,D. R., L. V. Cundiff, G. M. Smith, D. B. Laster and K. E. Gregory. 1978. Characterization of biological types of cattle. VII. Milk production in young cows and transmitted and maternal effects on weaning growth of progeny. J. Anim. Sci. 46:908-921.

OBlesness, G. V., L. D. Van Vleek, and C. K. Henderson. 1960. Heritabilities of some type appraisal traits and their genetic and phenotypic correlations with production. J. Dairy Sci. 42:1490  1498.

Paschal, J. C., J. O. Sanders, J. L. Kerr, D. K. Lunt, and A. D. Herring. 1995. Postweaning and feedlot growth and carcass characteristics of Angus-, Gray Brahman-, Gir-, Indu-Brazil-, Nellore-, and Red Brahman-sired F1 calves. J. Anim. Sci. 73:373-380.

Peacock, F. M., M. Koger, and E. M. Hodges. 1978. Weaning traits of Angus, Brahman, Charolais and F1 crosses of these breeds. J. Anim. Sci. 47:366-369.

Peacock, F. M., M. Koger, J. R. Crockett and A. C. Warnick. 1977. Reproductive performance and crossbreeding Angus, Brahman and Charolais cattle. J. Anim. Sci. 44:729-733.


Porter, V. 1991. Cattle. A Handbook to the Breeds of the World. Facts on File, Inc. New York, New York.

Primo, A. T. 1990. A South American report with special reference to Criollo cattle. In: L. Alderson (ed.) Genetic Conservation of Domestic Livestock, pp 85-107. C.A.B. International, Wallingford, U.K.

Riley, D. G., J. O. Sanders, R. E. Knutson and D. K. Lunt. 2001a. Comparison of F1 Bos indicus x Hereford cows in central Texas: I. Reproductive, maternal, and size traits. J. Anim. Sci. 79:1431-1438.

Riley, D. G., J. O. Sanders, R. E. Knutson and D. K. Lunt. 2001b. Comparison of F1 Bos indicus x Hereford cows in central Texas: II. Udder, mouth, longevity, and lifetime productivity. J. Anim. Sci. 79:1439-1449.


Roberson, R. L., J. O. Sanders, and T. C. Cartwright. 1986. Direct and maternal genetic effects on preweaning characters of Brahman, Hereford and Brahman-Hereford crossbred cattle. J. Anim. Sci. 63:438-446.

Rouse, J. E. 1977. The Criollo: Spanish Cattle in the Americas, pp 133-165. Univ. of Oklahoma Press, Norman.


Seifert, G. W. 1977. The genetics of helminth resistance in cattle. 3rd Int. Cong. Of the Soc. For the Advancement of Breeding Researches in Asia and Oceania, Canberra, Australia 7:4  8.

Shrode, R. R. and S. P. Hammack. 1971. Chute behavior of yearling beef cattle. J. Anim. Sci. 33:193.

Snijders, A. J. 1980. Internal parasites of cattle. Dairy Science Handbook. Clovis, California Agri. Services Foundation, 13:360-369.

Sonstegard, T. S. and L. C. Gasbarre. 2001. Genomic tools to improve parasite resistance. Vet. Parasitol. 101:387 - 403.

Stear, J. J. and M. Murray. 1994. Genetic resistance to parasite disease: particularly of resistance in ruminants to gastrointestinal nematodes. Vet. Parasitol. 54:161-176.

Stear, M. J., F. W. Nicholas, S. C. Brown, T. Tierney and T. Rudder. 1984. The relationship between the bovine major histo compatibility system and fecal worm egg count. In: J. K. Dineen, P. M. Outteridge (ed). Immunogenetic approaches to the control of endoparasites with particular reference to parasites of sheep. CSIRO, Melbourne, Australia p.p. 126  133.

Stricklin, W. R., C. E. Heisleg, and L. L. Wilson. 1980. Heritability of temperament in beef cattle. J. Anim. Sci. 51(Suppl1):109.

Thallman, R. M., J. O. Sanders, and J. F. Taylor. 1992. Non-Mendelian genetic effects in reciprocal cross Brahman 4 Simmental F1 calves produced by embryo transfer. Beef Cattle Research in Texas, 1992 PR-5053:8-14. Tex. Agri. Exp. Sta., College Station.

Thrift, F. A. 1997. Reproductive performance of cows mated to and preweaning performance of calves sired by Brahman vs alternative subtropically adapted breeds. J. Anim. Sci. 75:2597-2603.

Tulloh, N. M. 1961. Behavior of cattle in yards. II. A study of temperament. Anim. Behav. 9:25.

Turner, J. W., B. R. Farthing and G. L. Robertson. 1968. Heterosis in reproductive performance of beef cows. J. Anim. Sci. 27:336

USDA. 2002. Cattle Report. National Agricultural Statistics Service, United States Department of Agriculture, Washington, D.C. Released February, 2002.

Vercruysse, J. and P. Dorny. 1999. Integrated control of nematode infection in cattle: A reality? A need? A future? International J. Parasitol. 29:165-175.

Visscher, P. M., C. S. Haley, and S. A. Knott. 1996. Mapping QTLs for binary traits in backcross and F2 populations. Genet. Res. Camb. 68: 55-63.

Voisinet, B. D., T. Grandin, J. D. Tatum, S. F. OConner, and J. J. Struthers. 1997a. Feedlot cattle with calm temperaments have higher average daily gains than cattle with excitable temperaments. J. Anim. Sci. 75:892  896.

Voisinet, B. D., T. Grandin, S. F. OConner, J. D. Tatum, and M. J. Deesing. 1997b. Bos indicus-cross feedlot cattle with excitable temperaments have tougher meat and a higher incidence of borderline dark cutters. Meat Ssi. 46:367  377.

Wang, D. L., J. Zhu, Z. K. Li, and A. H. Patterson. 1999. Mapping QTLs with epistatic effects and QTL x environment interactions by mixed linear model approaches. Theor. Appl. Genet. 99: 1255-1264.

Weller, J. I. 2001. Quantitative Trait Loci Analysis in Animals. CABI Publishing, New York.

Wells, A. 1999. Integrated parasite management for livestock. Appropriate Technology Transfer for Rural Areas Livestock Systems Guide 800-346-9140.

Whitlock, J. H. 1955. Trichostrongylidosis in sheep and cattle. Proc. Am. Vet. Med. Assoc. 92:123  131.

Wilken, T. M., L. L. Lo, D. G. McLaren, R. L. Fernando, and P. J. Dziuk. 1992. An embryo transfer study of reciprocal cross differences in growth and carcass traits of Duroc and Landrace pigs. J. Anim. Sci. 70: 2349-2358.

Williams, J.C. and A.F. Loyacano. 2001. Internal parasites of cattle in Louisiana and other southern states. Louisiana State University, Agricultural Experiment Station, Research Information Sheet No. 104.

Williamson, W. D., and P. E. Humes. 1985. Evaluation of crossbred Brahman and continental European beef cattle in a subtropical environment for birth and weaning traits. J. Anim. Sci. 61:1137-1145.

Wyatt, W. E., and D. E. Franke. 1986. Estimation of direct and maternal additive and heterotic effects for preweaning growth traits in cattle breeds represented in the Southern region. Bull. 310. Southern Cooperative Series. Louis. Agri. Exp. Sta., Louis. State Univ. Agri. Center, Baton Rouge.


Young, L. E., and H. R. Fairburn. 2000. Improving the safety of embryo technologies: possible role of genomic imprinting. Therio. 53: 627-648.

Attachments

Land Grant Participating States/Institutions

AR, FL, GA, KY, LA, MS, NC, TX

Non Land Grant Participating States/Institutions

ARS, NIFA