Duration: 10/01/2024 to 09/30/2029

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Over the years, cattle and producers have always been able to adapt to different environments whether it be physical or economical. Cattle cycles usually occur every 10-12 years, however population size has been steadily decreasing since the early 1970’s. The projection is that cattle inventory will stay on this trend in the future due to urban sprawl with an increasing human population, rising input costs, and the decrease of the number of operations due to drought, average age of the producer, and change in culture. Therefore, it is of increasing importance that we pair each acre of land set aside for beef cattle production with the most efficient animal possible in order to provide a quality protein source for the whole world as well as make it profitable for families. With most of the cow herds being found in the Southern U.S. and extending into the Great Plains, and High Plains regions, cattle have to be well adapted to their environment in order to be productive. The goal of this project is to address traits with known environmental and genetic influence that impact the productivity of cow-calf operations in these locations. The objectives are to assess the relationship of economically relevant traits and performance of animals associated with hair and skin characteristics, efficiency of water usage, nutrient efficiency, and the use of Brahman influenced cattle. These evaluations will lead to recommendations for breeding strategies to enhance efficiency of beef cattle production.

Statement of Issues and Justification

Justification for Project:

Beef cattle production provides a large economic impact for many regions of the High Plains, Great Plains, and the Southern U.S.  These regions are locations of most of the cow-calf segment of the beef industry.  Improvement of commercial cow-calf performance in these regions of the United States has been due to breed complementary and utilizing genetics to improve calf performance, reproductive efficiency, carcass quality and maternal traits. This project will address several breeding and genetic aspects that are important to current and developing management strategies in these regions of the U.S.  A collaborative effort across locations in multiple states will be utilized due to limited resource situations of individual research universities and small university research herds of cattle. Genetic evaluation requires more sample size than individual research herds could provide. Combining the resources of the different states has great potential to augment the impact of the proposed research.

The overall goal of this project would be to address component traits with known environmental and genetic influence that impact productivity in cow-calf operations in the Southern, Great Plains and High Plains Regions. A thorough genetic evaluation of these adaptation-type traits may allow for previously unrecognized variation in beef cattle production systems to be identified. Many of the traits of interest are categorical in nature, and genetic evaluation could be complicated, but needs further study. This project will increase the global competitiveness of U.S. beef production and provide increased economic opportunities for cattle producers by improving their understanding of input and efficiency variability.

Objective Areas:

1. To evaluate adaptation of beef cattle to local production and environmental challenges.

Justification: Current information using modern cattle is needed so that cow-calf producers in the can make informed breeding decisions to profitably produce cattle under increasingly challenging environments. In the face of a changing global climate, these once temperate regions of the U.S. are becoming warmer.  Efficient cow-calf production will become increasingly dependent on heat tolerance, and at the same time, water sources may become scarce. These environmental changes may greatly impact gross performance and efficiency of beef production in these regions resulting in a less stable, and relatively more expensive protein supply if research is not conducted to identify adaptability for these environmental challenges. Production information is needed on local heat, humidity, and forage to identify how they may impact growth, carcass and fertility traits.  Hot temperatures and drought conditions are stressful enough to cattle production, but some areas of the upper South also deal with toxic endophyte infected tall fescue which amplifies heat stress conditions. It is important to provide current characterization of breeds that have potential to improve productivity in regions that have substantial environmental challenges.  Direct selection using estimated or predicted breeding values may represent another strategy for improvement of traits related to cow reproductive success and for calf survival.  Analyses of traits using data from across this region would permit accumulation of substantial numbers necessary for appropriate assessment and would expand application of results throughout this critical production area. We plan to document genetic components of thermotolerance pertaining to heat adaptive traits including sweat gland concentration, and hair coat shedding to improve sustainable beef cattle production.  Expected progeny differences and DNA testing are widely available in the U.S. beef industry. However, genetic improvement tools for economically relevant traits such as heat tolerance are less widely available and frequently are less accurate.

2. Estimate heterosis in Brahman-Bos taurus

Justification: Many cow-calf producers in the U.S. rely on breeding strategies that incorporate Bos indicus influence in breeding programs as both breed effects for adaptation and heterosis are advantages known to impact productivity. Breed comparisons are not static over time as these populations change due to selection strategies, and conclusions from breed comparisons at a single point in time during past research may not adequately explain current situations. Recent efforts are substantial to determine heterosis expressed by crosses of Bos indicus adapted breeds crossed with other traditional breeds in the U.S. but is early with emphasis mostly in the Great Plains (Engle et al., in press), and such information is needed by producers, especially in the South, to make the most appropriate choice of breeds to use in crossbreeding programs. It is important to characterize breeds that have potential to improve productivity in regions that have substantial environmental challenges.  Global warming will extend the adaptation and productivity for these breeds further north in the U.S. from the traditional area in the Southern U.S. to the Great Plains and High Plains regions.  Knowledge of heat tolerant breeds is limited compared to more established breeds. There is a need to estimate direct breed and additive genetic effects and heterosis resulting from crosses of Bos indicus influenced breeds bred to British and Continental breeds in specific production environments, especially in a genomics context. Characterization of heterosis levels between breeds will enhance breeding and production decisions and thereby profitability for cow-calf producers.  This characterization is necessary also to provide experimental setting for the application of genomics and DNA technology to this important improvement strategy.  Furthermore, non-additive gene interactions and epigenetic (non-traditional inheritance patterns) influences appear to be important for many body composition and health-related phenotypes in cattle, but investigation of these phenomena are novel and scarce in beef cattle. The intent in part of this project is to quantify these sources of variation in production systems utilizing Bos indicus-Bos taurus crosses regarding growth, health, and production efficiency related traits.

3. Estimate economically relevant traits as deviations from Angus across a United States North-South and East-West continuum.

Justification: In the past several years, new technologies have become available to identify individual genes throughout the bovine genome and independently assess their relationship to novel ERT in the beef cattle industry. To locate these genes, DNA markers (also known as genetic markers) have been developed to aid in locating and representation of genes that can positively or negatively affect the phenotype of a specific trait. Identification of genes with major effects would be beneficial for traits that are hard to measure and ones that are easily influenced by the environment, but this has not occurred, and marker-based improvement programs will be required. However, large populations of cattle of known genetic background are needed to fully characterize new and emerging genetic markers.  Current performance assessments are needed to enhance producer breeding decisions for traits related to cow production (birth weight, longevity, temperament, etc.), reproduction (fertility, heifer development), and carcass quality. There is limited characterization of the additive genetic control and prediction of breeding values for these important cow productivity traits. The effects of ERT’s on growth rate, meat quality and animal welfare and behavior need to be documented. Therefore, before engaging in a selection program to improve ERT’s, further research is needed to evaluate the genetic variation for these traits and the potential relationship between traits. Therefore, additional research is needed to determine the genetic variation that exists for these ERT’s and assess potential for genomic improvement. 

Related, Current and Previous Work

Related, Current, and Previous Work:

Adaptation to environmental stressors is a vital characteristic all animals have utilized to survive and become more efficient in the environment which they live.  With the current global climate changes experienced throughout the world, livestock must adapt to these changes to remain efficient at producing protein for human populations.  These climate changes can directly impact livestock (heat stress, loss of available water, etc.) but can also indirectly impact livestock productivity (alterations in forage quality and availability, energy expended on food acquisition, etc.).  Information regarding the change in performance of livestock during these environmental challenges is vital for making appropriate livestock management decisions. A large percentage of the beef cow herd inventory is in areas of the U.S. that spend most of the year in sub-tropical conditions. Because of this, heat tolerance is a common factor that must be considered when selecting breeds as well as animals within a breed to be used to be profitable and sustainable in a beef operation. A common solution to the problem is to incorporate sub-tropically adapted breeds into the breeding schemes to mitigate this issue. Depending on the markets pursued, this can create issues with traits of economic importance such as carcass quality and growth. Another approach is to select animals within the breed of choice that are more adapted to the environment and match the market better. The following objectives will help to gain insight into other factors that are associated with the ability of an animal to adapt to its environment.

 

Objective 1: To evaluate adaptation of beef cattle to local production and environmental challenges.

 

Selecting for hair coat characteristics has been shown to have promise in heat tolerance. Research by Gray et al. (2011) on purebred Angus cattle established a shedding scale to evaluate cattle and reported a moderate heritability estimate with a moderate negative genetic correlation with weaning weights. Using the same shedding scale, a study by Plank et al. (2013) reported that cows that shed earlier also had heavier calves at birth than cows that shed later while on predominately no fescue. Durbin et al. (2020) worked with the American Angus Association and evaluated over 9,000 females with over 40,000 weaned calf records to conduct a large-scale genetic evaluation. This involved herds from the South and Fescue belt of the U.S. where cattle grazed predominant endophyte-infected fescue and other forage species. Estimates of heritability were moderate and similar to previous literature. Genetic correlations between the maternal component of weaning weight and direct weaning weight were negative and moderate for grazing tall fescue and not grazing tall fescue. In another study, Hamblin et al. (2018) reported that coat type influenced vaginal temperature regulation.

 

With previous research, it has been suggested that there is an association between winter hair coat shedding ability in the dam and birth weights of their calves. The placenta is involved in transporting nutrients and wastes between maternal and fetal circulation and altered placental function has been associated with abnormalities in fetal development. The efficiency of placental nutrient transport is directly related to placental blood flow (Reynolds and Redmer, 1995; 2001). Therefore, researchers have addressed significant associations with adverse intrauterine environment to decreases in uterine and umbilical blood flows (Reynolds et al., 2005; 2006), and specifically, with alterations in nutrient transport across the placenta (Wallace et al., 2003; Kwon et al., 2004; Fowden et al., 2006). The exponential increase in transplacental exchange is vital for maintaining the exponential growth and development of the fetus during the last half of gestation (Redmer et al., 2004). It is possible that uterine blood flow in the dam changes due to shedding ability during gestation. While hair characteristics have been shown to be associated with heat tolerance through increased performance, skin histology has also been explored. The skin is an important way for cattle to release excess heat. Researchers have evaluated several skin measurements such as sweat and sebaceous gland number, and thickness of the dermis and epidermis. Dikmen and Mateescu (2019) evaluated these traits on Angus, Brahman, and crossbred heifers of the two breeds. They reported low to high heritability estimates for dermis and epidermis thickness and moderate to high for sweat gland and total sweat gland area. Thermoregulation was highly correlated to breed composition and number of sweat glands and average size of sweat glands.

 

Forages, like animals, adapt to the environment in which they exist.  This adaptation can directly impact nutritive value (chemical composition of the forage) and quality (ability of the animal to utilize the nutrients from that forage) for animals relying on these forages to meet the animal nutrient needs.  Hair shedding ability has recently been proposed as a method to evaluate cattle adaptation to environmental changes.  However, currently, there is limited information on the association of hair coat characteristics and nutrient efficiency in beef cattle, much less the association with shedding ability and apparent digestibility of feedstuffs in the literature. This novel approach attempts to explain an association in growth performance differences and shedding ability in cattle. Earlier work has been done in other species such as Inner Mongolia white cashmere goats (Zhang et al., 2019) and Persian cats (Kim et al. (2018). Nutritional demands for energy, protein, vitamins, and minerals becomes a great demand on cattle reaching their greatest genetic potential. Beef cattle can obtain a large portion of their nutritional demands from forages (Greene, 2000) even though forage alone does not provide a complete feed for beef cattle nutritional requirements (Greene, 1997). Some minerals such as Cu (Burnett et al., 2017), Mn (Humbert and Krutmann, 2011), Se (Guo and Katta, 2017), S (Kincaid, 1988), and Zn (Plonka et al., 2005) have been associated with hair characteristics. Burnett et al. (2017) and Loftin et al., (2023) have reported Fiber digestibility (Burnett et al., 2017 and Loftin et al., 2023) and retention of Fe (Burnett et al., 2017 and Loftin et al., 2023) and Zn (Burnett et al., 2017) by cows who shed their hair coat earlier in the year.

           

Objective 2: Estimate heterosis in Brahman-Bos taurus crosses.

 

Heterosis has been an important genetic improvement tool in livestock since the mid-20^th century.  It has been especially important in the cow-calf segment of the US beef industry, primarily because traits that are critical to that segment, such as reproduction, newborn survival, and adaptation, are immediately responsive to heterosis.  Selection programs for those traits are relatively slow because of the low heritability of those traits.

 

Dominance is a form of genetic action that occurs when the effect of one allele on a trait partially or completely masks the effect of the other allele; it could be considered an interaction of alleles within a gene (or locus).  Genes that are heterozygous are expected to contribute to heterosis, and dominance at many loci is responsible for heterosis although epistasis (the interaction of alleles or genotypes at more than one gene or locus) also may be responsible.  (Dickerson, 1969; 1973; Cunningham, 1982).  Heterosis is maximally expressed in the context of a single trait by the first cross (F₁) between two breeds.  Other crosses also express heterosis, but less than that expressed by the F₁.  The “dominance model” (heterosis expression is due in large part to dominance at many loci) permits rough prediction of heterosis expressed by a non-F₁ cross using expected breed of origin heterozygosity as a proxy for genuine heterozygosity in the genome.  This quick and easy prediction is widely used in livestock production when making mating system plans.  It, however, is dependent on the availability of reference heterosis information for a wide array of traits.  That is, F₁ performance needs to be routinely documented for pairs of breeds that are important and available to cow-calf producers. 

 

Brahman crosses usually express more heterosis for most traits than Bos taurus crosses (Franke, 1980).  Heterosis for traits has been estimated in structured beef cattle projects involving Brahman in Florida (Peacock et al., 1978, 1979; Peacock and Koger, 1980; Olson et al., 1993), Texas (Cartwright et al., 1964; Long et al., 1979a, b; Stewart et al., 1980; McElhenney et al., 1985); and Louisiana (Turner et al., 1968; McDonald and Turner, 1972) Arkansas (Brown et al., 1994?), Georgia (Comerford et al., 1987), Oklahoma (McCarter et al., 1990?), and Queensland, Australia (Seebeck, 1973).  Publication of heterosis in the Southern region of the United States was a large effort of an earlier project of this multistate research group (Wyatt and Franke, 1986).  Although, characterization of heterosis for pairs of Bos taurus breeds is also quite dated (e.g., Gregory et al., 1965; Cundiff et al., 1974a, b; Gregory et al., 1978a, b, d), large scale efforts at the United States Meat Animal Research Center (USMARC) in Nebraska are the source of modern estimates have been reported (Ribeiro et al., 2022; Engle et al., in press).  Although Ribeiro et al. (2022) and Engle et al. (2024) reported heterosis and breed effects for Brahman, no purebred Brahman were utilized in those estimates, and the evaluations were done in temperate areas.  The most recent documented heterosis for Brahman with other breeds was reported a decade ago (Riley et al, 2014a, b).  Heterosis retained by non-F₁ crosses, although well characterized in Bos taurus crosses (Gregory et al., 1991a, b; 1992a, b, c; 1999) has been the focus of very few investigations in Brahman crossbreds, especially for traits related to reproduction (Seebeck, 1973; MacKinnon et al., 1989; Hargrove et al., 1991; Olson et al., 1993; Riley and Crockett, 2006).  The potential for genotype-environment interactions in Brahman crossbreds is substantial (Olson et al., 1991).

 

Genomic information has become an integral part of beef cattle improvement worldwide.  Although earlier it was believed and hoped that genes with large effect on important traits would be characterized, that has not come to pass.  The most prominent usage of genomic information is in selection programs.  That is, mostly high-density single nucleotide polymorphism (SNP) arrays are used to improve accuracy of breeding values (Expected Progeny Differences; EPD).  An interesting, but not well explored opportunity is the merging of genomic information with heterosis expression (Legarra et al., 2023).  Work in crossbred Bos taurus (Akanno et al., 2017; 2018; Basarab et al., 2018; Kenny et al., 2022; Hay and Roberts, 2023) was in unstructured populations.  Work done in Canada (Akanno et al., 2017, 2018; Basarab et al., 2018) was the basis for a commercial DNA heterosis test.  The commercializing company was purchased by Neogen (Lincoln, NE) which now offers the genomic test for $21.  The product description lists Brahman as a “supported breed” (https://www.neogen.com/categories/igenity-profiles/igenity-envigor/?min=GS_SL_39) but the original work was based only on Bos taurus breeds in Canada and the breed’s role in product development is not clear.  Population and data structures of the project may be appropriate for utilization of modern haplotype-resolved genome assemblies (Low et al., 2020).  Participants in this multistate project regularly try to secure SNP array genotypes for animals in their programs.  There may be opportunities to unify those for some aspects of this project with efforts at USMARC, and/or support validation of the commercial test in Brahman crossbred populations

 

One application of genomics has been to assess levels of homozygosity in DNA due to inbreeding in cattle populations (Sumreddee et al., 2020), which is somewhat the antithesis of heterosis.

 

Objective 3 Estimate economically relevant traits as deviations from Angus across a United States North-South and East-West continuum.

 

Beef production in the United States is characterized by diversity of systems, goals, mating plans, sizes, resources, and structures.  Common to all is the need to improve economically relevant traits such as fertility (calving and weaning rates; the proportion of cows exposed to bulls in a given breeding season that subsequently give birth and wean a calf conceived in those exposures), size and growth, including weights measured at various times, characteristics of carcasses to include those affecting quantity and quality of the end product, and adaptability, including winter coat growth dynamics (Gray et al., 2011; Durbin et al., 2020) and temperament of growing animals (Littlejohn et al., 2018) and mature cows (Sims et al., 2023; Munguía Vásquez et al., 2024).  In the last half century, these have been evaluated and characterized in local areas, even though the focus has been national (e.g., at USMARC).  This time has also been characterized by reduced capacity for beef cattle research at most, but not all, land grant universities.  This occurrence combined with the almost exclusive support for development of genomic prediction methodology has moved most smaller research entities to short term applied research that in general, doesn’t have a genetic component.

 

The USMARC is an essential component of U.S. beef research, but that focus is largely (but not entirely) Bos taurus and genomic prediction of genetic merit.  Recently, researchers at USMARC have extended genomic efforts to characterize heterosis as well (R. M. Thallman and B. N. Engle, personal communication).  Although Bos indicus crossbred cows have been at the very top of the performance across several cycles of the Germplasm Evaluation program at USMARC (Cundiff et al., 1997; 2004), high percentage Brahman crossbred cows and their performance have not been trivial to characterize, primarily because of poor adaptation of purebred Brahman to the local conditions (R. M. Thallman, personal communication). 

 

All members have research herds with known Angus background.  This commonality across locations will serve as a foundation for joint data analysis and publication of results.

Objectives

1. 1. To evaluate adaptation of beef cattle to local production and environmental challenges.
   
2. 2. Estimate heterosis in Brahman-Bos taurus crosses.
   
3. 3. Estimate economically relevant traits as deviations from Angus across a United States North-South and East-West continuum.
   

Methods

Methods:

Objective 1.

Populations

1. Mississippi – hair shedding data has been collected on purebred cattle for approximately 15 years. As a result, two herds (early shedding and late shedding or extremes) are currently being developed to evaluate the performance differences between these two genotypes.
2. Arkansas – structured to evaluate performance in varieties of both cool and warm season forages.
3. Florida - structured to rearrange Brahman and Angus genomes in a variety of crossbred categories in a continuum of 0 to 100% Brahman (complementary percentage Angus).

Activities

1. Evaluate heat tolerance through hair coat and skin characteristics. Females and females with calves will be evaluated for hair characteristics. Relationships to performance traits will be evaluated regionally as well as nationally through cooperation with breed associations collecting similar information. Other information that will be collected include uterine blood flow, skin characteristics, and differences that can occur in cattle grazing toxic tall fescue.
2. Evaluate nutrient digestibility – digestibility trials will be conducted to evaluate dry matter and nutrient digestibility of forage consumed by early and late hair shedding cattle.

 

Objective 2.

Populations

1. Florida - structured to rearrange Brahman and Angus genomes in a variety of crossbred categories in a continuum of 0 to 100% Brahman (complementary percentage Angus).
2. Texas (Beeville) - Brahman-influenced American breeds (Brangus, Santa Gertrudis, Braford, etc.) and other Bos taurus breeds are being evaluated for traits of importance to the U.S. beef industry. This population originated from USMARC and will permit assessment of heterosis results from across all participating herds with those produced from that USDA research facility, similar to those reported by Ribeiro et al. (2022).
3. Texas (McGregor) – structured to deliberately estimate F₁ and back cross heterosis for Brahman-Angus, utilizing the same Brahman and Angus sires as USMARC and the Beeville station.

Traits

1. All economically relevant traits will be assessed.
2. Particular attention will be given to those traits difficult to improve using selection programs, such as those related to reproduction in females, survivability in calves, etc.

Activities

1. Estimate heterosis for Brahman-Angus for birth and weaning weight, and cow calving and weaning rate at McGregor.
2. Compare the estimates from activity 1 in cattle/data from Florida, Beeville, and USMARC with heterosis estimated by regression on heterozygosity.
3. Where possible, use commercial SNP arrays at all locations in evaluation of the heterosis expressed in the cattle from activities #1 and #2. Potential targets:
   1. Hot spots--Most desirable genomic regions to be heterozygous.
   2. Breed of origin hot spots—most desirable genomic regions to be of Brahman origin or Angus origin.

 

Objective 3.

1. Participating locations will annually combine information for joint analysis for economically relevant traits.
   1. A subcommittee will develop a trait list and procedures for combining information.
   2. One or two committee members will lead with respect to data combination and statistical analyses.
   3. Standard traits measured in most places such as weight at birth and weaning will be important to include.
   4. Cow fertility, which requires no extravagant data collection, is especially important as it is less well characterized in beef production and is more responsive to crossbreeding than to selection.
   5. Others—cumulative weight weaned (Snelling et al., 2019), cow temperament at calving, winter coat shedding and regrowth, ultrasound estimation of longissimus size and fat deposition, foot scores, and udder and teat scores.
2. Annual combination/evaluation will permit modeling genotype-environment combinations relative to broad systems such as
   1. Artificial insemination vs. natural matings.
   2. Spring vs. Fall calving systems.
   3. Regional or longitudinal/latitudinal characterization of performances (e.g., Delgadillo Liberona et al., 2018; Copley et al., 2022).
   4. Herd size dynamics—implementation of genetic improvement programs and implementation of technology in small, medium, and large beef production units.
3. Across-location/system estimates reported as deviations from Angus.
4. Members will recruit participation from:
   1. Smaller university research facilities that otherwise have no hope of working in genetics.
   2. Private herds.

Non-profit research groups such as the East Foundation in San Antonio and the Noble Foundation in Ardmore.

Measurement of Progress and Results

Outputs

• Outputs will include unique datasets that provide for assessment of genetic influences on multiple ERTs and adaptation traits in multiple production environments within the Southern and Great Plains regions.
• New measures of genetic assessment and economic values for breeding beef cows may be developed through meta-analyses.
• New region-specific considerations or weighting on production traits in cow-calf herds due to breed and production system combinations.
• New implementations of adaptability for heat tolerance.

Outcomes or Projected Impacts

• Improved characterization of and improvement in cow herd performance.
• Increased production and profitability in Brahman and Brahman crossbred females.
• Improvements in adaptation traits would not only allow for increased fertility in cow herds but also allow for less reliance on artificial inputs (insecticide, pharmaceuticals, purchased feeds, etc.) for improved environmental and economic sustainability.
• A complementary effort to characterize straightbred and crossbred cattle in beef production systems would serve as enhancement and validation of efforts and genomic tools developed at USMARC.
• Information regarding beef cattle breeding systems in the Southern Region will allow producers to tailor breeding and management decisions for improved production efficiency and therefore improved sustainability. Producers will become more familiar with consideration and incorporation of economic considerations based on corresponding breeding and management strategies, with increased emphasis on assessment and utilization of adaptation concepts.

Milestones

Projected Participation

View Appendix E: Participation

Outreach Plan

Traditional publication outlets will continue to be utilized and include scientific abstracts, peer-reviewed journal articles and proceedings papers. Presentations will be made to scientists and graduate students at scientific meetings such as the American Society of Animal Science sectional and national meetings. Information will be made to producers through state and university field days and short courses. Many participants will also be able to reach large numbers of producers on national levels through committee assignments and invited presentations associated with National Cattlemen’s Beef Association, the Beef Improvement Federation as well as state-level cattle industry groups. Publications and presentations will be audience appropriate.

Organization/Governance

The standard form of governance as described in Guidelines for Multistate Research Activities will be employed. Objective coordinators will be: 1) Dr. Trent Smith, Mississippi State University and Dr. Jeremy G. Powell, University of Arkansas, 2) Dr. David G. Riley, Texas A&M University, and 3) Dr. Brittni P. Littlejohn, University of Arkansas. Participants of each location provide guidance for joint analyses and associated publications.

Literature Cited

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