Brief Summary of Minutes of Annual Meeting

Objective 1. Develop selection tools to enhance reproduction and survival using field data. Georgia estimated trends in conception rate (CR) of Holsteins in the Southeast. For AI services, the average CR decreased from 55% in 1985-89 to 46% in 1995-99. Considering the month of service, the smallest decrease was 5% in January and the steepest decrease was 15% in June. High performing cows had CR about 3% lower. Fertility of Holsteins declined over time. Only a fraction of that decline can be attributed to increased milk yield in the first 100 days. The length of declined CR in the summer is increased indicating deterioration of heat tolerance over time. Illinois created a simulation to demonstrate the impact of changes in inbreeding, number of heterozygous loci, and total number of loci on the amount of survival reduction for calves. Increasing the number of loci decreased the amount of total survival reduction for a fixed number of defects per bull. Greatest survival was associated with more loci influencing survival, few heterozygous loci and low inbreeding. Illinois also showed that daughter inbreeding explained the majority of variation in calf survival and was a better predictor if survival than a sires own and expected future inbreeding. Iowa estimated genetic parameters for birth weight, dystocia, gestation length, and perinatal mortality in Holstein cattle using data from the Iowa State University research farm at Ankeny, IA. Heritability estimates ranged from 0.15 (perinatal mortality) to 0.53 (gestation length). Both dystocia and perinatal mortality have larger maternal components of variation than birth weight and gestation length. A negative direct-maternal genetic correlation will decrease the efficiency of phenotypic selection. North Carolina investigated whether dairy cow families could be selected for superior fertility. Cows from various generations were put in maternal family groups using dam identification within herd. Each family was entered into 1 of 4 quartiles based on average deviations in milk production and into 1 of four quartiles for average deviations in pregnancy rate. Analysis was performed on the 5th generation family members to determine if milk production and pregnancy rates in the 5th generation were significantly associated with historical performance of the respective cow families. These initial findings provide evidence that fertility as well as milk production is inherited on the maternal side. Thus, there is potential economic value in examining maternal family histories for fertility for use in planning selection of future bull dams. Nebraska estimated genetic correlations between yield traits of cows treated with bovine somatotropin (bST) and the same yield traits of untreated cows. Lactation records from registered Holstein cows were divided by parity into 3 data sets: 1, 2, and 3 through 5. Approximately 10% of the records in each data set were from cows treated with bST. Estimates of genetic correlations between records of treated and untreated cows were large enough to conclude that records of treated and untreated cows could be considered to be 1 trait with treatment as a fixed effect to account for differences in means. New York estimated the incidence of clinical diseases and survival in Swedish dairy heifers, and relationships between calf-hood and rearing factors and the performance of the heifers. Diseases were recorded by farmers and veterinarians. The total disease incidence rate was 13.8 per 100 animal-yr from 7 mo of age to conception and 4.71 per 100 animal-yr from conception to calving, with great variation between herds. Infectious disease were predominant, and diarrhea, respiratory disease and ringworm were the most common diagnoses. The performance of dairy heifers was highly influenced by herd-level factors such as housing and routines for grazing and breeding. The study did not provide good support for earlier findings that common infectious diseases early in life are associated with delayed maturation and impaired reproductive performance. Pennsylvania and Virginia investigated the relationship between body weight change between calving and 30 days in milk and occurrence of dairy cattle disease. Daily body weights were recorded electronically as cows exited the milking parlor and were available from 623 cows, of which 490 Holstein cows were from the Penn State herd, and 133 Holstein cows were from the Virginia Tech herd. Cows losing more weight had higher odds of developing a displaced abomasum, metabolic disease, infectious disease and all diseases. Cows with reproductive diseases lost less weight. Heritability and repeatability estimates for daily body weight were 0.45 and 0.75, respectively. Pennsylvania also estimated heritability for producer recorded mastitis episodes. Heritability estimates for mastitis treated as a linear or binomial variable were 2% and 8%, respectively. The correlation between EBV from the linear and binomial models was 0.98. After adjusting for reliability, the approximate genetic correlation between clinical mastitis and SCS was 0.75. An initial analysis of records from 3970 dairy herds indicated that cow death is the 3rd most frequently reported reason for a cow exiting a PA dairy herd. Tennessee acquired DHIA data from several states have begun to edit the data and identify approaches to analyze the data to address cow mortality rates. The mortality data is very complex and creates data editing challenges. Virginia investigated applying various models to extended lactation curves in Holsteins. The models were fitted to complete 305-d (>280 days in milk) and 999-d (>800 days in milk) lactations separately, and for first parity and, third and greater parities. All models considered were found to describe the 305-d as well as extended lactations satisfactorily. Less complicated models were sufficient for modeling extended lactations for milk yield. Models were also fit to extended fat and protein lactation curves. Fat and protein models required the inclusion of an additive constant to prevent over predicting the mid lactation and under predicting the lactation beyond 700 days. Virginia also evaluated the relationships of lactation persistency and disease incidence. Two separate investigations were performed to examine phenotypic relationships between health disorders and lactation persistency of Holstein cows estimated to be uncorrelated with yield. In the first study, treatment incidence data of 991 lactations from experimental dairy herds at Virginia Tech and Pennsylvania State University were used. Milk yield persistency was estimated for individual lactations using daily milk weights. In the second study, producer recorded health data of 87,555 lactations from 398 commercial herds were used. Overall, diseases tend to affect persistency of milk, fat, and protein more strongly than the impact of persistency on likelihood of disease. Lameness seems to have no association with lactation persistency. Relationships in these studies are phenotypic. Investigation into genetic relationships may produce different results. Wisconsin estimated genetic variability of Mycobacterium avium subspecies paratuberculosis infection in U.S. Holsteins. Heritability was estimated with 3 Johnes disease diagnostic tests: 1) fecal culture alone, 2) serum antibody ELISA alone, and 3) both tests (combined) with a positive animal defined as all animals with either a positive fecal culture or ELISA test. Heritability of infection based on the fecal culture test was 0.153. Heritability with the ELISA was 0.159 with a linear model and 0.091 with an ordered threshold model. Heritability of the combined tests was 0.102. This study demonstrates that exploitable genetic variation exists in dairy cattle for M. paratuberculosis infection susceptibility. Wisconsin estimated genetic parameters for production and fertility traits in the Spanish Holstein population. Days open had a larger genetic correlation (ranging from 0.63 to 0.76) with production traits than did days to first service (0.47 to 0.59) or number of inseminations (0.16 to 0.23). Greater antagonism between production and DO may be due to voluntary management decisions for high-yielding cows, resulting in longer lactation lengths. It was concluded that number of inseminations is the trait to be preferred when selecting for female fertility and because the target of attaining a 12- mo calving interval is changing in the dairy industry, routine genetic evaluation of actual total lactation milk yield should be considered. Wisconsin performed a genetic analysis of 21-day pregnancy rate in US Holsteins. The posterior mean of intra-herd-year heritability for number of 21-day opportunity periods required to achieve pregnancy was 0.06, with posterior standard deviation of 0.01. Posterior means for duration of the VWP ranged from 28 to 74 d postpartum among the 116 herd-parity classes represented in the study, whereas farmer-reported survey values for duration of the VWP ranged from 30 to 78 d postpartum. The model for genetic evaluation of female fertility accommodated heterogeneity in duration of the VWP between herds, as well as heterogeneity that may arise within herds due to management practices such as intentional delay of first insemination in high-producing cows or cows with poor body condition, and it can also accommodate censored records for non-pregnant cows. Wisconsin estimated the impact of inbreeding on production in Jersey cows. Yields were unaffected for inbreeding <7%, and depression seemed to stabilize at inbreeding > 20% for fat and protein yield. Effects of inbreeding on performance seem to be more complex than suggested by previous studies based on linear regression. Results should be taken with caution since the data was scarce at high levels of inbreeding. Objective 2. Explore the impact of crossbreeding on the lifetime performance of cows. Minnesota began crossing pure Holstein cows with Jersey sires beginning in 2000 at the St. Paul campus and Morris herds. Beginning December 15, 2003, a portion of the Holstein cows at the St. Paul campus and Morris herds were mated to Montbeliarde sires. The goal is to maintain one-third of the cows in the two herds as purebred Holstein, with two-thirds of cows being various crosses of Jersey, Montbeliarde, and Holstein. Pure Holsteins (n = 74 for 1st lactation, n = 43 for 2nd lactation) had significantly greater milk (+542 kg, +788 kg) and protein (+15 kg, +20 kg) production for both first and second lactations, respectively, than Jersey x Holstein crossbreds (n = 80 for 1st lactation, n = 57 for 2nd lactation). Pure Holsteins and Jersey x Holstein crossbreds did not differ for fat production in either first or second lactation. Least squares means for days open were 88 days for pure Holstein versus 78 days for Jersey x Holstein crossbreds. During first lactation, pure Holsteins (n = 17) consumed significantly more dry matter intake (20.2 kg versus 18.9 kg) than Jersey x Holstein crossbreds (n = 24). Furthermore, pure Holsteins had significantly greater body weight (513 kg versus 458 kg) and significantly lower body condition scores (2.78 versus 2.88). Minnesota collected field data from seven large dairies in California that mated Holstein heifers and cows with imported semen of the Normande and Montbeliarde breeds from France, as well as the Swedish Red (SRB) and Norwegian Red (NRF) breeds. The Swedish Red and Norwegian Red breeds share similar ancestry and exchange sires of sons; therefore, the breeds were collectively regarded as Scandinavian Red for this study. The Scandinavian Red-Holstein crossbreds (-3%), Montbeliarde-Holstein crossbreds (-5%) and the Normande-Holstein crossbreds (-9%) were all significantly lower than the pure Holsteins for fat (lb) plus protein (lb) in first lactation. The difference from pure Holsteins increased from 9% to 12% for the Normande-Holstein crossbreds, from 5% to 7% for the Montbeliarde-Holstein crossbreds, and from 3% to 6% for the Scandinavian Red-Holstein crossbreds in second lactation. The Montbeliarde-Holstein crossbreds returned to a 5% difference from pure Holsteins for fat plus protein production (lb) for third lactation. First-lactation cows in six of the seven California dairies were compared for survival. Pure Holsteins left these dairies sooner than all crossbreds groups, with 86% of pure Holsteins surviving 305 days post-calving compared to 93% to 96% of crossbreds. All of the crossbred groups had significantly fewer days open than the pure Holsteins. The difference from the pure Holsteins ranged from 14 days for Scandinavian Red-Holstein crossbreds to 23 days for Normande-Holstein crossbreds. An initial analysis of data from 3-breed crosses indicates that production levels between 2 and 3 breed crosses are similar. North Carolina reported breed differences in birth weights, calving difficulty, and mortality of Holstein, Jersey, and crossbred calves in a pasture-based dairy system. Mean birth weights were d 75 lbs for all combinations of breed, parity, and gender with the following exceptions: 1) male Holstein calves from Holstein sires and dams in either first parity (82 ± 3 lbs) or 2) second and later parities (83 ± 2 lbs) or in male calves born to 2+ parity crossbred cows mated to Holstein sires (78 ± 2 lbs). The highest calving difficulty scores were for male calves from Holstein sires and first parity dams. The overall mortality rate through 24 hours after birth for 456 calves born was 9.4 %. Calves born to a crossbred dam had significantly lower mortaility than calves born to pure Holstein. North Carolina estimated the effects of stocking rate and breed on milk production and reproduction in a pasture-based dairy system. Jerseys and Crossbreds had higher conception rates at 1st service and over all services as well as having higher pregnancy rate over the entire breeding season than Holsteins at any stocking rate. The Holsteins produced the most pounds of mature-equivalent milk, fat, and protein whereas Jerseys produced the least, and the crossbred cows were intermediate to both pure breeds. At 30d postpartum, 22% of Holsteins, and 43% of Jerseys and Crossbreds were cycling. By 90d postpartum, only 77% of Holsteins had initiated cycles compared to 97% of Jerseys and 100% of crossbred cows. By 90d of breeding, 59% of Holsteins and 84% of Jerseys and Crossbreds were confirmed pregnant. Pennsylvania and Tennessee compared Brown Swiss, Holstein and Brown Swiss x Holstein crosses for production, somatic cell score and days open. Brown Swiss x Holstein crosses had higher least squares means for daily yield of fat (+0.11 lb) and protein (+0.04 lb) than pure Holstein with 12.6 fewer days open. Backcrossing to Brown Swiss resulted in lower milk, fat and protein yield than anticipated due to apparent recombination in Holstein. A joint Holstein x Jersey crossbreeding project was initiated at Kentucky and Virginia Tech. The project consists of pure Holstein, pure Jersey, Holstein sire x Jersey dam and Jersey sire x Holstein dams. Kentucky reported calf immune parameters that differed significantly between breed groups. Virginia reported least squares means for body weight at 18 months of age were 459 kg for Holstein, 414 kg for Holstein sire x Jersey dam, 425 kg for Holstein dam x Jersey sire and 335 kg for Jersey. Preliminary results for production indicated no significant differences between Holstein and crossbreds for milk, protein, summit milk, and peak milk. Furthermore, fat production favored the crossbreeds over the purebreds, indicating over-dominance for fat. A total of 14 Holsteins and 21 crossbreds were scored on the basis of the Holstein Association scorecard. Significant differences that favored the purebred Holstein over the crossbreds were final score, mammary system, strength, stature, and udder depth. Feed intake, body weight, and blood metabolites, including progesterone levels, are currently being collected on the cows. Wisconsin reported changes in conception rate, calving performance, and calf health and survival from the use of crossbred Jersey x Holstein sires as mates for Holstein dams. Holstein sires (N = 74) and crossbred sires (N = 7) did not differ in male fertility. Calves from Holstein sires and multiparous Holstein dams (N = 99) were 1.9 kg heavier than calves from crossbred sires and multiparous Holstein dams (N = 211), leading to greater likelihood (odds ratio of 1.24) of dystocia. Furthermore, calves from crossbred sires and multiparous Holstein dams had higher serum protein and serum IgG levels between 24 and 72 hr of age, as well as lower rates of perinatal and pre-weaning morality than calves from Holstein sires and multiparous or primiparous Holstein dams. The research also demonstrated that body length, body weight, heart girth, and hip height were significantly affected by breed of animal. Variation in body size and growth rate are important for dairy producers and custom heifer growers, because genetic differences in these traits might lead to suboptimal nutrition or reproductive management of certain groups of heifers. A preliminary analysis indicated that pure Holstein had higher production levels than the crossbred cows. Objective 3: Develop breeding goals and appropriate indexes for optimum improvement of health, survival, reproduction, and production. Indiana has generated divergent selection lines for dairy form. Initial second generation matings were initiated in August 2005, and first generation heifers began to calve in June 2006. An attempt will be made to maintain approximately 60 cows per line in first and subsequent generations. Of heifers returning to the Purdue Dairy and calving, three heifers in the high group failed to survive to 150 days in milk, while all low group heifers survive. All high group culled heifers were sold for reasons resulting from difficult calving---uterine adhesions, calving paralysis, and broken median suspensory ligament. Minnesota continues to maintain cows and heifers in the 1964 control line, which were moved from the Southern Research and Outreach Center (Waseca) to the West Central Research and Outreach Center (Morris) during 2003. Plans are to maintain the control line into the future with approximately 30 lactating cows, which has been the size of the lactating herd during the years it was housed at Waseca. The change of location for the control line provides new opportunities for research. The Morris station has a low-input system of dairying, with heavy reliance on grazing, spring calving, and minimum shelter for cows. Control cows and heifers will be compared to pure Holstein cows and heifers as well as crossbred cows and heifers, which have contemporary genetics. Semen was collected in the early 1990s from about 3 sons of each of the original 20 control bulls to perpetuate the control line into the future. The control line of females has been converted to mostly a spring calving cycle for the low-input production system at Morris. New York investigated genotype by environment interaction between milk yield and reproductive traits in the US and Mexico. An unequal daughter response in age at first calving between countries in response to selection for milk yield may be evidence for genotype by environment interaction. Virginia reported results of augmented relative net income adjusted for opportunity cost (ARNIOC) as a method of deriving economic values for selection index. The Relative Net Income approach calculates net income of each cow from her lifetime performance as the first step, and then uses multiple regression between her net income versus her sire PTAs of all 10 traits so that the partial regression coefficients provide the economic values of traits. ARNIOC resulted in lower weight to productive life than the current $Net Merit. These results suggest the need to give higher weight to yield traits and lower weight to productive life in 2006 NM$ revisions. ARNIOC was also applied to generate weights for JPITM. In contrast to high SCS of the Jersey breed, the weight for PTA SCS was near to zero compared to estimates for Holsteins. In general the antagonism between yield and fitness traits seems to be less than in Holsteins. Wisconsin investigated the relationship of intramammary infection prevalence with somatic cell score in commercial herds. Pathogens were classified as contagious or environmental. The rate of increase with SCS was uniform for contagious pathogens, but differed among production systems (all pathogens) and parities (environmental and all pathogens). Maryland produced a revised $Net Merit index that was implemented in USDA genetic evaluations beginning in August, 2006. The relative weight on protein yield was reduced from 33% to 23%, the relative weight on productive life was increased from 11% to 17%, and a calving ability index was introduced (6% weight), which is a composite of sire and daughter calving difficulty and sire and daughter stillbirth. Work Planned for Next Year: Data from various crossbreeding studies will continue to be collected and at least one new trial to generate a rotational crossbreeding system using Holstein, Swedish Red, and Montbeliarde A.I. sires with careful health and fertility data recording is planned. Data will begin to be available for second generation crossbreds. Collection of health and fertility data from field trials will continue and cow health and fertility data will be accumulated, including data on novel fertility traits. Cow mortality rates and risk factors will begin to be described.