Brief Summary of Minutes of Annual Meeting

ANNUAL REPORT OF COOPERATIVE REGIONAL RESEARCH Project: S-1008, Genetic Selection and Crossbreeding to Enhance Reproduction and Survival of Dairy Cattle October 1, 2003 to September 30, 2004 PROGRESS OF WORK AND PRINCIPAL ACCOMPLISHMENTS: Objective 1: Develop selection tools to enhance reproduction and survival using field data. Georgia used a reaction norm approach to estimate the genetic parameters of days from calving to conception (DO) in GA, TN and NC with a model that accounted for heat stress. Heritabilities were highest for spring and lowest for fall calvings. Genetic correlations of spring/summer, and fall/winter were both 0.90. Genetic correlations between spring/summer and fall/winter were around 0.80. The reaction norm model for DO allows inexpensive genetic evaluation of fertility under heat stress. Illinois continued cooperation with IA on perinatal survival, MD on daughter pregnancy rate, and NC on estimated relative conception rate. A more rigorous detection criterion for bimodal inheritance of these traits was implemented this year. Sixteen of 54 bulls with at least 50 sons were identified as having a bimodal pattern of inheritance for perinatal survival. The low groups had reduced survival and high groups had higher survival. Location of descendants tended to follow the PTA for perinatal survival of the maternal grandsire. Bimodal inheritance was not as prevalent for the other traits. Correlations among daughter pregnancy rate, perinatal survival, and estimated relative conception rates were close to zero suggesting that each trait is separate unique. Maryland (USDA-AIPL) revised methodology for estimation of DO to allow pregnancy checks to improve the accuracy of estimates from 130 to 250 days in milk. Genetic evaluations for calving ease were expanded to include Brown Swiss, in addition to the Holstein breed. Joint evaluations with both breeds proved to be acceptable and correlated well with results from within-breed evaluation results for direct and maternal calving ease. Results passed Interbull genetic trend tests, meaning they are acceptable for inclusion in international bull rankings. Additionally, methodology was refined to allow single-trait longevity from foreign countries and multi-trait longevity estimates for US evaluations to be combined to improve estimates of genetic ability of longevity. Genetic correlations for longevity measures in other countries ranged from .67 (with France) to .88 (with Canada). Nebraska developed estimates of genetic parameters for lactations one, two, and three of Holstein cows for individual test-day milk, fat, and protein yields and somatic cell scores (SCS) with a cubic spline model with five knots. Estimates of heritability for lactation one ranged from 0.09 to 0.15, 0.06 to 0.10, 0.08 to 0.15, and 0.02 to 0.06 for test-day one to test-day ten for milk, fat, and protein yields and SCS, respectively. Estimates of heritability were larger in lactations two and three. Estimates of heritability increased over the course of the lactation. Estimates of genetic and phenotypic correlations were smaller for test-days further apart. Further, lactation curves were estimated with a cubic spline model for milk, fat, and protein yields and SCS for lactations one, two, and three of Holstein cows treated with bovine somatotropin (bST). The yield traits showed a response to bST for all lactations. New York evaluated interaction between milk yield and reproductive traits of Holstein cows in Mexico and the United States. Genetic correlation coefficients between ME milk first lactation all US data and age at first calving (AFC) in average and high Mexican environments were different from zero (P < 0.001). The unequal daughter response for AFC between and within countries is evidence of genotype by environment interaction. North Carolina continued studying the relationship of fertility of service sires for breeding virgin heifers versus breeding lactating cows. Holstein sires (n = 200) with a minimum of 300 inseminations in cows and also in heifers were evaluated. Data were for 70-day non-return rates from first inseminations from 1999 through early 2003. The correlation coefficient between non-return rates for cows and heifers within service sire was 0.34 (P < 0.05). Tennessee worked to estimate the heritability of milk urea nitrogen (MUN) concentration and describe the genetic relationship of MUN with reproductive performance and disease in Holsteins. Heritability estimates were low to moderate. Genetic correlations between wet chemistry MUN and various measures of reproductive performance, including days to first service, first service conception, services per conception, and interval from first service to conception, were very low. Higher WC MUN values were associated with increased DO. Approximate genetic correlations among MUN and diseases identified no important relationships. Wisconsin looked at the effect of synchronization of estrus or ovulation on genetic parameters of reproductive traits. Heritabilities and variance components were estimated for three traits: days to first breeding (DFB), DO, and pregnancy rate at 120 days (PR120). Individual animals were synchronized at first breeding, a later breeding or were never synchronized. Genetic variances and heritabilities varied little among synchronization categories. Heritability estimates were around 0.03 to 0.06 for DFB and DO and around 0.10 to 0.20 for PR120. Wisconsin also analyzed health trait data collected from herd management software. The objective was to examine the possibility for genetic improvement of health and fitness in dairy cattle using data recorded by farmers in their herd management software programs. Mean differences in probability of disease between the 10 best and 10 worst sires were 0.034 for displaced abomasums, 0.069 for ketosis, 0.130 for mastitis, 0.054 for lameness, 0.039 for ovarian cysts, and 0.120 for metabolic disorders. Significant genetic differences seem to exist between sires in daughters' susceptibility to common health disorders. At present, no standard program exists for recording, centralizing, storing, or analyzing disease data in US dairy cattle. However, increased interest in health traits will facilitate development of improvement programs for these traits. Objective 2: Explore the impact of crossbreeding on lifetime performance of cows. Kentucky has had 69 calvings in their joint Holstein-Jersey diallel crossbreeding trial project with VA and NC, which involve Holsteins, Jerseys, and their reciprocal crossbreds. Both males and females have been used to assess immune cell production from birth to six weeks of age. Preliminary data show Jersey with generally higher levels, Holsteins with lower levels and crossbreds with intermediate levels but tending more toward Jersey levels. Serum protein levels were most elevated for crossbreds after three weeks of age. Minnesota is researching crossbreeding of dairy cows at two research herds. Holsteins were mated 50% each to Holstein or Jersey sires. Beginning December 15, 2002, the purebred Holstein heifers were mated to Holstein sires and the crossbred heifers to Montbeliarde sires. For calving-related traits, crossbred calves were born with significantly less dystocia than Holstein calves. Beginning December 15, 2003, a portion of the Holstein cows were mated to Montbeliarde sires. Numerous measures will be made as the calves age. Minnesota is also conducting research into crossbreeding in commercial dairy herds. Data is from seven dairies in California that are crossbreeding with frozen semen from European breeds of dairy cattle, including Normandy, Montbeliarde, and Scandinavian Red. Early results are available for production and SCS during the first 150 days of lactation. In North Carolina, preliminary lactation and fertility data have been collected for Holsteins, Jerseys and their crosses, at the pasture-based dairy research herd. As expected, production data were intermediate for crossbred cows and reproduction was higher than the pure breeds albeit numbers of observations are limited. In cooperation with VA and KY reciprocal crossbred matings were initiated. Females resulting from those matings will be followed for lifetime performance in a pasture-based environment. Tennessee explored crossbreeding with Swedish Red sires. The objectives were to evaluate crosses of Swedish Red sires on Holstein, Jersey and crossbred cows in 10 herds in the Southeast. Holstein, Jersey and some crossbred cows have been serviced with the Swedish Red semen and contemporary Holstein and Jersey semen over the past year. First calves are now on the ground and will be compared over the next few years using data collected through on-farm software and DHIA. In Virginia, with cooperation from KY, initial matings to 4 Holstein or 4 Jersey bulls to create four breed groups, HH, HJ, JH, and JJ, were begun. Approximately 300 females have been bred at Virginia Tech using heterospermic semen from 16 pairs of sires of the same or different breeds. The goal of the project was 20 pregnancies per mix. Distribution of calves by progeny group is not equal and apparently depended on sire and breed. Homospermic inseminations will continue through 2005 to balance progeny group sizes. Virginia also compared breeds for survival, herdlife, and percent days in milk. Herds were identified that included both Holstein and Jersey or Holstein and Brown Swiss cows. In most regions of the country, Jerseys appeared to have an advantage in survival and total days in milk and completed more lactations. Wisconsin compared the male fertility of pure Holstein and crossbred Jersey x Holstein service sires in artificial insemination (AI) matings to pure Holstein cows. Pregnancy status was determined by ultrasound at 28 to 33 d after breeding. Conception rates were 31.5% for matings to pure Holstein sires and 31.2% for matings to crossbred sires. Based on the results of this study, it does not appear that crossbred Jersey x Holstein sires can provide a significant improvement in male fertility. Objective 3: Develop breeding goals and appropriate indexes for optimum improvement of health, survival, reproduction, and production. Indiana is developing divergent selection lines for dairy form. Recent studies have demonstrated that daughters of bulls that transmit lower dairy form produce healthier daughters that survive longer, are more fertile, and produce a greater economic return, despite somewhat lower milk yield. Indiana also examined the effect of heterogeneous variances on the estimation of genetic differences among grazing or conventional dairy herds. Adjustment for heterogeneous variance within herd-year for milk, protein, and fat resulted in lower coefficients of regression with lower standard errors. Thus, accounting for heterogeneous variance made little difference in the ability of genetic evaluations to predict performance of future daughters in grazing herds at low levels of production. Iowa sought to determine if significant enhancements in quantity and quality of milk can be achieved by selecting sires for high or average PTA fat plus protein yield. Selection has been ongoing since 1988. The high line had consistently higher yield for milk, fat and protein than the average line. There was little difference between the high and average lines for milk quality and components. There was, however, a slight tendency for the average line to have a lower fat percentage and SCS than the high line. A higher percentage of daughters survived to complete a first lactation in the average line than in the high line. Maryland (USDA-AIPL) made ongoing progress on genetic evaluation procedures. Plans have been made to account for past and future inbreeding by regressing on inbreeding in the animal model. Following adjustments, genetic evaluations remained highly correlated with previous evaluations; but genetic trends were reduced. With collaboration from IN, MD studied standardizing production records to average rather than mature age. Minnesota continued selection of cows in a 1964 control line. Plans have been to maintain the control line at a new location into the future with approximately 30 lactating cows. Control cows and heifers will be compared to contemporary pure Holstein cows and heifers as well as crossbred cows and heifers. Beginning in 2000, sires were selected using the Body Size Composite of the Holstein Association USA for the body size selection project. Nebraska studied evaluation of different test day models for estimation of genetic parameters for dairy cattle production traits. Models with autoregressive covariance structures for the permanent or residual effects had more resemblance to the multivariate approach than the simple repeatability model with the compound symmetry covariance structure for the TD records of milk, fat and protein yields and SCS data. Nebraska also examined genetic evaluation of dairy cattle with different test-d and 305-d models. More gain may be possible by using TD models to select for animals with higher yield and lower SCS genetic potential than using 305-d lactation model. Tennessee conducted work with objectives to estimate the genetic correlation between mastitis and electrical conductivity (EC). Heritability estimates ranged from about 0.36 in the beginning and at the end of the lactation to about 0.26 in mid lactation. A bivariate analysis was carried out and produced an estimated genetic correlation between EC and mastitis of 0.75. WORK PLANNED FOR NEXT YEAR Work will continue on analyses of reproductive, production and type traits using different models, including longitudinal and survival. Work will include identification of major gene(s) for selected fitness trait. Matings and data collection for the collaborative crossbreeding projects will continue. Further progress will be made in advancing selection lines of cattle for milk production versus controls, for body size, and dairy form. APPLICATION OF FINDINGS Recommendations of this committee are implemented for industry use. Perinatal survival of calves may be influenced by a major gene. MUN is heritable but selection may be limited. EC has a high genetic correlation with mastitis, and has potential for selection. Test-day models would be more accurate than the current genetic evaluation system used in the US if agreement is reached on the patent held by Cornell. Because the heritability of days open is highest under the peak of heat stress, the selection for increased fertility may be more successful under hot conditions. Graziers need to know that genetic evaluations may overestimate genetic ability of daughters in extensively managed grazing herds. Calving ease genetic evaluations for Brown Swiss will be available in February 2005. Adjustments for inbreeding will be included in February 2005 USDA genetic evaluations. Age adjustment to 36 months instead of mature will reduce breed means. The 1964 control line of cows phenotypic and genetic level of milk production is approximately 10,000 lb less than todays Holsteins. Early results suggest that crossbreeding might be helpful to improve reproductive efficiency and survival of dairy cows.