Estimates of daughter fertility were computed using first artificial insemination (AI) breedings reported to the US Dairy Herd Improvement Association (DHIA) from 1995 through 1997. An animal model was used to compute estimated breeding values (EBV) of daughter groups with fixed effects of herd-year-month bred and classes of early lactation energy-corrected milk, days in milk (DIM) when bred, and parity. Standard deviations and ranges of bull EBV for daughter fertility for DIM were 9.1 and -31 to 18; standard deviations and ranges of bull EBV for daughter fertility for nonreturn were 3.8 and -11 to 10. Correlations were computed for EBV for daughter fertility with EBV for mating bull fertility and with predicted transmitting abilities (PTA) for milk, somatic cell score (SCS), and productive life for bulls (213) with minimums of 200 matings and 100 progeny with reproductive traits. None of the correlations among EBV for reproductive traits differed from 0.0. Correlations of EBV for daughter fertility with PTA for productive life were significantly positive. PTA for yield traits were not correlated with EBV for daughter differences in nonreturn or DIM. Very low correlations of EBV for daughter reproductive traits with PTA for yield indicate that, in order to improve daughter fertility, fertility must be incorporated in sire selection decisions.

Objectives of this study were to investigate changes in predicted transmitting abilities (PTA) of yields from evaluations based on first records to evaluations based on first and later records of daughters and determine whether these changes are heritable. Data were USDA sire evaluations of July 1989 through May 2000 on Holstein bulls in standard progeny testing programs. Changes in PTA for milk, fat, and protein from evaluations based on first records of daughters to evaluations on first and second were obtained on 2001 bulls. These were divided into two sets: subset 1 (n = 889) included bulls first evaluated before 1995 and subset 2 (n = 1112) included bulls first evaluated in 1995 and later. Changes in PTA from first-record evaluation to most recent evaluation (May 2000) were obtained on 2524 bulls first evaluated in 1995 or later. Mean changes in PTA for bulls first evaluated in 1995 and later were smaller than mean changes for bulls evaluated earlier but standard deviations were similar. Regressions of changes in PTA on changes in parent average showed that a change of 1.0 kg in parent average resulted in 1.1 to 1.2 kg change in PTA. Heritabilities estimated with animal model ranged from 0.14 to 0.23 for changes from first-record evaluation to evaluation on first and second, and 0.27 to 0.35 for changes from first-record evaluation to most recent evaluation. Heritabilities of this magnitude allow for identifying bulls that decrease in PTA.

The objective of this work was to investigate the relationships of productive life with changes in bull evaluations for yield traits. Two datasets were analyzed. In the first, predicted differences for change in milk yield from first to second lactation of daughters of artificial insemination (AI) Holstein bulls used widely in the southeastern United States were available from a previous study. These were correlated with predicted transmitting abilities (PTA) of productive life from May 2000 USDA sire evaluations. Based on bulls with at least 10 daughters (n = 560) the correlation of PTA productive life with predicted differences for the change in milk yield was 0.30. The correlation increased to 0.36 for bulls with at least 50 daughters (n = 319) and to 0.40 for bulls with at least 75 daughters (n = 284). The second analysis included data on 1831 AI sampled Holstein bulls evaluated by USDA between July 1989 and May 2000. Changes in PTA yields were calculated as PTA from evaluations based on first and second records of daughters minus those from first-record evaluations. Correlation analyses showed that PTA yields from first-record evaluation and changes in PTA yields were positively associated with productive life. Regression coefficients on changes in PTA yields were all positive indicating that increases in PTA for yield traits as daughters aged corresponded with longer productive life. Using changes in AI bull evaluations for yields could improve prediction of productive life for little cost.

The objectives of this study were to predict most recent evaluations of young bulls entering artificial insemination (AI) sampling programs from pedigree information available at time of sampling and investigate whether prediction equations differ among AI organizations. Data were pedigree information and most recent USDA evaluations on bulls entering AI sampling programs from 1989 through 1994. Pedigree information included earliest available parent average, predicted transmitting abilities (PTA) of sire, dam, and maternal grand sire. Most recent evaluations were from May 2000 evaluations and included PTA and daughter yield deviations for milk, fat, and protein. Regression coefficients on PTA of sire and PTA of dam were less than the expected coefficient of 0.50. Accuracy of prediction as determined by R-square values was less than 12%. Inclusion of PTA of maternal grand sire after PTA of sire and dam increased the accuracy of prediction by less than 1%, but regression coefficients on PTA of maternal grand sire differed from 0. Regressions on parent average were not different among AI organizations for prediction of PTA and daughter yield deviations. Partial regression coefficients on PTA of sire differed among AI organizations for prediction of fat and protein but did not differ for milk. Coefficients on PTA of dam did not differ among organizations. These results indicate that AI organizations put different emphasis on PTA of sire in selection of sons for fat and protein.

The objective of this study was to compare daughters of proven (progeny-tested) and young sampling bulls available for use at the same time for yield traits, productive life, somatic cell score, and inbreeding.Data were from USDA sire evaluations of July 1989 through July 1994.Proven bulls used between 1989 and 1994 were identified based on the change in number of daughters.Young bulls were identified based on age and date a bull first entered artificial insemination.Young bulls were classified into two categories: one included all young bulls available in one year and the other included the top 50% on parent average for milk.Daughter deviations for yields, productive life and somatic cell scores, and average inbreeding were obtained from May 2000 evaluation.Daughter deviation milk was not different between proven and top 50% young bulls but was lower for all young bulls.Young bulls (all and top 50%) exceeded proven bulls in daughter deviation fat and protein.Progeny of proven bulls had favorably higher productive life in most years but unfavorably higher somatic cell score than progeny of young bulls.Inbreeding was consistently higher for daughters of young bulls than for those of proven bulls.Results indicate that young bulls were competitive with proven bulls.Use of young bulls from among the top 50% should result in equal or higher genetic progress in yields compared to contemporaries by proven bulls.

Trends in average days open and services per conception from 1976 to 1999 were examined in 532 Holstein and 29 Jersey herds from 10 Southeastern states. Three-year averages for eight intervals (time) were calculated (first: 1976 to 1978; eighth: 1997 to 1999). Milk, fat, fat-corrected milk, and number of cows increased across time. Herds of both breeds had linear, quadratic, and cubic effects of time on days open and services per conception. For 1976 to 1978, respective averages of days open and services per conception were 122 +/- 2.8 d and 1.91 +/- 0.08 for Jerseys, 124 +/- 0.7 d and 1.91 +/- 0.02 for Holsteins. Days open increased nonlinearly to 152 +/- 2.8 d for Jerseys and 168 +/- 0.7 d for Holsteins by 1997 to 1999, resulting in a breed x time interaction. Services per conception also increased nonlinearly, reaching 2.94 +/- 0.04 services for both breeds in 1994 to 1996, changing only slightly after 1996. Fat-corrected milk and number of cows had small but significant effects. Five subregions (one to three states) differed in mean days open and services per conception, but changes in those measures across time among subregions were similar. Days to first service increased by 16 (Holsteins) and 18 d (Jerseys) during the last five 3-yr periods, associated with increasing days open. Estrus detection rates generally declined from 1985 to 1999, associated inversely with services per conception. Reduced reproductive performance in Southeastern dairy herds is of concern. Multiple strategies are needed to attenuate further declines.

Animal model methodology was used to compute yearly measures of relative fertility of Holstein AI mating bulls based upon 70-d nonreturn of first breedings as reported to U.S. DHIA from 1988 through 1997. Estimated Relative Conception Rates (ERCR) were computed for bulls with a minimum of 50 first breedings in a single year using variance ratios 45.5 for mating bull, 45.5 for animal genetic effects, and 31 for permanent environment. The model assumed repeatability across lactations of 0.05 and included fixed effects of herd-year-month bred and classes of parity, early lactation energy-corrected milk and days open when bred. Estimates of fertility were greater for breedings to cows that were young, had low early lactation production, and were in late stages of lactation. ERCR were expressed as difference in nonreturn from the average AI mating bull of herdmates. Values ranged from -18 to +13. For ERCR computed from a minimum of 1000 breedings, 90% were within four units of zero. Early ERCR computed from a few breedings in a single year were tested for ability to predict later ERCR computed from a minimum of 1000 different breedings. Early ERCR computed from 300 or more matings accurately predicted later independent ERCR. For yearly estimates each based upon a minimum of 1000 breedings, 8% changed more than three units, and 4% declined more than three units. Correlations between ERCR and predicted transmitting abilities protein and type production index were significant but accounted for little variance. Correlations between ERCR and other traits were not significant.

The main objective of this study was to estimate genetic trends for 3.7% FCM, fat yield, days open, and predicted body weight after calving in six experimental dairy herds owned by the State Farm Division of the North Carolina Department of Agriculture. Body weights were predicted from heart girths measured at or before the first test day after calving. Data analyzed were 23,052 records from 8575 cows, daughters of 681 bulls. Heritabilities and breeding values were estimated using the multiple-trait, derivative-free REML programs and a single-trait repeatability model. Breeding values of cows were averaged by and regressed on birth year to estimate genetic trends. Genetic correlations between traits were estimated by correlating breeding values. Estimates of heritability were 0.25 for 3.7% FCM, 0.28 for fat yield, 0.03 for days open, and 0.17 for predicted body weight. Unfavorable genetic relationships were found between yields and days open and between yields and body weight. Genetically, cows that were heavier after calving produced less milk and fat but conceived earlier than smaller cows. Genetic changes in yields and days open were greater for cows born after 1970, but the greatest genetic changes were after 1980 (FCM, 94.7 kg/yr; fat yield, 3.46 kg/yr; days open, 1.1 d/yr). Breeding values for body weight increased for cows born from 1950 to 1970, decreased until 1980, and increased for later parities. The results of our study suggest that AI organizations may need to include fertility traits in progeny testing and relax the emphasis on increased body weight.

Three Holstein lines, were compared, based on different methods of sire selection, for genetic change in 3.7% FCM, fat yield, days open, and predicted body weight after calving. The three lines were 1) evaluated sires selected only for 3.7% FCM (milk line), 2) evaluated sires selected on an index that included 3.7% FCM and type traits (index line), and 3) young bulls selected on pedigree for 3.7% FCM (young line). Cows from these lines were born in 1971 through 1993 in five experimental herds owned by the State Farm Division of North Carolina Department of Agriculture. Breeding values of cows in each line computed with a repeatability model were averaged by and regressed on birth year to estimate genetic change. Genetic gains in 3.7% FCM were 81 kg/yr for the milk line, 61 kg/yr for the line selected on index, and 68 kg/yr for the young sire line. Estimates of genetic gain in fat yield were 2.99, 2.16, and 2.54 kg/ yr in the three lines, respectively. Genetic gains in 3.7% FCM and fat yield in the milk line were significantly different from the index and young sire lines, but the index and young sire lines were not significantly different. Estimates of genetic change in days open were 0.71, 0.57, and 0.63 d/yr in the milk, index, and young sire lines, respectively. These estimates were not significantly different. Average breeding values for body weight decreased for births from 1971 to 1981 then rapidly increased for later births in all lines.

The incidence of foot and leg problems and their direct and indirect consequences can be reduced by selection. The most promising approach is to select on an index that includes at least linear scores for foot angle or diagonal, rear legs rear view, and a locomotion score. Desirable are high foot angles, shorter diagonals, straighter rear legs from the rear with little to no closeness at the hocks, and locomotion scores that reflect easier walking. In some populations legs straighter than average at the hocks as observed from the side may have value. Low frequencies of direct observation of actual foot and leg problems limit their usefulness in selection decisions, but they might improve estimates of Breeding Value if used when they are available. Because the heritabilities of the foot and leg traits are low when based on the phenotype of individual animals, selection will be many times more effective when based on animal model estimates of progeny average breeding values. Antagonistic genetic correlations apparently exist between yields of protein, milk, and fat of first lactations and incidence of foot and leg problems. These indicate that the index used for feet and legs be a subindex or only part of the overall index used for selection of parents of future generations of dairy cattle.

Effects of days dry and previous and current days open on milk yields during the first three lactations were determined for Holsteins from Zimbabwe and North Carolina. The animal models used included animal; permanent environmental effects of cows for herd-year, month of calving, age, current days open, and DIM; and the inverse of additive numerator genetic relationships. Model 1 for first lactations included only these effects, but Model 2, the animal model for later lactations, included these effects plus previous days open, previous days dry, and previous milk yield. The dependent variable in both models was unadjusted milk yield for the lactation. Current and previous days open, previous days dry, and DIM were also fitted as dependent variables with Models 1 and 2, except for previous milk yield, when appropriate. As current days open increased, milk yield rose, regardless of milk yield during prior lactations. Milk yields were reduced for lactations following <60 d dry and showed little advantage for longer dry periods. The effects of previous days open are real but are overestimated unless permanent environmental effects of cows are considered simultaneously. The heritabilities and repeatabilities of current and previous days open and previous days dry were higher for cows in Zimbabwe than for those in North Carolina. Results suggest that, to obtain unbiased estimates of breeding values of sires and cows, yield data should be adjusted for the environmental effects of days dry as well as those of previous and current days open.

Two independent data files from the breeding herd of Iowa State University and six North Carolina herds were used to examine relationships between yield traits and mtDNA polymorphism. Maternal lineages were established by tracing ancestry of cows to founder females in the herd book of the Holstein Association. Data from Iowa State University were 1476 records from 602 cows from 29 maternal lineages. The nucleotides of mtDNA encoding rRNA were sequenced. Eleven sites of polymorphism were found. An animal model for gene substitution was used to examine the relationship between sequence differences and yield traits. Traits analyzed were mature equivalent yield of milk, fat, SNF, and milk energy as well as concentrations of fat, SNF, and milk energy. Effects of sequence differences were significant for most traits. Sequence information from the D-loop was available for 12 lineages from North Carolina. The effect of polymorphism at 4 sites was examined using 1472 records from 668 cows. Traits measured were the same, except that protein replaced SNF. No significant relationships existed between any of the traits and D-loop polymorphism, but results suggested that an association might exist between polymorphism and concentrations of milk yield, fat percentage, and energy. Whenever a significant relationship was detected, the effect of mutation (rare genotype) was detrimental.

Effects of maternal lineage on yield traits were examined by using animal models. Data were 6054 multiparous records of 2264 cows from six herds in North Carolina and the breeding herd of Iowa State University. Separate analyses were performed by using first lactation records from North Carolina, all records from North Carolina, and pooled records from North Carolina and Iowa. Traits were mature equivalent yields of milk, fat, and protein; percentages of fat and protein; and milk energy concentration and yield. Cattle were assigned to maternal lineages on the basis of the earliest female ancestor recorded. Fixed effects in the models were herd-year-season, parity, and maternal lineage; random effects were animal, permanent environment, and residual. All additive genetic relationships were considered. For all analyses, maternal lineage was associated with significant differences in fat percentage and milk energy concentration. Differences between maternal lineages for yield traits were not significant. Variance components were also obtained with REML using the same data and models, but with lineage as a random effect. Based on records pooled from Iowa and North Carolina, maternal lineage accounted for 2.7% of the variance in fat percentage. Otherwise, < 1.2% of the variance of any trait was associated with maternal lineage.

The goal of evaluating feet and legs is to identify bulls that transmit resistance to lameness. To be effective, this must be done accurately, cheaply, and in the initial progeny test based on first lactation progeny. Our experience indicates that we must use traits of feet and legs that are easily and accurately scored by eye to be efficient when evaluating progeny groups. Actual measurements are certainly more accurate than scores for most if not all traits, but not enough so to be justified for large progeny groups. The heritabilities of single eye scores or judgements of most traits of feet and legs are usually low. Thus, efforts must focus on sire progeny groups rather than on individual cows. Our criteria fbi determining the relative value of individual claw and leg traits is their ability to predict longevity, individually and collectively. Leg traits that appear to best fit these criteria are leg set viewed from the rear and leg set viewed from the side. Higher foot angles have proven to be associated with longer life and fewer claw problems. Research in the Netherlands, Germany and our preliminary findings in the USA indicate claw diagonal predicts longevity more accurately than other individual claw traits or combinations of them. Eye judgements of locomotion will require careful standardization and continuous training of evaluators.For highest efficiency, 40 or more progeny of bulls should be scored in commercial herds once for 1-2 claw traits, 1-2 leg traits, and locomotion. The goal of scoring or measuring claw and leg traits is to increase animal well-being, reduce lameness and the true costs of producing milk.

First lactation records of 1538 buffalo maintained at the Animal Production Research Institute farms in 1967 to 1990 were used to determine lactation curves for three lactation lengths: > 28 and < 150 d, > 149 d, and > or = 308 d, as well as all records. Daily milk yields were summed by 14-d intervals for analyses. Yields peaked at the first, fifth, sixth, and seventh periods for > 28 and < 150 d, > 149 d, > or = 308 d, and all records. Herd-year-season significantly affected milk yield in all periods. Persistency for all records and three groupings (> 28 d, > 149 d, and > or = 308 d in milk) was highest for the > or = 308-d group (1.02 vs. .85 for > 149 d, .57 for > 28 d, and .47 for all records). Herd-year-season of calving significantly affected persistency in all records and the three subset groupings. Persistency was higher for buffalo calving in spring and summer for all records, records > 28 d, and records > 149 d but in summer and autumn for the > or = 308 d, the correlation coefficient between persistency and milk yield (r = .06) was not significant but was negative with season of calving (r =-.11).

Genetic and phenotypic variations of hoof measurements were related to milk and fat yields, days open from calving to conception, and survival to various ages. Data were from 5551 measures in the first four lactations of 2972 Holstein cows in six herds over 15 yr. Estimates of heritabilities for hoof angles by multivariate REML averaged .18 but ranged from .03 to .39 by lactation. Similar averages for hoof lengths were .25 (range .08 to .53) and .07 (range .02 to .16) for heel depth. Hoof lengths had the highest phenotypic relationships with milk or fat yields and days open. Hoof angles of the first lactation were positively related to survival rates to various ages. For the second lactation, hoof lengths were the only useful predictors of survival. Days open, survival rate, and increase in age-adjusted milk yield from first to second lactation were favorably related to higher hoof angles and shorter hoof lengths. Within a lactation, higher angles and shorter lengths were undesirable for increased milk or fat yields. Genetic correlations of milk and fat yields with hoof angles were generally negative, but those for length were mostly positive. Genetically, days open decreased as hoof angle increased; some differences occurred among lactations. Longer hooves and deeper heels were positively related genetically to days open. Genetic correlations of hoof angles and heel depth with survival were positive, but those with hoof length tended to be negative.