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National bodies in Great Britain (GB) have expressed concern over young stock health and welfare and identified calf survival as a priority; however, no national data have been available to quantify mortality rates. The aim of this study was to quantify the temporal incidence rate, distributional features, and factors affecting variation in mortality rates in calves in GB since 2011. The purpose was to provide information to national stakeholder groups to inform resource allocation both for knowledge exchange and future research. Cattle birth and death registrations from the national British Cattle Movement Service were analyzed to determine rates of both slaughter and on-farm mortality. The number of births and deaths registered between 2011 and 2018 within GB were 21.2 and 21.6 million, respectively. Of the 3.3 million on-farm deaths, 1.8 million occurred before 24 mo of age (54%) and 818,845 (25%) happened within the first 3 mo of age. The on-farm mortality rate was 3.87% by 3 mo of age, remained relatively stable over time, and was higher for male calves (4.32%) than female calves (3.45%). Dairy calves experience higher on farm mortality rates than nondairy (beef) calves in the first 3 mo of life, with 6.00 and 2.86% mortality rates, respectively. The 0- to 3-mo death rate at slaughterhouse for male dairy calves has increased from 17.40% in 2011 to 26.16% in 2018, and has remained low (

The use of multi-trait across-country evaluation (MACE) and the exchange of genomic information among countries allows national breeding programs to combine foreign and national data to increase the size of the training populations and potentially increase accuracy of genomic prediction of breeding values. By including genotyped and nongenotyped animals simultaneously in the evaluation, the single-step genomic BLUP (GBLUP) approach has the potential to deliver more accurate and less biased genomic evaluations. A single-step genomic BLUP approach, which enables integration of data from MACE evaluations, can be used to obtain genomic predictions while avoiding double-counting of information. The objectives of this study were to apply a single-step approach that simultaneously includes domestic and MACE information for genomic evaluation of workability traits in Canadian Holstein cattle, and compare the results obtained with this methodology with those obtained using a multi-step approach (msGBLUP). By including MACE bulls in the training population, msGBLUP led to an increase in reliability of genomic predictions of 4.8 and 15.4% for milking temperament and milking speed, respectively, compared with a traditional evaluation using only pedigree and phenotypic information. Integration of MACE data through a single-step approach (ssGBLUPIM) yielded the highest reliabilities compared with other considered methods. Integration of MACE data also helped reduce bias of genomic predictions. When using ssGBLUPIM, the bias of genomic predictions decreased by half compared with msGBLUP using domestic and MACE information. Therefore, the reliability and bias of genomic predictions for both traits improved substantially when a single-step approach was used for evaluation compared with a multi-step approach. The use of a single-step approach with integration of MACE information provides an alternative to the current method used in Canadian genomic evaluations.

Dry cow therapy (DCT) in the Netherlands changed from mainly blanket to selective antimicrobial DCT. This transition was supported by a national guideline, with the individual somatic cell count (SCC) at the last milk recording before dry-off as the main selection criterion for antimicrobial DCT. The aim of this retrospective observational study is to evaluate the SCC dynamics during the dry period at the herd and individual dry period level following the national transition from mainly blanket to selective antimicrobial DCT. At the herd level, we used 2 data sets to evaluate the SCC dynamics during the dry period: (1) a national data set containing 3,493 herds with data available from 2011 through 2015 and (2) a veterinary practice data set containing 280 herds with data available from 2013 through 2015. The herd level analysis was carried out using key performance indicators provided via milk recording (CRV, Arnhem, the Netherlands): the percentage of cows that developed a new intramammary infection (IMI) during the dry period and the percentage of cows cured of an IMI during the dry period. The effect of DCT at individual dry period level was analyzed with a mixed-effects logistic regression model based on 4,404 dry periods from 2,638 cows in 20 herds within the veterinary practice data set. For these 20 herds, individual SCC data from milk recordings and individual cow DCT were available from 2013 through 2015. No significant changes were observed to the SCC dynamics during the dry period at the herd level. The percentage of cows that developed a new IMI during the dry period ranged between 16 and 18%, and the percentage of cows cured from an IMI during the dry period ranged between 74 and 76%. At the individual dry period level, a low SCC at the first milk recording following a dry period was associated with the use of intramammary antimicrobial DCT with or without the concurrent use of an intramammary teat sealer [odds ratio (OR) = 2.16 and OR = 2.07, respectively], the use of DCT with an intramammary teat sealer only (OR = 1.35), and a low SCC at the last milk recording before dry-off (OR = 1.78). This study demonstrates that the selection of cows for DCT without antimicrobials based on SCC thresholds at the last milk recording is possible without significant changes to udder health and reduced the use of antimicrobials.

A national data set of artificial inseminations in US Holsteins was used to obtain genetic evaluations for conception rate (CR). The objective of this study was to investigate the feasibility and resulting accuracy from using all available phenotypic, pedigree, and genomic information. Evaluations were performed by regular BLUP or by BLUP with the traditional pedigree and genomic relationships combined in a unified single-step procedure (SSP). Genetic parameters of CR in the first 3 parities were estimated with data from New York State only. Heritability estimates were around 2% and genetic correlations between CR in different parities were >0.73. The R(2) obtained with the SSP were almost twice as large as those achieved with regular BLUP. Computing the SSP took 2h, and it was 33% slower than a regular BLUP. A multiple-trait evaluation of CR using the SSP is both possible and advantageous.

A stochastic cost equation was estimated for US dairy farms using national data from the production year 2000 to determine how farmers might reduce their cost of production. Cost of producing a unit of milk was estimated into separate frontier (efficient) and inefficiency components, with both components estimated as a function of management and causation variables. Variables were entered as impacting the frontier component as well as the efficiency component of the stochastic curve because a priori both components could be impacted. A factor that has an impact on the cost frontier was the number of hours per day the milking facility is used. Using the milking facility for more hours per day decreased frontier costs; however, inefficiency increased with increased hours of milking facility use. Thus, farmers can decrease costs with increased utilization of the milking facility, but only if they are efficient in this strategy. Parlors compared with stanchions used for milking did not decrease frontier costs, but decreased costs because of increased efficiency, as did the use of a nutritionist. Use of rotational grazing decreased frontier costs but also increased inefficiency. Older farmers were less efficient.

The usefulness of multinational data for the improvement of national estimates of genetic merit of Holstein bulls was assessed. For 222 bulls, combined US-Canadian evaluations and evaluations from the US only from January 1993 for milk, fat, and protein yields were compared with their US only evaluations from August 1997. The correlations between the 1993 and 1997 evaluations and the standard deviations of differences in evaluations from added data favored the evaluations from the US only because of a part-whole relationship; often 1997 data were largely from US only data from 1993. However, the results for 35 bulls with reliability increases of >5% indicated that combining US and Canadian evaluations improved the prediction of future evaluations. The value of foreign data also was assessed from national and international evaluations on the scales of Canada, Germany, and the US. The changes from 1996 national evaluations to either 1996 international evaluations or 1997 national evaluations were compared to determine whether adding international data at the earlier time could provide a useful prediction of subsequent change in national evaluations. Although the degree of agreement among differences from added national and international data varied, international evaluations did provide useful information beyond the more limited national data available at the same time.

Factors that affect frequency of death of lactating cows were studied for cows with records that terminated from 1995 through 2005. Analyses included effects of herd, year, month, parity, and lactation stage at lactation termination as well as cow breed and milk yield. A national data set (15,025,035 lactations in 45,032 herds) was analyzed with PROC GLM. Overall death frequency was 3.1% per lactation (5.7% per cow). Death frequency increased by 1.6% from 1995 to 2005, with a sudden increase of 0.9% from 2003 to 2004, probably because of a USDA requirement in late 2003 for euthanizing downer cows. Death frequency was 16.5% greater for lactations that terminated ator=45 d than for those that terminated ator=251 d. Death frequency increased with parity (2% greater for eighth parity and later than for first parity) and with lactation milk yield (0.4%/1,000 kg for Holsteins and Jerseys and 0.5%/1,000 kg for other breeds). Deaths were most frequent in July and least frequent in November. Within-herd breed differences (Holstein, Jersey, and other breeds) were small. The heritability of likelihood of death estimated from a sample of 79,162 Holstein cows was 1.3%. Death losses are increasing, perhaps partly because of increased milk yield and more intensive management regimens.

Effects of procedures applied to widely deviant records on a mass basis to improve predictive ability of early Sire Summaries were investigated. Data were first lactation daughter records for 200 Holstein bulls with at least 500 daughters. Five subsets of the first 10, 30, 50, 70, or 90 daughters to calve for each bull were created to simulate data ordinarily available for the first few Sire Summaries in a bull's life. Three empirical procedures were developed based on SD appropriate for herd yield: 1) differences between daughter Modified Contemporary Deviation and sire ancestor merit were multiplied by probability function values (regression procedure), 2) length weights for calculating daughter Modified Contemporary Deviation were multiplied by probability function values (weighting procedure), and 3) records were excluded based on number of SD between daughter Modified Contemporary Deviation and sire ancestor merit (elimination procedure). Experimental sire evaluations were calculated and compared with July 1984 USDA-DHIA Sire Summaries. Maximum improvements of 1 to 3% in predicting genetc merit were found for all three procedures for evaluations based on smaller numbers of daughters. If these small increases in accuracy are repeatable, they would justify added computational expense necessary to implement adjustment procedures for a national data set.

Effective sire selection should result in predictable differences among progeny groups within herds. National data from cows with lactations in 1979 gave within-herd regressions for Holstein yield on Predicted Difference of sire of 1.00 for milk and 1.01 for fat. First-lactation data gave regressions of 1.20 for milk and 1.13 for fat. Holstein herds were stratified into 10 classes by average milk yield of herd. Within-herd regressions of first-lactation yield on Predicted Difference of sire ranged from .71 for the lowest yield class to 1.49 for the highest yield class. Yield response to Predicted Differences of sires was related positively to herd yield, which suggests that sire selection for increased yield gives a greater return for herds with high yield than for herds with low yield. These results were supported by data from other breeds. Phenotypic variation within herds increased with herd yield, but coefficient of variation decreased. Heritabilities for yield from paternal half-sisters increased markedly across six classes of increasing herd yield for Holsteins.