Inbreeding coefficients are calculated routinely for all animals included in national genetic evaluations for yield traits. The base population for inbreeding is defined as animals born during 1960. Animals with unknown parents are assumed to have inbreeding coefficients that are equal to the mean of coefficients for animals with known parents born during the same year. Mean inbreeding coeffici...

Genomic evaluations of dairy cattle in the United States have been available for Brown Swiss, Holsteins, and Jerseys since 2009. As of January 2013, 1,023 Ayrshires had genotypes in the North American database. Evaluation accuracy was assessed using genomic evaluations based on 646 bulls with 2008 traditional evaluations to predict daughter performance of up to 180 bulls in 2012. Mean gain in r...

Modeling extended lactations for the US Holsteins is useful because a majority (>55%) of the cows in the present population produce lactations longer than 305 d. In this study, 9 empirical and mechanistic models were compared for their suitability for modeling 305-d and 999-d lactations of US Holsteins. A pooled data set of 4,266,597 test-day yields from 427,657 (305-d complete) lactation recor...

a total of 136,250 monthly test day milk records collected from 13,625 iranian holstein heifers (three times a day milking) calved between 1991 and 2001 and distributed over 264 herds were used to study the effects of some environmental factors influencing lacta-tion curve parameters as well as production characteristics. wilmink’s function (yt = w0 + w1t + w2e-0.05t) was fitted to individual l...

The conceptual bases of recent NRC publications of nutrient requirements to meet dietary energy needs of growing Holsteins, emphasizing heifers gaining 0.75 kg/d, are described and compared with several world systems and with body composition data. Requirements of Holsteins for net energy for maintenance are generally thought to be higher (from 7 to 20%) than those of British beef breeds. Total...

Farmers' subjective evaluations of their cows' milking speed, scored as "very fast", "fast", "average", "slow", or "very slow", were recorded between 1982 and 1985 under Agriculture Canada's Record of Performance milk recording scheme. For the analysis, scores taken at the beginning (score 1) and the end (score 2) of the lactation were distinguished. Edited data comprised 20,909 records for sco...

some factors affecting crude protein balance (cpb), as a measure of efficiency, were studied using 2824 records of 501 lactating holstein cows. the cpb (kg d-1) was calculated as crude protein (cp) intake (kg) minus cp yield (kg). two different statistical methods including principal components (pcs) and general linear model analyses were used to study the effects of different factors. crude pr...

Genetic evaluations for milk yield of Holsteins in Mexico were computed from lactation and pedigree information from Holstein de México. The US animal model system for national evaluations was adapted for Mexico. The primary change was in defining unknown-parent groups. Paths of unknown parents of bulls and sires of cows were combined and separate unknown-parent groups defined for parents of US...