The purpose of this study was to evaluate the effect of adjusting for heterogeneous variances across breed groups on prediction of breeding values (PBV) of selected sires and on breed of sire effects. Data on weights at birth (BWT), 200 d (WW), and 365 d (YW) of purebred and crossbred calves from matings of Angus (A), Hereford (H), Polled Hereford, Charolais, Shorthorn, Simmental, Limousin, Mai...

Cumulative milk production of crossbred daughters of sires of several breeds was estimated using weigh-suckle-weigh procedures. Pooled-across-breed analyses were conducted to determine, in retrospect, relationships of sire expected progeny difference (EPD) values for milk and total maternal value to daughter milk yield and daughter's offspring weaning weight. The pooled coefficient for regressi...

Additive and dominance genetic variances were estimated for milk and fat yield in Canadian Holsteins using deriva-tivefree REML procedures. Traits were analyzed under two sire and dam models differing in assumptions on the data structure. Within herd, dam relationships were first defined to be hierarchical within sire to estimate the two genetic variances, assuming no maternal, epistatic geneti...

Mortality records of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center during the first year of life were studied using discrete survival analyses. Lamb mortality was studied across periods from birth to weaning, birth to 365 d of age, and weaning to 365 d of age. Animal-time data sets were created for each period using different time intervals: daily, weekly, fort...

Analysis of variance (ANOVA) and symmetric differences squared (SDS) methods for estimating genetic and environmental variances and covariances associated with beef cattle weaning weight were compared via simulation. Simulation was based on the pedigree and record structure of 503 beef weaning weights collected over 19 yr from a university herd. The SDS methodology was used with four models. Th...

Records (2,910) of birth (BWT), weaning (WW), and yearling weight (YW) of F1 calves produced in a top-cross experiment involving Angus, Hereford, Pooled Hereford, Charolais, Limousin, Simmental, Gelbvieh, Maine-Anjou, Chianina, Tarentaise, Shorthorn, and Salers bulls mated to Hereford and Angus cows and records (4,592) of WW on three-breed-cross calves out of 986 F1 females of the same breed cr...

Birth weight (BWT) and calving difficulty (CD) were recorded on 4,580 first parity females from the Germplasm Evaluation (GPE) program at the U.S. Meat Animal Research Center. Both traits were analyzed using a bivariate animal model with direct and maternal effects. Genetic groups for breed of AI sire were fitted to estimate breed differences. Bos Indicus influenced breeds tended to have the la...

Parasitic infections by the salmon louse, Lepeophtheirus salmonis (Krøyer), cause huge economic damage in salmon farming in the northern hemisphere, with combined treatment costs and production losses in 2014 having been estimated at US$ 350 million for Norway (annual production 1.25 million tonnes). The control of L. salmonis relies significantly on medicinal treatments, supplemented by non-ph...