Current trends in the United States dairy industry suggest that crossbred beef × dairy calves are replacing a proportion of the calf-fed Holstein steers slaughtered for beef each year. Economic pressures value preweaned beef × dairy calves at a premium over preweaned dairy bull calves; however, there is little modern data to support that intensively fed crossbred calves maintain their premium value over dairy steers across the supply chain. Data from international production systems and from historic research suggests that beef × dairy cattle had greater average daily gains and converted feed to gain more efficiently than dairy steers. Regarding carcass characteristics, across the literature crossbreds consistently yielded heavier carcasses that had lower proportions of trim than dairy steers. Fewer comparisons of beef × dairy and dairy steers exist in the literature for other economically relevant carcass characteristics such as ribeye area, backfat, marbling, tenderness, and eating quality. Existing published data are inconsistent among studies, highlighting the necessity for more research tailored to the United States beef production system

Horn flies (Haematobia irritans [L.]) contribute to major economic losses of pastured cattle operations, particularly in organic herds because of limitations on control methods that can be used. The objectives of this research were to determine if resistance to horn flies is a heritable trait in organic Holstein cattle, determine associations with yield traits, and to detect genomic regions associated with fly infestation. Observations of fly load were recorded from 1,667 pastured Holstein cows, of which 640 were genotyped, on 13 organic dairies across the United States. Fly load score was determined using a 0 to 4 scale based on fly coverage from chine to loin on one side of the body, with 0 indicating few to no flies and 4 indicating high infestation. The scoring system was validated by counting flies from photographs taken at the time of scoring from 252 cows. To mitigate the effect of our data structure on potential selection bias effects on genetic parameter estimates, survival to subsequent lactations of scored animals and herd-mates that had been culled before the trial was accounted for as the trait stayability. Genetic parameters were estimated using single-step genomic analysis with 3-trait mixed models that included fly score, stayability, and a third phenotype. Model effects differed by variable, but fixed effects generally included a contemporary group, scorer, parity, and stage of lactation; random effects included animal, permanent environment, and residual error. A genome-wide association study was performed by decomposing estimated breeding values into marker effects to detect significant genomic regions associated with fly score. The rank correlation between the subjective fly score and the objective count was 0.79. The average heritability of fly score (± standard error) estimated across multiple models was 0.25 ± 0.04 when a known Holstein maternal grandsire was required and 0.19 ± 0.03 when only a known Holstein sire was required. Genetic correlation estimates with yield traits were moderately positive, but a greater fly load was associated with reduced yield after accounting for genetic merit. Lower fly loads were associated with white coat coloration; a significant genomic region on Bos taurus autosome 6 was identified that contains the gene KIT, which was the most plausible candidate gene for fly resistance because of its role in coat pattern and coloration. The magnitude of heritable variation in fly infestation is similar to other traits included in selection programs, suggesting that producers can select for resistance to horn flies.

In a small sample of carriers of cholesterol deficiency, the genetic disorder that affects low density lipoprotein transportation in Holstein cattle, serum cholesterol was lower than that of their herdmates. Furthermore, cows that inherited the cholesterol deficiency mutation from their sire placed in the top 5 of their classes at World Dairy Expo more often than their noncarrier paternal sisters. Highlights • Cholesterol deficiency carriers had lower serum cholesterol than noncarriers. • Cholesterol deficiency carriers had faster milking speeds than noncarriers. • Cholesterol deficiency carriers had lower body weights than noncarriers. • Cows that carry cholesterol deficiency tend to have an advantage in the show ring.

Objectives were to compare feedlot performance and carcass traits of F1 beef × Holstein steers and Holstein steers. Angus or Limousin × Holstein crossbred [n = 27; age = 12 ± 3 months; body weight (BW) = 435 ± 8 kg] and Holstein (n = 20; age = 11 ± 2 months; BW = 400 ± 9 kg) steers were fed at the Pennsylvania Department of Agriculture Livestock Evaluation Center for 111 days. Feed intake was recorded using the GrowSafe Feed Intake Monitoring System (Model 4000E, GrowSafe Systems Ltd., Calgary AB, Canada). The diet contained corn silage, dried distillers grains, soybean meal, and cracked corn and was formulated to meet or exceed the requirements of beef cattle (NASEM, 2016). Growth performance variables of interest and carcass measurements were analyzed with the Mixed procedure of SAS (SAS 9.4; SAS Institute Inc., Cary, NC). USDA assigned quality grades (QG) and yield grades (YG) were analyzed the with GLIMMIX procedure of SAS. Breed was a fixed effect in all models. There were no differences (P > 0.05) between breeds in average daily gain or feed efficiency. Crossbreds exceeded Holsteins in initial (P < 0.01) and final BW (P = 0.01), dry matter intake (P = 0.03), hot carcass weight (P < 0.01), backfat (P = 0.03), and ribeye area (REA; P < 0.01). Thirty-five percent (35%) of the Holsteins received a QG of Choice or above while 74% of crossbreds graded USDA Choice or above (P = 0.01). However, 75% of Holsteins were YG 2 or lower while only 45% of crossbreds achieved YG 2 or less (P = 0.05). There was no improvement in efficiency when crossbreds were compared to Holsteins; however, carcasses from crossbreds were more likely to grade USDA Choice or above while yielding greater REA and backfat than Holsteins.