Predictive ability of a commercial mixed-breed genomic test for feedlot performance and carcass traits of beef × Holstein steers.

Abstract

Genomic tests are marketed as a method to appraise cattle value prior to feedlot entry. We aimed to evaluate the use of a commercial, multi-breed genomic test to predict terminal production characteristics of beef × Holstein steers. Phenotypes of feedlot performance and carcass characteristics were evaluated in beef × Holstein steers (n = 259) sired by 8 beef breeds. Steers were genotyped with Igenity Beef (Neogen Corporation, Lansing, MI), which ranks cattle for individual traits and by selection indexes on a scale of 1 to 10. Trait rankings were converted to molecular breeding values (MBV) derived from genotype. Expected progeny differences (EPD) of each steer's sire were accessed from their respective breed associations. US Meat Animal Research Center across-breed adjustments for beef cattle were applied to growth and carcass sire EPD for all cattle except the 11 Wagyu-sired steers (n = 248 steers with sire EPD). Breed-adjusted sire EPD and MBV of traits were correlated with associated phenotypes of beef × Holstein steers and phenotypes were regressed on sire EPD and MBV. Sire EPD and MBV of yearling weight (YW) and hot carcass weight (HCW) were positively associated with initial and final feedlot body weight, respectively. The MBV of average daily gain (ADG) was not associated with phenotypic ADG, though greater derived sire EPD of ADG was associated with greater ADG and dry matter intake (DMI). The MBV of residual feed intake (RFI) was associated with DMI (P = 0.02) but not RFI or gain to feed ratio. Each kg of RFI predicted by MBV resulted in 0.31 kg greater ADG (P < 0.01), suggesting that MBV of RFI in beef × Holstein steers are not independent of rate of gain. For each kg of HCW predicted by MBV and sire EPD carcasses were 0.52 and 0.80 kg heavier (P < 0.01). Neither sire EPD nor MBV of ribeye area and backfat thickness were related to the corresponding phenotypes of beef × Holstein carcasses (P > 0.05). Both MBV and sire EPD of marbling score were strong predictors of marbling score and intramuscular fat content (P < 0.05). Tenderness MBV accurately predicted tenderness of the longissimus muscle of beef × Holstein progeny (P < 0.01). Igenity Beef Terminal Index ranking was associated with greater feedlot profitability (P = 0.03), but marbling MBV and sire EPD were more strongly associated with feedlot net profit (P < 0.01). Breed-adjusted sire EPD performed similarly to Igenity Beef MBV in predicting growth performance, carcass characteristics, and net profit of beef × Holstein steers.