CARCASS TRAITS AND THE OCCURRENCE OF DARK CUTTERS IN PREGNANT AND NONPREGNANT FEEDLOT HEIFERS

The objective of this study was to determine whether the occurrence of dark cutters and selected carcass traits differ between pregnant and nonpregnant feedlot heifers. Feedlot heifers (n = 8,292) were identifi ed at slaughter as being either nonpregnant, pregnant with a moderate- sized fetus (midgestation), or pregnant with a large fetus (late gesta tion). This was based on visual appraisal of a gravid uterus at the ev isceration table. After chilling (24 to 72 h), carcass data were colle cted. Cattle originated from 23 different commercial feedyards located within a 350-km radius of a commercial slaughter facility located in southwest Kansas. Across slaughter lots, the incidence of pregnancy va ried from 0 to 25% with an overall mean of 4.74%. Carcass traits of he ifers with moderate or large fetuses did not differ (P > .15). Compare d with carcasses from nonpregnant heifers, carcasses from pregnant hei fers were 4.5 kg lighter (P < .01), had .11 cm more fat thickness (P < .01), and exceeded the number of carcasses that graded Choice or Prim e by 6% (P < .01). Carcasses from pregnant heifers had higher maturity scores (P < .01) and there was no incidence of dark cutters (P < .01) compared with a 1.7% incidence of dark cutters in carcasses from nonp regnant heifers. Any economical advantage in the pregnant heifers due to their higher percentage of Choice carcasses and lower incidence of dark cutters may be offset by their increased carcass fat thickness an d lower dressing percentage.