Carcass traits and the occurrence of dark cutters in pregnant and nonpregnant feedlot heifers1

Abstract

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 identified at slaughter as being either nonpregnant, pregnant with a moderate-sized fetus (midgestation), or pregnant with a large fetus (late gestation). This was based on visual appraisal of a gravid uterus at the evisceration table. After chilling (24 to 72 h), carcass data were collected. 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 varied from 0 to 25% with an overall mean of 4.74%. Carcass traits of heifers with moderate or large fetuses did not differ (P > .15). Compared with carcasses from nonpregnant heifers, carcasses from pregnant heifers 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 Prime 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 nonpregnant 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 and lower dressing percentage.