Nose Color of Charolais × British Crossbred Beef Steers Alters Body Weight at a Common Degree of Fatness and Marbling Score in Steers Reared Under Similar Management from Birth through Finishing

Abstract

This study evaluated differences in nose color (Black or Pink) on carcass traits and mature body weight in Charolais × British crossbred beef steers. Steers (n = 180; 280±18.2 kg) were weaned and fed for 244 days until harvest. The hypothesis was that steers with black noses had Black Angus dams and that steers with pink noses had Red Angus dams and that these genotypic differences might influence carcass traits and body weight a common fatness endpoint. Data were analyzed as a randomized complete block design using the GLIMMIX Procedure of SAS 9.4 (SAS Inst., Inc., Cary, NC) with the main effect of nose color and finishing phase pen included as a random effect. Individual steer served as the experimental unit for all analyses. Weaning Body Weight (BW) differed (P = 0.05) between black and pink. Final shrunk BW, hot carcass weight, dressing percentage, longissimus muscle area and mRatio did not differ (P ≥ 0.16) between black nose or pink. Rib fat depth was greater (P = 0.01) for black compared to pink. Measures for kidney-pelvic-heart fat tended to increase (P = 0.07) in black nosed steers. Marbling score was greater (P = 0.01) in black versus pink nosed steers. Steers with black noses had greater (P = 0.01) numerical yield grade and lower (P = 0.01) retail yield. Black nosed steers had greater (P = 0.01) estimated Empty Body Fat (EBF) and tended (P = 0.07) to have decreased BW at 28% EBF. The distribution of USDA Quality Grades tended (P = 0.10) to differ between nose classification. Total live weight gain was compromised in the black nosed steers if the steers would have been harvested at an equal fatness endpoint