PS10-26. Retail Meat Cut Yield and Meat Quality of Light Weight and Heavy Weight, Intact or Castrated Crossbred Lambs Fed Diets Containing Direct-fed Microbial Additives.

Abstract Enhancing retail meat-cut yield and lamb meat quality is important for meeting consumer preferences and improving the value of lamb products. Feed additives, animal type (AT), and initial body weight (IBW) during the finishing phase may influence carcass meat-cut yield and meat quality traits. The objective of this study was to evaluate the effects of direct-fed microbial additives (DFM), AT, and IBW on retail meat cut yield and meat quality of crossbred lambs. Thirty-two crossbred lambs were housed in pairs and fed a finishing diet containing 70% commercial concentrate and 30% chopped tropical grass hay. Lambs were classified by AT (intact or castrated) and IBW (heavy = 33 kg or light = 28 kg) and randomly assigned to four dietary treatments: control (CON), DFM1, DFM2, or a mixture of DFM1 and DFM2. The additives, containing different blends of bacteria and yeast, were manually mixed into the diet throughout the finishing period until lambs reached slaughter body weight (SBW = 48 kg). Lambs were slaughtered at a commercial slaughter facility, and cold carcasses were processed into retail meat cuts, including loin chops (LC), shoulder chops (SC), French chops (FC), and shanks (S). Each cut was weighed and expressed as a percentage of cold carcass weight. Samples of the longissimus dorsi muscle were collected to determine meat quality parameters, including color (L*, a*, b*), pH, and water holding capacity (WHC). Data were analyzed using a completely randomized design with a factorial arrangement of treatments (4 DFM × 2 AT × 2 IBW), and means were separated using Tukey’s test. Direct-fed microbials did not affect (P > 0.05) the yields of LC (CON = 12.08%, DFM1 = 12.07%, DFM = 11.86%, DFM1 + 2 = 12.30%), SC, FC, or S. Intact lambs had lower (P < 0.05) LC yield (11.08%) and greater SC yield (25.33%) than castrated lambs (13.07% and 23.52%, respectively), whereas FC and S yields were similar between animal types. Initial body weight did not influence SC, FC, or S yields (P > 0.05), but LC yield was greater (P < 0.05) in heavy-weight (12.93%) than in light-weight lambs. Dietary DFM did not affect meat color (L*, a*, b*), pH, or WHC (P > 0.05). However, intact lambs had greater (P < 0.05) L* and b* values and higher pH than castrated lambs, whereas WHC was greater (P < 0.05) in castrated lambs. Meat quality parameters were not affected by IBW. In summary, DFM and initial body weight did not influence retail cut yield or lamb meat quality. However, differences in several meat quality parameters were observed between intact and castrated lambs.