153 Meat Quality of Barbados Blackbelly and St. Croix Hair Sheep Lambs Rendered Short Scrotum or Castrated at Weaning

Abstract

Abstract This study evaluated meat quality parameters of short scrotum and castrated Barbados Blackbelly (BB; n = 16) and St. Croix (STX; n = 15) hair sheep ram lambs. Ram lambs born in April (n = 21) and December (n = 10) were rendered short scrotum (SS; n = 17) or castrated (CA; n = 14) using elastrator bands at weaning (63 days of age). Following a transition period of 2 months in a dry lot, ram lambs co-grazed with ewe lambs in a rotational pasture system and were provided soy hull at 3% BW daily. At target weights of app. 40 kg lambs were slaughtered and loin cuts from individual carcasses were collected for meat quality analysis. Data from the two lambing groups were pooled and analyzed as a completely randomized design with a 2 x 2 factorial treatment arrangement for breed (BB or STX) and sex class (SS or CA). The CIE L* (lightness), a* (redness), and b* (yellowness) values of loin cuts were not significantly influenced by breed or sex class. The longissimus muscle (LM) in loin cuts from CA lambs had a greater (P < 0.0001) fat content (3.73 vs 2.55 ± 0.155%) and tended (P = 0.06) to have a decreased moisture content (69.63 vs 70.75 ± 0.413%) than that from SS lambs. Neither breed nor sex class significantly affected the myoglobin content, percent metmyoglobin and thiobarbituric acid reactive substances (TBARS) values of LM from lamb cuts. Cuts from SS lambs had greater (P < 0.0001) shear force values (3.22 vs 2.64 ± 0.093 kg) than those from CA lambs. However, the cooking loss of loin cuts was not significantly influenced by breed or sex class. The fatty acid profiles of LM from experimental lambs were significantly influenced by breed and sex class. Compared with BB, STX had greater (P < 0.05) concentrations of myristic (C14:0;.38 vs.23%), palmitic (C16:0; 20.15 vs8.98%) and oleic (C18:1n9; 45.01 vs 42.81%), but less than (P < 0.05) concentrations of stearic (C18:0;7.29 vs9.33%) and linoleic (C18:2n6; 6.14 vs 7.47%) acids in LM. Furthermore, the LM from SS lambs had greater (P < 0.05) concentrations of C18:2n6 (8.09 vs 5.51%) and arachidonic (C20:4n6, 2.04 vs.40%), but lless than (P < 0.05) concentrations of C16:0 (19.07 vs 20.06%) and C18:1n9 (41.57 vs 46.24%) acids than that from CA lambs. Data suggest that meat quality parameters were more greatly influenced by sex class than breed when landrace hair sheep lambs were slaughtered at a target weight. Loin cuts from SS lambs were leaner, but less tender than those of CA lambs, and also differed in their fatty acid profiles. Hence meat quality will be impacted by the choice of rendering male lambs sterile.