Department of Agricultural and Environmental Sciences, Tuskegee University,Tuskegee, AL 36088, USA.
J Anim Sci. 2012 Jul;90(7):2092-108. doi: 10.2527/jas.2011-3945. Epub 2012 Jan 27.
The objectives of this experiment were to determine the effects of 2 different breeds (BR), Boer and Kiko, and 4 post-weaning harvest ages (HA; Days 0, 29, 56, and 85) on growth, carcass traits, blood metabolites, and lipogenic gene expression. Forty-eight goat (Capra hircus) kids (BW = 23.9 ± 1.50 kg; 3 to 4 mo) were used in a 2 × 4 factorial arrangement of treatments. Goats were stratified by BW within BR and randomly assigned to 4 HA. Kids were born between March 15 and April 7 to purebred does, and were represented by at least 3 purebred sires within each BR. They were fed a grain/hay (80:20) diet once per day. At designated HA, randomly pre-assigned goats (n = 6) from each BR were transported to the Meat Science Lab at Mississippi State University, Starkville, MS, and were harvested. There were no interactions (P > 0.10) between BR and HA. Boer tended (P = 0.08) to have greater initial BW, final BW (P = 0.05), and G/F ratio (P = 0.05). Although the 80:20 grain/hay diet was reinforced by adjusting DMI, both BR had similar total DMI, Boer kept that ratio, while Kiko consumed more (P = 0.001) hay (70:30, grain/hay) and had more (P = 0.001) DMI when expressed as g/kg BW. Boer tended to have greater transportation shrink (P = 0.07), HCW (P = 0.08), and cold carcass weights (CCW; P = 0.08), with greater (P = 0.001) carcass fat. No differences (P > 0.10) were observed in carcass shrink, dressing percentage, 12th rib fat thickness, and LM area between the 2 BR. When expressed as percentage empty BW, carcass bone was similar (P = 0.25), whereas muscle percentage (P = 0.02) was greater for Kiko and fat percentage was greater (P = 0.001) for Boer. Fat as a percentage of CCW remained relatively similar (P > 0.10) for both BR for the 2nd and 3rd HA. Differences were more evident (P = 0.01) at the 4th HA. Boer reached targeted harvest weight (29 kg) at the 3rd HA, while fat deposition continued (P = 0.01) during the 4th HA. Breed had no effect (P > 0.10) on meat color (L*, a*, b*) but HA affected (P = 0.001) all color values. Boer had similar 3-hydroxyl-3-methylglutaryl-CoA synthase mRNA abundance, but was greater (P < 0.03) in acetyl CoA carboxylase compared with Kiko. There was no difference (P = 0.52) in total serum fatty acids (FA, mg/mL) between the 2 BR. As animals aged, their total serum FA increased (P < 0.05) and changed to an undesirable profile. Kiko had a greater (P = 0.02) percentage of muscle and less (P = 0.001) fat in the carcass. We concluded that different BR might need different harvest endpoints and feed input according to consumer acceptability.
本实验的目的是确定 2 个不同品种（BR），即布尔山羊和基库羊，和 4 个断奶后收获年龄（HA；0 天、29 天、56 天和 85 天）对生长、胴体性状、血液代谢物和脂肪生成基因表达的影响。使用 48 只山羊（Capra hircus）幼崽（BW=23.9±1.50kg；3-4 月龄）进行 2×4 因子处理安排。根据 BR 内的 BW 对山羊进行分层，并随机分配到 4 个 HA。幼崽于 3 月 15 日至 4 月 7 日之间出生，来自纯种母羊，每个 BR 至少有 3 只纯种公羊代表。它们每天喂食一次谷物/干草（80:20）饲料。在指定的 HA，从每个 BR 随机预分配 6 只山羊（n=6）运往密西西比州立大学肉类科学实验室，斯塔克维尔，MS，并进行屠宰。BR 和 HA 之间没有相互作用（P>0.10）。布尔山羊倾向于具有更大的初始 BW、最终 BW（P=0.05）和 G/F 比（P=0.05）。尽管 80:20 的谷物/干草饮食通过调整 DMI 来加强，但两个 BR 的总 DMI 相似，布尔山羊保持了该比例，而基库山羊则更多地（P=0.001）消耗干草（70:30，谷物/干草），并且当以 g/kg BW 表示时，DMI 更多（P=0.001）。布尔山羊的运输收缩（P=0.07）、HCW（P=0.08）和冷胴体重量（CCW；P=0.08）较大，胴体脂肪较多（P=0.001）。两个 BR 之间在胴体收缩、出肉率、第 12 肋脂肪厚度和 LM 面积方面没有差异（P>0.10）。当以空 BW 的百分比表示时，胴体骨骼相似（P=0.25），而 Kiko 的肌肉百分比（P=0.02）较大，Boer 的脂肪百分比（P=0.001）较大。对于这两个 BR，CCW 的脂肪百分比在第二和第三个 HA 仍然相对相似（P>0.10）。在第四个 HA 时，差异更加明显（P=0.01）。Boer 在第三个 HA 达到目标收获体重（29kg），而脂肪沉积在第四个 HA 期间继续（P=0.01）。品种对肉色（L*、a*、b*）没有影响（P>0.10），但 HA 影响所有颜色值（P=0.001）。Boer 的 3-羟-3-甲基戊二酰辅酶 A 合酶 mRNA 丰度相似，但与 Kiko 相比，乙酰辅酶 A 羧化酶更高（P<0.03）。两个 BR 之间的总血清脂肪酸（FA，mg/mL）没有差异（P=0.52）。随着动物年龄的增长，其总血清 FA 增加（P<0.05），并呈现出不理想的模式。Kiko 的胴体肌肉百分比更高（P=0.02），脂肪百分比更低（P=0.001）。我们得出结论，不同的 BR 可能需要根据消费者的接受程度，采用不同的收获终点和饲料投入。
