Belay T, Teeter R G
Oklahoma State University, Animal Science Department, Stillwater 74078, USA.
Poult Sci. 1996 Nov;75(11):1383-92. doi: 10.3382/ps.0751383.
One experiment utilizing Cobb x Cobb male broilers was conducted to evaluate virginiamycin (VM; 0, 15, 20 ppm) and diet caloric density (CD; 2,945, 3,200 AMEn/kg) effects on broiler live performance, blood serum metabolites, and carcass composition. The starter period exposed birds to recommended brooding conditions, whereas from 3 to 7 wk birds were exposed to thermoneutral (TN, 24 C) or cycling temperature (CT, 24 to 35 C) environments (E). During the 21-d starter period, VM levels and high CD increased (P < 0.05) BW gain (G) and gain:feed (G:F) improved (P < 0.05) with 20 ppm VM and high CD. During 3 to 7 wk, CT reduced (P < 0.05) most live performance and carcass variables as well as heat production (HP) and energetic efficiency whereas energy content per gram of tissue increased. The main effect of VM and CD on blood serum constituents was not significant; however, CT decreased (P < 0.05) serum Na, K, Ca, Mg, Fe, albumin, and total protein. Within CT, G increased (P < 0.05) with high CD and with the 15 ppm VM combination, whereas within TN, G was unaffected by CD, but increased (P < 0.05) with the 20 ppm VM and low CD combination compared with the control. High CD increased (P < 0.05) BW, G, carcass weight, dressing percentage, carcass percentage fat, carcass dry matter, carcass energy content per bird, HP, fat, and protein gain but reduced (P < 0.05) carcass percentage protein and energetic efficiency. Carcass weight, breast yield, fat, and protein gains as well as dry matter carcass energy content increased (P < 0.05) with VM compared with controls. The reduced (P < 0.05) calorie intake and HP with concomitant increase (P < 0.05) in calorie gain with 20 ppm VM increased (P < 0.05) caloric efficiency. In summary, the results suggest that VM improves bird performance by reducing HP and that reduced HP during high CT improves body temperature homeostasis.
进行了一项利用科宝×科宝雄性肉鸡的实验，以评估维吉尼亚霉素（VM；0、15、20 ppm）和日粮能量密度（CD；2945、3200 AMEn/kg）对肉鸡生长性能、血清代谢物和胴体组成的影响。育雏期让雏鸡处于推荐的育雏条件下，而从第3周龄到第7周龄，雏鸡处于热中性（TN，24℃）或循环温度（CT，24至35℃）环境（E）中。在21天的育雏期内，VM水平和高能量密度增加了（P<0.05）体重增加（G），并且20 ppm VM和高能量密度组的料重比（G:F）得到改善（P<0.05）。在第3周龄到第7周龄期间，循环温度降低了（P<0.05）大多数生长性能和胴体变量以及产热量（HP）和能量效率，而每克组织的能量含量增加。VM和能量密度对血清成分的主要影响不显著；然而，循环温度降低了（P<0.05）血清钠、钾、钙、镁、铁、白蛋白和总蛋白。在循环温度环境下，高能量密度组和15 ppm VM组合使生长性能增加（P<0.05），而在热中性环境下，能量密度对生长性能无影响，但与对照组相比，20 ppm VM和低能量密度组合使生长性能增加（P<0.05）。高能量密度增加了（P<0.05）体重、生长性能、胴体重、屠宰率、胴体脂肪百分比、胴体干物质、每只鸡的胴体能量含量、产热量、脂肪和蛋白质增加量，但降低了（P<0.05）胴体蛋白质百分比和能量效率。与对照组相比，VM使胴体重、胸肉产量、脂肪和蛋白质增加量以及胴体干物质能量含量增加（P<0.05）。20 ppm VM使采食量和产热量降低（P<0.05），同时热量增加量增加（P<0.05），从而提高了（P<0.05）能量效率。总之，结果表明VM通过降低产热量来提高鸡的生长性能，并且在高循环温度期间降低产热量可改善体温稳态。
