Zinn Richard Avery, Jorquera Alejandro Plascencia
Department of Animal Science, University of California, Davis, CA 95616-8521, USA.
Vet Clin North Am Food Anim Pract. 2007 Jul;23(2):247-68, vi-vii. doi: 10.1016/j.cvfa.2007.03.003.
The inclusion of supplemental fats in growing-finishing diets for feedlot cattle also improves diet "condition." Quality factors that may influence the feeding value of fat include the source of fat; moisture, impurities, and unsaponifiables; free fatty acid concentration; degree of saturation or titer; and rancidity (peroxide value). The net energy value of fat declines linearly with an increasing level of supplementation because of constraints on postruminal fatty acid digestion. The authors recommend that receiving diets not contain more than 2% supplemental fat. Little evidence suggests that the feeding value of fat is different for Holsteins than for conventional beef breeds. Fat supplementation is not consistent in its effect on intramuscular fat distribution (marbling), longissimus (rib eye) area, and fat thickness, but can be expected to increase dressing percentage and kidney, pelvic, and heart fat percentage.
在育肥牛的生长育肥日粮中添加脂肪也能改善日粮的“状态”。可能影响脂肪饲喂价值的质量因素包括脂肪来源、水分、杂质和不皂化物、游离脂肪酸浓度、饱和度或滴定度以及酸败程度(过氧化值)。由于瘤胃后脂肪酸消化受到限制,随着添加水平的增加,脂肪的净能量值呈线性下降。作者建议育肥牛日粮中补充脂肪的含量不应超过2%。几乎没有证据表明,荷斯坦牛的脂肪饲喂价值与传统肉牛品种有差异。脂肪添加对肌肉内脂肪分布(大理石花纹)、背最长肌(肋眼)面积和脂肪厚度的影响并不一致,但有望提高屠宰率以及肾、盆腔和心脏脂肪比例。