Campbell C G, Titgemeyer E C, Cochran R C, Nagaraja T G, Brandt R T
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-1600, USA.
J Anim Sci. 1997 Apr;75(4):1167-78. doi: 10.2527/1997.7541167x.
Three studies were conducted to evaluate amino acid utilization by cattle. In Exp. 1, five steers (580 kg) were fed 86% rolled corn diets with mixtures of amino acids containing up to 6 g/d DL-Met, 24 g/d L-Lys, 6 g/d L-Thr, and 3 g/d L-Trp. Treatments had little effect on ruminal fermentation, diet digestibility, N flow to the duodenum, or microbial efficiency. Ruminal concentrations of Met and Lys increased linearly (P < .05) with amino acid supplementation, whereas Thr responded quadratically, and Trp was not altered. In Exp. 2, four steers (414 kg) were used to measure effects of dietary monensin or laidlomycin propionate in high-grain diets supplemented with amino acids. Ionophores had no significant effect on ruminal fermentation or outflows of amino acids from the rumen. In Exp. 3, 100 steers (287 kg initial BW) were fed diets containing 1% of a nonprotein N source. Treatments were 1) no supplemental N (UREA), 2) UREA plus soybean meal (SBM), 3) UREA plus 2 g/d DL-Met, 8 g/d L-Lys, 2 g/d L-Thr, and 1 g/d L-Trp, or 4) UREA plus 4 g/d DL-Met, 16 g/d L-Lys, 4 g/d L-Thr, and 2 g/d L-Trp. During the growing period (diets based on whole-plant milo silage), gains were higher for SBM-supplemented steers than for UREA steers and intermediate for steers supplemented with amino acids. Few significant differences in performance were observed among treatments during the finishing phase (diets based on dry-rolled corn) or for the entire experiment, but cattle fed SBM or amino acids tended to be fatter and have better marbling scores and quality grades. Amino acids did not greatly alter ruminal fermentation or cattle performance.
开展了三项研究来评估牛对氨基酸的利用情况。在试验1中，给5头阉牛（体重580千克）饲喂含86%压片玉米的日粮，并添加氨基酸混合物，其中DL-蛋氨酸含量最高达6克/天、L-赖氨酸含量最高达24克/天、L-苏氨酸含量最高达6克/天、L-色氨酸含量最高达3克/天。各处理对瘤胃发酵、日粮消化率、十二指肠氮流量或微生物效率影响不大。随着氨基酸添加量增加，瘤胃中蛋氨酸和赖氨酸浓度呈线性增加（P < 0.05），而苏氨酸呈二次曲线反应，色氨酸浓度未改变。在试验2中，用4头阉牛（体重414千克）来测定日粮中莫能菌素或丙酸拉沙洛西在添加氨基酸的高谷物日粮中的作用。离子载体对瘤胃发酵或瘤胃中氨基酸流出量无显著影响。在试验3中，给100头阉牛（初始体重287千克）饲喂含1%非蛋白氮源的日粮。处理方式有：1）不补充氮（尿素），2）尿素加豆粕（SBM），3）尿素加2克/天DL-蛋氨酸、8克/天L-赖氨酸、2克/天L-苏氨酸和1克/天L-色氨酸，或4）尿素加4克/天DL-蛋氨酸、16克/天L-赖氨酸、4克/天L-苏氨酸和2克/天L-色氨酸。在生长阶段（日粮以全株高粱青贮料为基础），补充豆粕的阉牛增重高于补充尿素的阉牛，补充氨基酸的阉牛增重居中。在育肥阶段（日粮以干压片玉米为基础）或整个试验期间，各处理间在性能上几乎没有显著差异，但饲喂豆粕或氨基酸的牛往往更肥，大理石花纹评分和胴体品质等级更好。氨基酸对瘤胃发酵或牛的性能影响不大。
