Cromwell G L, Cline T R, Crenshaw J D, Crenshaw T D, Ewan R C, Hamilton C R, Lewis A J, Mahan D C, Miller E R, Pettigrew J E
Dept. of Anim. Sci., Univ. of Kentucky, Lexington 40546.
J Anim Sci. 1993 Jun;71(6):1510-9. doi: 10.2527/1993.7161510x.
A cooperative research study involving three experiments and 2,318 pigs was conducted at 12 research stations to evaluate the protein (lysine) requirements of barrows and gilts. The two sexes were penned separately and fed fortified corn-soybean meal diets containing protein levels ranging from 12.0 to 17.2%. Lysine levels in these diets ranged from .52 to .90%. Protein levels in Exp. 1 were 12, 14, and 16%; in Exp. 2, protein levels were 13, 14, 15, and 16%; and in Exp. 3, they were 13.2 15.2, and 17.2%. Fat (5%) was added to one-half of the diets in Exp. 3. Each station that participated contributed a minimum of two replicate pens of pigs per diet-sex combination in a given experiment. Average initial and final weights were 35 and 99 kg in Exp. 1 and 51 and 105 kg in Exp. 2 and 3, respectively. At the end of the test period, pigs were slaughtered and hot carcass weight, 10th rib fat depth, and longissimus muscle area were measured. Percentage of carcass muscle was estimated from these data. Overall, barrows gained weight faster than gilts (P < .01), but gilts required less feed per unit of gain (P < .05) and had less backfat, larger longissimus muscle areas, and a greater percentage of carcass muscle (P < .01) than did barrows. Lean growth rate was similar for barrows and gilts (332 vs 329 g/d). Increasing the dietary protein or lysine level resulted in improved rate and efficiency of gain and increased carcass leanness and lean growth rate in gilts, but the increase was less pronounced or did not occur in barrows, resulting in protein level x sex interactions. Feeding low-protein (12 or 13%) diets decreased performance and carcass leanness to a greater extent in gilts than in barrows. The pooled data from the three experiments indicated that most traits tended to reach a plateau at 13% CP (.60% lysine) in barrows, whereas in gilts, weight gains, feed/gain, carcass muscle, and lean growth rate continued to improve, but at a decreasing rate, with up to 17.2% CP (.90% lysine). The results indicate that gilts require higher concentrations of dietary amino acids to maximize lean growth rate than do barrows.
在12个研究站进行了一项合作研究，该研究包含三个实验，涉及2318头猪，旨在评估去势公猪和后备母猪的蛋白质（赖氨酸）需求。将两种性别分开圈养，并饲喂强化玉米-豆粕日粮，日粮蛋白质水平范围为12.0%至17.2%。这些日粮中的赖氨酸水平范围为0.52%至0.90%。实验1中的蛋白质水平为12%、14%和16%；实验2中的蛋白质水平为13%、14%、15%和16%；实验3中的蛋白质水平为13.2%、15.2%和17.2%。在实验3中，一半的日粮添加了5%的脂肪。在给定实验中，每个参与的研究站针对每种日粮-性别组合至少提供两栏重复的猪。实验1中猪的初始和最终平均体重分别为35千克和99千克，实验2和3中分别为51千克和105千克。在试验期结束时，对猪进行屠宰，并测量热胴体重、第10肋处的背膘厚度和腰大肌面积。根据这些数据估算胴体肌肉百分比。总体而言，去势公猪增重比后备母猪快（P < 0.01），但后备母猪每单位增重所需饲料较少（P < 0.05），且背膘比去势公猪少，腰大肌面积更大，胴体肌肉百分比更高（P < 0.01）。去势公猪和后备母猪的瘦肉生长率相似（分别为332克/天和329克/天）。提高日粮蛋白质或赖氨酸水平可提高后备母猪的增重速度和效率，并增加胴体瘦肉率和瘦肉生长率，但去势公猪的增加不太明显或未出现，从而导致蛋白质水平×性别的交互作用。饲喂低蛋白（12%或13%）日粮对后备母猪生产性能和胴体瘦肉率的降低幅度比对去势公猪更大。来自这三个实验的汇总数据表明，对于去势公猪，大多数性状在13%粗蛋白（0.60%赖氨酸）时趋于平稳，而后备母猪的体重增加、料重比、胴体肌肉和瘦肉生长率继续提高，但增速逐渐降低，最高可达17.2%粗蛋白（0.90%赖氨酸）。结果表明，与去势公猪相比，后备母猪需要更高浓度的日粮氨基酸以最大化瘦肉生长率。
