【作者】 宋宇轩；

【导师】 姚军虎；

【作者基本信息】 西北农林科技大学 ， 动物营养与饲料科学， 2003， 硕士

【摘要】 将288羽21日龄艾维茵肉仔鸡分为6组，每组4个重复。设计粗蛋白质水平不同(16％、18％和20％)而主要氨基酸及其它营养成分均基本相等的三种日粮，并在此基础上分别添加0.1％尿素共构成六组日粮(CP16、CP16+U、CP18、CP18+U、CP20和CP20+U)随机分配给6组肉鸡，观测日粮粗蛋白质水平及添加尿素对肉鸡生产性能、胴休品质、血液生化指标、养分代谢及鸡体蛋白质沉积率的影响，试期28天。试验结果表明： 1．蛋白质水平(16％、18％和20％)及添加0.1％尿素显著影响肉鸡日采食量、日增重及料重比。随日粮粗蛋白质水平提高，采食量下降，CP16及CP16+U组显著高于其它组(P＜0.05)。全期平均日增重以CP16+U及CP18组最高(P＜0.05)。全期料重比以CP16和CP18+U组最高(P＜0.05)。 2．随日粮粗蛋白质水平上升，腹脂率下降，CP20及CP20+U组显著低于其它组(P＜0.05)，比CP18组分别降低33.77％、42.54％。胸肉率CP18组显著高于CP16、CP16+U及CP20+U组(P＜0.05)，分别高出13.52％、15.01％、20.68％。添加尿素趋于降低腹脂率(P＞0.05)。粗蛋白质水平为20％时添加尿素显著降低了胸肉率(P＜0.05)。 3．粗蛋白质水平及添加尿素显著影响血清BUN及BTP。CP16+U与CP20组之间BUN差异不显著(P＞0.05)，其余各组之间差异极显著(P＜0.01)。添加0.1％尿素可极显著提高BUN水平(P＜0.01)。血清BTP以CP16+U及CP18组最高(P＜0.01)。当粗蛋白质水平为18％时添加尿素可极显著(P＜0.01)降低BTP。 4．随粗蛋白水平提高，日粮粗蛋白质及氨基酸表观代谢率下降(P＜0.05)。添加尿素对日粮粗蛋白质表观代谢率无影响(P＞0.05)。当日粮粗蛋白水平为18％时添加尿素可显著降低日粮非必需氨基酸和总氨基酸表观代谢率(P＜0.05)。 5．日粮粗蛋白水平为16％时排泄物含水量显著降低(P＜0.05)。 6．随日粮粗蛋白水平增加，鸡体蛋白质沉积率有下降趋势(P＞0.05)。添加尿素对鸡体蛋白质沉积率无显著影响(P＞0.05)。 结论：即使满足所有必需氨基酸需要量，日粮中仍需适量的非必需氨基酸。在本试验能量水平及氨基酸模式下，21～49日龄肉鸡日粮的适宜粗蛋白水平为18％，当粗蛋白质水平降为16％时可能由于非必需氨基酸不足而引起生产性能下降。但低蛋白日粮(16％)补加0.1％尿素则可起到非必需氨基酸作用，使肉鸡获得较好的生产成绩。尿素可作为肉鸡蛋白质营养代谢的调控剂使用。更多还原

【Abstract】 To investigate the effect of dietary protein level and supplementation of urea on the performance, carcass quality, blood biochemical index, protein metabolism and body protein retention of broiler, 288 Avin commercial broilers aged 21d were divided into 6 groups, 4 replicates each group. The 3 basal diets (CP16, CP18 and CP20) were designed with 16%, 8% and 20% crude protein (CP) level and constant energy and main essential amino acids. The other 3 diets (CP16+U. CP18+U and CP20+U) were formed by supplementation of 0.1% urea in diets of CP16, CP18 and CP20. The 6 diets were assigned to 6 groups randomly. The experiment lasted 28 days. The results stated:1. The protein level of diets and supplementation of urea affect the feed intake (FI), weight gain (WG) and feed/gain (F/G) significantly. With diet CP level increasing, FI decreased, FI of CP16 and CP16+U were higher than that of other groups significantly (P<0.05). WG of CP16+U and CP18 were higher than that of other groups significantly (PO.05). F/G of CP16 and CP18+U were higher than that of other groups significantly (PO.05).2. With the CP levels of diets increasing, the abdominal fat decreased. The abdominal fat rate of CP20 and CP20+U were lower than other groups (P<0.05), depressed 33.77% and 42.54% than that of CP18 respectively. The breast meat rate of CP18 was higher than that of CP16 and CP16+U and CP20+U (P<0.05), increased 13.52%, 15.01% and 20.68% respectively. Supplementation of urea in diets has the trend of lowering the abdominal fat rate (P>0.05). Diet with 20% CP plus 0.1% urea lowered the breast meat rate significantly(P<0.05).3. CP level of diets and supplementation of urea affect BUN and BTP of broilers significantly. The difference of BUN level between CP16+U and CP20 is not significantly (P<0.05), but significant extremely between other groups (P<.01). Supplementation of 0.1% urea in diets can increase BUN level extremely (P<0.01). The BTP level of CP16+U and CP18 were higher than that of other groups extremely (P<0.01). Diet with 18% CP plus 0.1% urea lowered BTP level extremely (P<0.01).4. With the CP level of diets increasing, the apparent metabolic rate (AMR) of diet CP and amino acid were decreased (P<0.05). Supplementation of urea in diets has no effects on AMR of diet CP (P<0.05), but diet with 18% CP plus 0.1% urea lowered the AMR of non-essential amino acid and total amino acid significantly (P<0.05).5. Diet with 16% CP decreased the water content of excreta of broiler (P<.05).6. Body protein retention rate of broiler decreased with the CP level of diets increasing, but not significantly (P>0.05) .Supplementation of urea in diets has no effects on body protein retention rate of broiler (P>0.05) .The conclusion is:1. Though the requirement of all essential amino acids were meet to broiler, the moderate content of non-essential amino acid were needed in diet.2. Under the energy level and amino acid profile of this experiment, the appropriate CP level of diet is 18% for broilers aged 21 ~49d.3. The diet with 16% CP will hinder the performance of broilers because of the deficiency of non-essential amino acid, but diet with 16% CP plus 0.1% urea could compensate this deficiency and make broiler achieve higher performance. Urea can be used as a regulator of protein metabolism of broilers.更多还原