日粮蛋白水平对生长猪生产性能和氮平衡的影响

通过氮平衡试验和饲养试验,研究日粮不同蛋白水平(18.2%、16.5%、15.5%、14.5%和13.6%)对生长猪生产性能和氮平衡的影响。结果表明,粪氮、尿氮、总氮、氮吸收和氮沉积均随日粮蛋白水平的降低而降低(P<0.05);日粮蛋白水平显著影响了猪的生产性能、眼肌面积、血清尿素氮和血浆游离必需氨基酸浓度(P<0.05);在低蛋白日粮中添加赖氨酸、蛋氨酸和苏氨酸,可使生长猪日粮蛋白水平从18.2%降至14.5%,且大幅度降低氮排泄量而不影响其生产性能;当日粮蛋白水平降低4个百分点以上时,赖氨酸、蛋氨酸和苏氨酸均能够满足生长猪生长需要,但异亮氨酸、缬氨酸和精氨酸等必需氨基酸及酪氨酸和丝氨酸等非必需氨基酸则不能满足其生长需要。

Effect of dietary crude protein levels on growth performance and nitrogen balance in growing barrows

Two experiments were conducted with growing barrows to determine the effects of crude protein (CP) levels on growth performance and nitrogen (N) balance. Dietary CP levels were 18.2%,16.5%,15.5%,14.5% and 13.6%,respectively. Results showed that fecal,urinary,and total N excretion as well as N absorption and retention decreased linearly with dietary CP level decreasing (P<0.05);dietary CP intake affected (P<0.05) average daily gain (ADG),average daily feed intake (ADFI),feed efficiency,and longissimus muscle area,as well as plasma concentrations of urea and amino acid (P<0.05);reduction of dietary CP concentration from 18.2% to 14.5% and N excretion had little effect on growth performance;While the reduction of dietary CP was more than 4%;dietary contents of Lys,Met,and Thr are adequate for pig's requirement,but dietary contents of essential amino acids (e.g.Ile,Val and Arg) and some nonessential amino acids (e.g.Tyr and Ser) are inadequate.