通过2个试验探讨饲粮中标准回肠可消化缬氨酸(SID Val)水平对育肥猪生长性能、血浆氨基酸和尿素氮含量的影响。试验1、试验2分别选用360头初始体重为(53.75±2.63) kg、(83.67±2.92) kg的杜×长×大三元杂交育肥猪,按体重相近、遗传基础相似的原则,随机分为5个处理,每个处理6个重复,每个重复12头猪。同一试验中,各处理的饲粮除缬氨酸外,其余营养水平均参照NRC(2012)推荐标准设计。试验1中各处理试验饲粮的SID Val水平分别为0.50%、0.55%、0.60%、0.65%和0.70%,试验期为50~80 kg阶段;试验2中各处理试验饲粮的SID Val水平分别为0.43%、0.48%、0.53%、0.58%和0.63%,试验期为80~120 kg阶段。结果表明:试验1中饲粮SID Val水平为0.65%和0.70%的处理的平均日增重和料重比差异不显著(P>0.05),但较饲粮SID Val水平为0.50%的处理得到显著改善(P<0.05);试验2中饲粮SID Val水平为0.53%、0.58%和0.63%的处理的平均日增重和料重比差异不显著(P>0.05),但显著高于饲粮SID Val水平为0.43%的处理(P<0.05);随着饲粮SID Val水平的增加,2个试验中试验猪的平均日增重和料重比均呈线性和二次趋势(P<0.01)。除试验2中血浆谷氨酸和脯氨酸含量外,饲粮SID Val水平对试验1和试验2中试验猪血浆尿素氮及所有必需氨基酸和其他非必需氨基酸含量均无显著影响(P>0.05)。采用折线模型和二次曲线回归模型,综合平均日增重和料重比得出,育肥猪50~80 kg、80~120 kg阶段饲粮标准回肠可消化赖氨酸水平分别为0.85%、0.70%时,其SID Val需要量范围值分别为0.61%~0.66%、0.52%~0.56%,最佳需要量分别为0.65%和0.53%。

Two experiments were conducted to investigate the effects of dietary standardized ileal digestible (SID) valine (Val) level on growth performance, plasma amino acid and urea nitrogen contents of finishing pigs. Each experiment contained 360 barrows (Duroc×Landrace×Yorkshire) which were allotted to five treatments with six replicates per treatment and 12 pigs per replicate according to the similar body weight and genetic foundation. Average initial body weight of pigs in experiment 1 was (53.75±2.63) kg and in experiment 2 was (83.67±2.92) kg. In the same experiment, except dietary Val, the nutrient levels of experimental diets were referred to recommend the nutrient requirements of swine in NRC (2012). Dietary SID Val level was 0.50%, 0.55%, 0.60%, 0.65% and 0.70% in experiment 1, respectively, and the experiment lasted from 50 to 80 kg of body weight; dietary SID Val level was 0.43%, 0.48%, 0.53%, 0.58% and 0.63% in experiment 2, respectively, and the experiment lasted from 80 to 120 kg of body weight. The results showed as follows: in experiment 1, the average daily gain and feed/gain of treatments with the dietary SID Val level at 0.65% and 0.70% were not significantly different (P>0.05), but were significantly improved when compared with the treatment with the dietary SID Val level at 0.50% (P<0.05). In experiment 2, the average daily gain and feed/gain of treatments with the dietary SID Val level at 0.53%, 0.58% and 0.63% were not significantly different (P>0.05), but were significantly improved when compared with the treatment with the dietary SID Val level at 0.43% (P<0.05). With the dietary SID Val level increasing, the average daily gain and feed/gain had linear and quadratic trends in both experiments (P<0.01). In addition to plasma glutamate and proline contents of finishing pigs in experiment 2, plasma urea nitrogen, essential and non-essential amino acid contents of finishing pigs in both experiments were not significantly affected by dietary SID Val level (P>0.05). With broken-line model and quadratic regression model of the data from average daily gain and feed/gain, the dietary SID Val requirement is 0.61% to 0.66% when the dietary SID lysine level is 0.85% and the optimum SID Val level is 0.65% for 50 to 80 kg finishing pigs, and the dietary SID Val requirement is 0.52% to 0.56% when the dietary SID lysine level is 0.70% and the optimum SID Val level is 0.53% for 80 to 120 kg finishing pigs.