饲粮异亮氨酸水平对肥育猪生长性能、胴体性状和肉品质的影响

本试验旨在研究饲粮异亮氨酸水平对肥育猪生长性能、胴体性状和肉品质的影响。选取体重为(77.0±0.1)kg的杜×长×大三元杂交去势公猪72头,随机分为3组,每组6个重复,每个重复4头猪。3组试验猪分别饲喂含0.25%(低异亮氨酸水平,表现为异亮氨酸缺乏,L-Ile组)、0.39%(NRC推荐异亮氨酸水平,N-Ile组,作为对照组)和0.53%(高异亮氨酸水平,表现为异亮氨酸超量添加,H-Ile组)标准回肠可消化异亮氨酸的饲粮。试验期为28 d。结果表明:饲粮异亮氨酸水平对肥育猪的平均日增重和平均日采食量没有显著影响(P0.05),但L-Ile组料重比较对照组显著增加(P0.05);随着饲粮异亮氨酸水平的增加,肥育猪背最长肌肌内脂肪含量线性提高(P0.05),而剪切力线性下降(P0.05);与对照组相比,采食异亮氨酸缺乏饲粮的肥育猪的背膘厚、眼肌面积和肉色评分显著降低(P0.05),采食异亮氨酸缺乏或超量添加饲粮的肥育猪的热胴体重、屠宰率以及背最长肌滴水损失和黄度值均显著降低(P0.05);随着饲粮异亮氨酸水平的增加,血清甘油三酯含量线性提高(P0.05),血清尿素氮含量线性下降(P0.05);与对照组相比,采食异亮氨酸超量添加饲粮的肥育猪的血清葡萄糖含量显著增加(P0.05),采食异亮氨酸缺乏饲粮的肥育猪的血清中游离的必需氨基酸、非必需氨基酸和总氨基酸的浓度显著降低(P0.05),而采食异亮氨酸缺乏或超量添加饲粮的肥育猪血清总胆固醇、低密度脂蛋白和高密度脂蛋白含量均显著降低(P0.05)。由此得出,饲粮中异亮氨酸缺乏对肥育猪生长性能、胴体性状和肌内脂肪含量有负面影响,而超量添加异亮氨酸会显著改善肌肉的剪切力和滴水损失,增加肌内脂肪含量,但会以降低热胴体重、屠宰率为代价。

Effects of Dietary Isoleucine Level on Growth Performance,Carcass Traits and Meat Quality of Finishing Pigs

This experiment aimed to investigate the effects of dietary isoleucine level on growth performance, carcass traits and meat quality of finishing pigs.Seventy-two Duroc×Landrace×Large White barrows with the body weight of (77.0±0.1) kg were assigned into 3 groups with 6 replicates per group and each replicate had 4 barrows.The barrows in the three groups were fed diets contained 0.25% (low isoleucine level which showed isoleucine deficiency;L-Ile group), 0.39% (NRC recommended level of isoleucine;N-Ile group, as control group) and 0.53% (high isoleucine level which showed isoleucine excess;H-Ile) standardized ileal digestible isoleucine, respectively.The experiment lasted for 28 days.The results showed that dietary isoleucine level had no effects on average daily gain and average daily feed intake of finishing pigs (P>0.05), but the feed/gain of finishing pigs in L-Ile group was significantly increased compared with control group (P<0.05).As the isoleucine level increasing, the content of intramuscular fat in longissimus dorsi was linear improved (P<0.05), while the shear force was linear decreased (P<0.05).Compared with the control group, the back-fat depth, loin eye area and flesh color score of finishing pigs fed isoleucine deficient diet were significantly reduced (P<0.05), and the hot carcass weight, dressing percentage, and drip loss and yellowness value of longissimus dorsi of finishing pigs fed isoleucine deficient or excess diets were significantly reduced (P<0.05).As dietary isoleucine level increasing, serum triglyceride content was linear increased (P<0.05), while serum urea nitrogen content was linear decreased (P<0.05).Compared with the control group, the serum glucose content of finishing pigs fed isoleucine excess diet was significantly increased (P<0.05), while the concentrations of serum free essential amino acids, non-essential amino acids and total amino acids of finishing pigs fed isoleucine excess diet were significantly reduced (P<0.05), and the contents of serum total cholesterol, low density lipoprotein and high density lipoprotein of finishing pigs fed isoleucine deficient or excess diets were significantly reduced (P<0.05).The results indicate that isoleucine deficient diet has a negative effect on growth performance, carcass traits and intramuscular fat content of finishing pigs, but isoleucine excess diet can significantly reduce the shear force and drip loss of muscle and increase the intramuscular fat content of finishing pigs, even at the cost of reducing hot carcass weight and dressing percentage.