日粮组成和能量水平对乌金猪肉品质的影响

本文旨在研究不同日粮组成和能量水平对乌金猪肉品质的影响,确定最优肉品质所需的日粮适宜能量水平.选取体重(15.18±0.85)kg的乌金猪90头,公、母各占1/2,随机分为5组,每组18头,下设3个重复,每个重复6头.试验采用单因子随机分组设计,以中国肉脂型生长肥育猪饲养标准能量需要设计中能量水平(组Ⅲ,消化能12.98 MJ/kg),以NRC(1998)生长肥育猪饲养标准能量需要设计最高能量水平(组Ⅰ,消化能14.22 MJ/kg),此两个能量水平间设计中高能量水平(组Ⅱ,消化能13.60 MJ/kg),在中能量水平下依次分别设计中低能量水平(组Ⅳ,消化能12.36 MJ/kg)和最低能量水平(组Ⅴ,消化能11.74 MJ/kg),每个能量水平间的梯度为0.62 MJ/kg.各组在不同生长阶段日粮蛋白质、微量元素、氨基酸等水平基本固定.试验期至100 kg体重,分别在30、60和100 kg体重时屠宰,测定肉品质指标及肌肉营养成分,采用模糊综合评定系统分析并确定最优肉品质日粮适宜能量水平.结果表明,不同日粮组成和能量水平对乌金猪不同生长阶段肌肉pH、系水力、剪切力、烹煮损失和滴水损失有明显影响,组Ⅰ、Ⅲ、Ⅴ及其日粮的组间差异显著(P<0.05),大理石纹在60和100 kg体重时差异显著(P<0.05).随着日粮能量水平的降低,肌肉中粗蛋白质含量提高,在100 kg体重时达显著水平(P<0.05);粗脂肪、肌内脂肪和肌苷酸含量降低,不同生长阶段组Ⅰ、Ⅲ、Ⅴ及其日粮的组间差异显著或极显著(P<0.05或P<0.01).以大理石纹、剪切力、滴水损失为评定肉品质的代表指标,通过综合评定确定30、60和100 kg体重时最优肉品质适宜的日粮能量水平分别为13.10、13.08和13.11 MJ/kg.研究结果可为乌金猪的合理饲养和改善肉品质提供科学依据.

Effects of Dietary Digestible Energy Levels on Meat Quality in Wujin Pig

The aim of the study was to investigate the effects of diet composition and digestive energy levels on meat quality of Wujin pig and find out the suitable dietary energy levels according to the best meat quality by fuzzy comprehensive judgment model. Ninety pigs were randomly divided into 5 groups that were fed with diets containing 14.22, 13,60,12.98, 12.36 and 11.74 MJ/kg of digestive energy. There were 18 pigs in each group with 3 replicates and each replicate contained 6 pigs.Randomized block design with single factor was adopted in the experiment. The energy level of group Ⅲ (with digestive en-ergy of 12.98 MJ/kg) was designed according to the feeding standard energy requirement of Chinese meat-fat type of growth-finishing pigs, while the energy level of group Ⅰ (with digestive energy of 14.22 MJ/kg) was designed according to feeding standard of NRC (1998) growth-finishing pigs. The energy level of group Ⅰ(with digestive energy of 13.60 MJ/kg)was designed between groupⅠand Ⅲ. The energy levels of group Ⅳ and Ⅴ were designed under the energy level of group Ⅲ.The gradient of each adjacent energy level was 0.62 MJ/kg. The dietary crude protein, trace element and amino acids con-tents in each group during different growth stages were basically constant. The meat quality was measured when the pigs were slaughtered with the body weight of 30, 60 and 100 kg. Fuzzy comprehensive judgment model was adopted to analyze and determine the suitable dietary energy level to attain the best meat quality of Wujin pig during different growth stages.The results showed that the muscle pH, water holding capacity, shear force, cooking loss and drip loss were significantly af-fected by the diet composition and digestive energy levels during different growth stages. The differences were significant a-mong group Ⅰ, Ⅲ and Ⅴ (P<0.05 or P<0.01). The marbling of meat was significantly different among each group when the body weight of pigs were 60 and 100 kg(P<0.05). The muscle crude protein contents increased with the decrease of di-etary energy level and the difference was significant when the body weight was 100 kg (P<0.05). However, the muscle e-ther extract, intramuscular fat and inosine monophosphate contents reduced with the decrease of dietary energy level. The differences were significant among groups Ⅰ,Ⅲ and Ⅴ during different growth stages (P<0.05 or P<0.01). The applica-tion of fuzzy comprehensive judgment model was based on the marbling, shear forcer and drip loss which represented the meat quality. According to synthetically evaluation, the suitable dietary energy levels were determined as 13.10, 13.08 and 13.11 MJ/kg when the body weight were 30, 60 and 100 kg. The study results could provide scientific basis for the reasona-ble feeding and the improvement of meat quality of Wujin pig.