The research aimed to reveal the content and distribution rules of energy and protein in different body tissues for 20-35 kg Dorper and Thin-tailed Han crossbred ram lambs fed with different diet levels,and to establish some mathematical models to predict body composition and chemical composition by means of live weight in crossbred sheep.Twenty-one lambs were randomly assigned to three groups,one group fed ad libitum (AL),and the other two groups fed either 70％ (IR70) or 40％ (IR40) of ad libitum.Each group contained seven sheep and every sheep was a replicate.A slaughter trial was performed when the lambs in AL group reached 35 kg of live weight.Dry matter,crude protein,fat as well as gross energy content were measured in different tissues including bone,muscle,fat,blood+viscera,hide and fleece.In body composition,AL group lambs had the highest proportion of fat to moisture and showed significant difference to IR40 group (P＜0.05),while the proportion of protein/fat was higher in IR40 group than that in AL group (P＜0.05).No significant difference was found in the ratio of the muscle,blood+viscera or hide weight to fleece-free empty body weight (P＞0.05),but the ratio of bone to fleece-free empty body weight was significant difference (P＜0.05) among three treatments.Energy content (MJ · kg-1) and protein content(％) in the tissues showed no significant difference (P＞0.05) among three feeding levels.The ratio of dry matter or protein to fleece-free empty body weight showed no significant difference between the three groups (P＞0.05),however,IR40 group lambs had a higher ratio in moisture and ash than that of AL and IR70 group lambs(P＜0.05).The feeding level significantly affected the proportion of crude protein,fat and moisture in Dorper and Thin-Tailed Han crossbred ram lambs between 20 to 35 kg of live weight,and a highly negative correlationship was found between fat and moisture.The parameters of E/GE and CP/GCP in different tissues were affected by the feeding levels but the impact was not consistent.The protein content was relatively stable while the fat content was easily affected by age and the feeding levels.There was a strong correlationship between empty body weight and different tissues and organs,and a strong correlationship was also found between fleece-free empty body weight and the main chemical composition in body.%本研究旨在揭示不同饲喂水平对20～35kg杜寒杂交公羔羊机体组织中能量和蛋白质的含量及分布规律的影响,建立通过活体体重估测杂交羔羊机体组成和化学组成的预测模型.将21只杜寒杂交公羔随机分为3组,按照自由采食(AL)、自由采食量的70％ (IR70)和自由采食量的40％(IR40)3个水平饲喂,每个处理7只羊.当自由采食组羊只达到35 kg时进行屠宰试验,测定不同组织(骨骼、肌肉、脂肪、血+内脏、皮和毛)的干物质、粗蛋白、粗脂肪及总能含量.结果,从机体组成看,脂肪/水分在AL组最高,与IR40组差异显著(P＜0.05);蛋白/旨肪在IR40组最高,与AL组差异显著(P＜0.05);组织鲜重占去毛空体重的比例,肌肉、血+内脏和皮在3组间差异不显著(P＞0.05),但骨骼在3组间差异显著(P＜0.05);所有组织在不同组别间能量含量(MJ·kg-1)和蛋白质含量(％)均差异不显著(P＞0.05);羊毛中能量和蛋白总量在3个饲喂水平间差异不显著(P＞0.05);3组间干物质和粗蛋白占去毛空体重的比例差异不显著(P＞0.05),但水分和灰分比例在IR40组显著高于AL和IR70组(P＜0.05).饲喂水平会显著影响20～35 kg杜寒杂交公羔羊机体中粗蛋白、脂肪和水分的比例,其中脂肪和水分含量呈高度负相关关系;不同组织的能值/机体总能值和蛋白/机体总蛋白参数受饲喂水平的影响不尽相同;机体的蛋白含量相对稳定,脂肪含量易受年龄和饲喂水平的影响;羔羊空腹体重与不同的组织与器官存在强相关关系,去毛空体重与机体的主要化学成分存在强相关关系.
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