杂合型伴性矮小基因对正常体型鸡脂肪沉积的影响

【目的】通过探究杂合型伴性矮小基因对鸡脂肪沉积的影响,了解其脂肪沉积动态变化的规律,为优质肉鸡和地方鸡种生产性能研究奠定基础。【方法】将正常体型的固始公鸡和广西瑶鸡公鸡（Z^DWZ^DW）分别与正常型母鸡（Z^DWW）和矮小型母鸡（Z^dwW）交配,将杂交后代在同一条件饲养。分别于60日龄、90日龄、120日龄从每个杂交后代中各选取鸡只100只（公母各半）,进行体尺指标的测定;分别于60日龄和90日龄从固始鸡的杂交群体中各选取鸡只10只（公母各半）,进行体脂含量动态变化的研究;另于120日龄从固始和广西瑶鸡的杂交后代群体中各选鸡只10只（公母各半）,进行体脂含量的测定;采用全自动生化分析仪测试血清生化指标;采用索氏抽提法测定胸肌、腿肌中肌内脂肪（IMF）的含量;通过制作石蜡切片,在显微镜下测定肌纤维直径和肌纤维密度。【结果】杂交后代个体体型均为正常型,固始鸡母本正常型群体的公、母鸡随日龄呈现了不同的脂肪沉积特性。母鸡的体脂指标包括腹脂重、腹脂率、皮下脂肪厚和肌间脂肪宽前期均保持在低水平,在120日龄得到显著提高,而公鸡的体脂水平一直维持在低水平;固始鸡母本矮小型群体公、母鸡随日龄表现了相似的脂肪沉积动态变化特性,120日龄公、母鸡的体脂沉积水平均显著高于60日龄/90日龄;母本矮小型群体公鸡（dw杂合子）表现了完全不同于母本正常型群体公鸡（DW纯合子）体脂变化的特性,其90日龄和120日龄的腹脂重、腹脂率、皮下脂肪厚和肌间脂肪宽均显著高于母本正常型群体公鸡。进一步整合120日龄固始鸡杂交群体和广西瑶鸡杂交群体的体脂数据发现,群体因素对腹脂重、肌间脂肪宽、皮下脂肪厚和胸肌肌内脂肪含量的效应均达到显著水平,特别是母本矮小型公鸡（dw杂合子）的腹脂重、腹脂率、肌间脂肪宽、皮下脂肪厚和胸肌肌内脂肪含量均极显著高于母本正常型公鸡（DW纯合子,P<0.01）。母本矮小型与母本正常型群体间在总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白（LDL）含量、高密度脂蛋白（HDL）含量上均无显著差异。母本正常型和母本矮小型后代的肌纤维特性包括肌纤维密度、肌纤维面积、肌纤维直径均无显著性差异。【结论】杂合伴性矮小型基因改变了公鸡的脂肪沉积特性,显著提高了公鸡的腹部脂肪、皮下脂肪和肌间脂肪的沉积;改善了胸肌的肌内脂肪含量;而对血脂指标无显著影响;对肌纤维特性无显著影响。

Effect of the Heterozygous Sex-Linked Dwarf Gene on Fat Deposition in Normal Type Chickens

【Objective】 The aim of this study was to to investigate the effect of the heterozygous sex-linked dwarf gene on fat deposition of chickens, so as to provide a theory base for producing quality chicken and local chichen by using dwarf gene. 【Method】 In this study, the normal size Gushi chicken and Guangxi Yao chicken rooster (Z^DWZ^DW) were chosen to cross with the normal type hens (Z^DWW) and the dwarf hens (Z^dwW), respectively, and their offspring were raised under the same condition. 100 chickens (half male and half female) were randomly selected from each hybrid at the ages of 60 days, 90 days and 120 days for body measurement index, respectively. 10 chickens (half male and half female) were randomly selected from the hybrid populations of Gushi chickens to determine the dynamic change of body fat at 60 days and 90 days, respectively. In addition, 10 chickens (half male and half female) were selected from the hybrid populations of Gushi chickens and Guangxi Yao chickens at 120 days to determine the body fat deposition of different populations. The serum biochemical indexes were measured by using automatic biochemical analyzer, the content of intramuscular fat in breast muscle and leg muscle was determined by the Soxhlet extraction method, and the diameter and density of muscle fibers were measured by the paraffin section. 【Result】 The results showed that the offspring were normal in body size, and the male and female offspring from the normal type of female parent presented different characteristics of fat deposition with age. The female body fat indexes including abdominal fat weight, percent of abdominal fat, subcutaneous fat thickness and intermuscular fat width, which were all kept at a low level at 60 days, and increased significantly at the age of 120 days, while the male body fat maintained at low levels. In the meantime, the male and female offspring the dwarf type of female parent presented a similar dynamic change of fat deposition with age, and the body fat levels of the male and the female offspring at 120 days were significantly higher than that at 60 days and 90 days. However, the body fat change of the male offspring from the dwarf type of female parent (the heterozygote of dw) was different from that of the normal type of female parent (the homozygous of DW), whose abdominal fat weight, percent of abdominal fat, subcutaneous fat thickness and intermuscular fat width were significantly higher than that of the normal type of female parent at 90 and 120 days. Combining the data of body fat between Gushi chickens and Guangxi Yao chickens for 120 days, the result showed that population factor was significant for abdominal fat weight, percent of abdominal fat, intermuscular fat width and subcutaneous fat thickness. The abdominal fat weight, percent of abdominal fat, intermuscular fat width and subcutaneous fat thickness of the males from the dwarf type of female parent were significantly higher than that of the normal type of female parent (P<0.01). There was no significant difference in total cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein between the population (from the normal type of female parent and the dwarf type of female parent). There was no significant difference in the IMF content of the breast muscle in the female offspring from the normal type of female parent and the dwarf type of female parent. The breast muscle IMF content of male from the dwarf type of female parent was significantly higher than that from the normal type of female parent (P<0.01). There was no significant difference in muscle fiber characteristics, including muscle fiber density, muscle fiber area and muscle fiber diameter between the offspring of the normal type of female parent and the dwarf type of female parent. 【Conclusion】The results showed that the heterozygous dwarf gene changed the characteristics of fat deposition in the males, and it could significantly increase the deposition of abdominal fat, subcutaneous fat, intermuscular fat and breast IMF content in the male. The heterozygous dwarf gene had no significant effect on blood lipid index and the characteristics of muscle fibers.