血浆极低密度脂蛋白浓度的双向选择对肉鸡腹脂、肝脂和产肉性能的影响

对零世代８周龄血浆极低密度脂蛋白（ＶＬＤＬ）浓度进行降低腹脂的间接选择，一世代取得了明显效果：腹脂和肝脂向两极分化，其中肌胃脂和肝脂选择反应较大。低血浆ＶＬＤＬ的选择使腹脂降低，肝脂增加，对产肉性状未产生不利影响。９周龄腹脂率、板油率和肌胃脂率在高ＶＬＤＬ系分别高于低ＶＬＤＬ系２１％，１６％和５１％；肌胃脂率品系间差异极显著（Ｐ＜０．００１）。品系与性别互作对肌胃脂率有明显影响（Ｐ＜０．０５）。腹脂、肌胃脂存在性别差异，腹脂率雌性略高于雄性，而肌胃脂率雄性高于雌性。９周龄肝脂率，高ＶＬＤＬ系显著低于低ＶＬＤＬ系（Ｐ＜０．０１），雌性高于雄性。一世代８周龄血浆ＶＬＤＬ产生了直接选择反应，血浆ＶＬＤＬ浓度，高ＶＬＤＬ系高于低ＶＬＤＬ系。血浆ＶＬＤＬ存在性别差异，雄性高于雌性。一世代高、低ＶＬＤＬ系血浆ＶＬＤＬ和腹脂的变异系数仍然很大，继续对其选择仍然有效。由于血浆ＶＬＤＬ属中等遗传力，并且家系间差异显著，因此，在世代选育中应采取家系结合个体选择法

Effects of Divergent Selection for Plasma Very Low Density Lipoprotein Concentration on the Abdominal Fat, Liver Lipid and Meat Traits in Broiler Chickens

The indirect selection for low plasma very low density lipoprotein (VLDL) concentration resulted in a good effect on reducing abdominal fat (AF) of broilers, and selection responses of gizzard and liver lipid were greater than that of leaf fat. Selection for low plasma VLDL concentration decreased abdominal fat, but increased liver fat, and had no bad effect on meat traits of broilers. Compared with AF, inverse result was obtained in liver lipid by selecting for plasma VLDL concentration. AF, leaf fat and gizzard fat percentages of broilers were 21%, 16%, and 51% higher in high VLDL (H VLDL) line than in low VLDL (L VLDL) line at 9 weeks of age at the first generation. Line difference was significant in gizzard fat percentage (P<0.001). Interaction between the lines and sexes had significant effect on gizzard fat percentage (P<0.05). There was sex difference in AF and leaf fat. AF percentage of females was higher than that of males, whereas gizzard fat percentage of males were higher than that of females. Liver fat percentage was significantly higher in H VLDL line than in L VLDL line (P<0.01) and liver fat percentage was higher in females than in males. Direct response of plasma VLDL at 8 weeks at the first generation was resulted from divergent selection for plasma VLDL at 8 weeks of age in the base population, and plasma VLDL concentration of H VLDL line broiles was higher than that of L VLDL line ones. Sex difference existed in plasma VLDL concentration with the plasma VLDL concentration of males to be higher than that of females. Coefficients of variation of plasma VLDL and AF were still very high in HF and LF lines at the first generation, and it would be efficient to select plasma VLDL and AF continuously. Family combined with individual selection should be adopted during future generation selection and breeding because of mediate heritability of plasma VLDL and significant family difference in plasma VLDL.