Stewart P A, Washburn K W
Growth. 1983 Winter;47(4):411-25.
Developmental changes in body weight, lipid deposition, growth hormone (GH) and triiodothyronine (T3) concentration and lipogenic enzyme (malic and citrate cleavage) activity from day one through 42 days of age were examined in three strains of broilers. The three strains from diverse genetic backgrounds had been similarly selected for growth rate and a preliminary investigation had shown strain 2 to be faster growing and fatter than strains 1 or 3. In the present experiment, day one body weights did not differ between strains but by 14 days of age, strain 2 birds were heavier than those in strains 1 and 3. By 42 days, body weights were similar for strains 1 and 2 but were greater than strain 3. Percent carcass fat did not differ between strains before 28 days of age. At 28 and 42 days, strain 2 had a higher percent body fat than strains 1 and 3. Females grew slower, but deposited more carcass fat than males. Plasma T3 levels did not differ between strains until 42 days of age when strain 2 had higher T3 levels than strains 1 or 3. Males of all strains had higher T3 levels than did females. The slower growing strain 3 had significantly elevated GH levels compared to the faster growing strain 2, while GH concentration of strain 1 was intermediate to the other strains. Males had greater GH levels from 14 to 42 days of age compared to females. There were no consistent strain or sex differences in lipogenic enzyme activity. The temporal patterns of enzyme activity were similar between strains and sexes.
对三个品系的肉鸡从1日龄到42日龄期间体重、脂质沉积、生长激素（GH）和三碘甲状腺原氨酸（T3）浓度以及脂肪生成酶（苹果酸酶和柠檬酸裂解酶）活性的发育变化进行了研究。这三个具有不同遗传背景的品系在生长速度方面经过了类似的选择，初步调查显示品系2比品系1或品系3生长更快且更肥。在本实验中，各品系1日龄时体重无差异，但到14日龄时，品系2的鸡比品系1和品系3的鸡更重。到42日龄时，品系1和品系2的体重相似，但均大于品系3。在28日龄之前，各品系的胴体脂肪百分比无差异。在28日龄和42日龄时，品系2的体脂百分比高于品系1和品系3。雌性生长较慢，但胴体脂肪沉积比雄性多。直到42日龄时血浆T3水平在各品系间才出现差异，此时品系2的T3水平高于品系1或品系3。所有品系的雄性T3水平均高于雌性。生长较慢的品系3与生长较快的品系2相比，GH水平显著升高，而品系1的GH浓度介于其他两个品系之间。从14日龄到42日龄，雄性的GH水平高于雌性。脂肪生成酶活性在品系或性别上没有一致的差异。品系和性别之间酶活性的时间模式相似。
