Patel M B, McGinnis J
Poult Sci. 1980 Oct;59(10):2279-86. doi: 10.3382/ps.0592279.
Three experiments were conducted with White Leghorn chicks hatched from hens fed diets varying in levels of protein, fat, and vitamin B12. Adding animal fat at a level of 10% in the chick diet caused growth depression of vitamin B12 deficient chicks, regardless of protein or energy level of hen or chick diet. Increasing the level of fat to 20% in the chick diet caused further growth depression and increased mortality. Feed efficiency of vitamin B12 deficient chicks was severely depressed by each additional increment in the fat level. Increasing protein content from 20 to 30% in the chick diet resulted in severe growth depression and poor feed efficiency. Although the added fat in the 30% protein chick diet depressed growth of chicks hatched from hens fed the 16 and 32% protein with added fat, it improved growth of those hatched from hens fed the similar diets with no added fat. Added fat in the 30% protein chick diet also improved feed efficiency of all chicks regardless of breeder diet treatments. Chicks hatched with an adequate carry-over of vitamin B12 from hens or chicks fed a diet with 10 micrograms of added vitamin B12/kg of feed did not show the growth depression caused by the high level of fat in the 20 and 30% protein chick diets. Feed efficiency was greatly improved by the addition of vitamin B12 to all chick diets. In a 22% protein vitamin B12 deficient diet, isocaloric substitution of glucose for fat depressed chick growth significantly and this growth depression was counteracted by supplementing the diet with 10 or 100 micrograms of vitamin B12/kg of feed. The vitamin B12 requirement was not increased by such substitution in the 22% protein diet. In contrast, isocaloric substitution of fat for glucose in the 32% protein chick diet increased the vitamin B12 need for optimum growth.
用白来航鸡雏进行了三项实验，这些雏鸡由饲喂蛋白质、脂肪和维生素B12水平不同日粮的母鸡孵化而来。在雏鸡日粮中添加10%的动物脂肪会导致维生素B12缺乏的雏鸡生长受阻，无论母鸡或雏鸡日粮的蛋白质或能量水平如何。将雏鸡日粮中的脂肪水平提高到20%会导致进一步的生长受阻和死亡率增加。脂肪水平的每一次增加都会严重降低维生素B12缺乏雏鸡的饲料效率。将雏鸡日粮中的蛋白质含量从20%提高到30%会导致严重的生长受阻和饲料效率低下。尽管在30%蛋白质的雏鸡日粮中添加脂肪会抑制由饲喂添加脂肪的16%和32%蛋白质日粮的母鸡孵化出的雏鸡的生长，但它改善了由饲喂无添加脂肪的类似日粮的母鸡孵化出的雏鸡的生长。30%蛋白质的雏鸡日粮中添加脂肪也提高了所有雏鸡的饲料效率，无论种鸡日粮处理如何。由母鸡或雏鸡摄入每千克饲料添加10微克维生素B12的日粮而有足够维生素B12残留孵化出的雏鸡，并未表现出20%和30%蛋白质的雏鸡日粮中高脂肪水平所导致的生长受阻。在所有雏鸡日粮中添加维生素B12可大大提高饲料效率。在22%蛋白质的维生素B12缺乏日粮中，用葡萄糖等量替代脂肪会显著抑制雏鸡生长，而在日粮中补充每千克饲料10或100微克维生素B12可抵消这种生长抑制。在22%蛋白质的日粮中进行这种替代不会增加维生素B12的需求量。相反，在32%蛋白质的雏鸡日粮中用脂肪等量替代葡萄糖会增加达到最佳生长所需的维生素B12量。
