Farmer M, Roland D A, Clark A J
Poult Sci. 1986 Mar;65(3):555-8. doi: 10.3382/ps.0650555.
Sixteen hens, 67 weeks old, having oviposition times at 0700 +/- .25 hr, were used in Experiment 1. Hens were randomly divided into two treatments and fed a .08% calcium diet following oviposition. For 5 days, at either 0800 (AM) or 1600 (PM) hours, hens received 3.65 g of calcium by intubation. On Day 1, the calcium source contained 25 microCi of calcium-45 (45Ca). Eggs and excreta were collected daily for 45Ca analysis. Experiment 2 was similar to Experiment 1 except that 34-week-old hens were used. Calcium-45 activity of the egg shell, excreta, serum, and total contents of the gastrointestinal (GI) tract was determined. Results of Experiments 1 and 2 indicated that hens receiving their daily supply of calcium in the PM deposited significantly more of that day's dietary calcium on the following day's egg than hens receiving calcium in the AM. Excreta from the AM-treated hens contained significantly more 45Ca than that from the PM-treated hens during the first 24 hr in both experiments. In Experiment 2, the quantity of 45Ca in serum and GI tract contents was significantly higher from hens in the PM treatment. It was concluded that hens utilized significantly more calcium for egg shell formation from PM consumption rather than AM consumption and, therefore, were less dependent on bone reserves when the calcium was consumed in the PM.
实验1选用了16只67周龄、产蛋时间为上午7点±0.25小时的母鸡。母鸡被随机分为两组处理，产蛋后饲喂含钙0.08%的日粮。在5天时间里，母鸡在上午8点（AM）或下午4点（PM）通过插管接受3.65克钙。第1天，钙源中含有25微居里的钙-45（45Ca）。每天收集鸡蛋和排泄物进行45Ca分析。实验2与实验1相似，只是使用的是34周龄的母鸡。测定了蛋壳、排泄物、血清和胃肠道（GI）总内容物中的钙-45活性。实验1和实验2的结果表明，下午接受每日钙供应的母鸡在第二天的鸡蛋上沉积的当日日粮钙比上午接受钙的母鸡显著更多。在两个实验的头24小时内，上午处理组母鸡的排泄物中含有的45Ca显著多于下午处理组母鸡。在实验2中，下午处理组母鸡血清和胃肠道内容物中的45Ca含量显著更高。得出的结论是，母鸡从下午摄入的钙中用于蛋壳形成的钙显著多于上午摄入的钙，因此，当在下午摄入钙时，母鸡对骨骼储备的依赖性较小。
