Effect of crude protein level and refeeding method of postmolt diet on performance and egg quality in layers after forced molting.

摘要

One thousand Single Comb White Leghorn layers, 66 weeks old, were force-moulted under a starvation and photocontrol schedule. For a control group, another 60 layers did not undergo forced molting and were fed a layer diet (2.85 kcal ME/g and 17.3% CP). Starvation continued until the body weight (BW) of the layers decreased by about 30%, at which time they were divided into 4 groups and fed on a low-CP diet (ME 2.57 kcal/g and 14.3% CP) ad libitum, a low-CP diet on a restricted feeding schedule, a high-CP diet (ME 2.85 kcal/g and 17.3% CP) ad libitum, or a high-CP diet on a restricted feeding schedule. In the restricted-feeding groups, feed volume was increased gradually over 7 days, and then changed to ad libitum. Each group was fed on the post-molt diet until egg production reached 5%, and then fed on a layer diet. Ad libitum-feeding groups had less accumulated mortalities than the restricted feeding groups during the refeeding period. Layers fed on the high-CP post-molt diet tended to produce heavier eggs than those fed on the low-CP diet. Neither CP level nor feeding method affected egg production, egg mass, feed intake or egg quality after refeeding. The maximum improvement in egg quality (compared with the control group) occurred at week 12of the starvation period; egg shell strength increased by 1.23 kg/cm2, Haugh units by 10.7, egg shell thickness by 0.038 mm and egg specific gravity by 0.006. The results indicate that a CP content <14.3% in a post-molt diet is adequate for layers and that ad libitum feeding is better than restricted feeding for low mortalities.