Effects of a Pre-Molt Calcium and Low-Energy Molt Program on Laying Hen Behavior During and Post-Molt

Abstract

and Implications The objectives of this study were to compare the behavior of the laying hen kept in a cage system when offered a pre-molt calcium treatment and low-energy molt diets versus a traditional feed-withdrawal during induced molt. A total of 144 Hy-Line W-36 laying hens (85 wk of age), weighing 1.7 ± 0.2 kg, were used. Laying hens were housed 3 per cage (30.5 cm wide × 40.6 cm deep × 44.5 cm high), providing 413 cm 2 per hen. Six treatments were compared in a 2 × 3 factorial design with 2 Ca (coarse and fine) pre-molt treatments and 3 molt diets: feed withdrawal (FW), soybean hulls (SH), and wheat middlings (WM). The Ca pre-molt treatment was defined as the period when the hens received either a combination of fine (0.14 mm in diameter) and coarse (2.27 mm in diameter) CaCO 3 or an all-fine CaCO 3 mixed into a commercial diet for 1 wk. Both diets were formulated to contain 4.6% Ca, such that only the particle size of the CaCO 3 differed between the 2 treatments. Hens had free access to feed and water and had a 24-h photoperiod. The 3 molt diets were applied (FW, SH, or WM) for a total of 28 d. The hens assigned to the FW diet were deprived of feed for 7 d with free access to water followed by 21 d of skip-a-day feeding restricted to 60 g of feed/hen per feeding day. The hens fed the WM and SH molt diets were given free access to feed and water during the entire 28 d molt period. Lighting was reduced to 8 h for the first 3 wk and was then increased to 12 h at the start of the last week of molt. Behavior was recorded by camera once before molt, twice during molt, and twice post-molt for 2 h in the morning and 2 h at night. The acquisition of 2 postures and 5 behaviors were obtained by 2 experienced observers who viewed the recordings using 24 h mode onto the Observer software using a 1 min scan sampling technique. Postures and behaviors were not different among treatments during the baseline period. The Ca pre-molt treatment had no carryover effect during or post-molt. The hens assigned to the FW molt diet spent more time in active postures and feeding and drinking behaviors during molt compared to hens fed the other 2 molt diets. Post-molt, all hens, regardless of molt diet, spent the same amount of time in each of these behaviors. The hens assigned to the FW molt diet spent more time preening during molt compared to post-molt, whereas the hens fed the WM and SH molt diets did not differ between the 2 periods (Table 1). In conclusion, these low-energy molt diets did not adversely affect the postures and behaviors of the laying hen and are therefore acceptable dietary alternatives to FW for inducing molt.