No abstract

The objectives of this study were to compare the behaviors, postures, and heterophil-to-lymphocyte ratios (H:L) of laying hens housed in a cage system when offered a Ca premolt treatment and low-energy molt diets vs. a traditional feed withdrawal (FW) treatment during and after molt. A total of 144 Hy-Line W-36 hens (85 wk of age), housed 3 hens/cage (413 cm(2)/hen), were used. Hens were allotted to treatments according to a randomized complete block design, with the cage location and initial BW as the blocking criteria. Six treatments were compared in a 2 × 3 factorial arrangement with 2 Ca premolt treatments (fine or coarse) and 3 low-energy molt diets (FW, soybean hulls, or wheat middlings). The 2 Ca premolt treatments differed only in Ca particle size (fine was 0.14 mm and coarse was 2.27 mm mean diameter). Two postures and 5 behaviors were recorded and H:L was measured. Data were analyzed using the MIXED procedure of SAS, with P < 0.05 considered significant. There were no differences in behaviors, postures, or H:L during the premolt baseline period. The Ca premolt treatment had no carryover effects during or after molt for behaviors or postures. During molt, hens in the FW treatment were more active, and they ate and drank less compared with hens fed soybean hulls or wheat middlings, but there were no differences in aggression, nonnutritive pecking, or sitting. Drinking and aggression during and after molt were not different, but hens postmolt engaged in more sitting and feeding and less activity, nonnutritive pecking, and preening compared with during molt. There were no differences in H:L during or after molt. In conclusion, a Ca premolt treatment did not affect the behavior of the laying hen. The low-energy molt diets did not adversely affect behavior compared with FW and did not increase H:L; therefore, they could be useful alternatives for inducing molt in laying hens.

The objectives of this study were to evaluate and compare the effects of production, physiology, egg quality, and economics of laying hens housed in a cage system when offered a calcium premolt treatment and low-energy molt diets versus a traditional feed withdrawal (FW) treatment during and after molt. In total, 981 Hy-Line W-36 laying hens (85 wk of age) housed 3 per cage were used. Six treatments were compared in a 2 × 3 factorial design with 2 calcium premolt treatments (fine and coarse) and 3 molt diets (FW, soybean hulls, and wheat middlings). The coarse Ca was a 50:50 mix of fine (0.14-mm mean diameter) and coarse (2.27-mm mean diameter) CaCO(3), whereas the fine Ca was an all-fine CaCO(3). Both diets were formulated to contain 4.6% Ca, such that only the particle size of the CaCO(3) differed. Production parameters in experiment 1 included egg production, egg weight and mass, specific gravity, Haugh units, egg components, feed consumption and utilization, and BW. Physiological parameters in experiment 2 included ovary and oviduct weights, femur- and humerus-ash percentages, heterophil to lymphocyte ratios, plasma Ca and inorganic P concentrations, and alkaline phosphatase activity. Data were analyzed by ANOVA and P < 0.05 was significant. The fine-Ca premolt treatment was more effective than the coarse-Ca treatment at decreasing egg production during molt and increasing it postmolt, regardless of the molt diet. The FW molt diet resulted in the greatest decrease in production, but the soybean hulls diet resulted in lower production and ovary and oviduct weights during molt compared with those of the wheat middlings molt diet. Therefore, a fine-Ca premolt treatment and a low-energy molt diet, particularly soybean hulls, can be useful alternatives to a FW molt.

and ImplicationsThe objectives of this study were to compare stress measures and bone quality of laying hens when offered a Ca pre-molt treatment followed by low-energy molt diets versus a traditional feed withdrawal before, during, and after an induced molt. A total of 189 Hy-Line W-36 laying hens (85 wk of age, 1.7 ± 0.2 kg), housed 3 per cage, (413 cm 2 /hen) were used. Six treatments were compared in a 2 × 3 factorial design with 2 Ca (coarse and fine) pre-molt treatments (coarse and fine) 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 for a total of 28 d. The hens assigned to the FW molt 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 provided 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. During the 22 wk postmolt, hens were fed a laying hen diet and lighting was increased by 1 h each week to 16 h. None of the treatments resulted in an increased heterophil to lymphocyte ratio during or post-molt compared to baseline values, which would have suggested increased stress in the laying hen. Additionally, any changes reported during molt in bone quality returned to baseline values during the post-molt period. Therefore, these treatments are acceptable for inducing molt in the laying hen.

and Implications The objectives of this study were to compare the production of laying hens when offered a Ca pre-molt treatment and low-energy molt diets versus a traditional feed-withdrawal (FW) before, during, and after an induced molt. A total of 792 Hy-Line W-36 laying hens (85 wk of age, 1.7 ± 0.2 kg), housed 3 per cage, (413 cm 2 /hen) were used. Six treatments were compared in a 2 × 3 factorial design with 2 Ca (coarse and fine) pre-molt treatments and 3 molt diets: 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 for a total of 28 d. The hens assigned to the FW molt 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 provided 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. During the 22 wk postmolt, hens were fed a laying hen diet and lighting was increased by 1 h each week to 16 h. The fine-Ca pre-molt treatment was more effective than the coarse-Ca pre-molt treatment at decreasing egg production during molt and increasing egg production after molt regardless of which molt diet was fed (P < 0.05). The FW molt diet resulted in the most complete molt with a greater decrease in egg production during molt (P < 0.05). The SH molt diet compared to the WM molt diet was more effective at inducing molt with lower egg production and ovary and oviduct weights during molt (P < 0.05), however, the WM molt diet resulted in the highest egg production and body weight post-molt compared to the other 2 molt diets (P < 0.05). In conclusion, a fine-Ca pre-molt treatment and a low-energy molt diet containing WM or SH can be useful alternatives to a FW molt.