|Byrd Ii, James - Allen|
Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2003
Publication Date: N/A
Technical Abstract: The method most commonly used to induce molting and stimulate multiple egg-laying cycles in laying hens for commercial egg production is feed deprivation. Unfortunately, an increased risk of Salmonella enteritidis (SE) may result from the use of this method. Methods to stimulate multiple egg-laying cycles without increasing the risk of SE are needed. In each of three experiments, hens over 50 wk of age were divided into groups of 12 hens and placed in individual laying cages. One wk prior to dietary changes, hens were put on an 8-h light and 16 h-dark photoperiod that continued for the 9-day experiments. Individual hens in all treatments were challenged orally with 10**4 cfu of SE on the fourth day. Treatments were non-fed hens (molted, M), full fed hens (non-molted, NM), a zinc acetate diet (ZAC), and a zinc propionate diet (ZPR). The zinc diets contained 10,000 mg zinc per Kg of diet. Body weight losses were significantly higher in the M (-24%), ZAC (-11%), and ZPR (-15%) treatments than in the NM (-1%) treatment. When compared with the NM hens, ovary weights were reduced by 67 to 83% in the other treatments. Cecal propionic acid and total volatile fatty acids (VFA) were not significantly altered in any of the treatments; whereas, crop lactic acid was decreased in all the other treatments, when compared with the NM treatment. Crop pH was not consistently altered by treatments but tended to be inversely related to feed consumption. Colonization of SE in the crop and the ceca was higher in the M and ZPR hens. Organ invasion by SE was 7/93 for NM hens, 54/96 for M hens, 15/93 for ZAC hens, and 58/96 for ZPR hens. The ZAC regimen may be a useful tool to induce molting and stimulate multiple laying cycles without increasing the risk of SE.