Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2010
Publication Date: 3/14/2011
Citation: Peebles, E.D., Park, S.W., Branton, S.L., Gerard, P.D., Womack, S.K. 2011. Dietary poultry fat, phytase, and 25-hydroxycholecalciferol influence the digestive and reproductive organ characteristic of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum. Poultry Science. 90:797-803. Interpretive Summary: Egg production (EP) decreases of approximately 16 eggs per hen over a typical 45 laying cycle occur in laying chickens infected with Mycoplasma gallisepticum (MG). Changes in intestinal weight have also been associated with the level of EP in layers. Attempts to ameliorate the decreased egg production observed with MG infection have included the addition of dietary supplements to the feed. In this study, dietary poultry fat (PF), the enyzyme phytase(PHY) and 25-hydroxycholecalciferol (25[OH]D) were used to supplement the diets of laying chickens which were inoculated with MG at either 12 weeks of age (before lay) or at 22 weeks of age (onset of lay). The supplemental combination of 1.50% PF, PHY, and 25[OH]D did effect the oviduct as well as the small intestine but did not result in an influence on layer EP.
Technical Abstract: ABSTRACT Effects of 2 supplemental concentrations of dietary poultry fat (PF) and the combination of PF, phytase (PHY) and 25-hydroxycholecalciferol [25(OH)D] on the gross digestive and reproductive organ characteristics of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 (before lay) or 22 (onset of lay) wk, dietary treatments [basal control diet (BCD); BCD with 0.75% supplemental PF (LPFD); BCD with 1.50% supplemental PF (HPFD); HPFD additionally supplemented with 0.013% PHY and 0.025% 25(OH)D] were initiated at 20 wk of age, and organ characteristics were determined at 58 wk of age. In proportion to small intestine weight, jejuna were heavier in birds inoculated at 22 rather than at 12 wk of age. In hens inoculated at 22 wk of age, percentage infundibulum weight was increased by FMG. The proportional length of infundibula in birds fed HPFD with PHY and 25(OH)D were longer than those fed LPFD. In birds inoculated with FMG at 22 wk of age, BW was greater in those fed HPFD with or without added PHY and 25(OH)D in comparison to those fed LPFD; whereas LPFD increased percentage oviduct and magnum weights when compared to HPFD and BCD groups, respectively. Percentage duodenum weight in birds that were fed HPFD with PHY and 25(OH)D was greater compared to those fed LPFD in the wk 22 sham and wk 12 FMG inoculation groups, but was also greater than those fed BCD in the wk 12 FMG inoculation group. Conversely, percentage duodenum weight was greater in birds fed LPFD compared to HPFD after a wk 22 FMG inoculation. However, despite the effects of the supplemental combination of 1.50% PF, PHY, and 25(OH)D on oviduct and small intestine structure, it did not result in a subsequent influence on layer performance, as indicated in a previous companion report.