Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/10/2010
Publication Date: 10/1/2010
Citation: Peebles, E.D., Park, S.W., Branton, S.L., Gerard, P.D., Womack, S.K. 2010. Influence of supplemental dietary poultry fat, phytase, and 25-hydroxycholecalciferol on the egg characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum. Poultry Science. 89:2078-2082. Interpretive Summary: Presence of the bacteria Mycoplasma gallisepticum (MG) has been estimated to cost the table egg sector of the modern poultry industry approximately $140 million annually. Feed additives including poultry fat (PF), the feed enzyme phytase (PHY) and vitamin D3 have each been investigated and have each been shown to some extent to independently ameliorate losses attributable to MG. However the combined effects of supplementary PF, PHY and D3 have not been investigated. Thus, the goal of this research was to investigate the interactive effects of F strain MG (FMG) vaccination together with PF, PHY and D3 on the egg characteristics, particularly the percentage of egg yolk weight, of layer chickens between 24 and 58 weeks of age (WOA). Results of the study show that an increase in percentage of yolk weight is prevented in layer chickens vaccinated with FMG at 22 WOA and consuming diets with PF added at 1.50% together with supplementary PHY and D3 as compared to chickens that consumed diets supplemented only with 1.50% PF. These results could also be stated as the use of supplementary PHY and vitamin D3 in combination with 1.50% supplementary PF did not provide any synergistic effect that further increased percentage yolk weight.
Technical Abstract: The effects of 2 supplemental levels of dietary poultry fat (PF) and the combination of PF, phytase (PHY) and 25-hydroxycholecalciferol (D3) on the egg 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) and 22 (early in lay) wk and dietary treatments [basal control diet (BCD); BCD with 0.75% supplemental PF (LPFD); BCD with 1.50% supplemental PF (HPFD); BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D3 (HPFPHYD3D)] were initiated at 20 wk of age. Percentages of albumen, yolk, and eggshell weights; yolk:albumen ratio; yolk moisture and lipid concentrations; and eggshell weight per unit of surface area were determined at 24, 34, 44, 50, and 58 wk of age. Inoculation with FMG reduced yolk lipid concentration at wk 24 and increased yolk moisture concentration at wk 58. In birds inoculated on wk 22, percentage of yolk weight was lower in those inoculated with FMG in comparison to those that were sham-inoculated. Yolk:albumen ratio was lower in those that were FMG-inoculated at 22 wk of age in comparison to those that were sham-inoculated at the same age or that were FMG-inoculated at 12 wk of age. Percentage of yolk weight was greater in birds inoculated at wk 22 and fed the HPFD compared to those inoculated at wk 22 and fed the BCD or HPFPHYD3D and compared to birds inoculated at wk 12 and fed the LPFD. In conclusion, inoculation with FMG before or early in lay resulted in a decrease in yolk lipid content early in lay but an increase in yolk moisture late in lay, and FMG reduced percentage of yolk weight in birds inoculated on wk 22. Furthermore, when used in combination with added 1.50% PF in birds inoculated on wk 22, supplementary PHY and D3 prevented an increase in percentage of yolk weight that was found to occur in response to diets supplemented only with 1.50% PF.