Previous work has demonstrated that the P requirement for turkey breeder hens has not been adequately determined. It is becoming apparent that there are distinctive P requirements of turkey breeder hens compared to poults and growing birds. Therefore, the objective of this study was to provide additional information regarding P requirement and use of phytase in turkey breeder hen diets. An experiment was conducted to determine the effect of dietary phosphorus (P) levels and phytase enzyme levels on turkey breeder hen productivity from 31 to 62 weeks of age (WOA). Four hundred and eighty turkey breeder hens were reared in a curtain-sided house with 48 pens (10 birds per pen; 8 pens per treatment) at 31 WOA. Hens were fed a breeder ration with treatments as follows: high P (HP), available P=0.55%; high P + enzyme (HP+E), medium P (MP), available P=0.35%; medium P + enzyme (MP+E), low P (LP), available P=0.17%; and low P + enzyme (LP+E). The phytase enzyme product used (AllzymeTM Phytase, Alltech, Inc., Nicholasville, KY 40356) is derived from Aspergillus niger and contained 11.27 PTU/g. Feed and water were available ad libitum for a 28-week reproductive period. Diets were fed in mash form. All hens were photostimulated in January (31 WOA) with 15.5 h of light/day. Individual bird body weight and feed consumption, by pen, were determined at monthly intervals from 31 WOA to 62 WOA.Hens were inseminated weekly with pooled semen from same strain breeder males. Hens were observed for biweekly reproductive and hatchability performance for 28 weeks of lay (WOL) and recorded on a pen basis. The following parameters were measured: egg production, fertility, hatchability of all eggs, hatch of fertile, initial egg weight, % egg weight loss, conductance, and embryonic mortality. Egg weight, shell thickness, albumen P and yolk P were measured monthly. At the end of the study P concentration was measured in plasma, tibia, fecal P and water-soluble fecal P.There were no consistent differences for any of the reproductive parameters observed due to dietary treatments. Decreasing dietary P resulted in no major reproductive problems for turkey hens. However, the addition of enzyme did significantly increase the number of days hens remained in production. Lowering dietary P significantly decreased total fecal P and water-soluble fecal P suggesting that dietary P can be lowered in efforts to aid environmental concern without impairing reproduction.The hatchability of eggs from turkey breeder hens fed dietary treatments was also measured. The few significant differences observed may be due to the hen's endogenous ability to efficiently breakdown the phytate molecule regardless of the inclusion level.Therefore, it was suggested that feeding 0.17% aP provided a sufficient source of P without impairing reproductive parameters. This suggests that eggs from hens fed 0.17% aP hatch as well or better than those fed industry or NRC levels with or without the addition of phytase.In conclusion, the P requirement of turkey breeder hens may be lower than the current level recommended by the NRC (1994). This study has provided evidence that lowering dietary P levels does not affect the reproduction or hatchability of turkey breeder hens. Results suggest that poultry companies that feed turkey breeder hens lower levels of dietary P will maintain reproductive and hatchability status and lower the amounts of fecal P. This would reduce litter P which would lessen the impact of turkey production on the environment.
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Effect of Dietary Phosphorus and Enzyme Levels on Reproduction in Turkey Breeder Hens
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