title: Maintenance nitrogen requirement of the turkey breeder hen with an estimate of associated essential amino acid needs.
abstract: Nonproducing, small-type breeder hens in excess of 65 weeks of age were used to represent the maintenance state. All birds had been in laying cages since 30 weeks and accustomed to 16 hr of 70 lx lighting at 16 C. Nitrogen (N) balance was performed in metabolism cages under the same conditions. Ad libitum intake of a common breeder ration led to an intake of ca. 47 kcal metabolizable energy (ME)/kg body weight (BW)/day, which was considered to represent the maintenace energy requirement. Nitrogen retained while consuming this feed averaged 172 mg/kg BW/day. Force-feeding a N-free diet to satisfy the maintenance energy requirement resulted in an 85 mg N/kg BW/day endogenous loss. Total maintenance nitrogen requirement was considered to approximate 257 mg/kg BW/day. Nitrogen retention after force-feeding corn-soybean meal rations having a progressive protein content indicated that the associated amino acids were more efficient in satisfying the endogenous than the total N requirement. A model that estimated maintenance amino acid requirements was assembled by combining the relative concentrations found in muscle and feathers to represent endogenous and retained N, respectively. For the most part, model values agreed with published results for the rooster; however, verification in balance studies was less than successful and believed to be attributable to hen variation in feather cover and protein reserves.
mesh_terms: D000601:Amino Acids, Essential / Q000032:analysis / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001835:Body Weight; D004734:Energy Metabolism; D005241:Feathers / Q000032:analysis; D005260:Female; D009132:Muscles / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism*; D009751:Nutritional Requirements; D014422:Turkeys / Q000378:metabolism*
chemical_list: D000601:Amino Acids, Essential; D009584:Nitrogen