Effect of dietary fat concentration and energy to protein ratio on the performance, yield of carcass components and composition of skin and meat of turkeys as related to age

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Abstract
The effects of up to 12.9% added dietary fat (ADF) and a 10% variation in the relative energy to protein ratio (E : P) on performance to 24 weeks and the carcass composition of male turkeys at 4‐weekly intervals were determined. Poults given a low level of ADF required a narrower E : P to 4 weeks and were more sensitive to E : P imbalance than those given higher levels of ADF. The E : P requirement was less critical after 4 weeks. Energy conversion was more efficient with lower ADF to 4 weeks but became more efficient with higher ADF as the birds approached maturity. Energy utilisation was more, and protein utilisation less, efficient with narrower than with wider E : P's. Increased deposition of tissue fat at high ADF levels may explain the increased energy tolerance of poults fed on fat‐rich diets. Carcass finish and tissue fat deposition were influenced more strongly by the level of ADF than by varying the E : P. The pronounced influence of ADF on the skin and tissue fat of immature turkeys indicates the potential value of increased ADF in diets for early marketed small turkeys. The yield of carcass components other than skin was not strongly influenced by either ADF or E : P. The percentage eviscerated carcass and edible meat yield increased with age. The percentage yield of wing segments and drumstick decreased with age. Skin yield and tissue fat content first decreased, then increased with age. Equations were derived to express the relationship of fat content with protein, moisture and age in thigh and breast meat.