|Dozier, W -|
|Corzo, A -|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 25, 2011
Publication Date: May 25, 2011
Citation: Dozier, W.A., Corzo, A., Olanrewaju, H.A. 2011. Apparent metabolizable energy needs of male and female broilers ranging from thirty-six to forty-seven days of age. Poultry Science. 90:804-814. Interpretive Summary: Feed cost represents 65% of the total live production cost for broiler chickens that supports an industry that produces 8 billion birds annually. In the United States, the amount of corn used as an input for ethanol production has dramatically increased within the last 5 yrs. Consequently, the demand for corn reached market highs translating in unprecedented feed ingredient prices. The increase in feed ingredient prices had direct negative relationship on live production cost of broilers. One strategy to reduce live production cost has been to decrease energy density of the diet. Broilers fed diets low in apparent metabolizable energy results in poor feed conversion and caloric conversion. Apparent metabolizable energy response with broilers is dependent on environmental temperature. This study examined apparent metabolizable energy responses of male and female broilers subjected to low and moderate temperatures from 36 to 47 d of age. Results indicated that the broilers fed diets formulated to 3,200 kcal of apparent metabolizable energy/kg optimized feed conversion and caloric efficiency when grown during a low temperature environment. Conversely, male broilers subjected to moderate temperatures responded to diets having apparent metabolizable energy from 3,220 to 3,240 kcal/kg. During summer conditions, nutritionists may consider increasing apparent metabolizable energy in diet formulation due to the increase need of energy with latent heat loss.
Technical Abstract: Feed ingredient prices have fluctuated in recent yrs. In commercial practice, one strategy implemented to reduce live production cost has been to reduce AMEn minimums in diet formulation, which can result in poor feed conversion. Four experiments were conducted to examine AMEn responses of male and female broilers from 36 to 47 d of age. A 6 × 2 factorial arrangement of treatments was employed at 36 d of age. Male and female broilers were fed 6 levels of AMEn ranging from 3,140 to 3,240 kcal/kg in increments of 20 kcal/kg. Apparent metabolizable energy, BW gain, feed intake, feed conversion, caloric conversion, mortality, meat yields, plasma physiology parameters, and whole body composition were evaluated during experimentation. In experiment 1, broilers fed progressive additions of AMEn had lower (P = 0.02) feed intake, feed conversion, and caloric conversion from 36 to 47 d of age. Progressive increments of AMEn did not influence whole body accretion rate or breast meat yield. Apparent metabolizable energy × sex interactions were not apparent. Optimum growth performance was obtained when male and female broilers were fed diets approximating 3,200 kcal/kg. In experiment 3, AMEn × sex linear interactions (P = 0.05) were observed for BW gain, feed conversion, caloric efficiency, carcass weight, and total breast weight. Male broilers responded more dramatically to higher AMEn levels than female broilers. In experiments 2 and 4, energy balance assays were conducted from 42 and 44 d of age. Actual AMEn increased linearly (P = 0.001) with gradient additions of calculated AMEn. Calculated AMEn × sex interactions were not apparent. These data indicate that male broilers subjected to temperatures above their thermal neutral zone respond to AMEn levels from 3,220 to 3,240 kcal/kg.