The impact of diet energy and amino acid content on the feed intake and performance of broiler chickens
Three experiments were conducted to understand the effect of dietary energy and amino acids, and their interactions on broiler performance. To ensure accuracy of feed formulation, a trial was completed at two ages (5 or 6 and 21 days of age) to determine the digestibility of feed ingredients to be used in research diets. Apparent metabolizable energy (AME) and apparent ileal amino acid digestibility (AID) values were applied to feed formulation on an age appropriate basis. The second experiment investigated the effect of dietary energy content and bird age on broiler feed intake. Diets containing 2700, 2800, 2900 and 3100 kcal/kg AME were fed to broiler chickens with the introduction of the range of energy diets starting at the beginning of starter (S; 0-10 day), grower (G; 11-25 day) or finisher (F; 26-35 day) phases. The digestible amino acid (DAA) content in all the diets met or exceeded Aviagen 2007 recommended values. The broiler chickens did not adjust their feed intake based on energy content of the diet and there was no effect of age of treatment introduction. A final study investigated the effect of dietary energy on broiler feed intake and also examined the relationship between dietary energy and DAA levels. The 4 x 3 factorial arrangement utilized diets containing 2700, 2800, 2900 and 3100 kcal/kg AME and three levels of digestible lysine (0-10 days - 1.14, 1.02 and 0.89%; 11-25 days - 0.99, 0.88 and 0.77%; 26-35 days - 0.87, 0.78 and 0.68%). Feed intake was not affected by dietary energy at the two highest lysine levels. Feed intake decreased with increasing energy levels at the lowest level of digestible lysine as did body weight, and carcass and BY (breast meat yield). Growth rate, feed efficiency and BY increased with AME level at the highest dietary lysine, but were not affected at the moderate lysine content. In conclusion, broiler chickens in these experiments do not adjust their feed intake based on dietary energy levels and the results indicate that energy should be provided in the diet to meet maintenance requirements and match the protein synthesis capacity of the dietary level of amino acids.
Digestible amino acid, Broiler, AME, Lysine, Nutrient density
Master of Science (M.Sc.)
Animal and Poultry Science