Effects of dietary amino acid level and duration of finisher period on performance and carcass content of broilers forty-nine days of age

Specialized protein products in broiler chicken nutrition: A review

In poultry nutrition, most attention is given to protein products, due to the importance of protein as a major constituent of the biologically active compounds in the body. It also assists in the synthesis of body tissue, for that renovation and growth of the body. Furthermore, protein exists in form of enzymes and hormones which play important roles in the physiology of any living organism. Broilers have high dietary protein requirements, so identification of the optimum protein concentration in broiler diets, for either maximizing broiler performance or profit, requires more knowledge about birds' requirements for protein and amino acids and their effects on the birds' growth performance and development. It also requires knowledge about the protein sources available that can be used in poultry diets. The broad aim of this review is to highlight the importance of some of the available high-quality specialized protein products of both animal and plant origins which can be explored for feeding broiler chickens. Minimization of the concentration of anti-nutritional factors (ANFs) and supplementation with immunologically active compounds are the main focus of gut health-promoting broiler diets. These diet characteristics are influenced by feed ingredient composition and feed processing. The general hypothesis is that these protein products are highly digestible and devoid of or contain less ANFs. Feeding these products to broiler chicks, especially at an earlier age, can assist early gut development and digestive physiology, and improve broiler growth performance and immunity.

Optimization of phase feeding of starter, grower, and finisher diets for male broilers by mixture experimental design: forty-eight-day production period

A mixture experiment, a variant of response surface methodology, was designed to determine the proportion of time to feed broiler starter (23% protein), grower (20% protein), and finisher (18% protein) diets to optimize production and processing variables based on a total production time of 48 d. Mixture designs are useful for proportion problems where the components of the experiment (i.e., length of time the diets were fed) add up to a unity (48 d). The experiment was conducted with day-old male Ross x Ross broiler chicks. The birds were placed 50 birds per pen in each of 60 pens. The experimental design was a 10-point augmented simplex-centroid (ASC) design with 6 replicates of each point. Each design point represented the portion(s) of the 48 d that each of the diets was fed. Formulation of the diets was based on NRC standards. At 49 d, each pen of birds was evaluated for production data including BW, feed conversion, and cost of feed consumed. Then, 6 birds were randomly selected from each pen for processing data. Processing variables included live weight, hot carcass weight, dressing percentage, fat pad percentage, and breast yield (pectoralis major and pectoralis minor weights). Production and processing data were fit to simplex regression models. Model terms determined not to be significant (P > 0.05) were removed. The models were found to be statistically adequate for analysis of the response surfaces. A compromise solution was calculated based on optimal constraints designated for the production and processing data. The results indicated that broilers fed a starter and finisher diet for 30 and 18 d, respectively, would meet the production and processing constraints. Trace plots showed that the production and processing variables were not very sensitive to the grower diet.

Impact of dietary amino acid concentration on growth, carcass yield, and uniformity of broilers

Two studies were conducted to measure the effects of dietary amino acid regimens (high, medium, low) and gender on Arbor Acres Plus broilers. Body weight, feed conversion, mortality, carcass yields, and uniformity served as criteria evaluated. Growth and feed conversion were improved in broilers fed diets with high amino acid concentration until 35 days of age. Yields of some carcass parts were improved up to 35 days of age as diet concentration was increased. Flock uniformity was decreased when dietary amino acid concentration was reduced. Male broilers exhibited faster growth rate, whereas females had improved feed conversion at 28 and 35 days of age, but no differences were observed at 14 and 49 days of age. Male broilers had lower breast meat yield and relative abdominal fat than females. Variability within females was lower than in males. Results indicate that when high dietary amino acid concentration was provided at an earlier age, reducing concentration at later feeding phases did not compromise growth or carcass yields. Furthermore, moderate to high dietary amino acid levels may help reduce variability within flocks.