Abstract
ABSTRACT This study aimed to evaluate the effect of different reductions in digestible amino acids content (lysine, methionine, and threonine), according to two nutritional requirements in corn, soybean meal, and meat and bone meal based diets, with protease supplementation, on performance parameters and carcass characteristics. A total of 1080 day-old chicks, male, Cobb 500, were allotted to a completely randomized design, in a factorial arrangement 3 x 2, three reductions in digestible amino acids content (lysine, methionine, and threonine) and two nutritional requirements (Rostagno et al. 2005 and Cobb-Vantress Guidelines 2008), and all diets were supplemented with protease (200 ppm) with 6 replicates of 30 birds per pen. There was no significant interaction (p<0.05) between digestible amino acid reductions and both nutritional requirements for the performance variables and carcass yield and cuts. There was an effect of amino acid reduction and protease supplementation only on slaughter weight (p<0.05). Broilers fed according to the nutritional requirements of Rostagno et al. (2005) showed better (p<0.05) performance when compared to broilers fed as specified by the nutritional requirements of Cobb-Vantress (2008) with no significant differences in carcass characteristics. Protease supplementation of corn, soybean meal, and meat and bone meal based diets allows a reduction in the inclusion of crystalline amino acids (lysine, methionine, and threonine).
Highlights
Animal nutrition knowledge has been one of the factors responsible for driving productivity rates in the broiler industry
In the second (AR2) and third (AR3) amino acid reduction, the true amino acid digestibility of the feed ingredients were overestimate in 20 and 40%, respectively, in the diets supplemented with protease from 14 to 21 d and 36 to 42 d (Table 2)
Means followed by different letters in the columns are different according to Tukey’s test (p
Summary
Animal nutrition knowledge has been one of the factors responsible for driving productivity rates in the broiler industry. In Brazil, poultry feed is based on corn, soybean meal and meat bone meal. It is well known that the presence of antinutritional factors as trypsin inhibitors, lecithins and allergenic proteins in soybean meal (Rocha et al, 2014); non-starch polysaccharides and phytate in corn (Cowieson et al, 2010), and high variability of nutrient and energy composition in meat and bone meal (Troni et al, 2016), which can affect the nutritional value, utilization and digestibility of these feed ingredients, causing digestive losses to the broilers as well as reducing its performance. Protease supplementation in diets for broilers is a relevant tool to improve the efficiency in utilizing vegetable and animal protein (Stefanello et al, 2016; Vieira et al, 2016; Cowieson et al, 2018). Protease promotes a higher degradation of antinutritional factors present in feedstuffs improves protein digestibility and decreases synthesis of endogenous enzymes, resulting in higher availability of amino acids for protein deposition (Angel et al, 2011; Kamel et al, 2015).
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