Abstract
ABSTRACT Three experiments were conducted to estimate the digestible lysine requirements of slow-growing broilers on their performance, carcass traits, and breast meat quality. Different broilers were evaluated in each experiment. In Experiment 1, broilers were evaluated from 29-49 days of age (grower phase I), in Experiment 2, from 50 to 69 days old (grower phase II), and in Experiment 3, from 70-84 days old (finisher phase). A completely randomized design with five treatments of four replicates each was applied in all experiments. The following dietary digestible lysine values were investigated: 0.871, 1.011, 1.151, 1.291 and 1.431% in Experiment 1; 0.803, 0.943, 1.083, 1.223 and 1.363% in Experiment 2; and 0.766, 0.906, 1.046, 1.186 and 1.326% in Experiment 3. In all three experiments, digestible lysine values quadratically affected feed intake, weight gain, and feed conversion ratio. Lysine intake linearly increased with increasing digestive lysine values, whereas lysine utilization efficiency linearly decreased. Lysine requirements for maximum feed intake (1.298, 1.109, 1.150%), weight gain (1.183, 1.199, 1.162%), and feed conversion ratio (1.203, 1.162, 1.126%) were estimated in Experiments 1, 2 and 3. Digestible lysine requirement for carcass yield were estimated as 1.162, 1.068 and 1.107% in experiments 1, 2 and 3, respectively. Lysine influenced the physical-chemical parameters broiler breast meat. Digestible lysine levels of 1.203, 1.162 and 1.126% are recommended in the diets of Redbro Plume broilers during the phases 29-49, 50-69 and 70-84 days of age to optimize feed conversion ratio.
Highlights
Lysine is an essential amino acid and it is often the second limiting amino acid in diets based on corn and soybean meal
There was a quadratic influence of dietary digestible lysine levels on feed intake, weight gain and feed conversion ratio, and linear influence on lysine intake and utilization efficiency (Table 2)
The broilers fed the diets with lower digestible lysine values (0.871%) presented higher feed intake (2930 g), probably in an attempt to compensate for amino acid limitation
Summary
Lysine is an essential amino acid and it is often the second limiting amino acid in diets based on corn and soybean meal. Lysine has considerable quantitative importance in the diet and is directly involved in the body development of poultry. It is an essential amino acid with a significant physiological function in muscle protein synthesis (Costa et al, 2001; Lana et al, 2005). Lysine is the main amino acid taken into account in feed formulations based on the ideal protein concept, where the requirements of other amino acids are estimated in proportion to lysine (Pedroso et al, 2003). Determining the proper lysine requirement is essential for the formulation efficient feeds, with no limitations or excess of amino acids. Lysine -limiting diets have direct negative effects on muscle development, affecting the performance, carcass characteristics, and body composition of broilers (Oliveira et al, 2013)
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