Abstract
A total of 3,760 Ross male broiler chicks were used in two trials, one in the pre-starter (1-11 days) phase and the other in the starter (12-22 days) phase. Birds were distributed in a completely randomized experimental design with a factorial arrangement of 5 digestible lysine levels × 2 environments (clean and dirty environment), with eight replicates per treatment. The following dietary digestible lysine levels used were: 1.06, 1.12, 1.18, 1.24 and 1.30% in the pre-starter phase, and 1.00, 1.06, 1.12, 1.18 and 1.24% in the starter phase. Minimal relation of digestible lysine:digestible methionine + cystine, threonine, tryptophan and arginine (72, 67, 19 and 108%, respectively) were maintained, as well as 2.088 and 2.002% of glycine+serine in the pre-starter and starter diets, respectively. Weight gain, feed intake and feed conversion were evaluated. In all phases, dietary digestible lysine levels significantly influenced broiler performance, and broilers reared in the clean environment presented better performance than those reared in the dirty environment. The recommended digestible lysine levels during the pre-starter and starter phases are 1.30 and 1.24% when broilers are reared in the clean enviroment and 1.26 and 1.165% in the dirty enviroment, respectively.
Highlights
Genetic improvement programs have selected broilers and pigs for increasing weight gain and feed conversion ratio efficiency
During the pre-starter phase, broilers reared in the clean environment presented higher weight gain as compared with those reared in the dirty environment (P
There was a linear effect of lysine on the feed intake (P
Summary
Genetic improvement programs have selected broilers and pigs for increasing weight gain and feed conversion ratio efficiency. The nutritional requirements of these animals have increased. Geraert et al (2002) demonstrated that lysine requirements of poultry linearly increase as daily weight gain increases. Lysine is used as the reference amino acid in the formulation of feeds based on the ideal protein concept. While presenting higher performance efficiency, modern lines of poultry are more sensitive to stressors of pathogenic nature and others, which activate the immune system and lead to lower live performance (McFarlane et al, 1989; Klasing, 1997; Williams et al, 1997). The objective of the present study was to determine lysine nutritional requirements of male broilers reared in clean or dirty environments during the pre-starter and starter phases
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
