Exigência de lisina e restrição alimentar qualitativa para frangos de corte de menor potencial genético para crescimento

Abstract

Summary chapter 1 -------------------------- Lysine is an essential amino acid used as a reference in diet formulations based on the ideal protein concept and is also the main nutrient involved in the muscular development of broilers. Research related to the requirement of lysine for broilers with lower genetic potential for growth are scarce and sometimes quite divergent. The objective of this study is to determine digestible lysine requirements for male broilers with lower genetic potential for growth. A total of 520 male broilers of the RedBro-plumé commercial strain from 42 to 72 days of age and slaughtered at 73 days of age were used. The experimental design was completely randomized (DIC), with five treatments with four replicates with 26 broilers each. The treatments were constituted with the values 0.689, 0.842, 0.995, 1.148 and 1.301% of digestible lysine obtained from the addition of L-Lysine HCl to the basal diet, replacing the corn starch. In parameter of negative linear recess performance for feed conversion and linear and line use efficiency positive for lysine consumption. In carcass traits, there was a negative linear regression in absolute carcass, breast, wing, thigh + overcook and heart and quadratic effects for absolute fat weight, back yield and relative fat weight. The lowest digestible lysine in the feed, 0.689%, determining adequate performance and carcass characteristics. However, lower abdominal fat deposition would be obtained with 1.05% digestible lysine in the diet, it can be considered the requirement value for slow-growing male broilers in the evaluated phase. The qualitative food restriction consists in the dilution of the diets, through the inclusion of ingredients with low nutritional value, in order to reduce the amount of nutrients absorbed. The objective of this experiment was to evaluate the rates with different inclusion levels of ground Tifton 85 hay in the proportions of 0, 5, 10 and 15%. A total of 288 male broilers of the RedBro-plumé lineage were used, in a completely randomized design, in 4 treatments and 4 replicates of 18 broilers each. As broilers received as experimental feeds from 42 to 72 days of age. At 73 days the chickens were slaughtered for carcass analysis and intestine collections were performed in 8 broilers per replicate for morphological and morphometric analysis. A studied hay inclusion influenced linearly negative for weight gain and, in a positive way, feed consumption and feed conversion. Linear reductions without absolute carcass and breast weight, carcass yield and our liver and gizzard weights were also observed. Quadratic effect was observed for absolute weight of dorsum, liver and fat, yield of dorsum and villus height. The inclusion of Tifton 85 hay in the broiler ration of lower potential for growth from 42 to 72 days of age resulted in worsening performance and carcass yield. The use of hay was effective as a measure of qualitative restriction

Summary chapter 2 -------------------------- The qualitative food restriction consists in the dilution of the diets, by means of the inclusion of ingredients with low nutritional value, usually, rich in fibers to reduce the amount of nutrients absorbed. The aim of this study was to evaluate rations with different inclusion levels of ground Tifton 85 hay in rations at the proportions of 0%, 5%, 10% and 15%. A total of 288 male Red Bro-plumé commercial broilers were distributed in a completely randomized design in 4 treatments and 4 replicates of 18 broilers per treatment. The broilers received the experimental rations from 42 to 72 days of age. At 73 days all broilers were slaughtered for carcass analysis, and intestine samples from 8 broilers were collected per replicate for morphological and intestinal morphometric analysis. Increasing the inclusion values of dietary hay influenced linearly performance of broilers, with the decrease in weight gain, increase in feed consumption and impacting negatively in feed conversion values. Likewise, elevating the addition of hay in the ration showed linear reductions in absolute weight, carcass yield, and linear increases in the relative weights of liver and gizzard. The inclusion of Tifton 85 hay in broiler ration of lower potential for growth from 42 to 72 days of age affected negatively performance and carcass yield. The use of hay was effective as a measure of qualitative restriction of the ration if there is intention to control the growth of broilers according to a certain slaughter age