Estudo epigênico e morfométrico em uma linhagem de codornas de corte

Abstract

The aim of this thesis was to evaluate the gene expression of insulin-like growth factor I (IGF-I) and growth hormone receptor (GHR) in the liver and chest muscle of slaughter quails and to evaluate the muscle development of commercial cuts through the chest and thigh muscles fibers diameter. The birds were fed with diets containing different levels of methionine supplementation in two successive generations. Quails were used from 22 to 42 days old, distributed in three and five treatments in the first and second generations, respectively. At the end, samples were collected from the liver and chest muscle for extraction of total RNA, and from chest and thigh muscles for morphometric analysis. The results showed that GHR and IGF-I gene expression was influenced by supplementation. In the fifth treatment, where only the first generation received a supplementation above the standards requirements for the period, there was a significantly greater expression of GHR in both liver and chest muscle and also IGF-I in the chest muscle. The birds that received more methionine than the diet requirements in the laying phase (T3) presented lower weight at slaughter and smaller diameter of muscle fibers in relation to the thigh muscle when compared to the other treatments. In the laying phase, birds fed with a basal diet (T1) and diet according to the specie requirements (T2) presented higher body weights than those supplemented with 20% more methionine (T3) (P <0.05), where there was no significant difference from the birds that did not receive supplementation in the second generation. Regarding the chest muscle fibers diameter, the birds that received supplementation beyond methionine demands in the two generations had worse result compared to the other treatments, but did not differ significantly from those that received methionine excess only in the first generation.