Effects of dietary lysine on broiler performance and carcass yield - meta-analysis

There has been a great evolution and improvement in the nutrition of poultry and lysine has been used the reference amino acid to increase animal protein deposition. Therefore, a meta-analysis was performed with the objective of studying the effect of different dietary lysine levels on the performance and carcass yield of broiler chickens. In total, 21 studies published in Brazil since 1999 were included. Bird performance considered daily weight gain (178 observations) and feed conversion ratio (188 observations) results. Carcass quality was evaluated relative to carcass yield (24 observations), abdominal fat (24 observations) and breast meat yield (30 observations). Data were checked for normality and were submitted to analysis of variance. Weight gain and carcass yield increased with the addition of 1.05% of lysine to the diet, whereas feed conversion ratio and abdominal fat were reduced as dietary lysine concentration increased. The results, therefore, indicate that lysine is essential in bird nutrition and significantly affects bird performance and carcass yield

Gene expression profile of intramuscular muscle in Nellore cattle with extreme values of fatty acid

BACKGROUND: Fatty acid type in beef can be detrimental to human health and has received considerable attention in recent years. The aim of this study was to identify differentially expressed genes in longissimus thoracis muscle of 48 Nellore young bulls with extreme phenotypes for fatty acid composition of intramuscular fat by RNA-seq technique. RESULTS: Differential expression analyses between animals with extreme phenotype for fatty acid composition showed a total of 13 differentially expressed genes for myristic (C14:0), 35 for palmitic (C16:0), 187 for stearic (C18:0), 371 for oleic (C18:1, cis-9), 24 for conjugated linoleic (C18:2 cis-9, trans11, CLA), 89 for linoleic (C18:2 cis-9,12 n6), and 110 genes for α-linolenic (C18:3 n3) fatty acids. For the respective sums of the individual fatty acids, 51 differentially expressed genes for saturated fatty acids (SFA), 336 for monounsaturated (MUFA), 131 for polyunsaturated (PUFA), 92 for PUFA/SFA ratio, 55 for ω3, 627 for ω6, and 22 for ω6/ω3 ratio were identified. Functional annotation analyses identified several genes associated with fatty acid metabolism, such as those involved in intra and extra-cellular transport of fatty acid synthesis precursors in intramuscular fat of longissimus thoracis muscle. Some of them must be highlighted, such as: ACSM3 and ACSS1 genes, which work as a precursor in fatty acid synthesis; DGAT2 gene that acts in the deposition of saturated fat in the adipose tissue; GPP and LPL genes that support the synthesis of insulin, stimulating both the glucose synthesis and the amino acids entry into the cells; and the BDH1 gene, which is responsible for the synthesis and degradation of ketone bodies used in the synthesis of ATP. CONCLUSION: Several genes related to lipid metabolism and fatty acid composition were identified. These findings must contribute to the elucidation of the genetic basis to improve Nellore meat quality traits, with emphasis on human health. Additionally, it can also contribute to improve the knowledge of fatty acid biosynthesis and the selection of animals with better nutritional quality. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12864-016-3232-y) contains supplementary material, which is available to authorized users