Efeito da suplementação com L-arginina durante a lactação sobre a funcionalidade da glândula mamária e desempenho de fêmeas suínas de descarte

Abstract

Modern sows are highly productive and have a high nutritional requirement, nutritional strategies have been widely studied in order to optimize the productive efficiency of these females and minimize the consequences of high productivity. Among the nutrients that participate in important metabolic functions, L-arginine stands out, a functional amino acid indicated in studies as beneficial in several reproductive aspects of sows, however some points are still not clarified. Therefore, the objective of this research was to clarify how L-arginine supplementation during lactation influences the expression of some genes important for mammary gland tissue and the possible influence of gland position on performance parameters in pre-selected females for the discard. Study one aimed to review data from studies that performed L-arginine supplementation at key moments for the development of the mammary gland, being the final third of pregnancy and lactation. Twenty-one studies were selected and their results were summarized in order to evaluate the effects of L-arginine supplementation on parameters related to the development of the mammary gland. Dietary supplementation of arginine in sows in the final third of gestation and/or lactation may benefit the weight gain of piglets in the farrowing phase and the weight at weaning. L-arginine supplementation during lactation favors milk production mainly due to the modulation of the levels of prolactin and insulin hormones. More studies are needed to assess the impact of supplementation on mammary gland tissue. To establish a supplementation plan with L-arginine, aspects related to the supplementation period should be better evaluated. The aim of the study in article 2 was to evaluate the effects of L-arginine supplementation on performance parameters, nutritional modulation of milk, gene expression and redox status of the mammary gland of lactating sows. Twenty-four sows of the same genetic lineage were used in a commercial farm, located in the municipality of Oliveira, MG. The design used was completely randomized, with a control diet (CON) and a diet supplemented with 1.0% arginine (ARG), the amino acid was supplemented on top during the entire lactation phase. Performance parameters of the sow and piglets, amino acid composition of milk, blood levels of progesterone and prolactin, parameters of redox status and histology in mammary gland tissue, gene expression of impose genes were evaluated. Females fed with L-arginine had lower feed intake and greater weight loss during the lactation period. Piglets that suckled in the inguinal glands showed lower performance at weaning regardless of the diet adopted. There was no effect of supplementation on blood levels of progesterone and prolactin during lactation. The amino acid profile of milk was not influenced by L-arginine supplementation. The COX-1 gene showed lower messenger RNA (mRNA) expression in the thoracic and abdominal positions of treatment with L-arginine, and SLC27A4 was more expressed in the thoracic and inguinal positions. Supplementation with L-arginine did not affect the proportion in area evaluated on histological slides of parenchymal tissue,

adipocytes or blood vessels of breast tissue. Tissue antioxidant capacity was improved with l- arginine supplementation. These findings show that 1.0% ARG supplementation in lactating

females increases the expression of the fatty acid transporter protein and modulates inflammatory processes and the production of protaglandins by reducing the expression of COX-1. It improves the redox status of mammary gland tissue, but does not influence sow and piglet performance as well as milk characteristics.