Effects of dietary valine supplementation during late gestation on the reproductive performance and mammary gland development of gilts

Long Che,Zongyong Jiang,Mengmeng Xu,Kaiguo Gao,Xuefen Yang,Hao Xiao,Xiaolu Wen,Li Wang

doi:10.1186/s40104-019-0420-z

Abstract

BackgroundMammary gland development during late gestation in gilts is a major factor that alters the composition of colostrum and growth performance of piglets. Plasma valine is taken up and metabolized extensively by the mammary gland; however, the effects of valine on mammary gland development during late gestation are still unclear. Thirty primiparous gilts were divided into three treatment groups (n = 10) and received one of the three diets starting on day 75 of gestation until the day of farrowing. The total dietary valine to lysine ratio of the three diets was 0.63 (LV), 0.73 (MV), and 0.93 (HV), respectively.ResultsDietary valine supplementation during late gestation did not affect (P > 0.05) the litter size and weight at farrowing; however, the piglet weight and average daily gain at weaning were linearly increased (P < 0.05) as the dietary valine increased. The highest piglet weight at weaning was observed when the gilts were provided the HV diet. Dietary valine supplementation linearly elevated (P < 0.05) protein, fat and solids-not-fat and some free amino acids content in colostrum. The concentration of prolactin in plasma of gilts was linearly increased in response to valine supplementation at days 1 and 10 of lactation (P < 0.05). Furthermore, with increasing dietary valine allowance, a linear increase (P < 0.05) was observed in the area of the lumen of alveolus and the content of DNA, RNA, and total protein in the mammary tissues at day 1 of lactation. Moreover, the protein expression of cyclin D1, p-mTOR, p-S6, and p-4EBP1 was also linearly increased (P < 0.05) in the mammary tissue at day 1 of lactation. However, no difference (P > 0.05) was observed in the indices related to mammary development and the mTOR signaling pathway at day 21 of lactation.ConclusionThe results revealed that increasing the total dietary valine to lysine ratio to 0.93 during late gestation significantly enhances the piglet weight and average daily gain at weaning probably due to improved development of mammary gland.

Highlights

Mammary gland development during late gestation in gilts is a major factor that alters the composition of colostrum and growth performance of piglets
It has been shown that the crude protein content per gland of the mammary tissue increases by 0.14 g/d from day 0 to 80 of gestation and 3.41 g/d from day 70 of gestation suggesting that it is a critical window of mammary gland development [4]
Previous studies have shown that supplementation of valine increases the proliferation rate of porcine mammary epithelial cells in vitro and improves the milk protein and milk fat content in gilts [10, 11, 16], suggesting the importance of applying the nutritional approach to increase the mammary gland development and secretion of gilts

Summary

Introduction

Mammary gland development during late gestation in gilts is a major factor that alters the composition of colostrum and growth performance of piglets. Plasma valine is taken up and metabolized extensively by the mammary gland; the effects of valine on mammary gland development during late gestation are still unclear. A period of extensive mammary gland development in gilts begins in the third trimester of gestation [3]. Studies have highlighted that increasing the supplementation of dietary amino acids during late gestation can improve the lactation performance of sows and the growth of nursing piglets, for example lysine [5] and arginine [6]. Only a few studies have investigated the effects of dietary valine supplementation during late gestation on the subsequent reproductive performance

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