A meta-analytical approach for evaluating the effect of arginine supplementation on the productive performance of sows during gestation

Arginine (Arg) supplementation for gestating and lactating sows seems to play a primary role in litter development by promoting placental vascularization and improving colostrum and milk quality. The aim of this study was to investigate the effects of the supplementation of dietary standardized ileal digestible Arg (SID Arg) on the productive performance of gestating sows using a meta-analytical approach. A total of 19 studies conducted between 2007 and 2020 which tested the effect of additional SID Arg supplementation in diets for sows were chosen using a systematic literature search. Data regarding backfat thickness, number of piglets born and live born, litter birthweight and weaning weight were extrapolated from each experimental group and expressed as a percentage of the value of the control group within the studies. The SID Arg supplementation was expressed as the percentage of SID Arg in the treated group compared to the control group (Additional SID Arg). Linear and quadratic models were built using a mixed procedure utilizing Minitab® software including Additional SID Arg, parity and feed intake classes and the period of SID Arg supplementation as fixed factors, and the study as the random factor. The SID Arg in control groups was higher than the doses suggested by the National Research Council (NRC; 2012) (4.20–8.90 g/kg of feed vs 3.2–7.9 g/kg, respectively). A quadratic response of Additional SID Arg was observed for placental efficiency (PE; P = 0.003; a=0.0019), the number of total piglets born (P = 0.027; a=−0.0003), the number of live born piglets (P = 0.005; a=−0.0006) and backfat thickness loss (P = 0.057; a=0.0029). A linear increase in the plasma concentration of Pro (P = 0.004; b=0.120), Orn (P = 0.002; b=0.284) and Arg (P = 0.001; b=0.425), and a decrease in the concentration of urea (P = 0.037; b=−0.063) was observed with an increasing level of SID Arg. There was no effect on placenta weight, live litter birthweight, individual piglet weight at birth and weaning, litter size and weight at weaning, and average daily gain during lactation. The estimated requirements of SID Arg for improving PE, reducing backfat thickness loss, increasing the number of piglets born and live born were 11.17 g/kg, 13.03 g/kg, 14.83 g/kg and 15.71 g/kg of feed, respectively. This meta-analysis highlighted the importance of redefining the Arg requirements of gestating sows and suggested a dosage ranging from 11.17 to 15.71 g/kg of feed to improve reproductive performance.