Dietary Supplementation with L‐Arginine between Days 14 and 25 of Gestation Enhances Litter Size in Gilts

Abstract

Gilts were checked daily for estrus with boars in the morning and bred at onset of the second estrus and 12 h later (the time of breeding = d 0 of gestation). Between d 14 and 25 of gestation, 15 gilts per treatment were housed individually and fed twice daily 1 kg of a corn‐and soybean meal‐based diet supplemented with 0.0%, 0.4%, or 0.8% L‐arginine. All diets were made isonitrogenous by addition of L‐alanine. At d 25 of gestation, gilts were hysterectomized to obtain conceptuses. Compared with control gilts, dietary supplementation with 0.4% or 0.8% L‐arginine increased (P ≤ 0.05) concentrations of arginine in maternal plasma, total volume of amniotic fluid, total amounts of arginine in allantoic and amniotic fluids, total amounts of fructose and most amino acids in amniotic fluid, placental growth, and the number of viable fetuses per litter by 2. The numbers of total fetuses or corpora lutea, total fetal weight, total volume of allantoic fluid, maternal circulating levels of progesterone and estrogen, or total amounts of the hormones in allantoic fluid did not differ among the three treatment groups. Reproductive performance of gilts did not differ between the 0.4% and 0.8% L‐arginine groups. These results indicate that dietary supplementation with 0.4% or 0.8% L‐arginine between d 14 and 25 of gestation can enhance embryonic/fetal survival in gilts. Supported by USDA grants.