Productive and metabolomic consequences of arginine supplementation in sows during different gestation periods in two different seasons

Background: The prolificacy of sows (litter size at birth) has markedly increased, leading to higher post-natal mortality. Heat stress can exacerbate this issue. Arginine plays an important role in several physiological pathways; its effect on gestating sows can depend on the period of supplementation. This study evaluated the effects of arginine supplementation on the productive performance and physiological status of sows during different gestation periods and seasons, using a multi-omics approach. Methods: A total of 320 sows were divided into 4 groups over 2 seasons (warm/cold); a control group (CO) received a standard diet (including 16.5 g/d of arginine) and 3 other groups received the standard diet supplemented with 21.8 g/d of arginine (38.3 g/d of arginine) either during the first 35 d (Early35), the last 45 d (Late45) or throughout the entire gestation period (COM). The colostrum was analyzed for nutritional composition, immunoglobulins and metabolomic profile. Urine and feces were analyzed on d 35 and 106 for the metabolomic and microbial profiles. Piglet body weight and mortality were recorded at birth, d 6, d 26, and on d 14 post-weaning. Results: Interactions between arginine and season were never significant. The Early35 group had a lower percentage of stillborn (P < 0.001), mummified (P = 0.002) and low birthweight (LBW) piglets (P = 0.02) than the CO group. The Late45 group had a lower percentage of stillborn piglets (P = 0.029) and a higher percentage of high birthweight piglets (HBW; P < 0.001) than the CO group. The COM group had a higher percentage of LBW (P = 0.004) and crushed piglets (P < 0.001) than the CO group. Arginine supplementation modifies the metabolome characterization of colostrum, urine, and feces. Creatine and nitric oxide pathways, as well as metabolites related to microbial activity, were influenced in all matrices. A slight trend in the beta diversity index was observed in the microbiome profile on d 35 (P = 0.064). Conclusions: Arginine supplementation during early gestation reduced the percentage of stillborn and LBW piglets, while in the last third of pregnancy, it favored the percentage of HBW pigs and reduced the percentage of stillbirths, showing that arginine plays a significant role in the physiology of pregnant sows.