Oral administration of domperidone in the first or third week of lactation: Effects on prolactin concentrations and mammary gene expression in sows and piglet growth

The scope of the present study is endocrine and metabolic control of sow lactation. This project aimed to determine the impact of increasing prolactin concentrations via oral administration of the dopamine receptor antagonist domperidone in the first or third week of lactation in sows. Effects on sow hormonal and metabolic status, lactational performance, and gene expression in mammary epithelial cells were determined. Primiparous sows were divided in 3 treatments: 1) 10 mL of vehicle (table syrup) per os twice daily during the first and third weeks of lactation (Control, CTL, n = 23), 2) 0.5 mg/kg of domperidone per os twice daily during the first week of lactation (LACT1, n = 23), or 3) 0.5 mg/kg of domperidone given per os twice daily during the third week of lactation (LACT3, n = 22). Treated sows also received 10 mL of the vehicle twice daily during the other treatment period. Litter size was standardized to 12 ± 1 and piglets were weighed at birth, 24 h, and on d 8, 15, 22 (weaning), 35, and 56. Sow feed intake was recorded daily. Representative milk samples were obtained on d 7 and 21 of lactation for compositional analyses, and milk fat globules were used to measure mRNA abundances of various genes. Jugular blood samples were obtained from sows on d 1, 7, 14, and 21 of lactation to measure concentrations of prolactin, IGF-1, insulin, urea, and FFA. Concentrations of prolactin were increased (P < 0.01) at the end of the 7-d treatment period with domperidone, whether imposed in the first (LACT1) or third (LACT 3) week of lactation. No other blood variables were affected by treatments and neither was milk composition (P > 0.10). Sow BW, backfat thickness, or feed intake were not altered by treatments (P > 0.10), but piglet BW tended to be greater in litters from LACT3 compared with CTL sows on d 22 and 35 (P ≤ 0.10). Gene expression of EGF in milk fat globules tended to be (LACT1, P < 0.10) or was increased (LACT3, P < 0.05) after treatment, and the effect in LACT1 sows was maintained until d 21 of lactation. The mRNA abundance of SPP1 was increased (P < 0.05) in LACT1 vs CTL sows on d 7, and that of 3 major milk proteins tended to be (CSN1S2 and WAP, P < 0.10) or was greater (LALBA, P < 0.05) in LACT3 vs CTL sows on d 21 of lactation. Oral administration of domperidone during the first or third week of lactation increased prolactin concentrations and altered mRNA abundances of selected genes in milk fat globules. Yet, only the LACT 3 treatment positively affected piglet performance.