Resin acid-enriched composition (RAC) mainly containing tall oil fatty acid with an active component of resin acid (RA) can improve the microbial population in the digestive system, change the microbial fermentation, and improve the feed conversion ratio. We investigated the effects of dietary supplementation of RAC on sow colostrum yield (CY), colostrum composition and gut microbiota. Tall oil fatty acid and RA are commonly termed RAC and CLA, pinolenic, abietic, dehydrobiotic acids are characteristic components of RAC. The experiment was conducted in three trials in three respective herds. Sows were fed with a control diet and the same diet supplemented with 5 g RAC/day per sow during the last week of gestation. The 16S ribosomal RNA gene sequencing technique was used to assess sows’ faecal microbiota populations at farrowing. Colostrum nutritional composition, acute phase proteins (APPs) and immunoglobulin (Ig) content were also assessed. Individual piglets were weighed at birth and 24 h after the birth of first piglets in order to calculate CY and later at 3 to 4 weeks to calculate average daily gain. The RAC-fed sows had significantly higher IgG levels (P<0.05) in all three herds but treatment did not influence colostrum IgA and IgM concentration. There were no significant differences in colostrum protein, lactose and fat content in sows of the two diet groups (P>0.05), but those fed RAC had higher levels of colostrum serum amyloid A. Colostrum yield was significantly higher in RAC-fed sows in herds 2 and 3 with heavier piglets between 3 and 4 weeks of age (P<0.05), but not in herd 1 (P>0.05). Resin acid-enriched composition supplementation significantly increased some beneficial and fermentative bacteria (Romboutsia and Clostridium sensu stricto) than the control diet (P<0.01) while some opportunistic pathogens (Barnesiella, Sporobacter, Intestinimonas and Campylobacter), including Proteobacteria, were suppressed. Therefore, RAC added to the sow diet at late pregnancy increases colostrum IgG, colostrum availability for neonate piglets, and seems to promote better maternal intestinal microbial sources.
