The Impact of Oregano Essential Oil Supplementation over 2 Complete Reproductive Cycles in Multiparous Sows

We had previously reported that oregano essential oil (OEO) supplementation in a single gestation and lactation cycle shortened birthing interval in primparous and multiparous sows. The impact of OEO (0 or 2 g/d; By-O-Reg, Advanced Ag Products) supplementation in gestation and lactation over 2 reproductive cycles on sow and piglet performance was determined. A total of 32 sows (parity 2-6) completed 2 reproductive cycles. Experimental diets were offered once daily in gestation and twice daily in lactation (OEO was added as a top dress in the AM feeding). Diets were formulated to meet or exceed nutrient requirements for sows/gilts in gestation (0.6 % SID Lysine and 3280 kcal ME/kg) and lactation (0.9 % SID Lysine and 3280 kcal ME/kg). Assessment of sow performance included body weight and backfat at breeding, d110 of gestation, d1 of lactation, and at weaning, farrowing duration, piglet birth interval, piglet birth and wean weight, sow lactation feed intake, and colostrum and milk protein. Farrowing duration was determined as the time between birth of the first and last piglet. Data were analyzed as a RCB design with sow as the experimental unit. There was limited effect of OEO supplementation on sow reproductive performance in the second parity. Mean sow body weight and backfat at breeding, d110 of gestation, and weaning were 203± 10 and 11.3 ± 1.3, 258 ± 7 and 15.7 ± 0.8, and 225 ± 6 kg and 12.0 ± 1.2 mm, respectively. Mean gestation length, farrowing duration, birthing interval, and lactation feed intake were 115.8 ± 0.2, 5.5 ± 0.9 h, 18.8 ± 3.9, and 6.37 ± 0.42 kg/d. Oregano EO supplementation had limited impact on litter characteristics. Mean total born, born alive, stillborns, piglet birth and wean weights were 15.8 ± 0.90, 14.7 ± 0.6, 0.87 ± 0.44, 1.40 ± 0.12 kg and 6.67 ± 0.31 kg, respectively. Sows fed diet with OEO tended to have a lower (P = 0.06) presence of mummies (0.16 vs 0.71 ± 0.21). Colostrum protein content from sows fed diet with OEO tended to be greater (21.2 vs 17.9 ± 0.9%; P = 0.06) than from control-fed sows and there was no difference in milk protein content (mean 5.9 ± 0.1%; P = 0.70). Oregano EO supplementation through 2 parities had little additional benefit on sow and litter performance. The reduction in mummies may reflect an impact on embryo survival in subsequent parities.