Effects of Feeding Levels during Wean-to-Estrus Interval and First Week of Gestation on Reproductive Performance of Sows

This experiment was conducted to evaluate the effects of feeding levels during wean-to-estrus (WEI) and first week of gestation (1WK) on reproductive performance of sows. A total of 543 females (PIC-Camborough) were used from weaning to farrowing. Treatments were distributed in a factorial design 2×2 with 2 feeding levels during the WEI (2.8 or 5.2 kg/d) and 2 feeding levels during first week of gestation (2 or 3 kg/d). Dietary treatments were: Low-WEI, Low-1WK (LL), High-WEI, Low-1WK (HL), Low-WEI, High-1WK (LH) and High-WEI, High-1WK (HH). Females were individually housed, blocked by body condition score (1=thin, 2=ideal, 3=fat), parity group (P1, P2 and P3+), and randomly assigned to dietary treatments. The average body condition was 2.1±0.52 and average parity was 2.8±1.46. Sows were fed corn-soybean meal based diets with 3.4 Mcal ME/kg and 1.3% SID lys during the WEI and 3.2 Mcal ME/kg and 0.78% SID lys during gestation. All sows were fed 2 kg/d of the gestation diet after the first week of gestation until farrowing. Data were analyzed using generalized linear mixed models with pen as the experimental unit and week as random effect. Born alive weight index was calculated as farrowing rate × total born × born alive rate × 100 × individual born alive birth weight. There was no parity or body condition score interaction with dietary treatments. There was an increase (P=0.05) in farrowing rate (93.3 vs. 88.3%, SEM=2.78%) when sows were fed high vs. low feeding levels during the WEI. There were no evidences for differences between dietary treatments (P³0.24) in total piglet born or rate of mummified fetuses. There was a WEI × 1WK (P=0.04) interaction for stillborns where increasing feeding levels at WEI and 1WK, increased stillborn rate (HH: 7.6 vs. HL: 5.0%, SEM=0.93%). Consequently, there was a marginally significant (P=0.06) interaction for born alive, where HH had reduced born alive rate vs. HL (89.9 vs. 92.4%, SEM=0.85%). There was an increase (P=0.03) on born alive weight index when high feeding levels were fed during WEI compared to low. Furthermore, there was a marginally significant (P<0.10) interaction for individual piglet birth weight of total born, born alive, and stillborns, where HH had lower birth weight compared to HL. In conclusion, feeding 5.2 kg/d during wean-to-estrus interval increased farrowing rate by 5 percentage points; however, high feeding levels in the first week of gestation increased stillborn rate and reduced piglet birth weight.