Genetic Selection for Age at Puberty Altered Sow Colostrum Production and Piglet Survival

The objective was to evaluate the impact of divergent genetic selection for age at puberty on sow colostrum production and litter performance. Genetic lines were formed at the NCDA Tidewater Research Station (Plymouth, NC) by selecting gilts for young age at puberty (YOUNG) or old age at puberty (OLD). Second parity females (n=120) from generations three and four were used. In generation four, age at puberty for YOUNG and OLD was 163 and 183 d, respectively. Females were housed in modern, environmentally controlled facilities with ad libitum access to water. Sows were fed in gestation based on body condition and to appetite in lactation. At birth, piglets (n=1,639) were weighed prior to first suckle and individually identified. Piglets were reweighed at 24 h of age and individual piglet colostrum intake (CI) estimated using an equation incorporating BWT, 24 h weight gain and the duration of suckling. Sow colostrum production (CP) was the sum of litter CI. From generation four sows, a colostrum sample was collected on average 75 min after the birth of the first piglet and analyzed for macronutrient content (MC). Reproductive variables included total number born (TNB), number born alive (NBA), average piglet birth weight (BWT), total litter BWT, number weaned (NW), average 21 day piglet weight (WWT), total litter WWT and piglet survival. Piglet survival was calculated as NW ÷ TNB. Variables were analyzed in SAS using PROC GLM with fixed effects of genetic line and generation. Litter size was included as a covariate for BWT, litter BWT, CI, CP, WWT, litter WWT and piglet survival. Colostrum MC was corrected for collection time. Sow was experimental unit. Genetic lines did not differ (P>0.05) for colostrum protein, fat, lactose, total solids or energy. No differences (P>0.05) were observed between YOUNG and OLD for TNB (13.75 vs. 13.50), NBA (12.99 vs. 12.82), BWT (1.25 vs. 1.21 kg), litter BWT (16.62 vs. 15.97 kg) or WWT (5.75 vs. 5.64 kg). Yet YOUNG sows had greater (P<0.05) CI (453 vs. 418 g) and CP (5.49 vs. 5.10 kg) when compared to OLD. Compared to OLD sows, YOUNG sows had greater (P=0.01) piglet survival (84.7 vs. 79.3%), tended (P=0.06) to have higher NW (11.06 vs. 10.52) and had heavier litter WWT (P=0.01) (63.4 vs. 58.3 kg). Results suggest divergent selection for age at puberty impacted sow colostrum production and piglet throughput.