PSVII-15 Effect of birth weight on the performance of hyperprolific sows at the first service.

Abstract To determine the influence of birth weight (BW) on the performance of hyperprolific sows at first service, a prospective comparative observational study was conducted in northwestern Mexico. Six hundred eighty piglets from the PIC Camborough® were used, preselected as future breeders from the moment of birth. The piglets were classified into four groups according to their BW (≤1.1, 1.2 to 1.4, 1.5 to 1.6 and ≥1.7 kg). The data were analyzed with Chi-square and ANOVA (p ≤ 0.05). Pigs with BW ≤1.1 kg had a lower selection rate at 148 d of age (62.4 vs. 75, 79.3 and 75.2%; p = 0.003), a low growth rate (GR) from birth to 148 d of age (0.423 vs. 0.447, 0.477 and 0.462 kg/d; p = 0.001) and at first service (0.578 vs. 0.597, 0.614 and 0.627), and an older age at first service (263.4 vs. 249.5, 251.9 and 249.4 d; p = 0.003) compared to those with BW 1.2 to 1.4, 1.5 to 1.6 and ≥1.7 kg, respectively. BW did not influence age at puberty and, in general, the rate of gilts served within 262 d of age was low (24.3%), with a tendency (p = 0.11) to increase in gilts with BW ≥1.2 kg. The observed results allow us to conclude that preselected piglets with BW ≤1.1 kg have a lower retention rate, a lower GR and are served at an older age.