A dose titration study on the effect of virginiamycin on gilt/sow and piglet performance.

Virginiamycin (VM), a compound with proven performance-promoting properties in pigs, can also be considered as sow performance enhancer. The present dose titration study investigates the long-term effects of VM on gilt/sow and litter performance. A total of 140 healthy gilts, in 35 sets of 2 + 2 siblings each, were used in this trial; gilts in each set were randomly allocated to the four treatments (35 gilts per each treatment group): VM0 = negative control, virginiamycin 0 mg/kg, VM20 = virginiamycin 20 mg/kg, VM40 = virginiamycin 40 mg/kg and VM60 = virginiamycin 60 mg/kg of feed. VM was added to the gilt/sow feed for a period starting from 6 months of age up to conception of the fourth parity, covering three complete breeding cycles (pregnancy, lactation and weaning-to-conception interval). The feed given did not contain any other antibacterial agent or performance enhancer. Piglets were given exactly the same quantity of creep feed from the fifth day onwards; it did not contain any antibacterial agent or performance enhancer. The lactation period was the same in all gilts/sows (21 days). Results indicate that VM supplementation of the feed improved gilt/sow performance by: (i) increasing (P < 0.05) the mean body weight at each farrowing, (ii) decreasing (P < 0.05) the mean weight loss from farrowing to weaning, and (iii) decreasing (P < 0.05) the mean weaning-to-conception intervals. VM supplementation of gilt/sow feed also resulted in improved litter size and litter performance in terms of: (i) a higher (P < 0.05) mean number of piglets born alive at each birth, (ii) a higher (P < 0.05) mean number of piglets weaned, (iii) a higher (P < 0.05) mean piglet body weight at each birth, and (iv) a higher (P < 0.05) mean piglet body weight at each weaning. These beneficial effects of VM were more pronounced in the VM40 group.