Effetti della somministrazione parenterale di beta -carotene e vitamina E allo svezzamento sulla fertilità della scrofa

The effect of a single intramuscular (i.m.) beta -carotene (one mg/kg body weight) and vitamin E (1.3 mg/kg b.w.) administration on the day of weaning was evaluated in a swine herd for a period of one year. The proportion of sows in oestrus at different times of weaning, pregnancy rate and number of piglets born alive were considered, as well as environmental humidity and temperature conditions on the day of insemination (IS). The number of sows with a weaning-oestrus interval no longer than 5 days was significantly (p=0.01) higher in the treated group (126/142) compared to the control group (110/143). The pregnancy rate was also significantly (p<0.01) higher in the treated group (76.7%) than in the control group (61.5%). A double risk for pregnancy was observed in the treated sows (odds ratio=2.0644). On the other hand, insignificant differences were observed in the number of piglets born alive between the 2 groups. Concerning the environmental conditions recorded on the day of insemination, a significantly higher pregnant sow number was found when IS was performed at a temperature of <30 deg C (80.9 vs 60%, p<0.005) and humidity of more than or equal to 70% (78.8 vs 50%, p<0.005). The index of piglets born alive was unaffected by the treatment in any environmental condition. The statistical analysis confirmed that the environmental conditions to obtain better results were characterized by a <30 deg C temperature and <70% humidity.