Risposta dell’attività riproduttiva al trattamento con melatonina in pecore di razza Sarda con differenti BCS

The aim of this research was to investigate the influence of BCS (Body Condition Score) on the reproductive response to the male effect in Sarda ewes treated with melatonin implants. For the research 80 adult ewes at an average age of 4,2 ± 1,3 years giving birth to lambs in November, were used. The animals were divided into four groups (n = 20 per group) as follows: group A, animals with BCS > 2.5 treated on April 20th with a subcutaneous implant (at the base of the left ear) of 18 mg of melatonin (Melovine®, Ceva Vetem); group B, animals with BCS > 2.5 untreated; group C, animals with BCS <2.5 treated on April 20th with the same implant used in group A; group D, animals with BCS <2.5 untreated. On May 25th two males of proved fertility were introduced in each group. From May 25th to July 7th, blood samples were collected weekly from each animal for plasma progesterone dosage. Moreover their delivery dates were recorded. All the animals of the group A (100%), the 55% of the B group, the 60% of the C group and the 35% of the D group were cyclic within the first 28 days after male introduction. At the end of the experiment all the animals of the A and C groups were cyclic, vs the 90% of the B group and the 75% of the D group. In conclusion, BCS influences considerably the reproductive response to male effect and melatonin improves reproductive efficiency.