Miglioramento dell'efficienza riproduttiva nella bovina e nella bufala mediante intervento sull'attività luteale

Luteal dysfunctions, e.g., premature luteolysis and corpus luteum with low progesterone secretion, are common causes of reproductive failure in cattle. They may be due to: (1) inadequate growth of the preovulatory follicle; (2) decrease in luteotropic aids; and (3) premature luteolysis. Both non-steroid anti-inflammatory drugs (FANS) and GnRH agonists have been successfully used at different times post-insemination in order to support luteal activity by either preventing PGF2α release or developing a supplementary corpus luteum, respectively. This study is aimed at evaluating the effect of the two treatments affecting luteal activity on artificial insemination efficiency in bovine and buffalo cows. A GnRH agonist, buserelin (20 μg/head), and a FANS, ketoprofen (1.5 g/head), were administered 10-d post-insemination in bovine and buffalo cows. Bovine cows were reared on three farms and, when ready to breed, artificially inseminated at spontaneous estrus and, 10-d later, randomly submitted to these two treatments or used as control. Bovine bulls were chosen in relation to breeding schedules previously arranged on each farm and randomly distributed within groups. Buffalo cows, which were separated from bulls two months earlier and diagnosed empty and free from evident reproductive disorders, were divided into three homogeneous groups in relation to age, parity and days open, and submitted to fixed time insemination through two replicates 20-d apart. Briefly, an agonist of GnRH, lecirelin (50 μg/head), was first administered; after 7 days these animals received 150 μg D-cloprostenol/head and, two days later, again 50 μg lecirelin/head. Buffaloes were artificially inseminated after 17 hours and again 41 hours after the last lecirelin treatment. Two buffalo bulls were used in each replicate. Pregnancy was evaluated by rectal palpation on 50-d post-insemination. Data were analyzed by ANOVA after arcsine transformation of percentage values. A preliminary analysis of data found a homogeneous distribution of both bovine and buffalo cows within groups in relation to age, parity and days open. In buffalo, the bull effect did not significantly affect results. In bovine, a total number of 15 different bulls were used randomly distributed among groups and farms, and the bull effect was negligible. In bovine cows (n=102), both treatments gave a significantly higher conception rate than control (52±2% and 52±9% vs 32±5; P<0.01). In spite of an evident farm effect (P=0.08), treatments showed a consistent effect within farms. In buffalo cows (n=94), the conception rate significantly improved in the case of buserelin treatment (53±4 vs 37±6%; P<0.05), whereas ketoprofen treatment showed results similar to control group (41±5%). In conclusion, in bovine cows both ketoprofen and buserilin treatments at 10-d post-insemination significantly increased the conception rate whereas in buffalo cows this improvement was only observed in the case of buserelin treatment.