Effect of melatonin on follicular development parameters in a fixed-timed artificial insemination programme in water buffalo

BERDUGO, JESUS ALFREDO; KONRAD, JOSE LUIS; YUPONI, ROBERTO; BANDEO, ALEXIS; CAMELINO, RAMON; CARDONA-MAYA, WALTER D.; CRUDELI, GUSTAVO ANGEL

Veterinarska stanica

Instituto de Veterinaria de Croacia

Año: 2021 vol. 52

0350-7149

It is well known that buffaloes haveseasonal anoestrus and that the use ofmelatonin reduces the effects of season inreproduction, particularly among sheepand goats. This study evaluates the use ofmelatonin on water buffaloes to increasepregnancy rates in a fixed-time inseminationprogramme. The study was conducted onan Argentinian buffalo herd, located in theCorrientes Province, during an unfavourablereproductive season. Artificial inseminationcycles were performed in September andDecember 2018. Sixty animals were selected,and melatonin was administered to 29females at a dose of 18 mg/50 kg. Ten daysafter the melatonin implant, ovulationsynchronization was started. Animals wereinseminated with frozen semen of a singlebull. Pregnancy was evaluated by ultrasound35 days after insemination. The pregnancyrate of the two repetitions was 34.62% forSeptember and 6.4% for December (P=0.007).No significant differences were found inthe parameters associated with folliculardevelopment and formation of the corpusluteum. Analysis of the effects of melatoninon the two replicates showed that there wasno statistically significant effect of ovarianresponse regarding the analysed folliculardevelopment parameters. There was also noeffect on pregnancy rates (17.85% vs. 20.68%;P=0.15), or on follicular development fortreatment and control. In conclusion, thisstudy was not able to demonstrate an effectof melatonin on the ovarian response ofbuffaloes as reported by other authors. Otherfactors, such as environmental conditions ofsubtropical areas and species specificities,may have a more significant effect on buffaloendocrinology. These factors should beevaluated to improve the results of fixed-timed artificial insemination programmes.Key words: melatonin; buffaloes; folliculardevelopment; artificial insemination: reproduction