Reproduction and genetic diversity of the swamp buffalo

The water buffalo is one of the most important domestic animals in Southeast Asia including Thailand. As the Thai swamp buffalo population declined during the last two decades, the swamp buffalo reproductive performance needs to be improved. Lack of knowledge on swamp buffalo reproduction, improper management and failure to use genetic superior males and females in breeding programs are the major factors to be considered. Artificial insemination was applied in Thailand but is inefficient due to suboptimal heat detection. Our study emphasized that the presence of a buffalo teaser bull is a very helpful tool for heat detection in the female swamp buffalo and thus for the proper insemination time either natural or artificial. There are also other signs of estrus of the female buffalo which can be detected by trained experts. Postpartum anestrus is one of the major causes of poor reproductive performance in the buffalo leading to the long period of days open and thus a long calving interval. To improve postpartum buffalo reproduction efficiency, proper husbandry management such as quality of nutrition, optimal estrus detection and a fertile buffalo bull are crucial. In this study, the postpartum buffalo could be successfully mated within two months postpartum at the second spontaneous ovulation, even without hormonal treatment. Embryo transfer would allow a wider exploitation and dissemination of superior swamp buffalo genotypes. We demonstrated that oocytes for IVM and IVF can be collected successfully by OPU without hormonal pretreatment, and those twice weekly pick-up resulted in more oocytes than once-weekly pick-up. In order to reinforce a more effective management of buffalo genetic resources and reconstruct their genetic history, we studied the genetic diversity of both paternal and maternal lineages. We found evidence for a separate domestication of the river and swamp buffalo, a shared wild-ancestral origin of the swamp buffalo A and B mtDNA haplotype and a Southeast Asian domestication site of the swamp buffalo. Occurrence of Y-chromosomal DNA variants depends on the region within Thailand, indicating a restricted migration of water buffaloes. Our data warrant a wider investigation of swamp buffalo mtDNA and Y-chromosomal diversity as well as a comprehensive study of autosomal variation. Insight in the genetic constitution of water buffalo may prove essential for the preservation and utilization of the genetic resources of Thailand