The reproductive efficiency of buffalo is greatly affected by late age at first calving (47 months), seasonality of calving, long postpartum anoestrus, weak display of oestrus signs, low conception rate and long inter calving intervals (24 months). So far in buffaloes, various hormones (GnRH, oestradiol etc) are being used in combination with or without CIDR (Controlled Internal Drug Release). Progesterone is reported to have a good impact on inactive ovaries. Prostaglandin F2α is extensively used in Pakistan as a drug of choice for anoestrus dairy buffaloes. The PG group in this study was considered as control. In this study the effect of CIDR and prostaglandin (PGF2α) was studied during the low breeding summer season to synchronise oestrus. Materials and Methods: Experimental design: Buffaloes were randomly allocated to two treatment groups (n=60 per group). Group one was treated with a CIDR for 7 days and prostaglandin (PG) on day 6 with the CIDR being removed on day 7. Group two was treated with PG injection on day 0 and day 11. Pregnancy diagnosis was carried out after 40 days using transrectal ultrasonography (Honda; Model: HS-1500; 7.0MHZ). Statistical analysis: Data for oestrus response and comparisons of pregnancy rate between the two treatments, the impact of management (tied and untied) and the presence of a calf was compared using a Chi square analysis. The effect of body condition score (BCS) and parity on the oestrus response and pregnancy rate was confirmed with Logistic Model SPSS (version 20). The effect of age and daily milk production on the oestrus response, and the duration of anoestrus post-partum in days were compared using Anova and a t-test. A probability level with P value <0.05 was considered significant. Results: When the CIDR was used with PGF2α (Treatment 1) oestrus was detected in 84.5% of animals, but only in 23.3% of animals receiving a PGF2α regime only. This did not lead to a higher pregnancy rate (CIDR 19.6%; PGF2α regime 30.8%: P = 0.296) Discussion: This study demonstrated that oestrus expression was higher in animals receiving a protracted regimen of progesterone release using a CIDR device. The PG is only effective in the presence of a functional CL, while in summer the buffalo have small inactive ovaries without any palpable structures and so they do not respond to PG. Therefore the oestrus response was lower in PG receiving animals. The pregnancy percentage was lower in the CIDR group than the PG group animals and there were no significant differences across treatments. Conclusion: This study shows that the CIDR device is more effective in synchronizing oestrus than the use of PG. The high oestrus response and low pregnancy rate in CIDR group requires more research on the use of TAI techniques with the CIDR device to optimize the timing of AI.
|Qualification||Master of Philosophy|
|Award date||09 Aug 2013|
|Place of Publication||Australia|
|Publication status||Published - 2014|