Follicular dynamics in synchronized Italian Mediterranean buffalo cows

Reproductive management in buffalo by artificial insemination

Artificial insemination (AI) is important for genetic improvement and to control the period of breeding in buffalo and has increased significantly over the past 20 years. AI is more difficult in buffalo compared with cattle due to variable estrous cycles, reduced estrous behavior, and reproductive seasonality. The latter is associated with a higher incidence of anestrus and increased embryonic mortality during the nonbreeding season. Protocols to control the stage of the estrous cycle have undergone recent development in buffalo. These protocols are based on the control of both the luteal phase of the cycle, mainly by prostaglandins and progesterone, and follicle development and ovulation, by prostaglandins, progesterone, GnRH, hCG, eCG and estradiol. Protocols that synchronize the time of ovulation enable fixed timed AI, avoiding estrous detection. Factors to consider when selecting an AI protocol include animal category (heifers, primiparous or pluriparous), reproductive status (cyclic or anestrus), and season. This review looks at the current status of estrus synchronization and AI in buffalo and provides some practical suggestions for application of AI in the field.

Dominant follicles development and estradiol-17β concentrations in non-ovulating and ovulating post-partum Bulgarian Murrah buffaloes

This study was designed to evaluate the dominant follicles development and the estradiol-17β concentrations in non-ovulating and ovulating post-partum buffaloes. Sixteen Bulgarian Murrah buffaloes were submitted to transrectal ultrasonographic examination from the 1st post-partum day until day 50, 3 days apart. The follicular diameter of the different categories of follicles and the ovulations was recorded. The animals were allocated into two groups: I (n = 6) non-ovulating and II (n = 10) ovulating buffaloes. Serum estradiol-17β concentrations on the days for dominant follicle registration were measured by enzyme-linked immunosorbent assay. The results were statistically processed by analysis of variance, non-parametric and correlation analysis. The mean intervals between calving and first dominant follicle detection differed significantly (p < .05) among the groups (19.5 ± 6.2 vs. 13.8 ± 5.1 days), while the mean intervals between registered dominant follicles from two successive waves were comparable. The mean follicular diameters for the same category follicles in both groups were similar. Different estradiol-17β concentrations (p < .05) for the first dominant follicle between non-ovulating (23.5 ± 7.0 pg/ml) and ovulating (33.3 ± 8.4 pg/ml) buffaloes were determined. The cumulative percentages of buffaloes with firstly detected dominant follicle and ovulating animals correlated positively (r ≥ .84; p < .05) to post-partum days. In conclusion, non-ovulating and ovulating post-partum Bulgarian Murrah buffaloes showed differences in the development of the first dominant follicle and estradiol-17β concentrations during the time of dominant follicles detection.

Influence of season on corpus luteum structure and function and AI outcome in the Italian Mediterranean buffalo (Bubalus bubalis)

The aim was to ascertain whether relationships between corpus luteum (CL) vascularization, CL function, and pregnancy outcome in AI in buffaloes were consistent across the breeding season and transition period to the nonbreeding season in a Mediterranean environment. Stage of the estrous cycle in Italian Mediterranean buffaloes was synchronized using the Ovsynch with timed AI program and buffaloes were mated by AI in both the breeding season (N = 131) and transition period (N = 125). Detailed investigation of CL structure and function was undertaken in 39 buffaloes at each of the respective times using realtime B-mode/color-Doppler ultrasonography on Days 10 and 20 after AI. Progesterone (P4) concentrations were determined by RIA in all buffaloes. Pregnancy rate on Day 45 after AI was greater (P < 0.05) during the breeding season (58.0%) than the transitional period (45.6%) and this was primarily the result of a lower (P < 0.05) late embryonic mortality during the breeding season (7.3%) compared with the transition period (23%). Circulating concentrations of P4 on Days 10 and 20 after AI were greater (P < 0.01) during the breeding season (4.6 ± 0.3 and 3.4 ± 0.2, respectively) than during the transition period (1.6 ± 0.12 and 1.8 ± 0.2, respectively), and this was independent of reproductive status as there was no interaction between pregnancy and season. Corpus luteum time average medium velocity at Day 10 after AI was greater (P < 0.01) during the breeding season (19.3 ± 1.5) than in the transitional period (8.3 ± 0.7). There were positive correlations in pregnant buffaloes between CL time average medium velocity and P4 concentrations on Day 10 (r = 0.722; P < 0.01) and Day 20 (r = 0.446; P < 0.01) after AI. The findings were interpreted to indicate that relationships between CL vascularization, CL function, and pregnancy outcome in AI in buffaloes are consistent across the breeding season and transition period to the nonbreeding season. The distinction between the breeding season and the transition period is the relatively low proportion of buffaloes that have CL function and P4 concentrations required to establish a pregnancy during the transition period, which is manifested in a greater incidence of embryonic mortality.