Maturation competence of swamp buffalo oocytes obtained by ovum pick-up and from slaughterhouse ovaries.

This study was designed with the final goal of improving in vitro embryo production in the Thai swamp buffalo (Bubalus bubalis carabensis). Oocytes were collected by ovum pick-up (OPU) from six non-lactating multiparous swamp buffalo twice per week for 10 consecutive sessions followed by once-weekly collection for 10 consecutive sessions without hormone stimulation. In addition, oocytes were collected from slaughterhouse ovaries that were classified as follows: ovaries from non-pregnant cows with a visible corpus luteum (NPCL); pregnant cows with a corpus luteum (P); and non-pregnant cows without a corpus luteum (NP). Follicles in each group of ovaries were categorized as small (2-4 mm), medium-sized (5-8 mm) or large follicles (≥ 9 mm). The quality of the oocytes was assessed by their capacity to undergo in vitro maturation. The total number of observed follicles per session (all sizes combined) was larger in the once-weekly OPU group compared with the twice-weekly OPU group. In particular, the numbers of small and large follicles were higher in the once-weekly OPU group (5.2 ± 0.7 and 0.9 ± 0.2, respectively) than in the twice-weekly OPU group (3.9 ± 0.5 and 0.5 ± 0.1). The number of medium-sized follicles did not differ between the groups. The percentages of oocytes with an abnormal spindle morphology were not different between oocytes from the twice-weekly (30.0%) and the once-weekly (28.6%) OPU groups. A higher percentage of oocytes obtained in vitro (49.5%) exhibited nuclear abnormalities compared with those obtained in vivo (≤34.8%) after in vitro maturation. In conclusion, oocytes can be successfully collected by OPU in the swamp buffalo, without hormonal pretreatment, and per week more good-quality oocytes can be collected by twice-weekly OPU. In addition, oocytes collected from slaughterhouse ovaries can be used with the reproductive status of the cow having no influence on the maturation competence of oocytes.

Follicular dynamics and oestrous detection in Thai postpartum swamp buffaloes (Bubalus bubalis).

This study characterized follicular activity and oestrous behaviour from 5 to 9 days post-calving up to the 4th ovulation postpartum (pp) in 16 multiparous (range 2-7 parities) Thai swamp buffalo cows (Bubalus bubalis), aged 4-12 years and weighing from 432 to 676 kg. Ovarian follicular activity was examined by transrectal ultrasonography (TUS) every morning. Oestrous detection was performed twice daily by direct personal observation of behaviour and for presence of clear cervical mucus discharge and indirectly by video camera recording during 21 h/day. A follicular wave-like pattern was present before the 1st ovulation leading to short oestrous cycles. Growth rates and maximum diameters of the ovulatory follicles did not differ between the 1st and 4th ovulations. However, growth rate for non-ovulatory dominant follicles (DF) before the 1st ovulation was lower than for the ovulatory follicle (p<0.05). In addition, the diameter of all ovulatory follicles (14.3 ± 0.46 mm, n=39) was significantly larger (p < 0.01) than those of the preceding last but one non-ovulatory DF (10.8 ± 0.20 mm, n = 5), but similar to the last preceding non-ovulatory DF diameter (12.92 ± 0.96 mm, n = 14). Short oestrous cycles were most common between the 1st and 2nd ovulations (93.75%, 15/16 cows, 10.2 ± 0.38 days) decreasing in prevalence thereafter (50%, 3/6 buffaloes, 12.0 ± 1.53 days). Oestrous signs were relatively vague around the 1st ovulation pp to become more easily detectable thereafter. This study suggests that properly fed swamp buffaloes could be mated successfully within 2 months pp, at their 2nd spontaneous ovulation, provided oestrous detection is at least performed daily at 06:00-08:00 hour.