Plasma progesterone concentration and reproductive function relative to thyroid activity in postpartum buffaloes (Bubalus bubalis).

The lowest value for plasma protein bound iodine (PBI) (3.47 micrograms %) in 20 freshly calved Murrah buffaloes was observed on day 1 postpartum. The values then increased consistently up to day 36 and were almost constant thereafter. The plasma progesterone concentrations were lower in animals with relatively low PBI from day 22 to 57 postpartum, except on day 36. The mean values +/- SE (ng/ml) in the high and low PBI groups were 0.93 +/- 0.09 and 0.72 +/- 0.15. The correlation coefficient between PBI and progesterone was 0.80 (p less than 0.01). Relatively poor reproductive efficiency, in terms of a higher initiation of follicular development interval, postpartum oestrus interval, service period and number of services for conception, was observed in animals in the low PBI group.