Attenuation of luteolytic response following fish meal supplementation in dairy buffaloes (Bubalus bubalis)

Luteolysis of corpus luteum, due to un-inhibited PGF2α secretion, has been reported to be a cause of early embryonic mortality in dairy animals. The objective of this study was to determine the effects of fish meal (FM) supplementation on the uterine secretion of PGF2α and hence establish its supplementation as an antiluteolytic strategy in dairy buffaloes. Five cycling Murrah buffaloes were supplemented with 250 g FM daily for 55 days in addition to their routine feed and seven buffaloes were kept as non-supplemented control. After 30 days of FM supplementation, the oestrus was synchronized in all the buffaloes using Ovsynch protocol. On day 15 of synchronized cycle, animals were challenged with oxytocin (OT; 100 IU) intravenously and blood samples were collected at 15 min interval, 1 h before to 4 h after OT challenge. The PGF2α response was measured as the venous concentration of 13,14-dihydro-15-keto PGF2α (PGFM). The mean hourly concentration of PGFM in FM supplemented buffaloes was lower than in the control buffaloes at all the occasions. During peak response (1 h post-OT challenge), PGFM concentration was significantly lower (P < 0.05) in FM supplemented buffaloes than in the control (197.4 ± 41.7 pg/ml versus 326.3 ± 33.5 pg/ml, respectively). Also the percent rise in PGFM after OT-challenge in FM supplemented buffaloes was less than the control (11.73% versus 22.47%). The dietary supplementation did not affect the size of corpus luteum (CL) and plasma progesterone concentration. Plasma glucose and total protein concentrations remained within the normal physiological limits during FM supplementation. The present study indicated that supplementing FM decreased the concentrations of PGF2α without alterations in the size of CL and plasma progesterone concentrations in dairy buffaloes.