SUMMARY
A study was conducted on 12 pluriparous parturient Kankrej cows of the University Farm, in Anand, randomly divided into two equal groups (n = 6 each). Group-I cows were administered on the day of calving with a sustained release 80 g mega mineral rumen bolus (Prepavel® 1 bolus/animal, Neolait, France) intra-ruminal through a specially designed applicator, while group-II animals served as untreated control. The animals were monitored periodically from the day of calving till 140 days postpartum along with other herd mates. Blood samples were obtained at 10 days interval in heparinized vacutainers for plasma progesterone, biochemical, and macro-micro mineral profiling. Among the six Kankrej cows of group-I, only one animal exhibited prominent estrus signs on day 96 postpartum and conceived at first service (AI) giving CR of 16.66%, while in group-II three cows exhibited estrus between day 73 and 86 postpartum, and conceived with one or two AI giving CR of 50% by 150 days postpartum. In both the groups, all other cows remained subestrus for more than 150 days postpartum and conceived very late, though mostly with single service at spontaneous estrus. The mean values of plasma progesterone (0.74 ± 0.32 to 5.57 ± 0.78 ng/mL), total cholesterol (103.88 ± 3.20 to 237.17 ± 24.66 mg/dL) and triglycerides (17.07 ± 1.16 to 28.29 ± 1.75 mg/dL) differed significantly (p less than 0.01) between postpartum intervals in both the groups, but not between groups at any of the intervals. The values of plasma total protein, calcium, inorganic phosphorus, and magnesium as well as trace elements, viz., zinc, iron, copper, cobalt, and manganese, however varied insignificantly and inconsistently between intervals and also between groups from day 0 to day 140 postpartum. Thus, the insertion of Mega mineral ruminal bolus on the day of calving did not influence the plasma profile of biochemical/ metabolic constituents and macro-micro minerals profile in lactating postpartum Kankrej cows and was not beneficial in improving postpartum fertility. However, further study on a larger sample size is required to draw a valid conclusion.