Abstract
The reproductive performance of 40 multiparous cows, either grazing unsupplemented (control; n = 20) or given wet brewers’ spent grain (supplemented; n = 20), was studied over two years with the aid of peripheral plasma progesterone profiles. Thirty per cent of the control and 10%of the supplemented cows failed to calve during the experimental period. The mean calving interval (Cl) and postpartum anoestrous interval (PAI), which did not significantly differ between treatments were respectively, 512 and 129 days for supplemented cows and 455 and 121 days for control cows. Seven supplemented and three control cows had irregular oestrous cycles lasting 30-120 days following the first progesterone rise postpartum (FPRP). Calving interval was strongly correlated with PAI (r = 0.705) but not with the interval from FPRP to conception (r = 0.207). Relationships between CI and PAI and feeding frequency and number of animals dominated were not significant
