In evaluating body weight, body condition score change, and milk yield differences between healthy cows and cows experiencing disease, we saw no significant change in body weight or condition score, but highly significant losses in milk starting in the first week postpartum. This observation emphases that cows experiencing various postpartum disease conditions are losing milk prior to when the problem is diagnosed. Based on dry matter intake differences and known energy density of the diets, we predicted potential milk losses over this 5-week period. Observed milk losses were greater than we predicted, most likely due to effects of inflammatory cytokines altering nutrient usage in the body.
Another fascinating aspect of this data evaluation was the comparison of dry matter intake prepartum. Unlike what we observed during the postpartum period, there were not significant differences in daily dry matter intake between healthy cows and cows that went on to become sick. However, we did find a significant interaction between health status and week prepartum between these cow groups. Cows that went on to have postpartum disease showed a greater decline in dry matter intake during the last 2 to 3 weeks prior to calving. Healthy cows maintained a more stable prepartum intake up until the day of calving. This observation reinforces the Wisconsin work suggesting environmental factors that affect intake are significant contributors to postpartum disease problems. Other research from the University of British Columbia has also shown cows that go on to have postpartum metritis or ketosis problems have altered feeding patterns and lower overall intake during the prepartum period compared to cows that remain healthy. What exactly causes this altered intake resulting in greater disease susceptibility is unknown.
Although reports would suggest progress is slow in preventing transition cow problems, we have made a number of strides in better understanding underlying contributing issues. Significant progress has been achieved on many individual farms. As we have learned more about transition metabolism and cow-environment interactions, we are realizing just how complicated the adaptations to transition is for the cow. As we move forward in this field, we will need to better address the complex interaction of metabolism, environment, and immunologic response especially in relation to how this interaction influences cow eating patterns prior to parturition. Monitoring and controlling feed intake in the 4 to 5 weeks prior to calving may be our best approach to preventing transition problems and minimizing production losses.
Source: Penn State Dairy Digest