Effect of feeding an immune modulator to multiparous Holstein cows during the dry period and early lactation on health, milk and reproductive performance

Abstract

In this study we evaluated the effect of feeding an immune modulatory feed additive (OmniGen-AF®; OMN) during the dry period through early lactation on postpartum health, subsequent lactational and reproductive performance of multiparous Holstein cows. We hypothesized that feeding OMN beginning in the dry period and through 150 days in milk (DIM) would improve milk yield and reproductive performance as a result of improved immune response. To test our hypothesis, 1,392 multiparous pregnant Holstein cows of a commercial dairy herd were enrolled and randomly assigned at dry-off (47.6 ± 9.4 d before calving) to OMN (n = 706) or control (CON, n = 686) treatments. Both OMN and CON (placebo) supplements were fed once per day at a rate of 56 g/d per head from dry-off through 150 DIM. Cows were milked three times a day and daily milk yield was measured once per week, starting at the second week of lactation through 140 days in milk. Postpartum health disorders were monitored daily throughout the experiment. Cows were bred following a double OvSynch protocol after a 77-d voluntary waiting period (VWP). Final pregnancy status was assessed after supplementation ended at 230 DIM. Our results indicated that cows supplemented with OMN produced more milk than CON (40.8 kg/d vs. 40.1 kg/d; <i>P</i> < 0.01) during the first 140 d of lactation. Once they entered lactation, cows supplemented with OMN tended (<i>P</i> < 0.10) to have a reduced incidence of mastitis, retained placenta, displaced abomasum (<i>P</i> < 0.11) and reduced number of days spent in the hospital pen relative to CON. OmniGen feeding was also associated with a 10-d reduction in days open (<i>P</i> < 0.05) compared to CON. However, pregnancy rate at first, second and until ∼230 DIM did not differ between treatments. In conclusion, supplementing an immunomodulatory feed additive to dry and early lactation dairy cows was associated with improved milk yield, a tendency to reduce transition cow disorders and reduced number of days open.