178 Effect of phytogenic supplementation to primiparous Angus heifers on colostrum quality, transfer of passive immunity, and performance.

Abstract Phytogenic compounds can modulate humoral immune response, resulting in increased concentrations of serum immunoglobulins, and potentially improving health and performance. This study evaluated the effect of pre- and postpartum phytogen supplementation to primiparous beef heifers on colostrum and milk quality, passive transfer of immunity, and cow-calf performance. Twenty-three (BW = 451 ± 28 kg; 23 mo) purebred Angus heifers were stratified by expected calving date and weight and then randomly assigned to one of three treatments: 1) No supplemental phytogen (CON, n=8); 2) 250 mg∙hd-1∙d-1 of supplemental phytogen (P250; n=8); or 3) 500 mg∙hd-1∙d-1 of supplemental phytogen (P500; n=7). Heifers were individually fed their supplement from 30 days pre-calving (d -30) to 60 days post-calving (d 60). Colostrum was collected at calving (pre-suckling) and 24- and 48-hours post-calving and milk was collected on days 45 and 90 post-calving. Nutrient composition and antibody concentrations of colostrum and milk were analyzed. Blood samples were collected from dams on d -30, 0, and 60, and calf blood was collected on d 0 (prior to nursing), 2, and 60. Heifer and calf serum was analyzed for IgG and IgA concentrations. Heifers were weighed and BCS was assigned biweekly, from d -30 to d 56. Calves were weighed at birth and at the same time points as their dams. At weaning, dam and calf weight was recorded and calf weight was adjusted to a 205-day weight. Colostrum IgM concentration tended (P = 0.09) to increase with increased phytogen supplementation (132, 178, 211 mg IgM/dL for CON, P250, and P500, respectively). Heifer serum IgA concentration tended (P = 0.08) towards a treatment × day interaction resulting from a gradual increase in concentration from 30 days pre-calving to 60 days post-calving in P250 and P500 heifers, compared to a relatively constant concentration in CON heifers. A significant day effect (P < 0.01) was observed for serum IgG in both heifers and calves, with heifers having lower concentrations at calving compared to d -30 and d 60 and the calves having a significantly higher concentrations 2 days post-calving compared to at birth: the result of successful passive transfer of immunity. Between days 0 and 56, CON heifers lost the least weight (-29.7 kg), followed by P250 (-33.1 kg), and P500 heifers lost the most weight (-49.0 kg; linear, P = 0.02). However, there was a linear tendency (P = 0.06) for calf gain to increase during the same time frame which was characterized by CON calves (49.0 kg) gaining the least and P500 (56.4 kg) the most. These findings suggest potential immunomodulation and enhanced performance in response to phytogenic supplementation; however, additional research is needed to further validate the value of phytogenic supplementation in cow-calf operations.