Use of avian polyclonal antibody preparations against lipopolysaccharide to enhance performance in early lactation dairy cows.

Subacute ruminal acidosis is a nutritional disorder associated with reduced milk yield and characterized by metabolic and inflammatory disturbances, including elevated ruminal LPS under conditions of impaired barrier function. This translocation triggers a systemic inflammatory response that suppresses DMI and impairs milk production. Hence, this study evaluated the effects of an avian-derived anti-LPS polyclonal antibody preparation (PAP-LPS) on inflammation and milk production in early-lactation dairy cows. A total of 400 Holstein cows (174 primiparous [Pr] and 226 multiparous [Mu]) from a single herd were randomly assigned to one of 3 treatments: PAP-LPS (3 g/d via oral drench, n = 125; Pr = 55 and Mu = 70), a placebo control (PLC, 3 g/d inactivated PAP-LPS via oral drench, n = 143; Pr = 66 and Mu = 77), or an untreated control (CTL, n = 132; Pr = 53 and Mu = 79). Treatments were administered daily from calving until 14 DIM, and milk yield and composition were monitored through 98 DIM. Blood samples were collected on d 1, 6, and 14. Statistical analyses were performed using SAS software (v. 9.4) using linear mixed models with a first-order autoregressive covariate structure and repeated measures, where applicable. Drenching PAP-LPS increased ECM during the first 98 DIM compared with both PLC and CTL, with estimated yields of 41.28 ± 0.3, 40.43 ± 0.28, and 39.78 ± 0.3 kg for PAP-LPS, PLC, and CTL, respectively. Total milk production also increased when compared with CTL (3,881 and 3,769 kg, respectively), and it only tended to increase when compared with PLC (3,785 kg). A week × treatment interaction was observed for weekly average milk production and was greater for PAP-LPS versus CTL on wk 3, 4, and 10. On wk 6, cows fed PAP-LPS had greater milk production than both PLC and CTL cows. No difference in haptoglobin, ceruloplasmin or health disorders was observed among groups. In conclusion, administration of an avian-derived anti-LPS polyclonal antibody during the first 14 d of lactation improved milk production and ECM yield in early-lactation dairy cows. Although no differences were observed in systemic inflammatory markers or health disorders among groups, the enhanced milk performance suggests that PAP-LPS may help mitigate the challenges of the transition period, a time of high metabolic stress and elevated risk of SARA. These findings support PAP-LPS as a promising nutritional strategy to enhance productivity in early lactation.