Effects of spray-dried plasma protein in diets of early lactation dairy cows on health, milking and reproductive performance

Abstract Spray-dried plasma (SDP) proteins are recognized as safe, high-quality feed ingredients for livestock due to their immune modulatory components, including immunoglobulins, bioactive peptides and growth factors. The objective of this study was to investigate the effects of feeding a SDP product during the first 200 d of lactation on milk production and reproduction performance in dairy cows. Nine hundred ninety-eight Holstein cows, 260 d pregnant, were enrolled in a completely randomized design. Before calving, cows were fed a late gestation ration containing blood meal (BM; 13.3 g/kg of DM; Control; n = 503) or SDP (16.0 g/kg of DM; 250 g SDP/d; n = 495) replacing BM on N basis. After calving, Control cows were randomly distributed in two pens and fed a lactation ration containing 15.6 g/kg BM (DM basis). Cows on SDP were randomly distributed in 2 pens and fed a lactation ration that contained 18.3 g/kg SDP (DM basis. 400 g/d of SDP), which replaced BM. Cows were milked three times per day and milk production and composition were monitored monthly at one milking. First service consisted of a timed AI protocol applied to all cows that were > 44–50 DIM. Following AI, cows were examined daily for return to estrus or for confirmation of pregnancy by rectal palpation at 35–41 and 70–76 d after AI. At 72–78 DIM, cows not pregnant were enrolled into an intrauterine progesterone program. Cows fed SDP had greater milk yield (P