Effects of prepartum metabolizable protein supplementation from either blood meal or feather meal on subsequent lactation and calf performance

The objectives of this study were to evaluate different amounts and sources of MP in prepartum diets on cow performance during the nonlactating, early, and peak-lactation periods, as well as colostrum quantity and quality, and calf performance through 46 ± 3 d of age. This study enrolled 39 multiparous and 22 primiparous animals that were blocked based on expected calving date, BCS, and 305-d mature equivalent milk yield for multiparous cows then randomly assigned to one of 3 treatments. Treatments were: low MP control (LCON 1,070 g/d MP; n = 21, 14 multiparous, 7 primiparous), high MP feather meal (HFM 1,265 g/d MP; n = 20, 13 multiparous, 7 primiparous), and high MP blood meal (HBM 1,242 g/d MP; n = 20, 12 multiparous, 8 primiparous). Treatment diets were fed from 7 wk before expected calving date to parturition, and all animals were fed common diets after parturition. Measurements of BW and BCS were collected at wk -7, -3, -1, parturition, wk 1, 2, 3, and 8. Blood insulin, total proteins, NEFA, and BHB were measured at wk -1, 1, and 2 relative to parturition. Colostrum weight, IgG concentration, and Brix percent were measured post-parturition. Daily DMI and milk weights were recorded, and milk components were measured weekly through 8 wk in lactation. All calves (n = 67) were weighed and a blood sample for serum total protein was collected before receiving colostrum. Hip width and wither height were measured within a day of being born. Calf intake was recorded daily and calves were measured and weighed weekly through 7 wk of age. Data were analyzed using PROC MIXED in SAS v9.4 with the fixed effects of treatment, parity, week and their interactions, and the random effects of block and cow. Repeated measures were used when appropriate. In the first 3 wk of lactation, high MP prepartum increased milk protein content regardless of parity, and increased milk yield by 2.1 kg/d in primiparous animals. Treatments did not affect ECM in either parity group. From wk 4-8, LCON multiparous animals produced 6.0 kg/d more milk and consumed 2.0 kg/d more DM compared with HBM and HFM animals. Supplemented primiparous cows maintained 2.7 kg/d greater milk yield than LCON from wk 4-8. Through the first 8 wk of lactation, multiparous cows lost greater amounts of BW and BCS compared with primiparous cows. There was no difference in birth weight of calves from dam MP supplementation, but calves born to supplemented dams were 2.0 cm taller with 1.0 cm wider hips and had higher serum total protein at birth, with differences not detectable at 24 h. Calves from HBM and HFM primiparous dams had greater starter intake and ADG. Wither height was larger in MP calves at weaning but weaning hip width and BW were not affected by treatment of the dam. Prepartum MP supplementation increased milk yield and decreased BW and BCS loss through the first 8 wk of lactation in primiparous cows but decreased milk yield in multiparous cows.