Effects of Enzymatically Hydrolyzed Yeast Supplementation and Supplementation Frequency on Immune Parameters, Performance, and Digestibility among Periparturient Beef Cows and Calves

摘要

Effects of enzymatically hydrolyzed yeast (EHY) and supplementation frequency (FREQ) on immune parameters among beef cows and calves was evaluated. Eighty multiparous (parity = 4.2 +/- 0.3) cows were fed a common brome hay-based diet (CP = 8.0 ? 0.17%). Cows were blocked by expected calving date and stratified by body condition score (BCS) before random assignment of treatment. Beginning 88 +/- 5 d prior to parturition, cows were provided 1 kg daily or 3 kg every 3 d of a soybean hull-based supplement (CP = 34.0, % of DM) that contained 0 or 3 g/kg EHY. The daily supplement was designed to meet ruminal N requirements (total or DIP?). Cows were vaccinated against rotavirus at 62 and 48 +/- 5d prior to parturition. Sera and plasma samples were collected at 62, 48, 40, 24 and 14 d prior to parturition. At parturition, colostrum was collected via portable milking unit from cows prior to feeding to calves and plasma and sera was collected from cows and calves. Subsequently, calf plasma was collected at 2 and 14 d after parturition. Calf plasma Immunoglobulin G (IgG) concentration increased (quadratic < 0.01) as age increased and passive transfer status among calves was 'excellent' (i.e. plasma IgG concentration was greater than 15 g/L among calves aged 2 d; APHIS, 2010). Plasma IgG was greater (P = 0.03) among calves born to cows receiving EHY and FREQ had no effect on plasma IgG in calves. Despite differences among calf plasma IgG concentrations, there was no significant effect of EHY or FREQ on colostrum yield, colostral IgG or calf intake of colostrum. Similarly, apparent efficiency of IgG absorption (AEA) and sera rotavirus neutralization titers (RNT) among calves aged 14 d was not affected by treatment (P ≥ 0.36). Cow plasma IgG decreased (quadratic = 0.02) as cows neared parturition and were not affected by EHY (P = 0.56) or FREQ ( P = 0.14). We observed a quadratic increase in rotavirus neutralization titers in cow sera in response to vaccination, as expected. Sera rotavirus neutralization titers were not impacted by EHY (P = 0.70) nor FREQ (P = 0.42).;Effects of enzymatically hydrolyzed yeast (EHY) and supplementation frequency on cow BW, cow BCS, calf BW, and cow milk production was evaluated. The same 80 multiparous (parity = 4.2 +/- 0.3) cows were fed a common brome hay-based diet (CP = 8.0 +/- 0.17%). Cows were blocked by expected calving date and stratified by BCS before random assignment of treatment. Beginning 88 +/- 5 d prior to parturition, cows were provided 1 kg daily or 3 kg every 3 d of a soybean hull-based supplement (CP = 34% of DM) that contained 0 or 3 g/kg EHY. The daily supplement was designed to meet ruminal N requirements (total or DIP?). Cows were weighed on 88, 62, 48, 40, 24, 14 and 0 d prior to parturition. Although cow BW was recorded, it was not analyzed (Why?). Three trained technicians recorded BCS on the same day. After calving, milk production was recorded on 30, 90, and 150 d. Samples of milk from each cow were sent to Dairy Herd Improvement Agency (DHIA) for analysis. Cow BCS increased (linear < 0.01) as cows neared parturition. Frequency of supplementation tended (P < 0.06) to increase BCS, whereas, effect of supplementation with EHY (P < 0.91) on cow BCS was not significant. Total cow milk yield (kg/d) decreased ( quadratic < 0.01) by day. Neither FREQ (P = 0.23) nor EHY (P = 0.59) significantly affected total milk yield. Milk fat yield, milk protein yield, and energy corrected milk (ECM) yield was calculated. Milk fat yield decreased (quadratic < 0.01) by day. Neither FREQ (P = 0.34) nor EHY (P = 0.63) effected milk fat yield. Energy corrected milk yield decreased (quadratic < 0.01) by day and neither FREQ (P = 0.25) or EHY (P = 0.78) affected ECM. Milk protein yield was not affected by FREQ (P = 0.13) or EHY ( P = 0.69) but was affected by d (quadratic < 0.01).