Health and growth of weaned Holstein and crossbred calves fed bovine plasma proteins in grower feed.

Feeding plasma protein has been shown to have health benefits and help ameliorate stress in preweaning calves, aiding their ability to handle the challenges of weaning and initial social interactions. We hypothesized that feeding plasma proteins would improve health and growth in newly weaned calves under stress from postweaning commingling. The objectives of this study were to assess the health, growth, and stress responses of calves fed bovine plasma proteins in their grower feed, specifically evaluating whether feeding plasma proteins could reduce plasma cortisol concentrations during the transition to group housing. During experiment 1, 21 castrated male Holstein calves were housed outdoors in groups of 3 from 10 to 14 wk of age. Experiment 2 included 40 castrated male and female Holstein-Angus cross calves housed outdoors in groups of 6 or 7 from 9 to 13 wk of age. Both experiments were randomized, complete block designs. Data from experiments 1 and 2 were pooled. Treatments were a control grower diet with no bovine plasma protein (CON; 20% CP, 2.4% fat) and a grower diet including spray-dried bovine plasma protein (SDP; 20% CP, 2.9% fat). Experiment 1 had 3 CON pens and 4 SDP pens, and experiment 2 had 3 CON pens and 3 SDP pens. Pen was the experimental unit. Both experiments provided ad libitum water and grower feed with a 2.5% inclusion of chopped wheat straw. Data collection was the same during both experiments. Feed intake and health scores, including assessment of fecal, ocular, nasal, ear, and respiratory events, were recorded daily. Body weight was recorded weekly, and skeletal growth measurements were recorded on d 0 (experiment 1) or d -1 (experiment 2), and d 28. Blood samples were collected via jugular venipuncture on d 0 (experiment 1) or -1 (experiment 2), d 3, and d 7 (experiment 1) or d 6 (experiment 2); plasma was stored at -20°C for later analysis. Average daily gain, feed intake, and plasma cortisol data were analyzed using the MIXED and UNIVARIATE procedures in SAS, and health data were analyzed using the FREQ and GLIMMIX procedures. No differences were detected for BW, frame growth, or ADG, and no differences were observed between treatments for health scores. Grower feed intake was not different between treatments. No differences in cortisol concentrations (1.04 ng/mL for CON and 1.06 ng/mL for SDP) were observed between CON and SDP calves. Bovine plasma proteins did not enhance growth, health, or feed intake in this study. Weaning-related stressors did not raise plasma cortisol concentrations, and plasma protein supplementation had no effect on growth or cortisol concentrations.