Abstract
An objective of this study was to determine the associations of passive transfer status, by assessment of serum total protein (TP), with serum metabolites, daily gain, morbidity, and mortality in neonatal male Holstein calves (n=1,631). Calves were purchased from dairy farms in the western United States and placed in a calf ranch as one day old. Calves were assigned an individual electronic identification and recorded in Feedlot Health Management Services proprietary software, iFHMS (Feedlot Health Management Services, Okotoks, Alberta). Cause-specific morbidity and mortality was recorded for each calf daily from entry to exiting or death. A 5-mL tube of blood was collected from each animal at 48 ± 6h post-arrival. Whole blood was centrifuged at 2000 g for 10 min and serum was stored at -20°C. Serum TP was measured using a digital refractometer. Calves were categorized based on proposed USDA serum TP guidelines into poor (TP < 5.1 g/dL, n=159, mean ± SD 4.68 ± 0.31 g/dL), fair (5.1 < TP ≤ 5.7 g/dL, n=399, 5.45 ± 0.19 g/dL), good (5.8 ≤ TP ≤ 6.1 g/dL, n=322, 5.96 ± 0.11 g/dL) and excellent (TP > 6.1 g/dL, n=751, 5.96 ± 0.11 g/dL). Samples were analyzed using a reverse-phase HPLC using a C18 column for vitamins and a colorimetric assay for glucose. Data were analyzed using generalized linear mixed models and logistic regression models with significance declared at P ≤0.05. Significant differences between poor and excellent were observed in mortality and otitis disease treatments (P < 0.05 for both). Differences were observed when comparing poor and fair to good and excellent TP categories for serum glucose (P < 0.05). For serum retinol, comparison of the poor protein category with all other groups indicated significant differences (P = 0.001). Serum β-carotene and α-tocopherol were different when comparing all TP categories against the excellent (P < 0.05 for both). Average daily gain at 90 d and for the overall feeding period was not statistically different among TP categories. Generally, serum metabolites showed differences among TP categories, suggesting a potential associative relationship with health and the immune system.