The role of calcidiol supplementation in optimizing vitamin D status, growth performance, and immune function in beef cattle

Abstract

A series of experiments were conducted to evaluate vitamin D status in beef cattle and the effects of supplemental calcidiol (HyD®; DSM Nutritional Products, Plainsboro, NJ) on serum 25-hydroxyvitamin D3 [25(OH)D3] concentrations on performance and health. In experiment 1, 96 high-risk, crossbred heifer calves (initial BW = 222 ± 17.0 kg) were sourced from auction markets around Dickson, TN, and transported 1,086 km to Manhattan, KS. Upon arrival, Calves were allocated randomly to one of four dietary treatments: neither supplemental vitamin D3 nor calcidiol (CON); 0.075 mg (3,000 IU) per head per day of vitamin D3 (D3); 0.5 mg calcidiol per head per day (HyD Low); or 1.0 mg calcidiol per head per day (HyD High). Cattle were fed once daily, and treatments were top-dressed onto feed. Blood samples were collected on days -1 (prior to transport), 0 (on arrival), and at days 14, 31, and 60 of dietary treatment period and analyzed for serum 25(OH)D3 concentration (TMAS, Belvidere, NJ). HyD High heifers had greater (P < 0.001) serum 25(OH)D3 concentrations compared to all other treatments at days 14, 31, and 60. HyD Low heifers had greater (P < 0.001) serum 25(OH)D3 than CON and D3 heifers at days 14, 31, and 60. In experiment 2, 603 crossbred steers and heifers were evaluated at four seasonal time points (spring, summer, fall, and winter) at a commercial feedlot in western Kansas to investigate vitamin D status. Cattle were housed in outdoor pens without shade and fed a common corn-based finishing diet supplemented with 275 IU per kg of vitamin D3. Cattle were stratified by lot number; odd lot numbers received 1.0 mg per head per day HyD® (HyD) while even lot numbers did not receive HyD® (CON). Serum 25(OH)D3 concentrations in CON cattle were greatest in summer (108 ± 22.6 ng/mL), intermediate in spring and fall (61 ± 15.3 and 59 ± 24.5 ng/mL), and least in winter (35 ± 6.4 ng/mL; P < 0.001). Cattle supplemented with HyD maintained significantly greater (P < 0.01) serum 25(OH)D3 across all seasons compared with non-supplemented cattle: 196 ± 58.0, 258 ± 54.3, 183 ± 40.4, and 184 ± 30.7 ng/mL in spring, summer, fall, and winter, respectively. In addition, hide pigmentation influenced vitamin D status. Red-hided cattle had greater (P < 0.01) serum 25(OH)D3 than black and white-hided cattle. No effect of sex was observed (P = 0.40). In experiment 3, eight cannulated, crossbred heifers (initial BW = 289 ± 44.9 kg) were randomly assigned to receive a single pulse dose of calcidiol solution via ruminal fistula at 3 or 5 mg per 272 kg BW. The elimination half-life (t1/2) of calcidiol was 7.1 days. Calcidiol remained circulating in serum above baseline for an average of 32.6 days. Multiple predictive modeling simulations were analyzed. According to the model simulations performed for this experiment, the combination of two oral doses of 5 mg calcidiol 14 days apart with daily supplementation of 1 mg has the potential to sustain elevated serum 25(OH)D3 concentrations above 100 ng/mg during a 56 day period; however, this should be confirmed in vivo. In experiment 4, 480 market-sourced, high-risk, crossbred heifer calves (226 ± 16.9 kg), were used to evaluate the effects of calcidiol supplementation on health and growth performance. Heifers were blocked by truck load on arrival and assigned randomly to one of four dietary treatments for 56 days: 0.075 mg (3,000 IU) vitamin D3 per head per day (D3), 0.5 mg calcidiol per head per day (HyD Low), 1.0 mg calcidiol per head per day (HyD High), or 1.0 mg calcidiol + 100 mg beta-carotene per head per day (HyD + BC). All treatments were top-dressed onto the daily ration. Individual BW was recorded on days 0, 14, 28, and 56. There were no significant differences (P = 0.36) in final BW, average daily gain, dry matter intake, or feed efficiency across treatments. Respiratory-related morbidity and mortality was not different between treatments (P = 0.16). Serum 25(OH)D3 concentrations were greater (P < 0.001) in HyD-supplemented groups compared to D3 on d 14, 28, and 56. Dietary treatment did not influence antibody titer levels or haptoglobin concentrations (P > 0.10). Antibody titers for bovine viral diarrhea type 1 and type 2 increased linearly (P < 0.01) over time, with the greatest levels on d 56. Titers for infectious bovine rhinotracheitis increased linearly (P < 0.01) until d 28. In summary, calcidiol supplementation increased and maintained serum 25(OH)D3 concentrations in beef cattle under various management and environmental conditions. Although growth performance and health outcomes in high-risk cattle were unaffected in the short term, the consistent elevation in serum 25(OH)D₃ concentrations suggests that calcidiol was absorbed and metabolically circulating potentially supporting vitamin D-dependent functions not directly measured in this study. It was observed that seasonal variation in vitamin D status existed, vitamin D supplementation may be beneficial during periods of limited sunlight exposure. Further research is warranted to determine the optimal serum 25(OH)D3 concentration for achieving optimal health and performance outcomes in beef cattle.