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The article discusses the assessment of the nutritional properties of protein sources in supplements for Holstein x Zebu bulls grazing Brachiaria decumbens Stap. in the dry-rainy transition season. The animals fed with diets of grounded corn grain + urea treatment demonstrated neutral detergent fiber intake of 12.1g/kg of BW. The supplementation with corn and urea gives greater dry matter intake and digestibility compared with the mineral mix.

This experiment was conducted in a commercial beef farm located in Rio Brilhante, MS, Brazil during the spring/summer breeding season (September to October 2016). A total of 430 suckled multiparous beef cows (Nellore; Bos indicus, 417.2 ± 57.9 kg) were used. Cows were maintained on 4 paddocks of Brachiaria brizantha with ad libitum access to water. At the beginning of the trial (30 d before the first timed-AI), animals were assigned according to calving date, stratified by BCS (mean of 2.5 ± 0.5, 1 to 5 scale) and ß-carotene blood concentration (mean of 4.2 ± 1.8 mg/L), and randomly assigned to treatments: Control (mineral supplement: no ß-carotene nor vitamins) and Treated (combination of 500 mg ß-carotene, 70,000 IU Vit. A, 10,000 IU Vit. D3, 500 mg Vit. E, and 10 mg biotin/cow/d in the mineral supplement). The mineral supplement (8% Na; 30% TDN; 35% CP; 22.5% NPN) was daily offered to the animals in collective feeders at an amount of 200 g/cow/d. The ß-carotene, vitamins, and minerals used were from DSM® Produtos Nutricionais Brasil SA. Cows were rotated through the paddocks every 8 d to avoid effects related to pasture amount and quality. Animals were synchronized using an estradiol/progesterone-based timed-AI protocol: d 0, insertion of the progesterone device and 2.0 mg of estradiol benzoate i.m.; d 9, treatment with 0.15 mg of PGF2α analogue (D-cloprostenol), 300 IU eCG, and 1.0-mg estradiol cypionate i.m., and the intravaginal progesterone device was removed; d 11, FTAI. Blood samples were collected at the beginning of the experiment and at the moment of the FTAI. Serum ßcarotene was quantified using portable photometer (iCheck®; BioAnalyt, GmbH, Teltow, Germany). Data were analyzed using the GLIMMIX 9.3 procedure of SAS. The conception rate at FTAI was greater (P = 0.04) in cows supplemented with ß-carotene and vitamins (66.6%; 142/213) than control group (57.6%; 125/217). The blood ß-carotene concentration at the beginning of the experiment was 4.2 ± 1.7 mg/L for the control group and 4.3 ± 2.0 ng/mL for the ß-carotene and vitamins group (P > 0.05). At FTAI, the blood ß-carotene concentration was 5.1 ± 1.5 mg/L for the control group and 4.8 ± 1.5 mg/L for treated cows (P > 0.05). In conclusion, despite no difference in blood ß-carotene concentration, feeding grazing beef cows with the combination of ß-carotene and vitamins A, D, E, and biotin in the mineral supplement increased conception rate to timed-AI by 15.6%. [ABSTRACT FROM AUTHOR]

Our objective was to determine the effects of feeding 25-hydroxyvitamin D 3 [25(OH)D 3 ], or vitamin D 3 (cholecalciferol) on plasma, mineral, and metabolite concentrations, mineral balance, mineral excretion, rumination, energy balance, and milk production of dairy cows. We hypothesized that supplementing 3 mg/d of 25(OH)D 3 during the prepartum period would be more effective than supplementing vitamin D 3 at the National Research Council (2001) levels to minimize calcium imbalance during the transition period and improve milk production of dairy cows. Forty multiparous, pregnant nonlactating-Holstein cows were enrolled in this study. Body weight, body condition score, parity, and milk yield in the previous lactation (mean ± standard deviation) were 661 ± 59.2, 3.46 ± 0.35, 1.79 ± 0.87, and 33.2 ± 6.43 kg/d, respectively. Cows were enrolled into the blocks (n = 20 for each treatment) at 30 d of the expected day of calving to receive an acidogenic diet (373 g/kg of neutral detergent fiber and 136 g/kg of crude protein, dry matter basis; -110 mEq/kg) associated with the treatments: (1) control (CTRL), vitamin D 3 at 0.625 mg/d (equivalent to 25,000 IU of vitamin D 3 /d) or (2) 25(OH)D 3 at 3 mg/d (equivalent to 120,000 IU of vitamin D 3 /d). All cows were fed with the base ration for 49 d after calving. Blood samples were taken on d 7, 0, 1, 2, 21, and 42, relative to calving. No effect of treatment was observed for prepartum dry matter intake or body condition score. A trend for increase of ionized Ca was observed for the cows fed 25(OH)D 3 , compared with the CTRL, but no effect of treatment was detected for total Ca or total P. Feeding 25(OH)D 3 increased colostrum yield. The plasmatic concentration of 25-hydroxyvitamin D 3 was increased with 25(OH)D 3 supplementation. 25-Hydroxyvitamin D 3 supplementation increased plasma glucose concentration at parturition. The postpartum dry matter intake was not influenced by treatments. Feeding 25(OH)D 3 increases milk yield, 3.5% fat-corrected milk, and energy-corrected milk and improves milk yield components in early lactation. Overall, these findings suggest that 25(OH)D 3 at 3 mg/d can improve the energy metabolism and lactation performance, compared with the current-feeding practice of supplementing vitamin D 3 at 0.625 mg/d., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)