Effects of vitamin B inclusion rates in milk replacer on health and growth of preweaned Holstein-Angus crossbred calves.

The adequacy of current recommendations for B-vitamin content of milk replacer has received little research attention, particularly with producers feeding more milk than historical standards. The aim of this study was to evaluate the effects of varying inclusion levels of B vitamins in milk replacer (MR) on health and growth of preweaned calves through 9 wk of age. Forty-two Holstein-Angus cross calves (≤7 d old) were randomly assigned to 1 of 3 treatments: control (CON, basal MR with no added B vitamins), basal plus (BP, MR with moderate B vitamin supplementation: 1.9 mg/kg B1, 1.7 mg/kg B3, 0.3 mg/kg B6, 43 µg/kg B12), or NASEM plus (NP, MR with supplemented B vitamins above current recommendations: 19.5 mg/kg B1, 9.9 mg/kg B2, 30 mg/kg B3, 19.5 mg/kg B6, 210 µg/kg B12,0.04 mg/kg biotin, 1.4 mg/kg folic acid, and 19.6 mg/kg pantothenic acid). The non-supplemented CON was below current recommendations for all B vitamins except biotin.and pantothenic acid Calves were housed individually and fed MR using a step-up/step-down protocol. Water was offered ad libitum from d 0; starter feed was offered ad libitum starting on d 50. Health scores and MR intake were recorded twice daily; starter intake, coprophagia, and fecal color were recorded daily. Weekly measurements included BW and skeletal growth. Health outcomes were analyzed using GLIMMIX, and growth and intake data using MIXED procedures in SAS. No clinical signs of vitamin deficiency were observed. Compared with BP calves, CON calves had more days with ocular discharge, while BP calves tended to have more respiratory events (coughing, heavy breathing) than CON. Starter intake was greater in BP vs CON during wk 8-9. The NP calves tended to have increased withers height compared with CON. No significant differences were observed in MR intake, BW, or most growth metrics. In summary, B vitamin supplementation showed some health benefits, though effects varied by inclusion level. Increased starter intake in BP calves may reflect improved well-being, although gains in growth were limited. Further research is needed to define optimal B vitamin inclusion rates in preweaned calf nutrition.