Effects of coenzyme Q10 on growth performance, rumen fermentation, blood metabolites, antioxidant status, and immune responses of pre-weaned Holstein dairy calves

This study was conducted to investigate the effects of coenzyme Q10 (CoQ) dietary supplementation on growth performance, rumen fermentation, diarrhea frequency, and serum biochemical metabolites of pre-weaned Holstein dairy calves. Forty-five Holstein female calves (37.86 ± 2.38 kg of body weight BW; 1 d of age) were randomly assigned into 1 of the 3 treatments: a control group (Q0; without CoQ supplementation) and CoQ supplementation at low dose (Q50; 50 mg/kg dry matter DM of CoQ) or high dose (Q100; 100 mg/kg of CoQ) ( n = 15). All experimental calves were fed pasteurized whole milk twice daily (06:30 and 17:00) starting from d 2 of age. From d 61 to 70, the calves were gradually weaned following a step-down approach. Calves had free access to clean water and the starter diet, which was introduced from d 7 onward. The study terminated on d 70. The results showed that calves supplemented with both low and high doses of CoQ had significantly higher average daily gain (linear, P = 0.007) and dry matter intake (DMI, linear, P < 0.001) compared with the Q0 group. There was a treatment by age interaction for BW ( P < 0.001), where BW at 10 weeks of age was greater at Q50 and Q100 groups than at the Q0 group. Diarrhea frequency from 1 to 5 weeks of age was significantly affected by treatment ( P = 0.026), with Q100 calves showing the lowest values. At 10 weeks of age, the Q100 calves showed higher serum total antioxidant capacity (linear, P = 0.012), superoxide dismutase (linear, P = 0.018), glutathione peroxidase (linear, P = 0.012), and β-hydroxybutyrate (linear, P = 0.006) compared with the Q0 group. The serum malondialdehyde was lower in Q100 calves than Q0 calves (linear, P = 0.015). Compared with the Q50 and Q0 groups, serum contents of insulin, growth hormone, and non-esterified fatty acids increased in calves receiving high CoQ dose (linear, P = 0.006, 0.012, 0.006, respectively). Conversely, the Q50 calves showed higher serum glucose compared with the other treatments (quadratic, P = 0.003). The results of the present study suggest that the supplementation of CoQ to milk may promote growth performance, health status, blood metabolites, and hormones, and improve the antioxidant capacity of the Holstein dairy calves. The use of CoQ may be an alternative to feeding antibiotics at 100 mg/kg DM to improve calf health and decrease diarrhea frequency.