Supplementation with Schizochytrium sp. enhances growth performance and antioxidant capability of dairy calves before weaning

This study aimed to determine the effect of microalgae (Schizochytrium sp., SZ) supplementation on the growth performance, rumen fermentation parameters, and antioxidant capacity of dairy calves. Fifty newborn female Holstein calves (1 d old, 39.8 ± 0.77 kg initial body weight) were randomly assigned to 1 of 5 groups (n = 10). The 5 groups of calves were fed with whole milk (d 4 to d 22) or milk replacer (d 23 to d 60) supplemented with (per calf per d) 0 g (control, SZ0), 5 g (SZ5,0.55 g/d DHA), 10 g (SZ10, 1.11 g/d DHA), 20 g (SZ20, 2.22 g/d DHA), or 40 g (SZ40, 4.44 g/d DHA) of SZ powder from day 4 to day 60. The daily supplementations of SZ were equally divided and offered twice daily (via milk pail) at 0800 and 1500 h. During the experiment, dry matter intake of whole milk/milk replacer and starter and fecal score were recorded daily, while bodyweight (BW) was measured biweekly at days 1, 14, 28, 42, and 60, and withers height was measured at days 1 and 60. Blood was sampled after the afternoon feeding from the jugular vein at days 28 and 60 for serum antioxidant capacity detection (malondialdehyde, glutathione peroxidase, catalase and superoxide dismutase). Rumen fluid was sampled after the morning feeding via a flexible esophageal tube at days 14, 28, 42 and 60 for pH, ammonia nitrogen and volatile fatty acids measurements. The final BW and average daily gain (ADG) increased quadratically as SZ increased (P < 0.05), and SZ20 group of ADG was numerically higher than other groups. Feed:gain (F:G) ratio decreased quadratically as SZ increased (P < 0.05), and SZ20 group was numerically lower than other groups. Withers height tended to increase linearly as SZ increased (P < 0.1). The concentration of propionate tended to decrease linearly as SZ increased in rumen fluid (P < 0.1). Malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and catalase (CAT) increased linearly as SZ increased in blood (P < 0.05). Taken together, this study demonstrated the positive effects of SZ supplementation on growth performance and antioxidant capacity of calves. At the same time, SZ supplementation tended to reduce the concentration of rumen propionate, particularly in high dosage SZ group. Considering the above, the optimal amount of SZ supplementation for dairy calves suggested by the present study is 20 g/d. © 2020 Elsevier B.V.

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DOI:

https://doi.org/10.1016/j.anifeedsci.2020.114779

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