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.
Tag: antioxidant
Supplementation with Yucca schidigera improves antioxidant capability and immune function and decreases fecal score of dairy calves before weaning
Yucca schidigera (YS) is a species of plant rich in antimicrobials, antioxidants, and immunomodulators. It has been used as feed additive to improve animal performance and decrease methane emissions in cattle. However, few studies have evaluated YS in dairy calves. In this study, we evaluated the effects of YS on the growth performance, antioxidant capacity, and immune function in dairy calves before weaning. We randomly assigned 40 newborn female Holstein calves (4 d old; 40 ± 5 kg of body weight) to 1 of 4 treatments (n = 10 per treatment), which were fed 0, 3, 6, or 9 g/d of YS powder. The YS allowance was mixed into milk or milk replacer and fed twice daily. Dry matter intake (both liquid and starter feed) and fecal score were recorded daily, and body weight, withers height, body length, and heart girth were measured at 4, 14, 28, 42, and 60 d of age. Blood was sampled from the jugular vein at 14, 42, and 60 d of age after the afternoon feeding for analysis of serum antioxidant capacity and immune function. Feeding YS did not affect dry matter intake, but decreased the feed-to-gain ratio with a quadratic dose effect. Over the whole study period, the average daily gain tended to linearly increase with the increasing YS doses, and it was 6.8% higher in diets supplemented with 9 g/d of YS than in the basal control diet without YS. The YS supplementation linearly decreased fecal score in a dose-dependent manner, and the frequency of diarrhea was significantly decreased as the YS supplementation increased throughout the whole study period. The YS supplementation also linearly decreased maleic dialdehyde concentration in the serum compared with the control group. The activity of catalase tended to linearly and quadratically increase, and that of glutathione peroxidase increased linearly with the increased YS supplementation. Serum concentrations of IgA and IgG increased linearly with the increased YS supplementation, and that of IgG tended to increase quadratically. To the best of our knowledge, this is the first study that demonstrated that feeding YS to young calves could improve growth, feed efficiency, and immunity, and decrease fecal score and diarrhea. The results of this study indicated that feeding YS at 9 g/d may be recommended to benefit dairy calves before weaning. © 2021 American Dairy Science Association
Impacts of heat stress-induced oxidative stress on the milk protein biosynthesis of dairy cows
Heat stress (HS) is one of the most important factors posing harm to the economic wellbeing of dairy industries, as it reduces milk yield as well as milk protein content. Recent studies suggest that HS participates in the induction of tissue oxidative stress (OS), as elevated levels of reactive oxygen species (ROS) and mitochondrial dysfunction were observed in dairy cows exposed to hot conditions. The OS induced by HS likely contributes to the reduction in milk protein content, since insulin resistance and apoptosis are promoted by OS and are negatively associated with the synthesis of milk proteins. The apoptosis in the mammary gland directly decreases the amount of mammary epithelial cells, while the insulin resistance affects the regulation of insulin on mTOR pathways. To alleviate OS damages, strategies including antioxidants supplementation have been adopted, but caution needs to be applied as an inappropriate supplement with antioxidants can be harmful. Furthermore, the complete mechanisms by which HS induces OS and OS influences milk protein synthesis are still unclear and further investigation is needed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.