Effects of Dietary Zinc Source and Level on Mammary Epithelia and Dairy Food Chemistry

Abstract

Twelve lactating Holstein cows (132 ± 21 days in milk) were enrolled in a Latin square experiment to explore the extent to which source and amount of supplemental dietary Zn can impact barrier function of mammary epithelial tissue. Cows received either 970 mg supplemental Zn/day as ZnSO 4 (LS), 1,640 mg supplemental Zn/day as ZnSO 4 (HS), or 1,680 mg supplemental Zn/day as a mixture of ZnSO 4 and Zn methionine complex (HC). Treatments lasted for 17 days followed by 4 days of sample collection. Blood and milk were collected and analyzed for markers of blood-milk leak including plasma lactose and αlactalbumin and milk electrolytes. Total RNA was also isolated from milk cells and abundance of Zn transporter 2 (ZnT2) and clusterin, genes with potential impact on Zn-dependent apoptosis and cell survival, were measured. Finally, dairy food properties of milk (heat coagulation time, nonprotein nitrogen, and noncasein nitrogen) were also analyzed. Cows on the HS treatment tended to have higher feed intake than LS (P = 0.06), and milk fat percentage tended to increase for HC compared to LS (P = 0.08). No other effects on milk composition, yield, or production efficiency were observed. No effects were observed on markers of blood-milk leak, mRNA abundance of ZnT2 or clusterin, or dairy food chemistry properties. Concentration and source of dietary Zn did not impact mammary epithelial integrity in lactating cows during late lactation. SummaryTwelve lactating Holstein cows (132 ± 21 days in milk) were enrolled in a Latin square experiment to explore the extent to which source and amount of supplemental dietary Zn can impact barrier function of mammary epithelial tissue. Cows received either 970 mg supplemental Zn/day as ZnSO 4 (LS), 1,640 mg supplemental Zn/day as ZnSO 4 (HS), or 1,680 mg supplemental Zn/day as a mixture of ZnSO 4 and Zn methionine complex (HC). Treatments lasted for 17 days followed by 4 days of sample collection. Blood and milk were collected and analyzed for markers of blood-milk leak including plasma lactose and α-lactalbumin and milk electrolytes. Total RNA was also isolated from milk cells and abundance of Zn transporter 2 (ZnT2) and clusterin, genes with potential impact on Zn-dependent apoptosis and cell survival, were measured. Finally, dairy food properties of milk (heat coagulation time, nonprotein nitrogen, and noncasein nitrogen) were also analyzed. Cows on the HS treatment tended to have higher feed intake than LS (P = 0.06), and milk fat percentage tended to increase for HC compared to LS (P = 0.08). No other effects on milk composition, yield, or production efficiency were observed. No effects were observed on markers of blood-milk leak, mRNA abundance of ZnT2 or clusterin, or dairy food chemistry properties. Concentration and source of dietary Zn did not impact mammary epithelial integrity in lactating cows during late lactation.

Enhancing bovine immune, antioxidant and anti-inflammatory responses with vitamins, rumen-protected amino acids, and trace minerals to prevent periparturient mastitis

“…Notably, studies have demonstrated that the supplementation of zinc preparations in Holstein cows can lead to improved integrity of the mammary epithelium ( 109 ), although contradictory results have been reported by Shaffer et al. ( 110 ). Zinc is crucial for the development and proper functioning of cells involved in innate immunity, such as neutrophils.…”

“…The integrity of the intact mammary epithelium, which acts as an impermeable barrier to microorganisms, is recognized as an intrinsic component of the udder immune system. Notably, studies have demonstrated that the supplementation of zinc preparations in Holstein cows can lead to improved integrity of the mammary epithelium (109), although contradictory results have been reported by Shaffer et al (110). Zinc is crucial for the development and proper functioning of cells involved in innate immunity, such as neutrophils.…”

The Association between Selected Dietary Minerals and Mastitis in Dairy Cows—A Review

“…Intact mammary epithelium impenetrable for microorganisms is considered an innate part of the udder immune system. Weng et al [ 69 ] reported improved integrity of mammary epithelium when Holstein cows were supplemented with Zn preparations; however, conflicting results were obtained by Shaffer et al [ 70 ]. Zinc is crucial for the development and proper function of cells mediating innate immunity such as neutrophils.…”

The effects of organic zinc supplementation on production performance and health of high producing dairy cows

“…Statistically significant (P < 0.10)The majority of studies observed numerical increases in DMI of lactating cows ranging from 0.2 to 1.3 kg/d when inorganic Zn was replaced with organic Zn. On the contrary,Shaffer et al (2016) reported a statistically significant decrease in DMI. Moreover, the majority reports improvements in milk yield relative to controls but only those inBallantine et al (2002) andBakhshizadeh et al (2019) were statistically significant.…”