Impacts of feeding a Saccharomyces cerevisiae fermentation product on productive performance, and metabolic and immunological responses during a feed-restriction challenge of mid-lactation dairy cows

Abstract

Saccharomyces cerevisiae fermentation products are commonly used in dairy cattle ration to improve production efficiency and health. However, whether these benefits will persist during feed-restriction-induced negative energy balance is unknown. The objective of this experiment was to examine the effect of a Saccharomyces cerevisiae fermentation product (NT, NutriTek, Diamond V) on performance, metabolic, inflammatory, and immunological responses to a feed-restriction challenge in mid-lactation dairy cows. Sixty Holstein cows were blocked by parity, days in milk, and milk yield and then randomly assigned to 1 of the 2 supplements: NT or placebo (CTL). The supplements were mixed in total mixed ration before feeding at a rate of 19 g/d per cow. The production phase of the experiment lasted 12 wk. Intake and milk yield were recorded daily, and milk composition was measured weekly. After the production trial, a subset of cows (NT: n = 16; CTL: n = 16) were immediately enrolled in a 5-d feed-restriction challenge with 40% ad libitum intake followed by a 5-d realimentation. Milk yield and composition were measured at each milking from d -2 to 10 relative to feed restriction. Blood samples were collected on d -2, -1, 1, 2, 3, 4, 5, 6, 8, and 10 relative to the initiation of feed restriction to measure circulating metabolites, insulin, cortisol, IL-10, tumor necrosis factor-α, lipopolysaccharide binding protein, and haptoglobin. Immune function assessments, including peripheral mononuclear cell proliferation and functional assays of circulating granulocytes, were performed on d -3 and 4 of the feed restriction. No differences were observed in dry matter intake, milk yield, or concentrations or yield of components except for fat yield. An interaction of parity and treatment was observed for milk fat yield that was lower for CTL than NT in primiparous cows, but no differences were observed among treatments in milk fat yield of multiparous cows. Feed restriction successfully induced negative energy balance and its associated metabolic changes, including reduced concentrations of plasma glucose and increased nonesterified fatty acids and β-hydroxybutyrate. Cows fed NT had a similar decrease in milk yield but had a more pronounced reduction in plasma glucose concentration and greater β-hydroxybutyrate concentration during feed restriction than those fed CTL. Feed restriction did not induce evidence of systemic inflammation but did reduce granulocyte functional activity. Compared with CTL, feeding NT improved the reactive oxygen species production by granulocytes after stimulation by extracellular antigens. In conclusion, feeding NT increased milk fat production of first-lactation cows but did not affect overall productive performance. However, supplementation with NT improved induced granulocyte oxidative burst. This may explain the greater glucose utilization by cows fed NT rather than CTL during feed restriction.

Keywords: Saccharomyces cerevisiae fermentation product; feed restriction; immunity; inflammation.