Physically effective neutral detergent fiber improves chewing activity, rumen fermentation, plasma metabolites, and milk production in lactating dairy cows fed a high-concentrate diet

Subacute ruminal acidosis (SARA) continues to be a common and costly metabolic disorder in high-producing dairy cows worldwide. The objective of this study was evaluate if increasing the concentration physically effective neutral detergent fiber (peNDF) diets can reduce risk SARA fed high-concentrate diet. Thirty second-parity Holstein mid lactation (131 ± 8.3 d milk) were randomly allocated 3 dietary treatments (10 per group): high (11.3%, peNDF8.0), medium (10.6%, or low (9.0%, peNDF8.0) peNDF8.0. prepared by mixing same total mixed ration (57% concentrate 43% roughages) for 10, 18, 60 min, respectively. 36 with 21 adaptation 15 sampling. peNDF8.0 intake positively correlated concentration. Chewing ruminating times adjusted dry matter NDF linearly increased diet decreased number meals day. rumen fluid pH, molar percentage acetate isobutyrate, acetate-to-propionate ratio, ammonia nitrogen concentration, but percentages propionate valerate. VFA butyrate isovalerate remained unchanged. Meanwhile, increase activities carboxymethyl cellulase, avicelase, β-glucanase, ferulic acid esterase fluid, did not affect xylanase. Total plasma antioxidant capacity, γ-glutamyl transpeptidase activity, concentrations protein, albumin, creatinine, malondialdehyde raised glucose, triglyceride, cholesterol, blood urea nitrogen. Somatic cell counts milk feed energy efficiencies unaffected treatments. Shortening time may practical strategy diets.