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Switching lactating Jersey cows from a high neutral detergent fiber diet to an isoenergetic high soluble carbohydrate diet induces mild inflammation
The objective was to investigate whether switching to a high soluble carbohydrate diet induced a systemic inflammatory response in peak lactating Jersey cows. Seven multiparous Jersey cows were selected from a commercial dairy farm. Cows were 71 ± 3 DIM and had an average BW of 407 ± 17.9 kg (mean ± SD). Each cow was individually housed in a 4 x 10 m soil surface pen. All cows received the high neutral detergent fiber (NDF; 33.8% DM)/low non-fiber carbohydrate (NFC; 34.3% DM) diet for 2 wk and then switched to an isonitrogenous/isocaloric reduced NDF (30.2% DM)/high NFC (40.7% DM) diet for 1 wk. The NFC content of the diet was increased by replacing corn distillers products and whole cottonseed with steam flaked barley and canola meal. Feed intake was collected from -7 to 7 d relative to the diet change. Milk yield, milk composition, and peripheral blood samples were collected immediately before switching the diets and 2, 4, and 7 d after the diet change. Blood hematology and plasma haptoglobin, zinc, interleukin-6, and tumor necrosis factor-α concentrations were analyzed. The switch in diet caused a decrease in DMI (19.6 vs 17.0 ± 0.46 kg / d; P < 0.0001). Milk production decreased on d 2 (27.9 vs 25.5 ± 1.17 kg / d for d 0 and 2 relative to the diet switch, respectively; P = 0.042), but had returned to baseline yields by d 7. No differences (P > 0.473) were observed in blood hematology, except that hemoglobin concentrations were increased after the diet switch (9.9 vs 10.9 ± 0.35 g/dL; P = 0.02). Plasma haptoglobin concentrations tended to be elevated on d 7 relative to d 0 (62.4 vs 142.3 ± 23.5 μg / mL; P = 0.095). In addition, plasma zinc concentrations were reduced on d 7 relative to d 0 (1.82 vs 1.42 ± 0.138, mg/L; P = 0.048). There were no differences (P > 0.324) in the plasma concentrations of either interleukin-6 or tumor necrosis factor-α in plasma after the diet change. These data indicate that switching from a lower NFC diet to an isoenergetic high NFC diet suppressed DMI and caused mild inflammation among peak lactating Jersey cows as evident by the greater plasma concentrations of the positive acute phase protein, haptoglobin, and reduced concentrations of plasma zinc, a negative acute phase metabolite.
Keywords: inflammation, neutral detergent fiber, soluble carbohydrate