Fibrous coproducts of corn and citrus as forage and concentrate sources for dairy cows

Abstract

This study evaluated the effect of fibrous coproducts from corn and citrus (Cargill, Brazil) on milking performance, digestibility, chewing behavior, and economics of dairy cows. Holstein cows (n = 20; 143 DIM) were fed in 5, 4 × 4 Latin squares with 21-d periods, a combination of factors in a 2x2 factorial arrangement: 1) Concentrates (C): the partial replacement of wet corn gluten feed (GF) by an iso-N blend of pelleted citrus pulp plus corn distillers dried grains (CD), 2) Forages (F): the partial replacement of whole-plant corn silage (CS) with corn ear fibrous coproduct (CO). The goal was to have diets with 20 and 5% of DM of both GF and CO, and to have a 50% replacement of CS by CO. The statistical model had the effects of cow, period, C, F, and C × F interaction. The CS-CD diet had the highest (P ≤ 0.05) yields of 4% FCM (28.5 kg/d) and ECM (30.0 kg/d) relative to the other diets (27.0 and 28.4 kg/d, respectively). Milk fat content was lower (3.24 vs 3.67 %) and DMI was higher (21.2 vs 20.2 kg/d) on CO than CS (P ≤ 0.03). CO reduced (P ≤ 0.04) the intake of peNDF > 8 (kg/d) and the intake as % BW of peNDF > 8, forage NDF, and total NDF. CO diets had greater meal frequency and lower daily meal time, meal duration, meal size, and rumination and eating behaviors than CS (P ≤ 0.04). The total-tract starch digestibility was lower (P < 0.01) on CO than CS, but the intake of digestible starch was higher (P < 0.01) on CO than CS. The GF reduced (P < 0.01) milk yield (29.6 vs 30.8 kg/d), tended (P = 0.06) to reduce DMI (20.4 vs 21.0 kg/d), and reduced (P < 0.01) the intake of digestible organic matter relative to CD. Concentrate source did not affect (P = 0.52) the intake of peNDF > 8. The GF increased (P ≤ 0.02) meal frequency and rumination (min/d, min/kg DMI, and min/kg peNDF > 8) and reduced (P = 0.04) meal size. The intake of digestible starch tended (P = 0.10) to be increased by GF. Rumen microbial yield was not affected (P ≥ 0.13) by any treatment. Income over feed cost (IOFC) was higher (P < 0.01) on CS than CO and concentrate source had no effect (P ≥ 0.61) on IOFC. All strategies evaluated were nutritionally viable.