Replacement of Concentrate Mix With Vetch (<i>Vicia dasycarpa</i>) Hay on Feed Intake, Digestibility, Milk Yield and Composition of Lactating Crossbred Dairy Cows Fed Urea- Molasses Treated Wheat Straw

Abstract

The experiment was conducted with the objective to assess the effect of replacing vetch for concentrate mix on feed intake and digestibility as well as milk production and composition in lactating crossbred (Boran x Friesian) cows kept on a basal feed of urea- molasses treated wheat straw (UMTWS). Eight crossbred cows of similar milk yield (8-10 kg d^-1), body weight (BW) and stage of lactation (early lactation), but differing in parities were arranged in 4 x 4 double Latin square design. The treatments included offering urea molasses treated wheat straw basal diet ad libitum and supplementation with concentrate mix (T₁), and replacement of the concentrate mix with vetch (Vicia dasycarpa) hay at the level of 25% (T₂), 50% (T₃) and 75% (T₄). The concentrate mix consisted of 74% wheat bran, 25% noug seed (Guizotia abyssinica) cake and 1% common salt. The CP content of UMTWS was 86.7 g/ kg dry matter (DM), whereas that of vetch hay and the concentrate mix were 199 and 225 g/ kg DM, respectively. The contrary was true for neutral detergent fiber (NDF) content which was 767 g/ kg DM in UMTWS, and 545 and 479 g/ kg DM in vetch hay and the concentrate mix respectively. In sacco degradability studies showed that the concentrate mix and vetch were similar in rumen degradability parameters, except that rate of degradation was relatively faster for vetch hay. Total DM intake was higher (P < 0.05) for cows in T₃ compared to cows in the other treatments. Nutrient intakes and apparent digestibility were found to be similar (P > 0.05) among treatments, except for cows in T₃ that had higher (P < 0.05) NDF and acid detergent fiber (ADF) intakes than cows in T₁ and T₂. Crude protein (CP) and ME intakes were sufficient to meet daily requirements for the observed mean daily milk yield of 6.5 kg. Cows in T₁ produced higher (P < 0.05) milk yield compared to cows in T₄. Body weight change and milk composition were similar (P > 0.05) for cows in the different treatments. It is concluded that vetch hay could substitute 50% of the concentrate mix without compromising feed intake and digestibility of nutrients as well as milk yield and composition of lactating Boran x Friesian cows.

Keywords: Concentrate Mix; Rumen Degradability; Urea Molasses Treatment; Wheat Straw; Vetch