Preference, Voluntary Feed Intake, and Digestibility of Sheep Fed Untreated Rice Straw and Supplemented with Sole or Combined Fodder Tree Leaves

Abstract

Three experiments were conducted to measure the preference, voluntary feed intake (VFI), and digestibility of forest type (FT) sheep fed untreated rice straw (RS) and supplemented with either sole or combined fodder tree leaves [Leucaena (L), Samanea (S) or Gliricidia (G) and their equal combinations]. The preference index (PI) was determined by consumption difference of the three fodder tree leaves (FTL), using 12 FT sheep (6 rams and 6 ewes of average weight 17.0 ± 1 kg). The sheep were offered the FTL in a cafeteria-style, and the consumption within the first 1 h was used to rank them. The sheep showed marked preference (P < 0.0001) for Leucaena over either Samanea or Gliricidia. The PI followed this order: Leucaena > Samanea > Gliricidia. For the VFI study, a total of 24 FT sheep (16 rams and 8 ewes) of average weight 17.0 ± 1.0 kg were randomly assigned to 1 of 8 dietary treatments in a completely randomized design. The treatments were T1 (100% urea-ammoniated straw), T2 (RS + 100% L), T3 (RS + 100% S), T4 (RS + 100% G), T5 (RS + 50% L: 50% S), T6 (RS + 50% L: 50% G), T7 (RS + 50% G: 50% S), T8 (RS + 33% L: 33% G: 33% S). There were significant differences in the total and straw DM intakes. Total DM intake ranged from (523 to 694 g/d) whilst straw DM intake ranged from (430 to 692 g/d). The highest (P < 0.0001) total and straw DM intake were observed in sheep fed T8 and T1 diets compared to the other treatment diets. Feeding sole Gliricidia resulted in the lowest straw and total DM intakes but combining it with either Leucaena or Samanea improved intakes. In the digestibility study, 16 rams (average weight = 17.0 ± 1.0 kg) and same treatments for the VFI study were used to determine DM digestibility (DMD) and digestible organic matter in dry matter (DOMD). The DMD values ranged from 52.50% to 67.20 % while the DOMD was between 55.14 and 70.36%. Feeding T1 resulted in the highest (P = 0.027) DMD, and (P < 0.0001) DOMD but combining the FTL improved DMD and DOMD for the supplemented diets. The results of the study indicated that feeding combined FTL (3 FTL) resulted in a similar performance as that of the urea-ammoniated straw and could be used a low-cost protein supplement for sheep on low-quality roughage.