Effect of <i>in-vitro</i> yeast treatment on the <i>in-sacco</i> degradability of some tropical crop residues in rumen fistulated west African dwarf sheep

Abstract

The effect of in vitro bioactive yeast (Saccharomyces cerevisiae, strain 1026) treatment on the degradability of dry mater fraction of some crop residues using the in-sacco degradability technique in West Arican Dwarf sheep was studied. Sixteen (16) adult rumen fistulated WAD sheep of average body weight o 16.84 ± 343 kg were used. Degradability of crop residues; rice straw, groundnut foliage, pigeon pea foliage and maize stover was studied. The results showed a significant (p<0.05) treatment effect. Time (length of yeast treatment) effect was positive for 2-6 day yeast treated groundnut foliage and pigeon pea foliage and for 8-10 day treatments for rce straw and maize stover. There was a negative correlation coefficient (r = -0.76) between degradability and length of yeast treatment for 8 and 10 day treated groundnut and pigeon pea foliages. There was a positive correlation (r = 0.69) between length of treatment and percentage degradation for all crop residues at 2, 4 and 6 day treatments. At 48hours incubation, the degradability of pigeon pea (96.41 ± 3.89 %) and groundnut foliages (93.17 ± 3.10 %) foliages were significantly (p<0.05) higher than rice straw (55.54 ± 7.11%) and maize stover (61.08 ± 6.42 %) particularly at 4 and 6 days yeast treatment periods compared with the control. On the other hand, the rumen degradability of 8 and10 day yeast treated rice straw (81.72 ± 5.91 % and 94.20 ± 2.81 % respectively)and maize stover (89.93 ± 4.16 % and 95.61 ± 4.22 % respectively) were significantly(p<0.05) higher than the control (49.06 ± 4.11 % for rice straw and 43.18 ± 4.78 % for maize stover) at 72 hours but not 48hours during which groundnut and pigeon pea foliages were optimally degraded following 4 and 6 day yeast treatments. It was evident from this study that length of in vitro yeast treatment, period of rumen incubation andtype of crop residues had remarkable effects on rumen degradability of dry matter fraction. Thus, treating crop residues for appropriate periods, in vitro, with yeast cultures could provide opportunity for enhancing the fermentative potential and utilization efficiency of crop residues in ruminants generally but particularly in West African Dwarf sheep.