Semi arid browse forages: Their antinutritive substances and in sacco neutral detergent fibre and organic matter degradability

Abstract

Three ruminally cannulated bulls were used to determine variations in dry matter (DM) degradability of forage consumed by ruminants in the semi-arid region of north Nigeria. Organic matter and crude protein (CP) contents were higher (P< 0·05) in all the browse forages. Higher numerical values of neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and cellulose were recorded. Condensed tannin varied from 0.08 mg/g DM in Kigalia africana to 0.41 mg/g DM in Maerua angolensis. A range of 0.24 mg/g DM in Olea hochstteteri to 0.48 mg/g in Khaya senegalensis was obtained for phenolic. Saponin content of the experimental leaves range from 1.08 mg/g DM in Poupartia sirrea to 2.95 mg/g DM in Garderna sokotensis. Oxalate in the browses used ranged from 4.59 mg/g DM in Maerua angolensis to 8.14 mg/g DM in Olea hochstteteri. The highest value of 5.81 mg/g DM was obtained in Khaya senegalensis while Olea hochstteteri had the lowest value of 2.02 mg/g DM for Phytic acid in the browses studied. The hydrogen cyanide and Fluoroacetate are generally low in all the browse samples studied. The result showed no significant difference among the browse forages.NDF degradability after 24 and 48 h of ruminal incubation were higher (P< 0·05) in all the browses. Higher values (P< 0·05) in DM bag losses at zero time ('a' fraction) were high for the browses. The insoluble but fermentable NDF ('b' fractions) were low (P< 0·05) among browse forages. Numerically lower values of NDF 'c' fraction were found in browses except for Kigalia africana, whereas NDF potential degradability were higher (P< 0·05) in all the experimental leaves. High (P< 0·05) contents of CP in the browse forages, NDF degradability after 48 h of ruminal incubation, and a+b, were observed in the browse leaves. Thus, these results may be related to both the better feeding value of forage consumed by the animals and better performance of livestock during in these areas. Then, the NDF degradability after 48 h, together with the soluble fraction 'a' and insoluble but fermentable fraction 'b' and the c fraction permit the nutritive value of the forage consumed by grazing goats to be accurately described. The rate of OM disappearance was highest for Garderner sokotensis 97.20% though the values were generally high for all the browse forages studied. The soluble fraction 'a', rate of degradation 'c' and effective degradability 'ED' were generally low for all the browse forages while the insoluble but degradable fraction 'b' and potential degradability a+b were high for all the browse forages. Base on these findings, it can be concluded that the browse forages are of good nutritive value and can be use as supplement.