European Journal of Scientific Research - EuroJournals

313 Odeyinka, S.M, Hector, B.L and Ørskov, E.R
Estimations of rumen degradability were made using the nylon bag technique described by
Ørskov et al. (1980). The nylon bags used were 8cm x 14cm, 40 to 60-micron pore size (IFRU, The
Macaulay Institute, Aberdeen, UK). Duplicate samples were incubated in 2 different sheep receiving
the same diet as above. The following incubation times were used: 4, 8, 16, 24, 48, 72, and 96 hours.
The results of the experiments were analysed using “Fitcurve” macro (Chen, X.B., 1995. IFRU,
The Macaulay Institute, Aberdeen, UK) for Microsoft Excel. The program is a utility for processing
data of feed degradability or in vitro gas production, it fits the data to the exponential equation
p=a+b(1-e -ct ) developed by Ørskov and McDonald (1979). For degradability characteristics, p is the
percentage degraded at time t, a is the intercept of the line at time zero, b is the insoluble but
degradable fraction, therefore a+b is the potential degradability and c is the rate of degradation. While
this equation was originally developed for protein supplements in which the intercept was also an
approximate expression of solubility, this is not the case for trees and shrubs due to the occurrence of a
lag phase or a period in which there is no net disappearance of the insoluble but fermentable substrate
(Ørskov and Ryle, 1990). Accordingly, A is solubility and small particle loss, B is the insoluble but
fermentable fraction (B=(a+b)–A). For in vitro gas production, the data is fitted to the same equation, p
is the volume of gas produced at time t, a is the intercept of the line at time zero, b is the potential gas
production and c is the rate constant (Ørskov and Ryle, 1990).
In vivo digestibility
In this experiment, 12 mature sheep were used. Animals were housed in metabolism crates. Total 24hour
urine and faeces collections were made throughout the experiment by means of chutes and
separators fitted underneath the metabolism crates. The experiment consisted of individual
experimental periods, separated by periods of 14 days. During each experimental period, animals were
randomly allocated to different experimental treatments in a partial Latin square design.
Animal 1 Animal 2 Animal 3 Animal 4 Animal 5 Animal 6
Period 1 A B A+B+C D E D+E+F
Period 2 B A+B B+C E D+E E+F
Period 3 C C A+C F F D+F
Period 4 A+B+C B+C A D+E+F E+F D
Period 5 A+B A A+B D+E D D+E
Period 6 B+C A+C B E+F D+F E
Period 7 A+C A+B+C C F+D D+E+F F
Animal 7 Animal 8 Animal 9 Animal 10 Animal 11 Animal 12
Period 1 G H G+H+I J J J
Period 2 H G+H H+I K K K
Period 3 I I G+I L L L
Period 4 G+H+I H+I G J+K+L J+K+L J+K+L
Period 5 G+H G G+H J+K J+K J+K
Period 6 H+I G+I H K+L K+L K+L
Period 7 I+J G+H+I I L+J L+J L+J
A letter (A, B, C, D, etc) represents an individual plant material.
Statistical Analysis: The results were subjected to statistical analysis using GENSTAT 5
Release 4.1 software package. Analysis of variance was done to detect differences between treatments.
Differences between treatments were analysed using means across replications. Least significant
difference (LSD) test was used to compare treatment means