Evaluation of nutritional values five common weed forages using in-vitro gas production and in
situ rumen degradability techniques
Introduction The most widely available low-cost feeds for ruminants in most countries are usually native pasture containing
weed forages. However there is limited information about nutritional value of the weed forages on local area. The in vitro
and in situ techniques are useful tool for indirect measure of substrate fermentability and degradability of nutrient in the
rumen. These techniques can be applied for evaluation and ranking of feedstuff. Therefore the objective of this work to try
the assess of nutritional value of five local weed forages in the pasture, using in vitro and in situ technique.
Materials and methods Samples of weed forage were collected in March 2007 from Kashmar in the North East of I.R.Iran.
The leaves and stems were dried for 48 h at 60 °C followed by grounding in mill thought 2 mm screen. Proximate analyses
were done using the AOAC method (2005). The procedure of in vitro gas production was followed that described by Menke
and Steingass (1988). Rumen fluid was taken from 3 rumen fistulated steers feed twice daily containing urea treated wheat
straw and corn silage and concentrate. They fed at maintenance level.0.400 g of dry matter of samples was weighted in
triplicate into glass syringes which were incubated in the a water bath at 39 °C and volume of gas production were recorded
after 2, 4, 8, 12, 24, 48, 72 and 96 hours after incubation. Total gas volume was corrected for blank incubation. The
procedure used to determination of dry matter disappearance was based on the method described by Ørskov and McDonald
(1979). 500 mg of dried samples were weighted into of 20×20 with approximately pore size of 50 µm. Bags were incubated
in the rumen for 0, 2, 4, 8, 12, 24, 48, 72 and 96 hours. All data obtained from the trial were subjected to the general linear
models procedure of SAS according to a completely randomised design (3 replicate per treatment).
Results Obtained data from in situ dry matter degradability are given in Table 1. The mean values of dry matter degradation
characteristics for five native weed forages are significantly different (P < 0.05). Values obtained from the parameter of a,
normally considered as a soluble fraction dry matter, of Eruca sativa and Setaria Spp. were higher and lower than others
weed forages, respectively (P<0.05), but the insoluble degradable fraction (b) of Setaria Spp was higher than other weed
forages. Among the studied weed forages, Cardaria daraba had lower fraction of b compared to others. Cumulative gas
production kinetics during 96 h of incubation is shown in Figure 1. Higher values were obtained in the Eruca sativa.
However, lower value of total gas production were obtained for the Cardaria daraba.
Table 1 The parameter estimated from in situ of five weed
forages.
Estimated Parameters
a
b
b
c
e
0.106a
Cardaria
daraba
53.16
Triticum
aestivum
46.05c
46.27b
0.059c
Corcus
sativus
42.76d
42.66c
0.075b
Setaria Spp.
35.95e
50.14a
0.058c
Eruca sativa
a
d
a
a b c
56.17
30.29
35.54
0.106
Means in the same column with different superscripts
differ significantly (P < 0.05).
100
Gas production
treatment
Figure 1 In vitro gas production of five weed forages.
80
Triticum aestivum
Setaria Spp.
Corcus sativus
Eruca sativa
Cardaria daraba
60
40
20
0
0
12
24
36
48
60
72
84
96
Incubation Time (h)
Conclusions The differences between dry matter degradability and gas production between different sources of weed
forages may reflected in their composition. The observed variations in dry matter degradability suggest that the potential of
degradability (a+b) of Triticum aestivum and Eruca sativa were higher than others. However, pasture improvement through
incorporation of high quality forages in native pasture is a solution to ruminant livestock production.
References
Ørskkov, E.R. and I. McDonald. 1979. The estimation of protein degradability in the rumen from incubation measurements
weighted according to rate of passage. G. Agric.Sci. 92: 499-504.
Menke, K.H. and H. Steingass. 1988. Estimation of energetic feed value obtained from chemical analysis and in vitro gas
production using rumen fluid. Animal Research and Development, 28: 7-12.
SAS User’s Guide: Statistics, version 6, 4th edition. 1990. SAS. Inst., Inc., Cary, NC. , pp. 549-640.