Effect of replacement of the mung bean straw (Vigna radiate) with wheat straw or low grain-corn silage on digestibility and some blood and ruminal parameters in Arabi lambs

The dry and semi-arid climates and the deficiency of rainfall in Iran have led to increasing the nutrition cost, which will be affected the incomes of animal farmers. In recent decades, demand for livestock products (like meat and milk) has grown because of population growth and economic progress. In order to reduce feed costs, in many countries, crop residues are used as agricultural by-product in feeding of farm animal, including mung bean straw. Mung bean is a plant that has been cultivated in the arid and semi-arid regions of Iran and elsewhere in the Middle East. This plant is important because of the ability to stabilize nitrogen in the soil, to strengthen and prevent its erosion. Most of the nutrition studies that have been done in relation to mung beans have been more focused on mushy seed, but few studies have been conducted on mung bean straw. Therefore, the present experiment was conducted to study the effects of replacing mung bean straw with wheat straw or corn silage on digestibility, rumen fermentation and protozoa population in Arabic lambs.
Material and The present experiment was conducted in two steps. The first step was to determine the appropriate level of replacing the mung bean straw with wheat straw or corn silage in the diet using a gas production technique. In the second step, by examining the results of the first stage of the experiment, some levels of replacing mung bean straw instead of wheat straw and corn silage were selected and digestion and metabolism of diets were investigated. After determining the appropriate level of replacing mung bean straw with wheat straw and corn silage in diet, 16 lambs fed with selected diets from first step. The experimental diets included: diet without mung bean straw (control ration), 100% replacing of mung bean straw with wheat straw (ration 1), 25 and 50% replacing of mung bean straw instead of corn silage (rations 2 and 3 respectively) were fed in a completely randomized design. In order to estimate blood and ruminal fermentation parameters, and protozoa population count at the end of the experiment, rumen fluid and blood was taken from the lambs 3 and 4 h after the morning feeding, respectively.
Mung bean straw had a higher crude protein and crude fats than wheat straw and more crude fat than corn silage. While the crude protein content of corn silage was higher than mung bean straw. Although no statistical analysis was performed, protein content, NDF, ADF, ME mung bean and corn silage had a slight difference, but differences were considerable with wheat straw. Wheat straw had the highest amount of NDF, ADF and lignin and the lowest amount of crude fat and ME. Mung bean straw had the highest amount of fat. In one experiment, mung bean straw had 88.20% dry matter, 9.70% crude protein, 26.56% crude fiber, 2.39% crude fat and 11.43% ash in dry matter base (Khatik et al. 2007), the data of present experiment was closely same with them. Based on the results of chemical analysis, wheat straw or corn silage were detected as a suitable replacement for mung bean straw in diet. In the first step of study, replacing mung bean straw with wheat straw in the diets, for all levels (25 to 100%) increased the potential of gas production (GP) compared to control (P0.05). Only the rumen fluid pH in the diet 3 had significant difference with control and was the lowest amount (P Therefore, due to proper price and abundance of mung bean straw in some regions of the Iran included Khuzestan province, we can recommend using it as replacement for wheat straw or low-grain corn silage in feeding of sheep.