Effect of Some Physical and Chemical Treatments of Millet Straw on Nutritive Valued

Abstract

Limited use of cereal straws in livestock feeding is due to their low voluntary intake, low protein contents and low digestibility. Nutritional value of these roughages can be improved through chemical, physical or biological methods. Efficacy of treating straw with urea for improving its nutritive value is considered equivalent to anhydrous or aqueous ammonia. However, the adoption rate of urea treatment by farmers is low, maybe due to relatively tedious technology and higher requirement of labor. There is need to simplify urea treatment methods. The study was carried out at North Darfur State, Sudan. The mean, minimum and maximum temperatures are 17.7Co and 34.7Co respectively(Elfasher Metrological Station, 2014).The state lies between latitudes 12° 30" and 21° 55" N and longitudes 24° 00" and 27° 30" E within the arid and semi-arid zones. The state can be divided into two main geographical zones based on average amount of annual rainfall and soil types. These are the desert and semi-desert zones; the two together cover an area of about 296,400 km2; about 60% of it is rangelands. There are three distinct seasons in the area, the hot rainy season or autumn (Khareef) from June to September, the cool season or winter from November to February and the hot dry season or summer from March to May. The average annual rainfall for the last ten years was 218.09 mm. The main objective of the study was to investigate, ways to improve the nutritive value of millet straw for use as feed during the dry season when there is acute shortage of fodder from rangelands both on quantity and quality. In the present study an effort has been made to simplifythe existing urea treatment method so that farmers could easily adopt this technique.

The present method involves weighing the required amount of urea (4% of weight of straw), giving 30% moisture by adding 50liter water, putting this mixture in a plastic bag, piling the straw covered and keep it air-tight, three weeks at room temperature. In this method three steps including preparation of urea solution, sprinkling of solution on straw and pressing the straw during treatment process, have been eliminated which resulted in saving labor by 55%. (the three steps included: prepared by chopped and grinded millet straw, sprayed and mixed with urea solution, stored straw treated in plastic bags and sealed, kept air-tight and left for three weeks at room temperature). Taking into account the straw processor to sunlight display before it is submitted to the animal to get rid of the excess concentration of urea. The results obtained showed that treatment with urea resulted in increased CP% both in the ground and chopped form (14.58 and 14.61% respectively) compared with untreated straw (7.8 and 11.9% respectively). Neutral detergent fiber was also lower in urea treated straw compared with untreated straw both in the ground and chopped form (62.50 and 66.0% respectively) compared with untreated straw (65.50 and 72.50% respectively).Neutral detergent fiber (NDF), and Acid detergent lignin (ADL) were decreased consistently, while the content of ether extract (EE) increased. Urea treatment had a positive influence on millet straw digestibility. Dry matter digestibility of millet straw treated with urea was higher both when the straw was ground and chopped (64.1 and 65.0%) compared with that of untreated straw(56.5 and 52.4%).The improvement in digestibility could be attributed to an enhancement of rumen microbial activity as a result of increased nitrogen. Ground untreated millet strawhad a higher digestibility than untreated straw in the chopped form, however the difference was not significant (P>0.05). Effect of treatments on dry matter intake of millet straw by Sheep revealed no significant differences between treatments as regards intake of dry matter, despite the decline in dry matter intake by sheep there are noticeable increases in the animal weight.However, voluntary intake of millet straw may be limited byphysical factors causing low rates of passage. Grinding usually breaks the lignin bonds of the cell wall and exposes a larger surface area to rumen microbial action, resulting in faster removal of digesta from the rumen.