Effects of Mulberry (Morus Alba) Foliage Supplementation on Sheep Fed with Rice Straw

Feeding of fibrous agricultural by-product is the most appropriate strategy to reduce the cost of feeding of ruminants. However, these by-products have low nutritive values and the use of tree foliages as supplement could improve the utilisation of these fibrous feeds. A study consisting of three experiments was conducted with the aim of enhancing the utilization of rice straw by supplementation of the diet with mulberry foliage in sheep. The first experiment evaluated the effect of adding fermentable energy in the mulberry-rice straw basal diet by in vitro gas production technique. Molasses supplementation to mulberry-urea treated rice straw based (TRSM) significantly (P<0.05) improved fermentation of the diet as indicated by the increase in gas production, microbial biomass yield and proportion of propionic acid. Supplementation of molasses at 5% level was sufficient to improve fermentation of the diet. The second experiment was carried out based on the result from the first experiment. It was postulated that mulberry supplementation also provide fermentable nitrogen and energy in the rumen. Therefore in the second experiment was conducted to compare the effect of mulberry foliage or urea-rice bran mixture supplementation on nutrient digestibility, N utilization, rumen fermentation and fibre degradation. Sheep were fed urea treated rice straw basal diet and three different supplements namely; (i) mulberry, (ii) 50% of the mulberry replaced with urea-rice bran mixture and (iii) mulberry was replaced by to rice bran and urea. DMI, nutrient digestibility, nitrogen balance, and efficiency rumen microbial protein synthesis was similar in sheep fed on urea treated rice straw based diet supplemented by mulberry foliage or urea-rice bran mix. Hence, mulberry supplementation at 30% level in urea treated rice straw basal diet provided fermentable energy and protein. The rate of protein degradability of mulberry in the rumen was reduced in sheep fed mixed urea-rice bran supplement. Supplementation of mulberry or urea-rice bran mixed to urea treated rice straw basal diet resulted in similar fibre degradation of rice straw or urea treated rice straw. Hence, mulberry or urea-rice bran mixture offers an alternative source of fermentable nitrogen and energy to improve the utilisation of rice straw by sheep. The third experiment determined the effect of mulberry and mulberry-leucaena foliage supplementation on feed utilization, rumen fermentation and growth of lambs fed urea-treated rice straw basal diet. In an in vitro gas production study, mulberry was mixed with either one of the two leucaena varieties (Leucaena leucocephala hybrid and Leucaena leucocephala local) at 2 levels (25 and 50%). Supplementation of leucaena to mulberry decreased in vitro true organic matter digestibility (IVOMD), the rate of gas production and protein digestibility in the rumen buffered medium. Protein digestibility in acid pepsin which is an estimate of protein availability in intestine was increased. Tannin derived from leucaena hybrid supplementation to mulberry at ratio 1:1 was most effective level to decrease protein digestion in the rumen, but increased the protein digestibility in acid pepsin incubation. In a feeding trial, supplementation level at 30% of mulberry-leucaena mixture at the ratio of 1:1 to urea treated rice straw basal diet showed similar effect to mulberry or rice bran supplementation on nutrient digestibility, N balance, microbial protein synthesis and body weight gain. Hence, supplementation of either mulberry-Leucaena mixture or mulberry or urea-rice bran mixture provided the critically deficient nutrient required by rumen microbes to stimulate rumen fermentation digestion and thus the efficiency forage utilization. It is concluded that mulberry utilization improved when molasses was also supplemented to the rice straw basal diet. In addition, mulberry supplementation also provided the fermentable energy and nitrogen. However, due to the rapid microbial fermentation of mulberry protein in the rumen, mixing of Leucaena that has high tannin content with mulberry could reduce protein degradability in the rumen (in vitro). Feeding of Leucaena-mulberry mixture had similar effect to mulberry supplementation on growth of lambs.

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