Effect of Citrus Pulp Silage on Fattening Performance of Zel Male Lambs

Introduction Today, the citrus industry supplies the large quantities of diversed by-products such as whole citrus fruits, fresh or dried citrus pulp, citrus molasses, and silage as feed for animals. In 2000-2003, global production of citrus was 4.69 MT. Iran has produced 3.5 MT citrus fruits (3.5 % of the world's production) and is known as the world's sixth-largest citrus producing country. Citrus by-product feedstuff can be used as a high energy feed in ruminant rations to support rumen microflora, growth and lactation, with fewer negative effects on rumen fermentation than starch rich feeds (Leiva et al., 2000), andimproves dietary fiber digestion, rumen fermentation and microbial protein synthesis. To increase the usefulness of citrus pulp it can be preserved by drying, but direct drying is difficult because of the slimy consistency of the waste. Citrus pulp may be ensiled alone or in combination with high dry matter cereal crop residues, such as wheat straw to control effluent outputs from silages. Application of wheat straw in silage as an absorbent additive decreases ensiling losses but also decreases quality of silage (. However, using wheat straw and urea in silage citrus pulp silage and their effects on feedlotting lambs has not evaluated. Therefore, this experiment conducted to test the effect of citrus pulp silage on fattening performance of Zel male lambs.
Materials and Methods Sixteen Zel male lambs (BW=25±0.5kg) in 4 treatments with 4 replications over 90 days fed with 4 experimental diets including: 1) basal diet with 14.61% of the citrus pulp silage withowt additives, 2) basal diet with 24.46% of the citrus pulp silage with 40% wheat straw, 3) basal diet with 24.22% of the citrus pulp silage with 38.5% wheat straw and 1.5% urea, and 4) basal diet with 23.76% of the citrus pulp silage with 37% wheat straw and 3% urea when forage to concentrate ratio was 40: 60%. Rations formulated using SRNS® (version 1.9.4208), mixed and fed twice daily at 700 and 1900. The daily gain, feed intake, feed conversion ratios were determined each 15d. Particle size distribution of ration was determined with dry sieving. Digestive kinetics were measured using Cr-mordanted NDF wheat straw a single dose. At 53 th d, rumination and chewing activity animal was measured visually with five-minute intervals over 24 h for all animals.
There were no significant difference in daily weight gain, dry matter intake and feed conversion ratio among treatments. Gado et al (2011) showed that the intake of nutrients was not changed with orange pulp silage without additives or orange pulp silage treated with the enzyme lambs except the fiber fractions (i.e., NDF and ADF) were consistent with the results. Treatment 1 had highest apparent digestibility of nutrients than other experimental treatments therefore, additives significantly decreased digestibility in comparasion to treatment control. Increase dry matter digestibility with orange pulp is two reasons: (1) a large amount of pectin as a major component of orange pulp. 2- highly digestible NDF (Aregheore, 2000). Citrus pulp pectin and increase the surface area of the particle size reduction in treatment 1 increased digestibility (Mertens, 1997). Wheat straw, urea, increasing the diet particles size and physical effective fiber, increased chewing and rumination times in comparasion to treatment control and decreased the resting time. Krause and Combs (2003) reported consuming diets with equal cell wall, with reduce the particle size of corn silage in the ration, dry matter intake increased, rumen fluid pH and chewing activity decreased. Treatment 1 had the highest ruminall particulate passage rate and lowest ruminal mean retention time, but treatment 4 had the lowest ruminall particulate passage rate and the highest ruminal mean retention time. Particle size reduction and fresh citrus pulp in the low quality diet by increasing the digestibility and passage rate improve voluntary feed intake, in treatment 1 This research was observed (Teimouri et al., 2004; Scerra et al., 2001). Addition of urea in treatments 3 and 4 significantly increased ruminal pH and NH3N. Iow pH of fresh orange pulp silage and decreased rumination and chewing activity lead to lower rumen pH treatment 1 (Krause and Combs, 2003).
The results experiment showed that the citrus pulp silage treated with urea, produced suitable alternative from protein source for fattening lambs and reduced costs, also partly resolved the problem of disposal of byproducts in the factories. So that 15% citrus pulp in diet improvements digestibility of nutrients, daily weight gain, feed conversion ratio and fattening lambs performance without negative effect.