Effect of rice straw in the diet for growing goats on site and extent of digestion and N balance

Abstract

Effect of reducing dietary rice straw on N balance, site and extent of digestion, and efficiency of microbial protein synthesis were evaluated in this trial. Four Liuyang black goats (average body weight 19.3±2.1 kg), fitted with the ruminal, proximal duodenal and terminal ileal cannulas were used in a 4×4 Latin square design. Goats were assigned to four dietary treatments designed by increasing maize grain inclusion at the expense of rice straw: 1. 40% forage (20% maize stover and 20% rice straw, HR); 2. 35% forage (20% maize stover and 15% rice straw, MR1); 3. 30% forage (20% maize stover and 10% rice straw, MR2) and 4. 25% forage (20% maize stover and 5% rice straw, LR). Experimental diets were similar in chemical composition except for dietary NDF and metabolizable energy content. The amount of diet offered to each goat was restricted to 85% of its ad libitum intake to maintain no orts during the whole experimental period. There were no differences in DMI as a result of restricting intake. Totaltract digestibility of OM (P<0.01), N (P<0.01) and NDF (P<0.05) increased with reducing dietary rice straw. Retained N increased from 12.04% for HR to 21.62% for LR (P<0.01). Efficiency of microbial protein synthesis was not affected by dietary rice straw (P>0.05). When expressed as a percentage of N intake, ruminal N disappearance was not affected (P>0.05) by treatments. The true ruminal OM, apparent ruminal OM and ruminal NDF disappearance increased (P<0.01) with reducing dietary rice straw. There were no differences (P>0.05) in small intestinal digestibility of OM and N among the treatments. N BALANCE IN GOATS FED RICE STRAWOur data indicated that reducing dietary rice straw from 40 to 25% could improve utilization of nutrients by growing goats.

Effects of Rice Straw Particle Size on Chewing Activity, Feed Intake, Rumen Fermentation and Digestion in Goats

“…The DM intake of goats ranged from 567.8-568.6 g/d, which was a little higher than the 506-507 g/d observed previously (Zhao et al, 2007). The increased feed intake was due to the increased proportion of rice straw in the TMR (Zhao et al, 2007). This study corroborated results from elsewhere on the effects of particle size on feed intake.…”

“…When compared with our previous results (Zhao et al, 2007), ruminal OM digestibility was not significantly different with increased proportions of rice straw in the TMR (i.e. 50.4-55.5% vs. 51.2 -56.5%), but the intestinal and total tract OM digestibility (i.e.…”

“…Hybrid rice is the most widely grown cereal crop in China, and rice straw is an important feed source for goat production by smallholders. Our previous investigations revealed that increasing proportions of rice straw increased the dietary NDF, but decreased the utilization of nutrients by growing goats (Zhao et al, 2007). However, as an important factor affecting the peNDF level in diets, the effects of particle size of rice straw in ruminant animals has rarely been reported.…”

Effects of rice straw particle size on digesta particle size distribution, nitrogen metabolism, blood biochemical parameters, microbial amino acid composition and intestinal amino acid digestibility in goats

“…Variables of N metabolism are showed in Table 3. The N intake, absorbed N, total tract N digestibility, microbial protein synthesis efficiency were ‘12.11–12.16 g/day’, ‘9.74–10.33 g/day’, ‘80.44–85.55 %intake’ and ‘2.3–2.7 g N/100 g of OMDA’, respectively, in a previous study of increased proportion of rice straw (5–20%) in TMR (Zhao et al . 2007), and were greatly higher than in our study with 40% in TMR.…”

Effects of Increasing Level of Dietary Rice Straw on Chewing Activity, Ruminal Fermentation and Fibrolytic Enzyme Activity in Growing Goats

“…Increasing the level of rice straw in the diet leads to an increased dietary neutral detergent fibre (NDF) content. Studies have shown that increasing dietary rice straw negatively affects nutrient digestibility in ruminants (Fimbres et al, 2002;Zhao et al, 2007). However, increasing dietary NDF content may have a positive effect on the maintenance of normal rumen function, which is associated with adequate salivation, optimal pH for cellulolytic microorganisms and energy supply (Jaster and Murphy, 1983;Allen, 1997;Krause et al, 2002).…”