Effect of Dietary Structural to Nonstructural Carbohydrate Ratio on Rumen Degradability and Digestibility of Fiber Fractions of Wheat Straw in Sheep

Abstract

The effect of different dietary structural carbohydrate (SC) to nonstructural carbohydrate (NSC) ratios on fiber degradation, digestion, flow, apparent digestibility and rumen fluid characteristics was studied with a design using 18 wethers fitted with permanent rumen and duodenum cannulae. All sheep were divided into six groups randomly, receiving six diets with varying SC to NSC ratios. All diets contained the same proportion of wheat straw and concentrate. The dietary SC to NSC ratios were adjusted by adding cornstarch to the concentrate supplements. The duodenal and fecal flows of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HC) and cellulose (CEL) were estimated using chromium-mordanted wheat straw as a flow marker. The degradation parameters of wheat straw DM, NDF, ADF, HC and CEL were determined by incubating the ground wheat straw in nylon bags in the rumen for different periods of time. There was no effect (p>0.05) of the different dietary SC to NSC ratios on rumen pH or NH 3 -N, but acetate, propionate and butyrate concentrations were significantly affected (p<0.05 or p<0.01) by dietary SC to NSC ratios in the rumen fluid. When the dietary SC to NSC ratio was 2.86, the highest rumen degradability of wheat straw DM, NDF, ADF and CEL was found, but the highest apparent rumen digestibilities of DM, NDF, ADF, HC and CEL occurred at a 2.64 SC to NSC ratio. However, because of compensatory digestion in the hindgut, the apparent digestibilities of DM, NDF, ADF, HC and CEL were highest when the dietary SC to NSC ratio was 2.40. In conclusion, there is a optimal range of dietary SC to NSC ratios (between 2.86 and 2.40) that is beneficial to maximize wheat straw fiber degradation and apparent digestibility.

Microbial community profiles of the colon from steers differing in feed efficiency

“…The gradual association with ADFI over ADG as digesta moves distally through the GIT may be expected as the metabolic function and capacity of the tissues change, from the rumen to that of the colon (Myer et al 2015 ). In addition, digestible fiber that is not degraded in the rumen or escapes digestion in the rumen, partially due to high ADFI, becomes available for further processing in the lower GIT (Tan et al 2002 ). Only two taxa/OTUs associated primarily with ADG alone.…”

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

“…Duodenal and ileal Cr concentration was used in conjunction with nutrient concentration to determine duodenal and ileal nutrient flow (Tan et al, 2002). The ruminal bacteria were separated from protozoa and feed particles in ruminal fluid according to the method of Reed et al (2004).…”

In vitro evaluation of effects of gut region and fiber structure on the intestinal dominant bacterial diversity and functional bacterial species

“…For ruminants with high performance, high energy density and intake levels tend to decrease ruminal fiber digestibility, and this enhances the contribution of hindgut fiber digestibility to total-tract digestibility [24]. Potentially digestible fiber that escapes from ruminal degradation should be available for digestion in the distal digestive tract.…”

“…The design of this experiment was a split plot design with gut regions (jejunum, ileum, cecum and colon) as main plot, and substrates (NDF and CEL, 0.4 g) as subplot. Also, four time points (12,24,48 and 72 h) were selected to explore the kinetic changes in the intestinal bacterial diversity and functional bacterial species. To minimize variations by different conditions such as different diets and individual animal, three adult Liuyang black wether (a local breed in south China) goats (1.5 years old with average body weight of 20.1 ± 1.2 kg) were fed the same diet (forage:concentrate ¼ 55:45) as in our previous study [7] and were slaughtered at 1 week intervals after acclimatization of two weeks.…”