Journal of Animal Science, Vol 77, Issue 4 898-905, Copyright © 1999 by American Society of Animal Science

JOURNAL ARTICLE

Effect of fiber source on cell wall digestibility and rate of passage in rabbits

J. Garcia, R. Carabano and J. C. de Blas
Departamento de Produccion Animal, ETS Ingenieros Agronomos, Universidad Politecnica, Madrid, Spain.

The influence of fiber source on fiber digestion and mean retention time was investigated. Six fibrous feedstuffs with wide differences in chemical composition and particle size were selected: paprika meal, olive leaves, alfalfa hay, soybean hulls, sodium hydroxide-treated barley straw, and sunflower hulls. Six diets were formulated to contain one of these ingredients as the sole source of fiber. To avoid nutrient imbalances, fiber sources were supplemented with different proportions of a concentrate free of fiber based on soy protein isolate, wheat flour, lard, and a vitamin and mineral mix to obtain diets containing at least 18.5% CP and 5% starch. Fecal apparent digestibility of nonstarch polysaccharides (NSPd) and its monomers, NDF, NDF-ADL, and ADF-ADL, were determined using four New Zealand White x California growing rabbits per diet. Total, ileorectal, and cecal mean retention times (tMRT, i-rMRT, and cMRT, respectively) were determined for diets based on paprika meal, olive leaves, soybean hulls, and sunflower hulls in 16 does (four per diet) fitted with T-cannulas at the terminal ileum. In both trials, DMI was negatively correlated with the proportion of fine particles (FP: < .315 mm) and positively correlated with the proportion of large particles (LP: > 1.25 mm) (P < .01). Stepwise regression analysis showed that FP was the dietary characteristic best related to digestibilities of NSP, uronic acids, glucose and NDF, tMRT, and cMRT (P < .001), showing a positive correlation with these variables. In all these cases, this procedure selected the proportion of large particles as a second variable in the model. Degree of lignification of NDF, considering lignin as the difference between ADL and acid detergent cutin, was only included as the third variable for the model of NDF digestibility. Digestibility of NSP was positively correlated with those of NDF, NDF-ADL, and ADF-ADL (r = .82, .87 and .85, respectively, P < .001); the latter was also highly correlated with the digestibility of the glucose included in the NSP fraction (r = .86; P < .001). Cecal mean retention time accounted for 63% of average tMRT, for most of the variability in tMRT (r = .99; P < .001), and was positively related to NSPd (r = .89; P < .001). From these results, we conclude that particle size is a major factor affecting fiber digestion efficiency, rate of passage, and feed intake in rabbits.

This article has been cited by other articles:

				M. Garcia, R. Lazaro, M. A. Latorre, M. I. Gracia, and G. G. Mateos Influence of Enzyme Supplementation and Heat Processing of Barley on Digestive Traits and Productive Performance of Broilers Poult. Sci., May 1, 2008; 87(5): 940 - 948. [Abstract] [Full Text] [PDF]

				M. S. Gomez-Conde, J. Garcia, S. Chamorro, P. Eiras, P. G. Rebollar, A. Perez de Rozas, I. Badiola, C. de Blas, and R. Carabano Neutral detergent-soluble fiber improves gut barrier function in twenty-five-day-old weaned rabbits J Anim Sci, December 1, 2007; 85(12): 3313 - 3321. [Abstract] [Full Text] [PDF]

				N. Nicodemus, J. Garcia, R. Carabano, and J. C. De Blas Effect of substitution of a soybean hull and grape seed meal mixture for traditional fiber sources on digestion and performance of growing rabbits and lactating does J Anim Sci, January 1, 2007; 85(1): 181 - 187. [Abstract] [Full Text] [PDF]

				I. K. Hindrichsen, M. Kreuzer, J. Madsen, and K. E. B. Knudsen Fiber and lignin analysis in concentrate, forage, and feces: detergent versus enzymatic-chemical method. J Dairy Sci, June 1, 2006; 89(6): 2168 - 2176. [Abstract] [Full Text] [PDF]

				J. A. Coverdale, J. A. Moore, H. D. Tyler, and P. A. Miller-Auwerda Soybean hulls as an alternative feed for horses J Anim Sci, June 1, 2004; 82(6): 1663 - 1668. [Abstract] [Full Text] [PDF]