Effects of the ruminal comminution rate and microbial contamination of particles on accuracy of in situ estimates of ruminal degradability and intestinal digestibility of feedstuffs.

Effects of considering the comminution rate (k(c) ) and the correction of microbial contamination (using (15) N techniques) of particles in the rumen on estimates of ruminally undegraded fractions and their intestinal digestibility were examined generating composite samples (from rumen-incubated residues) representative of the undegraded feed rumen outflow. The study used sunflower meal (SFM) and Italian ryegrass hay (RGH) and three rumen and duodenum cannulated wethers fed with a 40:60 RGH to concentrate diet (75 g DM/kgBW(0.75) ). Transit studies up to the duodenum with Yb-SFM and Eu-RGH marked samples showed higher k(c) values (/h) in SFM than in RGH (0.577 vs. 0.0892, p = 0.034), whereas similar values occurred for the rumen passage rate (k(p) ). Estimates of ruminally undegraded and intestinal digestibility of all tested fractions decreased when k(c) was considered and also applying microbial correction. Thus, microbial uncorrected k(p) -based proportions of intestinal digested undegraded crude protein overestimated those corrected and k(c) -k(p) -based by 39% in SFM (0.146 vs. 0.105) and 761% in RGH (0.373 vs. 0.0433). Results show that both k(c) and microbial contamination correction should be considered to obtain accurate in situ estimates in grasses, whereas in protein concentrates not considering k(c) is an important source of error.

[1]  C. Centeno,et al.  A simplified management of the in situ evaluation of feedstuffs in ruminants: Application to the study of the digestive availability of protein and amino acids corrected for the ruminal microbial contamination , 2009, Archives of Animal Nutrition.

[2]  Javier González,et al.  In situ evaluation of the protein value of wheat grain corrected for ruminal microbial contamination. , 2009 .

[3]  R. Caballero,et al.  Effects of feed intake on in situ rumen microbial contamination and degradation of feeds , 2008 .

[4]  A. Martínez,et al.  Effects of ensiling on ruminal degradability and intestinal digestibility of italian rye-grass , 2007 .

[5]  P. Lecomte,et al.  Effect of feed 15N incorporation into solid-associated bacteria on the in situ nitrogen degradability of 15N labelled Italian ryegrass , 2007 .

[6]  C. Rodríguez,et al.  In situ study of the relevance of bacterial adherence to feed particles for the contamination and accuracy of rumen degradability estimates for feeds of vegetable origin , 2006, British Journal of Nutrition.

[7]  J. Kowalczyk,et al.  Dynamics of microbial contamination of protein during ruminal in situ incubation of feedstuffs , 2006 .

[8]  P. Udén,et al.  Measurement of soluble protein degradation in the rumen , 2006 .

[9]  C. Centeno,et al.  Protein value for ruminants of a sample of whole cottonseed , 2006 .

[10]  Javier González,et al.  Effects of considering the rate of comminution of particles and microbial contamination on accuracy of in situ studies of feed protein degradability in ruminants , 2006 .

[11]  P. Huhtanen,et al.  Quantitation of the flow of soluble non-ammonia nitrogen entering the omasal canal of dairy cows fed grass silage based diets , 2002 .

[12]  C. Centeno,et al.  Composition of bacteria harvested from the liquid and solid fractions of the rumen of sheep as influenced by feed intake. , 2000, The British journal of nutrition.

[13]  M. Alvir,et al.  Estimation of intestinal digestibility of undegraded sunflower meal protein from nylon bag measurements. A mathematical model. , 1999, Reproduction, nutrition, development.

[14]  Javier González,et al.  Rumen degradability and microbial contamination of fish meal and meat meal measured by the in situ technique , 1998 .

[15]  B. B. Jensen,et al.  True Digestibility of Protein in the Small Intestine and the Hind Gut of Cows Measured with the Mobile Bag Technique using 15N-Labelled Roughage , 1994 .

[16]  P. V. Soest,et al.  Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. , 1991, Journal of dairy science.

[17]  J. Murphy,et al.  Mobile nylon bag for estimating intestinal availability of rumen undegradable protein. , 1987, Journal of dairy science.

[18]  P. V. Van Soest,et al.  Investigation of chromium, cerium and cobalt as markers in digesta. Rate of passage studies. , 1980, Journal of the science of food and agriculture.

[19]  J. Matis,et al.  Quantitating ruminal turnover. , 1979, Federation proceedings.

[20]  E. R. Ørskov,et al.  The estimation of protein degradability in the rumen from incubation measurements weighted according to rate of passage , 1979, The Journal of Agricultural Science.

[21]  W. Grovum,et al.  Rate of passage of digesta in sheep , 1973, British Journal of Nutrition.

[22]  L. Bernard,et al.  Colonisation bactérienne de différents types d'aliments incubés in sacco dans le rumen ; conséquences pour l'estimation de la dégradabilité de l'azote , 1988 .

[23]  C. Poncet,et al.  Mesure de la digestion de l'azote alimentaire dans les différentes parties du tube digestif du mouton par la technique des sachets de nylon , 1988 .

[24]  C. Poncet,et al.  Effets du pourcentage de concentré de la ration et du niveau d'ingestion sur la vitesse de passage dans le rumen de différents types d'aliments chez le mouton , 1987 .