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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2009-1841v1 87/10/3363    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Gozho, G. N. Articles by Mutsvangwa, T. PubMed PubMed Citation Articles by Gozho, G. N. Articles by Mutsvangwa, T.

Effects of type of canola protein supplement on ruminal fermentation and nutrient flow to the duodenum in beef heifers¹

Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Canada S7N 5A8

² Corresponding author: tim.mutsvan{at}usask.ca

Ruminal fermentation, nutrient digestion, and flows to the duodenum in growing cattle fed differently produced canola protein supplements were studied in a 4 x 4 Latin square design using Speckle Park heifers (initial BW = 451 ± 26 kg). Canola protein supplement treatments consisted of the following: 1) 8.78% regular canola meal (RCM); 2) 9.25% RCM plus 1.80% canola oil (RCMO); 3) 11.1% canola presscake from biodiesel oil extraction (CPC); and 4) 8.14% high ruminally undegradable protein (RUP) canola meal (RUCM) plus 1.32% canola oil (RUCMO). Experimental diets also contained 39.9, 40.2, 39.9, and 39.9% barley grain; 31.7, 31.4, 31.2, and 31.4% barley silage; and 17.5, 15.2, 15.6, and 16.5% oat hulls for the RCM, RCMO, CPC, and RUCMO diets, respectively. Feeding the CPC, RCMO, and RUCMO diets decreased (P 0.05) ruminal NH₃-N concentration compared with feeding the RCM diet. Compared with the RCM diet, adding canola oil in the RCMO diet or residual oil in the CPC diet resulted in greater ruminal concentrations of propionate (P 0.09). Additionally, feeding the RCMO diet also resulted in greater ruminal concentrations of acetate (P = 0.07), valerate (P = 0.06), and total VFA (P = 0.07) compared with the RCM diet. Also, compared with the RCM diet, heifers on the RUCMO diet had decreased acetate (P = 0.02) concentrations. The changes in ruminal concentrations of acetate and propionate resulted in reduced acetate:propionate ratios in the RCMO (P = 0.08), CPC (P = 0.02), and RUCMO (P < 0.01) diets. Ruminal digestion and flows of nutrients to the duodenum were not affected by dietary treatment. However, adding canola oil to the RCMO and RUCMO dietary treatments decreased the digestibility of ADF (P 0.08) and NDF (P 0.08) in the total tract compared with the RCM diet. Total tract digestibility of OM was also decreased (P = 0.02) in heifers fed the RUCMO compared with the RCM diet. Notwithstanding the different processing methods employed in making RCM, CPC, or RUCM, there were no differences among the diets for ruminally degraded protein, ruminal microbial protein synthesis, and the flow of N fractions to the duodenum.

Key Words: amino acid • beef heifer • canola protein • microbial N