TY - JOUR
T1 - Intestinal digestibility of amino acids in rumen undegradable protein estimated using a precision-fed cecectomized rooster bioassay
T2 - I. Soybean meal and Soyplus
AU - Boucher, S. E.
AU - Calsamiglia, S.
AU - Parsons, C. M.
AU - Stein, H. H.
AU - Stern, M. D.
AU - Erickson, P. S.
AU - Utterback, P. L.
AU - Schwab, C. G.
N1 - Funding Information:
The authors thank West Central (Ralston, IA), Adisseo (Antony, France), Novus International Inc. (St. Louis, MO), and Venture Milling (Salisbury, MD) for financial support of this project. We also thank the staff at the Fairchild Dairy Teaching and Research Center (University of New Hampshire, Durham) for feeding and caring for the cows and the following individuals who helped with this experiment: Anna Pape, Holli Pinard, Heather Tucker, Nancy Whitehouse, and Carly Crawford (University of New Hampshire, Durham, NH).
PY - 2009/9
Y1 - 2009/9
N2 - The objectives of this experiment were to measure intestinal digestibility of AA in rumen undegradable protein (RUP-AA) in soybean meal (SBM) and expeller SBM (SoyPlus, West Central, Ralston, IA; SP) and to determine if these feeds contain a constant protein fraction that is undegradable in the rumen and indigestible in the small intestine, as assumed in the French Institut National de la Recherche Agronomique (Paris, France) and Scandinavian AAT-PBV (AAT = AA absorbed from small intestine; PBV = protein balance in the rumen) models. Three samples of SBM and 3 samples of SP were obtained from the Feed Analysis Consortium Inc. (Savoy, IL). To obtain the RUP fraction, samples were ruminally incubated in situ for 16 h in 4 lactating cows, and the collected rumen undegraded residues (RUR) were pooled by sample. Subsamples of the intact feeds and RUR were crop intubated to 4 cecectomized roosters, and total excreta were collected for 48 h. Intact feeds, RUR, and excreta were analyzed for AA. Basal endogenous AA loss estimates were obtained from fasted birds and were used to calculate standardized digestibility of AA in the intact feeds and RUP-AA. Indigestibility coefficients of the intact feeds were calculated as (100 - % standardized AA digestibility), and indigestibility of the RUR was calculated as {(100 - % ruminal degradation of AA) × [(100 - % standardized RUP-AA digestibility)]/100}. Results indicated that standardized digestibility of feed-AA was similar to standardized digestibility of RUP-AA for SBM and SP samples and that standardized digestibility of individual AA differed within samples. Standardized feed-AA and RUP-AA digestibility values were lowest for Lys and Cys and highest for Trp and Met. Results also indicated that SBM and SP did not contain a constant protein fraction that was both undegradable in the rumen and indigestible in the small intestine. Indigestibility values of RUR were lower than in intact feeds, suggesting that SBM and SP contain a protein fraction that is indigestible in the intestine but partly degradable in the rumen, digestible in the intestine after ruminal incubation, or both.
AB - The objectives of this experiment were to measure intestinal digestibility of AA in rumen undegradable protein (RUP-AA) in soybean meal (SBM) and expeller SBM (SoyPlus, West Central, Ralston, IA; SP) and to determine if these feeds contain a constant protein fraction that is undegradable in the rumen and indigestible in the small intestine, as assumed in the French Institut National de la Recherche Agronomique (Paris, France) and Scandinavian AAT-PBV (AAT = AA absorbed from small intestine; PBV = protein balance in the rumen) models. Three samples of SBM and 3 samples of SP were obtained from the Feed Analysis Consortium Inc. (Savoy, IL). To obtain the RUP fraction, samples were ruminally incubated in situ for 16 h in 4 lactating cows, and the collected rumen undegraded residues (RUR) were pooled by sample. Subsamples of the intact feeds and RUR were crop intubated to 4 cecectomized roosters, and total excreta were collected for 48 h. Intact feeds, RUR, and excreta were analyzed for AA. Basal endogenous AA loss estimates were obtained from fasted birds and were used to calculate standardized digestibility of AA in the intact feeds and RUP-AA. Indigestibility coefficients of the intact feeds were calculated as (100 - % standardized AA digestibility), and indigestibility of the RUR was calculated as {(100 - % ruminal degradation of AA) × [(100 - % standardized RUP-AA digestibility)]/100}. Results indicated that standardized digestibility of feed-AA was similar to standardized digestibility of RUP-AA for SBM and SP samples and that standardized digestibility of individual AA differed within samples. Standardized feed-AA and RUP-AA digestibility values were lowest for Lys and Cys and highest for Trp and Met. Results also indicated that SBM and SP did not contain a constant protein fraction that was both undegradable in the rumen and indigestible in the small intestine. Indigestibility values of RUR were lower than in intact feeds, suggesting that SBM and SP contain a protein fraction that is indigestible in the intestine but partly degradable in the rumen, digestible in the intestine after ruminal incubation, or both.
KW - Amino acid digestibility
KW - Rumen-undegradable protein
KW - Soybean meal
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U2 - 10.3168/jds.2008-1884
DO - 10.3168/jds.2008-1884
M3 - Article
C2 - 19700710
AN - SCOPUS:70349289691
SN - 0022-0302
VL - 92
SP - 4489
EP - 4498
JO - Journal of Dairy Science
JF - Journal of Dairy Science
IS - 9
ER -