Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol84.Issue1-2.Apr2000:
Animal Feed Science and Technology
84 (2000) 23±32
Measuring resistance to ruminal degradation and
bioavailability of ruminally protected methionine
Alex Bach1, Marshall D. Stern*
Department of Animal Science, University of Minnesota, 180A Haecker Hall,
1364 Eckles Ave., St. Paul, MN 55108, USA
Received 9 February 1999; received in revised form 11 May 1999; accepted 26 January 2000
Abstract
The objectives of this study were to evaluate ruminal degradation and intestinal digestion of two
ruminally protected methionine (RPM) products and to assess the potential use of changes in
plasma methionine concentrations as an indication of methionine availability to the animal.
Ruminal degradation of the protected methionine was assessed using the in situ technique. The
intestinal availability of methionine after ruminal incubation was determined in vitro using an
enzymatic procedure. Four Holstein cows receiving a typical mid-lactation ration (16.5% CP,
1.6 Mcal NEL/kg) were supplemented with 0, 30, and 60 g per day of a slowly degraded ruminally
protected methionine (SDM), or 60 g per day of a moderately slowly degradable ruminally
protected methionine (MSDM) in a 44 Latin square design. Blood samples were collected from
the jugular vein at 0, 6, 12, 18, 24, and 36 h after feeding the RPM sources. Ruminal degradation
rates of SDM and MSDM were 0.03 hÿ1 and 0.07 hÿ1, respectively. The calculated amount of
methionine available for absorption, based on the in situ and in vitro results, was 17.9, 11.9 and
23.8 g per day when dosing 60 g of MSDM, 30 and 60 g of SDM, respectively. The highest
(p
84 (2000) 23±32
Measuring resistance to ruminal degradation and
bioavailability of ruminally protected methionine
Alex Bach1, Marshall D. Stern*
Department of Animal Science, University of Minnesota, 180A Haecker Hall,
1364 Eckles Ave., St. Paul, MN 55108, USA
Received 9 February 1999; received in revised form 11 May 1999; accepted 26 January 2000
Abstract
The objectives of this study were to evaluate ruminal degradation and intestinal digestion of two
ruminally protected methionine (RPM) products and to assess the potential use of changes in
plasma methionine concentrations as an indication of methionine availability to the animal.
Ruminal degradation of the protected methionine was assessed using the in situ technique. The
intestinal availability of methionine after ruminal incubation was determined in vitro using an
enzymatic procedure. Four Holstein cows receiving a typical mid-lactation ration (16.5% CP,
1.6 Mcal NEL/kg) were supplemented with 0, 30, and 60 g per day of a slowly degraded ruminally
protected methionine (SDM), or 60 g per day of a moderately slowly degradable ruminally
protected methionine (MSDM) in a 44 Latin square design. Blood samples were collected from
the jugular vein at 0, 6, 12, 18, 24, and 36 h after feeding the RPM sources. Ruminal degradation
rates of SDM and MSDM were 0.03 hÿ1 and 0.07 hÿ1, respectively. The calculated amount of
methionine available for absorption, based on the in situ and in vitro results, was 17.9, 11.9 and
23.8 g per day when dosing 60 g of MSDM, 30 and 60 g of SDM, respectively. The highest
(p