Partitioning of Amino Acids Flowing to the Abomasum into Feed, Bacterial, Protozoal, and Endogenous Fractions

Shabi, Z.; Tagari, H.; Murphy, Michael R.; Bruckental, I.; Mabjeesh, S.J.; Zamwel, S.; Çelik, Kemal; Arieli, A.

doi:10.3168/jds.s0022-0302(00)75120-4

Cited by 35 publications

(37 citation statements)

References 20 publications

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“…Van Bruchem et al (1997) used a continuously abomasal infusion of 15 N-labelled, grass meal-beer yeast suspension and reported that the endogenous contribution accounted for 12% of the duodenal N flow in sheep. N from the endogenous origin varied between <1% (Shabi et al, 2000) and 32% (Larsen et al, 2001) of the duodenal flow of total N in dairy cows using a mathematical approach to estimate the composition of AA from each origin. Sandek et al (2001) reported that endogenous N contributed to 3% up to 12% of the duodenal flow of total N determined by 15 N-labelled method in sheep fed for diets ranging from 15% to 25% crude fibre content.…”

Section: Estimation Of Endogenous N and Aa Flowsmentioning

confidence: 99%

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

Zhou

Tan

Tang

et al. 2010

Journal of Animal Physiology and Animal Nutrition

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The effect of dietary methionine (Met) levels on endogenous N and amino acids (AA) flows at different part of the digestive tract of growing goats was determined using a (15)N isotope dilution technique. Three goats (25 ± 2.5 kg) were fitted with the ruminal, duodenal and ileal cannulae and allocated to three dietary treatments in a 3 × 3 Latin square design. The dietary treatments consisted of a total mixed ration containing three levels of Met (0.15%, 0.25% and 0.35%) respectively. It was found that at 0.15% Met level, the lowest flow in endogenous N and total AA at the duodenum and ileum occurred. The endogenous N secretion contributed to 26% and 23% of the duodenal and ileal total N flows, respectively, and the proportions were not affected by the dietary Met levels. The duodenal and ileal flows of endogenous total AA were 11.1, 11.8, 11.3 g/d and 2.9, 3.9, 4.1 g/d respectively. The average real digestibility of N was 65%, 87% and 95% in the forestomach, intestine and whole digestive tract respectively.

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Section: Estimation Of Endogenous N and Aa Flowsmentioning

confidence: 99%

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

Zhou

Tan

Tang

et al. 2010

Journal of Animal Physiology and Animal Nutrition

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“…Furthermore, in a second study in lactating cows using an infusion of 15 N-leucine (Ouellet et al, 2005), the endogenous contribution to duodenal N flow averaged 18% when silage was fed, and 20% when hay was offered, representing in this latter case, 5.9 g of N/kg of DMI. In dairy cows, using a mathematical approach including estimates of the composition of AA in each fraction, N from endogenous origin varied between <1% (Shabi et al, 2000) and 32% (Larsen et al, 2001) of total duodenal N flow.…”

Section: Duodenal Flowmentioning

confidence: 99%

What is the True Supply of Amino Acids for a Dairy Cow?

Lapierre

Pacheco

Berthiaume

et al. 2006

Journal of Dairy Science

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Improving the prediction of milk protein yield relies on knowledge of both protein supply and requirement. Definition of protein/amino acid supply in ruminants is a challenging task, due to feedstuff variety and variability and to the remodeling of nutrient intake by the rumen microflora. The questions arise, therefore, how and where should we measure the real supply of AA in the dairy cow? This review will follow the downstream flow of AA from duodenum to peripheral tissue delivery, with a glance at the efficiency of transfer into milk protein. Duodenal AA flow comprises rumen undegradable feed, microbial protein, and endogenous secretions. Most attention has been directed toward definition of the first two contributions but the latter fraction can represent as much as 20% of duodenal flow. More information is needed on what factors affect its magnitude and overall impact. Once digested, AA are absorbed into the portal vein. The ratio of portal absorption to small intestinal apparent digestion varies among essential AA, from 0.43 (threonine) to 0.76 (phenylalanine), due to the contributions of preduodenal endogenous secretions to the digestive flow, non-reabsorption of endogenous secretions and gut oxidation of AA. Few data are available on these phenomena in dairy cows but the evidence indicates that they alter the profile of AA available for anabolic purposes. Recent comparisons of estimated duodenal flux and measured portal flux have prompted a revisit of the NRC (2001) approach to estimate AA flows at the duodenum. Changes to the model are proposed that yield predictions that better fit the current knowledge of AA metabolism across the gut. After absorption, AA flow first to the liver where substantial and differential net removal occurs, varying from zero for the branched-chain AA to 50% of portal absorption for phenylalanine. This process alters the pattern of net supply to the mammary gland. Overall, intermediary metabolism of AA between the duodenum and the mammary gland biologically explains the decreased efficiency of the transfer of absorbed AA into milk protein as maximal yield is approached. Therefore, variable, rather than fixed, factors for transfer efficiencies must be incorporated into future predictive models.

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“…Recently, linear programming was used to partition N flowing to the duodenum into feed, bacteria, protozoa, and endogenous fractions (Shabi et al, 2000;Reynal et al, 2003). Using the same approach, we have calculated the relative proportions of SAB and LAB in duodenal content (Vlaeminck et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Effect of variation in the proportion of solid- and liquid-associated rumen bacteria in duodenal contents on the estimation of duodenal bacterial nitrogen flow

Vlaeminck¹,

Fievez²,

Demeyer³

et al. 2007

J. Anim. Feed Sci.

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The aim of this research was to examine to what extent variation in the relative proportions of solid-(SAB) and liquid-associated rumen bacteria (LAB) in duodenal bacteria have an impact on the estimation of duodenal flow of bacterial N. For this, four dairy cows were fed diets varying in forage: concentrate ratio (80:20, 65:35, 50:50 and 35:65). SAB and LAB were separated from rumen contents four h after the morning feeding. Adenine, cytosine and odd and branched-chain fatty acids were determined both in SAB and LAB and used to estimate bacterial N flow. Bacterial N flows were also calculated using a SAB:LAB ratio in duodenal bacteria, as estimated from the odd and branched-chain fatty acid pattern. Compared with calculations based on the estimated SAB:LAB ratio, estimations based on SAB or LAB only as a bacterial reference on average over-and underestimated bacterial N flow by 37 and 55 g N/d, respectively (P<0.05) when cytosine or adenine were used as bacterial marker. In contrast, due to the small differences in the OBCFA:N ratio between SAB and LAB, these differences were less than 15 g/d when OBCFA were used as bacterial marker. The results suggest that, depending on the marker used, changes in the proportions of SAB and LAB can have a substantial impact on estimated duodenal flow of bacterial N.

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Partitioning of Amino Acids Flowing to the Abomasum into Feed, Bacterial, Protozoal, and Endogenous Fractions

Cited by 35 publications

References 20 publications

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

ORIGINAL ARTICLE: The effect of dietary methionine levels on endogenous nitrogen and endogenous amino acids flows in growing goats

What is the True Supply of Amino Acids for a Dairy Cow?

Effect of variation in the proportion of solid- and liquid-associated rumen bacteria in duodenal contents on the estimation of duodenal bacterial nitrogen flow

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