Effect of Supply of Metabolizable Protein on Splanchnic Fluxes of Nutrients and Hormones in Lactating Dairy Cows

Blouin, J.P.; Bernier, Jacques; Reynolds, C.K.; Lobley, G. E.; Dubreuil, Pascal; Lapierre, H.

doi:10.3168/jds.s0022-0302(02)74347-6

Cited by 54 publications

(68 citation statements)

References 43 publications

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“…The butyrate fermentation following intake of grass with high sugar content might be part of the explanation for the typical decreasing milk production and milk fat production experienced when cows start to graze in the spring. In an experiment with intraruminal infusion of Figure 4 Portal-drained visceral (PDV) extraction of arterial urea-nitrogen in lactating dairy cows plotted against the arterial concentration of urea-N. Means from the following studies were used to establish the regression line (R 2 5 0.50) closed square (Reynolds et al, 2003); closed triangle up (Benson et al, 2002); closed triangle down (Blouin et al, 2002); closed diamond (Delgado-Elorduy et al, 2002a); closed hexagon (Delgado-Elorduy et al, 2002b); open square (Casse et al, 1994); open triangle down (Bach et al, 2000); open triangle up (Berthiaume et al, 2006); closed circle (Reynolds et al, 1988b); and open circle (Raggio et al, 2004). The mean PDV extraction of urea-N observed in the present study is indicated as an open diamond.…”

Section: Hourmentioning

confidence: 99%

Urea and short-chain fatty acids metabolism in Holstein cows fed a low-nitrogen grass-based diet

Røjen

Lund

Kristensen

2008

Animal

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Three ruminally cannulated and multicatheterised lactating dairy cows were used to investigate the effect of different supplement strategies to fresh clover grass on urea and short-chain fatty acid (SCFA) metabolism in a zero-grazing experiment with 24-h blood and ruminal samplings. Fresh clover grass was cut every morning and offered from 0800 to 1500 h. Maize silage was fed at 1530 h. The three treatments, arranged in a Latin square, differed by timing of feeding rolled barley and soya-bean hulls relative to fresh clover grass. All diets had the same overall composition. Treatments were soya-bean hulls fed at 0700 h and barley fed at 1530 h (SAM), barley fed at 0700 h and soya-bean hulls fed at 1530 h (BAM), and both soya-bean hulls and barley fed at 1530 h (SBPM). The grass had an unexpectedly low content of crude protein (12.7%) and the cows were severely undersupplied with rumen degradable protein. The treatment effects were numerically small; greater arterial ammonia concentration, net portal flux of ammonia and net hepatic flux of urea during part of the day were observed when no supplementary carbohydrate was fed before grass feeding. A marked diurnal variation in ruminal fermentation was observed and grass feeding increased ruminal concentrations of propionate and butyrate. The net portal fluxes of propionate, butyrate, isovalerate and valerate as well as the net hepatic uptake of propionate, butyrate, valerate and caproate increased after feeding at 0700 h. The hepatic extraction of butyrate showed a relatively large depression with grass feeding with nadir at 1200 to 1330 h. The increased net portal absorption and the decreased hepatic extraction resulted in an approximately six-fold increase in the arterial blood concentration of butyrate. The gut entry rate of urea accounted for 70 6 10% of the net hepatic production of urea. Saliva contributed to 14% of the total amount of urea recycled to the gut. Urea recycling to the gut was equivalent to 58% of the dietary nitrogen intake. Despite the severe undersupply of rumen degradable protein, the portaldrained viscera did not extract more than 4.3% of the urea supplied with arterial blood. This value is in line with the literature values for cows fed diets only moderately deficient in rumen degradable protein and indicates that cows maximise urea transfer across gut epithelia even when the diet is moderately deficient in rumen degradable protein.

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Section: Hourmentioning

confidence: 99%

Urea and short-chain fatty acids metabolism in Holstein cows fed a low-nitrogen grass-based diet

Røjen

Lund

Kristensen

2008

Animal

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“…essential AA and 50 to 100% of the remainder is secreted into milk (Berthiaume et al 1999(Berthiaume et al , 2002Blouin et al 2002). However, the proportions are not static (Lapierre et al 2000).…”

mentioning

confidence: 99%

“…1. Leucine, Lys and Phe flux from small intestinal disappearance to milk protein, presented as a proportion of available flux (mesenteric appearance minus endogenous loss) and as a proportion (mol 100 mol -1 ) of the sum of essential AA fluxes [adapted from MacRae et al (1997), Berthiaume et al (2001) and unpublished data, Blouin et al (2002), and Ouellet et al (2002)]. …”

mentioning

confidence: 99%

Responses of the bovine mammary glands to absorptive supply of single amino acids

Cant¹,

Berthiaume²,

Lapierre³

et al. 2003

Can. J. Anim. Sci.

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Responses of the bovine mammary glands to absorptive supply of single amino acids. Can. J. Anim. Sci. 83: [341][342][343][344][345][346][347][348][349][350][351][352][353][354][355]. In this review, we discuss the mechanisms of responses of various tissues of the lactating dairy cow, particularly the mammary glands, to perturbations in supply of single amino acids that result in observed milk protein yields. Additions of methionine, lysine, histidine or leucine to the absorptive supply cause arterial concentrations of these amino acids to increase, mammary extractions to drop and mammary blood flow to decrease. Single subtractions of essential amino acids have the opposite effect. Changes in mammary blood flow that have been recorded can be explained as attempts by the mammary glands to restore intracellular ATP balance in the face of altered concentrations of energy metabolites in the general circulation. In a quantitative sense, milk protein yield is relatively insensitive to fluctuations in arterial amino acid concentrations but can be stimulated by any one of a number of amino acids. In this context, it is suggested that the designation of a limiting amino acid is not appropriate to the purpose of predicting milk protein yield. Rather, milk protein synthesis appears to operate at a predetermined rate set by external communications of milk withdrawal rate, physiological state and overall nutritional status. Utilization of amino acids (AA) by splanchnic and peripheral tissues, in coordination with the mammary setpoint, offsets imperfections in the dietary AA supply. How strongly an individual AA influences the mammary setpoint, arterial concentrations of energy metabolites, and mammary AA transport capacity will determine the magnitude of the milk protein yield response when its absorptive supply is changed. Dans cet article, les auteurs examinent comment certains tissus de la vache laitière en lactation, principalement la glande mammaire, réagissent à une modification de l'apport de certains acides aminés entraînant un changement du rendement du lait en protéines. L'addition de méthionine, de lysine, d'histidine ou de leucine aux acides aminés absorbés augmente leur concentration dans le sang artériel et la diminue dans les sécrétions et le sang de la glande mammaire. La soustraction d'un de ces acides aminés a l'effet contraire. On explique les variations observées au niveau de la circulation sanguine dans la glande mammaire par les efforts que cette dernière déploie pour rétablir l'équilibre de l'ATP après modification de la quantité de métabolites porteurs d'énergie dans la circulation générale. Sur le plan quantitatif, le rendement du lait en protéines est relativement insensible aux fluctuations de la concentration d'acides aminés dans le sang artériel, mais il est stimulé par plusieurs acides aminés. On estime qu'il est impossible de prévoir le rendement du lait en protéines à partir d'un acide aminé limitant. En effet, les protéines laitières semblent être synthétisées à un taux préétabli par les rappo...

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“…The result in Experiment 2 confirmed this viewpoint. Some researchers also observed that dietary protein degradability did not affect the urea content in blood (Blouin et al, 2002;Reynal and Broderick, 2003) or milk (Rodriguez et al, 1997), whereas Davidson et al (2003) reported that MUN was affected significantly by the varying dietary RUP level. It has been suggested that a restriction in energy supply increases MUN (Kirchgessner et al, 1986).…”

Section: Resultsmentioning

confidence: 99%

Responses of milk urea nitrogen content to dietary crude protein level and degradability in lactatingHolsteindairy cows

Zhai¹,

Jx²,

Wu³

et al. 2006

CZECH J ANIM SCI

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 Two experiments were conducted to investigate the effects of dietary crude protein level and degradability on milk urea nitrogen (MUN) content. In experiment 1, twelve multiparous lactating cows averaging 176 days in milk were divided according to DIM and milk production into three 4 × 4 Latin squares with four 2-week periods. Cows were fed four diets with different crude protein levels (13.0, 14.0, 15.0, and 16.0%, DM basis) with isocaloric, respectively. Crude protein levels had a low effect on milk yield and composition (P > 0.05), but a significant effect on MUN content. There were significant differences in the MUN content of cows fed either of the two diets (P < 0.01). In experiment 2, fifteen multiparous Holstein dairy cows averaging 91 days in milk were classified according to DIM and milk production into five 3 × 3 Latin squares with three 3-week periods. Cows were fed one of the three isocaloric and isonitrogenous diets with RUP being 30.8%, 36.2%, and 41.6% (CP basis), respectively. Milk yield, milk composition, and MUN content were not significantly affected by protein degradability, and there were no significant differences between any two dietary treatments (P > 0.05). These results indicated that MUN might be used as a parameter to monitor the change in dietary protein levels.  

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Effect of Supply of Metabolizable Protein on Splanchnic Fluxes of Nutrients and Hormones in Lactating Dairy Cows

Cited by 54 publications

References 43 publications

Urea and short-chain fatty acids metabolism in Holstein cows fed a low-nitrogen grass-based diet

Urea and short-chain fatty acids metabolism in Holstein cows fed a low-nitrogen grass-based diet

Responses of the bovine mammary glands to absorptive supply of single amino acids

Responses of milk urea nitrogen content to dietary crude protein level and degradability in lactatingHolsteindairy cows

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