Effect of Form and Level of Nitrogen on Magnesium Utilization

Wf, Moore; Jp, Fontenot; Ke, Webb

doi:10.2527/jas1972.3551046x

Cited by 21 publications

(5 citation statements)

References 12 publications

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“…In our experiments, ruminal fluid ammonia-nitrogen levels tended to increase as intake of readily fermentable carbohydrate decreased. The ruminal ammonia levels observed in experiment 1 were similar to those reported by Moore et al (1972) for sheep fed high-nitrogen diets. In the study of Moore et al (1972), ruminal ammonia levels increased as nitrogen intake by lambs increased, but apparent absorption of magnesium was not affected.…”

Section: Discussionsupporting

confidence: 87%

“…A hypomagnesemic response to intraruminal infusion of ammonium acetate and ammonium carbonate has been observed in cows (Head and Rook, 1955) and lambs (Henry and Cunningham, 1975). However, Moore et al (1972) found that increased intake of nitrogen, provided as either soybean protein alone or with urea, had no effect on blood serum magnesium levels of lambs even though ruminal ammonia levels increased substantially compared to control animals. In addition, other investigators (Christian and Williams, 1960;Wilson, 1963) were unable to induce hypomagnesemia in sheep by markedly increasing their urea intake.…”

Section: Discussionmentioning

confidence: 88%

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Magnesium Utilization in Wethers Fed Diets with Varying Ratios of Nitrogen to Readily Fermentable Carbohydrate

House

Mayland

1976

Journal of Animal Science

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Two experiments were conducted to study magnesium utilization in wether lambs fed diets with varying ratios of nitrogen to readily fermentable carbohydrate (N: RFC). Semipurified diets fed to the lambs contained about 4.1% nitrogen (25.6% crude protein), .08% magnesium, .4% calcium, 2.4% potassium and varied amounts of readily fermentable carbohydrate provided mainly as either starch (experiment 1) or sucrose (experiment 2). Dietary ratios of N:RFC were .2, .4, .7 and .9 in experiment 1 (five lambs/treatment), and .2 and 1.6 in experiment 2 (nine lambs/treatment). In experiment 1, ruminal fluid ammonianitrogen levels increased as starch intake decreased, but differences between treatments were not significant (P>.05). Apparent absorption, retention and plasma concentration of magnesium were not affected (P>.05) by decreased starch intake. In experiment 2, ruminal ammonia levels increased (P<.05) as sucrose intake decreased. Urinary excretion (P<.05) and apparent absorption (P<.1) of magnesium were higher in lambs fed supplementary sucrose than in those fed the diet without added sucrose; plasma magnesium levels were similar in both groups. Results of experiment 2 support the hypothesis that supplemental energy may enhance the availability of dietary magnesium to ruminants.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 88%

Magnesium Utilization in Wethers Fed Diets with Varying Ratios of Nitrogen to Readily Fermentable Carbohydrate

House

Mayland

1976

Journal of Animal Science

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“…However, Kemp (1960) suggested that dietary CP might interfere with Mg absorption because signs of tetany were observed when cows were fed herbage heavily fertilized with N. However, under controlled feeding conditions, dietary CP did not affect Mg absorption (Grace and MacRae, 1972;Moore et al, 1972;Fontenot et al, 1973;Gä bel and Martens, 1986). Furthermore, a wide array of dietary compounds in relation to Mg absorption, including CP, was recently evaluated by Weiss (2004) and it was found that only Mg intake and dietary K concentration were significantly related to Mg absorption.…”

Section: Resultsmentioning

confidence: 99%

Quantitative Prediction of Magnesium Absorption in Dairy Cows

Schonewille

Everts

Jittakhot

et al. 2008

Journal of Dairy Science

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The objective of the current study was to predict magnesium (Mg) absorption in dairy cows based on data from our own studies and those of other investigators. Balance data from 15 independent studies with 68 different rations and 323 dairy cows or cow-periods were used. In 12 studies, grass feeds were the main source of roughage and in about one-half of the studies, MgOsupplemented rations were used. Out of the 68 rations, 14 rations contained supplemental K in the form of bicarbonate, and in 2 rations additional K was incorporated mainly in form of KCl. The K content of the rations ranged from 6.9 to 75.6 g/kg of dry matter (DM; mean 29.4 g/kg of DM). In most studies (10/15), dry, nonpregnant cows were used. For lactating animals, milk yield ranged from 4 to 22 kg/d (mean yield, 15 kg/d). All studies provided quantitative information with respect to feed intake (DM intake, Mg, and K) and total Mg excretion in feces. The mean dietary Mg content was 4.5 g/kg of DM and ranged from 0.45 to 17.3 g/kg of DM. On average, Mg absorption (% of intake) was 26.2% and ranged from 9.9 to 73.7%. The variation in Mg absorption was at least partly explained by the variation in dietary K concentrations. Magnesium absorption (% of intake) was significantly decreased by 0.31 percentage units/g of K in the DM. To counteract the depressant effect of dietary K on Mg absorption, Mg intake must be increased by 4 g/d when the dietary K concentration increases by 10 g/kg of DM so that the amount of absorbed Mg is maintained.

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“…Increasing the phosphate concentration favours Mg absorption (Beardsworth et al, 1989b). The results for the effect of increasing ammoniacal nitrogen are conflicting: a decrease, sometimes marked, in Mg absorption (Martens and Rayssiguier, 1980;Care et al, 1984;Martens et al, 1988) or no effect (Moore et al, 1972;Grings and Males, 1987). The experimental methods used probably partly account for these differences; the results of Moore et al (1972) and Grings and Males (1987) (Martens et al, , 1991 An increase in intraruminal K may have several effects, reducing the paracellular diffusion of Mg by raising the ddpt, and reducing the transcellular diffusion by lowering ddpt in the apical membranes (Martens et al, 1991 Males, 1987;Holler et al, 1988a).…”

Section: Mineralsmentioning

confidence: 99%

Metabolites, water and mineral exchanges across the rumen wall: mechanisms and regulation

Rémond¹,

Meschy²,

Boivin³

1996

Ann. Zootech.

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Summary — In ruminants, the forestomachs, and especially the reticulorumen, have walls with anatomical and histological properties that permit the exchanges of various metabolites, water and minerals between the rumen contents and the blood. The development of papillae on the walls and the local blood circulation favour these exchanges. They depend to varying degrees on the food supply and the concentrations of volatile fatty acids (VFA) produced by the microbial catabolism of polysaccharides. The absorption of VFA and ammonia occurs essentially by a process of passive diffusion of their nonionised form through the epithelial cell membranes. For each of these substances, the existence of a transport system for the ionised forms is also suspected, but its relative importance is unknown. Shortterm modifications in the absorption of these two substances are thus primarily determined by variations in their intraruminal concentrations and pH. Other factors may also be implicated, and it is known in particular that the absorption of ammonia is enhanced when the intraruminal concentration of VFA or the carbon dioxide (C0 2 ) level increases. The movement of urea through the wall occurs from the blood towards the rumen content according to the concentration gradient. The main factors liable to influence the transepithelial flux of urea seem to be the blood urea levels and factors that act on the contact surface between the blood compartment and the epithelium (C0 2 , VFA). Ruminal ammonia concentration also affects the net urea transfer across the rumen wall but the mechanisms involved in this regulation are not clearly understood. The absorption of water through the rumen wall results from an osmotic pressure gradient between the rumen and the plasma. This is modified not only by factors that modify the blood flow rates at the wall, but also by electrolyte concentrations. The absorption of minerals from the rumen has also been demonstrated (Mg, Ca, Na, Cl, K,

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Effect of Form and Level of Nitrogen on Magnesium Utilization

Cited by 21 publications

References 12 publications

Magnesium Utilization in Wethers Fed Diets with Varying Ratios of Nitrogen to Readily Fermentable Carbohydrate

Magnesium Utilization in Wethers Fed Diets with Varying Ratios of Nitrogen to Readily Fermentable Carbohydrate

Quantitative Prediction of Magnesium Absorption in Dairy Cows

Metabolites, water and mineral exchanges across the rumen wall: mechanisms and regulation

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