Some effects of conservation of grass upon magnesium metabolism in sheep

Powley, G.; Johnson, C. L.

doi:10.1017/s0021859600034997

Cited by 4 publications

(3 citation statements)

References 12 publications

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“…Gueguen (1982) comments that the Ca availability in forages is variable and true absorption rarely exceeds 0-5 even when the requirement for the element is high relative to its intake. Other reports have recorded differences in apparent availability of the major minerals in different species of grass and with different conservation techniques (Gueguen and Demarquilly, 1965;Perdoma, Shirley and Chicco, 1977;Powley and Johnson, 1977;Powell, Reid and Balasko, 1978;Reid, Jung, Roemig and Kocher, 1978). Other reports have recorded differences in apparent availability of the major minerals in different species of grass and with different conservation techniques (Gueguen and Demarquilly, 1965;Perdoma, Shirley and Chicco, 1977;Powley and Johnson, 1977;Powell, Reid and Balasko, 1978;Reid, Jung, Roemig and Kocher, 1978).…”

Section: Introductionmentioning

confidence: 95%

Mineral retentions and body composition of grazing lambs

1988

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Growth rates and chemical compositions were measured with ram lambs grazing pure stands of perennial ryegrass, timothy, cocksfoot and tall fescue. A group of lambs slaughtered at the start of the trial enabled estimates to be made of the live-weight gains over the summer and the composition of these gains. The composition of the grass was also measured in samples taken at weekly intervals and estimates were made of the nutrients consumed from the different grass plots.The quantities of ash, Ca, P and Mg in the empty bodies of the lambs were within the range of published values from similar studies. They support the contention that grass-fed lambs tend to have larger contents of ash, Ca and P in their empty bodies than concentrate-fed lambs of similar weight. Perennial ryegrass provided a superior diet in that lambs eating this grass grew more quickly, with leaner tissues and higher levels of ash, Ca and P in their empty-body gains. Lambs consuming tall fescue grew most slowly but their mineral contents were as large as the ryegrass-fed lambs when data were adjusted for differences in empty-body weight. Lambs fed on timothy or cocksfoot were the most poorly mineralized in spite of consuming considerably more Ca, P and Mg than the lambs on ryegrass. The data suggest that the efficiencies of absorption of Ca and P in ryegrass may be high, at about 0-64 for Ca and 0-71 for P.

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Section: Introductionmentioning

confidence: 95%

Mineral retentions and body composition of grazing lambs

1988

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“…Using grass from the same harvest but conserved by ensiling, by artificially drying O J by deep-freezing, Powley & Johnson (1977) showed in ewes that the extent of the fall in plasma Mg concentration was influenced by the method of herbage conservation. The apparent availability of herbage Mg also varied with the method of conservation.…”

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confidence: 99%

Effect of change of diet on the mineral composition of rumen fluid, on magnesium metabolism and on water balance in sheep

Johnson

Jones

1989

Br J Nutr

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I . The effects of four diets on water intake, rumen fluid outflow-rate, rumen pH and mineral metabolism were studied in wether sheep. The diets were barley and hay, flaked maize and hay, dried grass and frozen grass.2. Experimental periods were of 12 d duration, and plasma magnesium concentrations were lower at the end of treatment periods when the grass diets were given and were significantly different ( P < 0.05) at 11.00 and 20.45hours. Also, the concentration was significantly lower with the dried-grass diet than with the frozen-grass diet ( P < 0.05).3. The concentration of Mg in rumen fluid centrifuged at 30000g (ultracentrifuged) varied with the diet.Maximum concentrations (rmax) were reached 4 h later on the grass diets than on the hay and concentrate diets.In the latter case f , n , , coincided with that for calcium, potassium, chloride and ammonia. At this time sodium and phosphate were at a minimum. The concentration of Mg in ultracentrifuged rumen fluid was negatively correlated ( r -0.89) with pH, which was significantly higher ( P < 0.01) at all times on the grass diets. This relation was also reflected in the apparent availability of Mg. 4. Total water intake on the frozen grass was about twice that on the barley and hay diet. The outflow rate of liquid from the rumen was higher on the frozen grass than on the other three diets.5. The proportion of absorbed Mg excreted in urine was significantly influenced by diet.It is well known that there is a fall in the plasma magnesium concentration of cattle and sheep immediately following a change of diet from forage and concentrates to young grass. This occurs even when diets are isomagnesaemic (Care et at. 1967).More recently, Johnson et al. (1988) have shown a fall in plasma Mg concentration when lactating Jersey cows were changed from a diet of hay and concentrates to one of frozen grass (ad iib.), even though the daily intake of Mg increased by approximately 44 YO on the grass diet. The concentrations of ultrafilterable Mg and calcium in rumen fluid varied inversely with pH. There were also changes in water intake, rumen volume, dilution-and outflow-rates associated with the diets.Using grass from the same harvest but conserved by ensiling, by artificially drying O J by deep-freezing, Powley & Johnson (1977) showed in ewes that the extent of the fall in plasma Mg concentration was influenced by the method of herbage conservation. The apparent availability of herbage Mg also varied with the method of conservation.The present experiment was made to study the effect of method of conservation of grass and of diets containing cereal with different fermentation characteristics on rumen pH, water intake, rumen volume and liquid outflow rates and on Mg metabolism in sheep fed on controlled amounts of food. M A T E R I A L S A N D M E T H O D S SheepFour rumen-cannulated wether sheep ranging in weight from 47 to 64 kg were used, and treatments were allocated in a 4 x 4 Latin-square design. At 10 d before the experiment began the sheep were housed in metabolis...

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“…Apparent availability of Mg was significantly higher in ensiled than in frozen or artificially dried grass (Powley and Johnson, 1977). The availability of Mg may range from 5 to 33% in succulent feeds and from 10 to 40% in hay and concentrates (Wilkinson and Stuedemann, 1979).…”

Section: Natural Sourcesmentioning

confidence: 99%

Magnesium

McDowell

2003

Minerals in Animal and Human Nutrition

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Some effects of conservation of grass upon magnesium metabolism in sheep

Cited by 4 publications

References 12 publications

Mineral retentions and body composition of grazing lambs

Mineral retentions and body composition of grazing lambs

Effect of change of diet on the mineral composition of rumen fluid, on magnesium metabolism and on water balance in sheep

Magnesium

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