Changes in phosphorus metabolism of sheep in response to the increased demands for P associated with an intravenous infusion of calcium

1984 ◽  
Vol 102 (1) ◽  
pp. 135-139 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Intravenous Infusion ◽  
Calcium Metabolism ◽  
Research Council ◽  
Agricultural Research ◽  
Close Association ◽  
High Rate ◽  
Phosphorus Metabolism ◽  
Agricultural Research Council ◽  
P Absorption ◽  
P Retention

SummaryThe effect on phosphorus and calcium metabolism of a high rate of Ca infused directly into the blood of 10-month-old sheep, already receiving an adequate Ca and P intake, has been studied by a combination of balance and radioisotope techniques. Ca retention was significantly increased during the infusion and most of the extra Ca was retained in bone. Urinary Ca excretion also showed a small but significant increase and the efficiency of Ca absorption a small but significant decrease. Because of the close association of Ca and P in bone, the increased skeletal retention of Ca resulted in an increased skeletal P retention and hence an increased demand for P. This increased P demand was met partly by a decrease in the rate of endogenous faecal loss of P and partly by an increase in the rate and efficiency of P absorption. Because the increase in P demand was relatively small, it was not possible to decide whether the endogenous faecal loss of P can be reduced in response to increased demands to the level found at zero P intake as suggested by the Agricultural Research Council (1980) or whether higher losses at normal P intakes are inevitable.

scholarly journals Adaptations in the calcium and phosphorus metabolism of sheep in response to an intravenous infusion of Ca

1978 ◽  
Vol 40 (1) ◽  
pp. 17-21 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Intravenous Infusion ◽  
High Rate ◽  
Phosphorus Metabolism ◽  
Active Absorption ◽  
Rate Of Absorption ◽  
Calcium And Phosphorus ◽  
Maximum Retention ◽  
P Retention ◽  
Low Rate

1. The effect on calcium and phosphorus metabolism of a high rate of Ca infused directly into the blood of Ca-deficient wethers, already receiving an adequate Ca intake, has been studied by a combination of balance and radioisotope techniques.2. The rate of Ca retention, which was already high, increased only slightly during the infusion before it reached a maximum. The surplus Ca was compensated for by a decrease in the rate of absorption and an increase in the rate of urinary Ca excretion.3. These findings support the theory that at maximum retention the rate of Ca absorption becomes regulated according to the rate at which Ca can be stored in bone.4. Results suggest that the decreased absorption was due to a decrease in the rate of active absorption and that the low rate remaining was due to diffusion.5. The rate of P retention was increased by the Ca infusion, possibly as a result of the increased Ca retention.

Endogenous faecal loss of phosphorus in growing lambs and the calculation of phosphorus requirements

1985 ◽  
Vol 105 (1) ◽  
pp. 67-72 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Research Council ◽  
Agricultural Research ◽  
Constant Level ◽  
Direct Relation ◽  
Agricultural Research Council ◽  
Phosphorus Requirements ◽  
P Absorption

SUMMARYThe endogenous faecal loss of P has been investigated in growing lambs given diets either grossly deficient, moderately deficient or just adequate in P. This loss was found to increase in direct relation to the increased P intake, in spite of the high P requirements of the deficient animals, which suggests that some increased loss with increased P intake is inevitable. Results throw doubt on the validity of the assumption made by the Agricultural Research Council (1980) in their calculations of P requirements, that the endogenous faecal loss of P is maintained at a constant level equal to that which occurs at zero P intake, until requirements are met.Even on the diet which was, according to Agricultural Research Council (1980) recommendations, just adequate in P, lambs were unable to retain the expected amount of P commensurate with their growth. This inability to retain P was not due to a failure of P absorption, since the efficiency of absorption from this diet was higher than the value used by the Agricultural Research Council (1980) in their calculations. Rather, it must have been due to an inevitable endogenous faecal loss of P that was considerably higher than the value assumed by the Agricultural Research Council (1980).It is suggested that in future the value of endogenous faecal loss used in calculations of P requirements is the minimum one that allows a particular requirement to be achieved.

Phosphorus and calcium metabolism in growing calves with special emphasis on phosphorus homoeostasis: 1. Studies of the effect of changes in the dietary phosphorus intake on phosphorus and calcium metabolism

1988 ◽  
Vol 110 (3) ◽  
pp. 573-581 ◽  
Author(s):  
J. Challa ◽  
G. D. Braithwaite
Keyword(s):  
Calcium Metabolism ◽  
Agricultural Research ◽  
Kinetic Studies ◽  
Basal Diet ◽  
Salivary Secretion ◽  
Direct Relation ◽  
Agricultural Research Council ◽  
Dietary Phosphorus ◽  
P Concentration ◽  
P Absorption

SummaryCalves were fed continuously at 4 h intervals a low P basal diet with or without P supplementation to give three levels of dietary P intake: one was deficient in P (2·5 g/day), the second adequate (6·0 g/day) and the third contained an excess of P (10·0 g/ day) according to Agricultural Research Council (1980) recommendations. Once steadystate conditions were achieved (after 2–3 weeks on the diet) 32P and 46Ca kinetic studies were carried out, together with measurements of P flow rates at the reticulorumen and P and Ca balances. With increased dietary P intake, the amount of dietary P absorbed increased as initially did the efficiency of P absorption. Both the serum P concentration and the rate of P retention increased in direct relation to increased P intake and increased P absorption. Salivary secretion of P increased with increased P absorption and in direct relation to serum P concentration. Endogenous faecal losses of P were also directly related to P intake and P absorption and results suggest that increased loss with increased P intake is inevitable.Despite a constant and adequate Ca intake, the rate and efficiency of Ca absorption, which was low on the low-P diet, increased significantly on the adequate and high-P diets. Similarly, Ca retention increased substantially on the higher P diets, showing that Ca metabolism can be controlled according to P status.

scholarly journals Calcium and phosphorus requirements of the ewe during pregnancy and lactation

1983 ◽  
Vol 50 (3) ◽  
pp. 723-736 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Research Council ◽  
Agricultural Research ◽  
Late Pregnancy ◽  
Early Lactation ◽  
Mineral Balance ◽  
Agricultural Research Council ◽  
Pregnancy And Lactation ◽  
Calcium And Phosphorus ◽  
Phosphorus Requirements ◽  
P Absorption

1. Mineral balance and radioisotope studies have been carried out to test the adequacyof the recent Agricultural Research Council (1980) recommendations for calcium and phosphorus for pregnant and lactating ewes. At the same time, P metabolism was compared throughout pregnancy and lactation in ewes fed according to these recommendations and in ewes fed a plentiful supply of dietary Ca and P.2. Bone mineral stores were mobilized in late pregnancy and early lactation, irrespective of the rate of P absorption. These stores were then replaced in mid- to late lactation in ewes given the plentiful Ca and P intake but not in the ewes given the restricted intake.3. Results suggest that these changes in bone stores occurred as a result of changes in Ca requirements rather than in P requirements, and that accretion of P into bone or resorption of P from bone occurred merely as a conseqence of this change in Ca requirements.Immediate demands for P for maintenance and fetal or milk production do not reflect net Pdemands, which also take into account changes in bone P metabolism.4. The rate of P absorption was directly related to net demands and the rate of endogenous excretion was inversely related to net demands.5. Absorption and endogenous faecal loss of P were also both directly related to P intake.6. A lack of dietary Ca, particularly in mid- to late lactation, makes it impossible to draw conclusions on the adequacy of the Agricultural Research Council (1980) recommendations for P. Results do suggest, however, that P requirements ought to be calculated according to net demands for P rather than immediate demands.

Phosphorus requirements of ewes in pregnancy and lactation

1986 ◽  
Vol 106 (2) ◽  
pp. 271-278 ◽  
Author(s):  
G. D. Braithwaite
Keyword(s):  
Research Council ◽  
Agricultural Research ◽  
Late Pregnancy ◽  
Experimental Period ◽  
Early Lactation ◽  
Agricultural Research Council ◽  
Pregnancy And Lactation ◽  
Phosphorus Requirements ◽  
P Absorption ◽  
Subsequent Replacement

SUMMARYThe adequacy of the Agricultural Research Council (1980) recommendations for phosphorus for pregnancy and lactation has been investigated in ewes given a plentiful supply of dietary calcium.The efficiency of absorption of P remained high and fairly constant throughout the whole experimental period and the rate of P absorption varied in direct relation to the P intake.The endogenous faecal loss of P also varied with P intake and at all stages of pregnancy and lactation was higher than the value assumed by the Agricultural Research Council (1980) in their calculations of P requirements.Bone mineral stores of Ca and P were lost in the normal way during late pregnancy and early lactation but were not replaced, as normal, in mid- to late lactation. At the end of the lactation, ewes were still in deficit of 125 g P and 100 g Ca.It is argued that the Agricultural Research Council (1980) recommendations for P, particularly in mid- to late lactation, are too low and it is recommended that future calculations of requirements for pregnancy and lactation allow for the inevitable loss and subsequent replacement of skeletal mineral stores and also for the increased endogenous faecal losses of P that appear inevitable at the high P intakes needed to meet the increased demands.

XIV.—Rowett Research Institute

1951 ◽  
Vol 64 (3) ◽  
pp. 257-276
Author(s):  
D. P. Cuthbertson
Keyword(s):  
Royal Society ◽  
Research Council ◽  
Medical Research Council ◽  
Agricultural Research ◽  
Research Work ◽  
Animal Nutrition ◽  
College Of Agriculture ◽  
The North ◽  
Agricultural Research Council ◽  
The University

The Rowett Institute for research on animal nutrition had its origin under a scheme for promoting scientific research in agriculture adopted by the Development Commission in 1911.The Governing Body, which originally consisted of an equal number of members appointed by the Court of the University of Aberdeen and the Governors of the North of Scotland College of Agriculture, was constituted in 1913. Within recent years it has been expanded to include persons nominated by the Secretary of State for Scotland, the Royal Society, the Royal Society of Edinburgh, the Agricultural Research Council, and the Medical Research Council. Research work was begun in temporary accommodation in Marischal College in 1914, under the direction of Dr John Boyd Orr—now Lord Boyd-Orr—who continued as Director until his retirement in 1945.

Validation of new systems for protein evaluation in ruminants by testing the effect of urea supplementation on intake and digestibility of straw with or without sodium hydroxide treatment

1978 ◽  
Vol 91 (2) ◽  
pp. 483-486 ◽  
Author(s):  
E. R. Ørskov ◽  
D. A. Grubb
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Research Council ◽  
Agricultural Research ◽  
Barley Straw ◽  
Protein Requirements ◽  
Agricultural Research Council ◽  
Ad Libitum ◽  
Four Levels ◽  
Sodium Hydroxide Treatment

SUMMARYMilled barley straw, either untreated or treated with 70 g of NaOH/kg straw was supplemented with four levels of urea, namely 0, 6, 12 or 18 g/kg and fed ad libitum to young sheep. For the untreated straw, dry-matter intakes were (g/day) 423, 451, 441 and 463, while the digestibility of organic matter was 458, 467, 490 and 483 g/kg, respectively. For the treated straw, the intakes of dry matter were 355, 402, 531 and 567 g/day and the digestibility of organic matter was 423, 480, 589 and 628 g/kg respectively.The different responses to urea supplementation of treated and untreated straw are discussed in relation to a new system of estimating protein requirements for ruminants put forward by the Agricultural Research Council.

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