Calcium absorption during lactation in sheep with demineralized skeletons

Sykes, Andrew G.; Dingwall, R

doi:10.1017/s0021859600052357

Cited by 17 publications

(9 citation statements)

References 20 publications

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“…In part this reflects their depleted body condition and therefore weight, but even if calculated relative to mating weight the rate of absorption (> 90 mg Ca/kg W per day) is still high. The value is, however, close to that of 115 mg/kg W per day calculated to have been absorbed by sheep consuming semi-purified diets during lactation after skeletal Ca had been depleted by undernutrition during pregnancy (Sykes & Dingwall, 1975). It therefore seems possible that other factors may be involved in the poor Ca balances.…”

Section: -52supporting

confidence: 63%

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Calcium and phosphorus balances of lactating ewes at pasture

Sykes

Geenty²

1986

J. Agric. Sci.

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Differences in maternal body weight (12-15 kg) were induced in two groups (n = 43-50) of ewes during pregnancy by controlled allowance of pasture. Following parturition equal numbers (9-12) were allocated to one of three herbage allowances in a 2 x 3 factorial design during 42 days of lactation. This design was employed on two occasions; in one (Expt 1) the sheep were machine-milked twice daily, in the second (Expt 2) they each suckled two lambs. Balances of Ca and P in the body were determined by comparative slaughter during early pregnancy, at parturition and after 42 days of lactation. Herbage Ca intake and milk Ca output were determined on a weekly basis.Mean daily milk production during the 42 days of lactation ranged from 1-48 to 2-68 kg/day amongst treatment groups. The general trend, irrespective of level of milk production, was for negative Ca balances, ranging from 0-71 to 1-42 g Ca/day. It is argued that variation in apparent absorbability (0-17-0-46) and in rate of absorption (30-113 mg/kg W per day) of Ca among groups suggest that these factors are not in themselves responsible for the poor Ca balances observed.It is suggested that demand for Ca from the diet during early lactation is reduced as a consequence of bone Ca resorption due to matrix osteoporosis resulting from a protein deficiency state. Negative Ca balances in sheep undernourished during pregnancy were similarly attributed to poor protein balances.Although negative P balances were observed these were not attributed to low P intake.energy and protein balances of lactating sheep at pasture. The opportunity was therefore taken to The data on which the Agricultural Research determine Ca and P balances and these, together Council (1980) based their estimates of Ca require-with estimated of rates of Ca absorption, are prement and the most extensive series of kinetic sented here, studies of Ca metabolism in lactating sheep (Braithwaite & Glascock, 1976;Braithwaite, 1983) MATERIALS AND METHODS were derived from experiments in which conserved, mixed roughage-concentrate diets were used.The sheep and their management were described Whether these data can be adapted to lactating in detail by Geenty & Sykes (1986). Briefly, mixed sheep at pasture does not appear to have been age Dorset sheep were used in two experiments, assessed. There is evidence from ewes grazing hill In Expt 1 two groups (n = 43 and 45) were formed pastures during summer that skeletal remineral-during early pregnancy; they were offered herbage ization following lactation may be slow (Sykes, Field (ryegrass-white clover) ad libitum (HP) or in reft Gunn, 19746) despite adequate Ca and P intake, stricted amounts (LP) in order to achieve differMoreover, the early studies of Ewer & Bartrum ences in maternal body weight between groups, (1957) described poor skeletal mineralization in post-partum, of 12-15 kg. The lambs were then sheep consuming herbages which Grant & O'Hara removed and 9-12 sheep allocated from within each (1957) attributed to high vitamin A and low vitamin group to o...

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Section: -52supporting

confidence: 63%

“…Milk production was assessed directly by machine-milking or, in ewes rearing lambs, by a combination of the lamb suckling and oxytocin methods (Geenty & Sykes, 1986). Milk samples obtained weekly by machine-milking were analysed for Ca and P after deproteinization by the methods of Sykes & Dingwall (1975).…”

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confidence: 99%

Calcium and phosphorus balances of lactating ewes at pasture

Sykes

Geenty²

1986

J. Agric. Sci.

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“…From the data in Table 1 and in Table 3 the efficiency of absorption of Ca is estimated to be less than 0-5 and is considerably below its upper limit of 0-68 (TCORN, 1989). Ca appears to be absorbed according to body needs and changing requirements are met by adjustments in the efficiency of absorption (Braithwaite and Glascock, 1976;Sykes and Dingwall, 1975;Scott and McLean, 1981). Ca appears to be absorbed according to body needs and changing requirements are met by adjustments in the efficiency of absorption (Braithwaite and Glascock, 1976;Sykes and Dingwall, 1975;Scott and McLean, 1981).…”

Section: Discussionmentioning

confidence: 99%

Effect of growth rate on mineral retention and body composition of growing lambs

Zahari

Thompson

Scott³

et al. 1989

Anim. Sci.

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1989). Effect of growth rate on mineral retention and body composition of growing lambs. ABSTRACT Groups of wether lambs were grown at different rates from about 24 kg live weight to 50 kg, by feeding them different amounts of the same concentrate diet. The slow growing lambs had higher contents of protein, ash, calcium (Ca), and phosphorus (P), and less fat and magnesium (Mg) than other groups. Differences in composition were significant between slow (120 g/day) and fast growth (230 g/day; P < 0-05) but not always between intermediate (160 g/day) and other growth rates. The differences became small and insignificant when data were expressed on a fat-free basis except for Mg which decreased with slow growth. Ash, for example, increased from 47 g/kg fat-free gain with fast growing animals to 54 g/kg with slow growth. Mg decreased from 0-44 g/kg fat-free gain with fast growth to 0-24 g/kg with slow growth. The data support the view that the ratio of ash to fat-free empty-body increases only slightly with age.The basic diet contained 3-9 g Ca per kg dry matter and the effect of a substantial supplement of calcium carbonate on lambs growing at the fast rate was to increase their retentions of ash, Ca and P by a factor greater than 1-25. There are alternative explanations for this finding. One possibility is that the availability of Ca in the basic diet had been reduced by unknown factors. It is also possible that the supplementary carbonate altered the acid/base status of the animals and resulted in conditions which favoured skeletal mineralization.

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“…The composition of the semi-purified diets (g/kg) was starch, 110; sugar, 115; blood meal, 44; dried skimmed milk, 109; arachis oil, 30; H 2 O, 30; NaHCO 3 , 2-5; NaCl, 1-5; Na 2 SO 4 , 0-3; MgO, 0-4; CaHPO 4 and CaCO 3 , 0, 0-8 and 4-6 and 1-2, 1-5 and 2-5 respectively, for the Pj, P 2 and P 3 diets. All diets were made up to 1 kg with the appropriate amount of a 50:50 mixture of whole and ground oat hulls, and were supplemented with trace elements and vitamins (Sykes & Dingwall, 1975).Theaverageanalysis (g/kg D.M.) was: crude protein (CP), 84; Ca and P, respectively, 5-0 and 1-5 for V 1 ; 9-2 and 2-8 for P 3 and 23-6 and 9-3 for the P 3 diet.…”

Section: Discussionmentioning

confidence: 99%

“…The tibiae, 3rd ribs and 3rd and 4th lumbar vertebra were removed from the ewes and lambs; the right members and 3rd lumbar vertebra were used for histology and the remainder for chemical composition. Empty body water, fat, N, Ca and P contents of the ewes were determined by the methods of Sykes & Dingwall (1975), and Ca and P content of the lambs by the methods of Sykes & Field (19726). One P 2 ewe was barren and was therefore excluded.…”

Section: Discussionmentioning

confidence: 99%

The phosphorus requirement of pregnant sheep

Sykes

Dingwall

1976

J. Agric. Sci.

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Thirty-eight mature Scottish Blackface sheep were mated at pasture and 32 brought indoors when 3-4 weeks pregnant. Eight were killed at this stage as controls (CI). The remaining 24 were offered a basal hay ration (200 g/head/day) supplemented with a semi-purified diet containing 84 g crude protein/kg and either 1-5 (Px), 2-8 (P 2 ) or 9-3 (P 3 ) g P/kg dry matter. The rate of feeding of the supplement allowed a mean daily P intake (g/day) in groups P x , P 2 and P 3 of 1-1, 1-6 and 4-7 and 1-6, 2-5 and 7-9 during weeks 4-15 and 16-21 of pregnancy, respectively. Six well-nourished sheep, fed conventionally, provided control ewes and lambs.Balance trials were conducted on four sheep from each of groups P 1( P 2 and P 3 during weeks 9-10, 14-15 and 19-20 of pregnancy. All sheep were slaughtered at parturition and selected bones of ewes and lambs removed for histological and chemical examinations. Whole body fat, nitrogen, Ca and P contents of the ewes and mineral content of the lambs were determined.The faecal P excretion of the P x sheep ranged from 10-8 to 19-1 mg/kg body weight/ day; urinary P excretion ranged from 0-7 to 2-9 mg/kg body weight/day in early and mid-pregnancy and from 1-0 to 8-1 mg/kg body weight/day in late pregnancy. It is suggested that on this evidence the minimum net faecal and urinary endogenous P loss can be no greater than about 13-5 mg/kg body weight/day. Carcass analysis and bone histology and chemical composition confirmed that the P requirement of pregnant ewes is much smaller than has been generally assumed.It is suggested that for a 50-kg ewe carrying twins the P requirement increases from an average of 1-1 g/day during the first to about 2-5 g/day during the last month of pregnancy.

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Calcium absorption during lactation in sheep with demineralized skeletons

Cited by 17 publications

References 20 publications

Calcium and phosphorus balances of lactating ewes at pasture

Calcium and phosphorus balances of lactating ewes at pasture

Effect of growth rate on mineral retention and body composition of growing lambs

The phosphorus requirement of pregnant sheep

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