A potassium and sodium balance study in two breeds of sheep

Am, Beal; Budtz-Olsen, O. E.

doi:10.1071/ar9680113

Cited by 9 publications

(2 citation statements)

References 7 publications

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“…The potassium retention seems unlikely to result from increased growth or unmeasured loss. The sheep gained 0-7kg per cycle which, together with the likely dermal loss [Beal and Budtz-Olsen, 1968] would account for less than 30% of the daily retention (20 mmol). Moreover neither would be likely to increase beyond luteal levels since progesterone increases both weight gain and sebaceous secretion [Landau, 1973].…”

Section: Discussionmentioning

confidence: 99%

Water and Electrolyte Excretion During the Oestrous Cycle in Sheep

Michell

1979

Exp Physiol

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Electrolyte excretion was observed during 24 oestrous cycles in housed sheep, together with mixed salivary Na/K ratio during 10 additional cycles. 1. The sharp fall in food and fluid intake at oestrus accompanied a peak of sodium excretion which changed to peak retention 3 days later, both in faeces and urine. 2. Potassium excretion declined with food intake at oestrus but subsequently failed to recover to pre-oestrous levels dispite full recovery of dietary intake. 3. Curiously, water intake also recovered completely whereas urinary and faecal water retention continued; faecal loss actually exceeded renal excretion on these liberal water intakes. 4. Changes in salivary, urinary and faecal Na/K indicated an aldosterone peak neither during the luteal phase nor at oestrus but three days later. The data rarse questions concerning the regulation of water and electrolyte balance within the normal cycle. They also provide a baseline for the investigation of renal effects of gonadal steroids. Possible roles for aldosterone, ADH and progesterone in maintaining fluid and electrolyte balance are discussed, emphasising problems confronting species which have evolved with heavy obligatory potassium excretion but undependable supplies of sodium and water.Sheep vary their sodium intake during the oestrous cycle, taking least at oestrus and most at the climax of the luteal phase [Michell, 1975]. This seemed consistent with the idea that oestrogens stimulate salt retention whereas progesterone promotes natriuresis [Landau, 1973], but specific data in sheep were lacking.Salt retaining effects of oestrogens were suspected almost as soon as those of adrenal steroids [Thorn, Nelson and Thorn, 1938] but considerable conflict emerges from the literature on gonadal steroids and electrolyte excretion [Christy and Shaver, 1974;Lindheimer and Katz, 1977]. The factors influencing aldosterone levels during the human cycle remain uncertain [Schwartz, 1975]. The luteal rise can be attributed to sodium loss induced by progesterone but the rise near ovulation is less easily explained [Sundsfjord and Askvaag, 1973]. Such questions have practical significance since the aetiology of both premenstrual tension and contraceptive hypertension remain uncertain

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Section: Discussionmentioning

confidence: 99%

Water and Electrolyte Excretion During the Oestrous Cycle in Sheep

Michell

1979

Exp Physiol

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“…In calculating balances, nitrogen (N) and S stored in wool were regarded as tissue losses; these S losses were measured directly while N losses were calculated assuming a N content of 16-85 % for clean, dry wool (Paladines et al 1964). Sodium and K losses in skin secretions were assumed to be 0-01 and l-2g/day respectively (Beal & Budtz-Olsen, 1968). Intakes of Ca, Mg, Na and K included amounts derived from drinking water although these were insignificant, reaching a maximum of only 0-04 g/day for any individual element.…”

Section: Digestibility and Balance Studiesmentioning

confidence: 99%

The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

Coombe¹,

Christian²,

Holgate

1971

J. Agric. Sci.

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Seven, groups of adult Merino wethers were fed for 16 weeks on a diet of pelleted oat straw and urea, either alone or supplemented with trace minerals and various combinations of the major minerals. In some treatments, the same diet was fed throughout; in others, diets were changed after 8 weeks.Sulphur (S) was by far the most important mineral supplement; sheep fed diets supplemented with all minerals except S performed as poorly as those on the basal diet. Of the other minerals, only calcium (Ca) and magnesium (Mg), which were fed in combination, had a small, additional beneficial effect. Supplementary phosphorus (P) had no effect whether or not S was included.Intakes of sheep on S-supplemented diets increased over the first 6 weeks to reach stable levels of 1200-1400 g D.M./day compared with approximately 800 g/day for controls, while O.M. digestibilities stabilized at about 40 and 33 % for S-supplemented and unsupplemented diets respectively. Live-weight change and wool growth were closely related to intake. Mean live-weight losses during the first and second 8 weeks for sheep without supplementary S were 9-5 and 4-8 kg respectively, and were about 50 % of this for supplemented sheep. Sheep which were changed from diets without supplementary S to S-supplemented diets after 8 weeks showed slight increases in live weight from then on. Wool growth was about 115 g clean wool/sheep on all treatments during the first month, after which it remained steady at about 105 g/month on S-supplemented diets and fell to 60 g/month on diets without supplementary S.Sheep without supplementary S were in negative nitrogen (N) and S balance throughout. With the S-supplemented diets, urinary excretion of N and S was high, and few positive balances were recorded until the final 4 weeks of the experiment. Serum urea levels were high (60-130 mg/100 ml) throughout, and showed no effect of diet or period. Phosphorus balances were uniformly negative in sheep without supplementary P, and generally positive in P-supplemented sheep. Serum inorganic P levels were apparently affected by P intake and by live-weight loss, but mean values never fell below 4-5 mg/100 ml.Sheep without supplementary Ca were in negative Ca balance throughout the experiment; however, Ca supplementation generally resulted in high faecal Ca losses and few positive balances were recorded. In some sheep, serum Ca fell to moderately low levels (7-5 mg/100 ml), but this appeared to be associated more with high serum inorganic P levels than low Ca intake or retention. All sheep were practically in Mg, Na and K balance throughout, and supplementation had little effect on the retention of these elements.All sheep were in very poor condition at the end of the experiment, even when their D.M. intakes had been high, and wool growth rates were mediocre throughout. It appears that urea was poorly utilized in this experiment, and that satisfactory sheep production on diets of ground straw supplemented only with urea and minerals is unlikely.

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Role of saltbush (Atriplex Spp.) in animal production systems of Mediterranean climate

Atiq-ur-Rehman

2002

Tasks for Vegetation Science

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A potassium and sodium balance study in two breeds of sheep

Cited by 9 publications

References 7 publications

Water and Electrolyte Excretion During the Oestrous Cycle in Sheep

Water and Electrolyte Excretion During the Oestrous Cycle in Sheep

The effect of urea on the utilization of ground, pelleted roughage by penned sheep: III. Mineral supplements

Role of saltbush (Atriplex Spp.) in animal production systems of Mediterranean climate

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