Search

In this study, we compared in vitro calcium binding by the taurine and glycine conjugates of the major bile acids in human bile: cholic (CA), chenodeoxycholic (CDCA) and deoxycholic (DCA) acids, together with the cholelitholytic bile acids ursodeoxycholic (UDCA) and ursocholic (UCA) acids. At physiological total calcium (CaTOT) (1-15 mM) and bile acid (BA) (10-50 mM) concentrations, all the bile acids caused concentration-dependent falls in [Ca2+], suggesting calcium binding. Except for glycine-conjugated CDCA, all the other calcium-bile acid complexes were soluble in 150 mM NaCl. The calcium binding affinities followed the pattern: dihydroxy (CDCA, UDCA and DCA) greater than trihydroxy (CA and UCA) bile acids, and glycine conjugates greater than taurine conjugates. The glycine conjugate of UDCA, which increases during UDCA treatment, had the highest calcium binding affinity. Ten-20 mM phospholipid modestly increased calcium binding by CA conjugates, but not by CDCA, UDCA, and DCA conjugates. Phospholipid also prevented the precipitation of glyco-CDCA in the presence of calcium. Bile acid-calcium biding was pH-independent over the range 6.5-8.5. The different calcium binding affinities of the major biliary bile acids may partly explain their varying effects on biliary calcium secretion. The results also suggest that neither precipitation of calcium-bile acid complexes nor impaired calcium binding by bile acids is important in the pathogenesis of human calcium gallstone formation.

In the first experiment designed to identify the deficiencies in mulga leaves, four groups of sheep were fed mulga and offered one of the following supplements; cobalt, sulfur, cobalt plus sulfur, and molasses. A fifth group acted as a control. All sheep received a phosphorus supplement. The cobalt supplement had no beneficial effect on liveweight or clean wool production. In contrast, the sulfur and molasses supplements significantly improved liveweight gain, clean wool production and sulfur balance. The liveweight and wool growth responses were more than twice as large in the sheep receiving a molasses supplement as in those receiving sulfur. In a second experiment, three groups of sheep on a diet of mulga leaves were supplemented with molasses and phosphorus and, in addition, two groups received 50 g/head.d of either formaldehyde treated or untreated cottonseed meal. Both cottonseed meal supplements significantly improved liveweight gain, but formaldehyde treatment of the meal had no additional effect. Under the conditions of the experiment rumen ammonia was a major limiting nutrient.

Twenty cows in early- to mid-lactation were used in a 12-week experiment to determine the effect of Na supplementation on milk yield. All cows were fed 1 kg maize/cow day-1 and half received 40 g coarse salt/cow day-1. There was an immediate response in milk yield to Na supplementation. Average yields over the 12-week period were 10.8 and 12.0 kg/cow day-1 (P< 0.05) for the unsupplemented and Na supplemented groups, respectively. At the start of the experiment, the mean saliva Na levels of 88.6 (S.D.) 4.9 mmol l-1 indicated that all cows were deficient in Na. Saliva Na levels in the supplemented group had returned to normal (> 145 mmol l-1) by week nine of the experiment.

The performance of Brahman crossbred cows grazing annual grass plus Townsville stylo (Stylosanthes humils) pasture with or without superphosphate fertilizer was monitored over a two year period. The animals were introduced to the experimental areas as yearling helfers and remained until weaning of their first calf. Levels of phosphorus In rib bone varied between 145 and 172 mg/ml. At weanlng, levels were higher on the fertilized than on the unfertilized pasture (172 vs. 157 mg/ml). Calcium levels in rib bone varied between 329 and 362 rng/ml and paralleled bone phosphorus levels. Pasture nitrogen levels were similar on both pastures but phosphorus levels were higher on the fertilized area. Faecal analyses reflected this same pattern with faecal nitrogen levels being similar on both pastures, and faecal phosphorus levels higher on the fertilized pasture. Liveweight changes of cows and calf weaning weights were greater in groups grazing the fertilized pasture. It is hypothesized that this superior performance is a function of increased feed intake resulting from increased phosphorus intake on the fertilized area although the possible contribution of sulfur cannot be overlooked.

The effect of levamisole treatment every 3-4 weeks, cobalt therapy, or both, on the performance of yearling cattle grazing together on known cobalt-deficient pastures on a siliceous sandy soil in south-eastern Queensland was studied between August 1978 and October 1979. In the first stage of the observations, from August to March, the responses (Pc0.05) in liveweight gain compared with the controls (C) were 18, 54 and 75 kg for levamisole (L), cobalt bullets (B), and both (LB) respectively. Thus the responses were additive with no interaction. Deaths were recorded in the control and levamisole only groups in March. Steers in the levarnisole only group were treated with cobalt in March (L + B). Liveweight gains between March and October were 9, 71,47 and 41 kg for C, L + B, B and LB groups, respectively (L + B > B, LB > C, P< 0.05). Cobalt therapy increased faecal worm egg counts in undrenched groups between November and April (P<0.05). At 30 weeks after the start of the study many animals in groups C, L and B were anaemic. Cobalt concentrations in green panic ranged from 0.015 to 0.029 g/g dry matter and in Siratro from 0.036 to 0.048 g/g dry matter.

The effects of feeding dry season supplements of salt and urea (NaU), salt, urea and sulfur (NaUS) and molasses and urea (MU) on the liveweight of steers grazing native pasture in northern Queensland were studied over four years. Liveweight during the feeding period was improved (P < 0.05) by each supplement in three years out of four, with a mean level of response of 49 g/d. The supplements gave similar results in two years while in one year NaU and MU were better than NaUS (P < 0.05) and in another NaUS was better than NaU (P < 0.05). Compensatory growth by unsupplemented animals after the feeding period eroded liveweight responses to supplements in most cases. Blood sulfate level was not affected by treatment, nor was it related to liveweight in either the feeding or post-feeding periods. Mean levels for unsupplemented animals were 15.8 and 21.2 g/ml for the feeding and post-feeding periods, respectively. Salivary Na:K ratios exceeded 18:1 throughout the year for unsupplemented and NaUS groups, indicating sodium sufficiency.

Hereford cattle grazing native pastures on the eastern Darling Downs, Queensland, were deemed sodium (Na) deficient on the basis of salivary Na and potassium (K) levels. Common salt (NaCl) was offered ad libitum to one half of the animals. Cows receiving the supplement had significantly better rates of liveweight increase (0.35 v. 0.14 kg head-1 day-1, P < 0.01) than unsupplemented cows. Calves of supplemented cows grew significantly faster than calves of unsupplemented cows (0.77 v. 0.62 kg head-1 day-1, P < 0.01). After 21 days of Na supplementation, cows in the supplemented group had mean saliva values of 139.1 m-equiv l-1 Na and 7.4 m-equiv l-1 K; these values are considered normal. Corresponding values in the unsupplemented group were 60.2 m-equiv l-1 Na and 71.7 m-equiv l-1 K, which are indicative of severe Na deficiency. Levels of this magnitude remained throughout the duration of the experiment. Blood and milk concentrations of Na and K were not affected by Na intake. Urinary levels of Na and K were attered by Na intake but were extremely variable.