This research aimed to examine the impact of varying levels of dietary copper (Cu) hydroxychloride on the performance, egg quality, yolk antioxidant capacity, tibia traits, and mineral excretion in laying quails. 125 female 10-week-old quails were randomly distributed into five experimental groups with five replicates, each consisting of five quails. Five experimental isonitrogenous and isoenergetic diets were designed to contain different Cu hydroxychloride (54% Cu) levels at 7.20 (basal diet), 15, 30, 45 and 60 mg/kg respectively. Quails were fed with trial diets for 12 weeks. Performance, egg production, eggshell quality, and biomechanical traits of the tibia were not impacted (P > 0.005) by variations in dietary Cu levels. Yolk antioxidant capacity, measured as yolk DPPH value, exhibited an increase (P < 0.01) in the high-dose group (60 mg/kg). Regarding tibia mineral concentration, Cu concentration decreased linearly (P < 0.001) with increasing Cu level, manganese and zinc content recorded the highest values in quails that had received 60 mg/kg Cu in the diet (P < 0.01), while the lowest phosphorus content was described for 45 and 60 mg/kg. Contrarily, increases (P < 0.01) in dietary Cu resulted in raised faecal Cu content, while phosphorus, manganese, and zinc, were reduced when Cu was added. It can be inferred that adding Cu to the diet of laying quails would not be necessary, which in turn decreases Cu excretion and prevents substantial environmental harm.

Twelve male 8-month-old lambs were used in a 6-month feeding experiment to determine the effects of dietary Mo, Mo + S and Zn supplements on the body retention and tissue accumulation of dietary Cu, Zn and Fe. The lambs were divided into four groups of three lambs each and each group was fed ad libitum one of four diets. A control diet was based on palm kernel cake (PKC) and grass hay. Three additional diets were the control supplemented with either Mo or Mo + S or Zn. At 3 months of the experiment, feces and urine were collected and sampled for 6 days. At the end of the experiment (6 months), blood was sampled and then the sheep were slaughtered. The liver and kidney were removed and sampled for chemical analysis. In comparison with the control, each dietary supplement decreased (P < 0.05) the Cu concentration in the liver, but only the Mo + S supplement decreased it to a safe range of below 350 μg/g dry matter. This was accompanied by the body retention of dietary Cu of 24.6%, 6.7%, 2.5% and 6.5% for the control, Mo, Mo + S and Zn treatments, respectively. The blood plasma concentration of Cu was decreased (P < 0.05) by the Zn supplement, but was not affected by other supplements (P > 0.05). It was concluded that from the supplements tested, only Mo + S appeared to be effective in reducing the retention and liver accumulation of the dietary Cu to prevent chronic Cu toxicity in sheep fed PKC-based diets.

We investigated the adverse effect of phytate on mineral absorption and the effect of dietary phytate and age on the relationship between faecal phytate and faecal mineral excretion. Fourteen young women (aged 19–24 years) and fourteen elderly women (64–75 years) were studied for two metabolic periods (MP). In MP1, the subjects consumed a controlled high-phytate (HP) diet for 10 d; in MP2, they were on a low-phytate (LP) diet for 10 d. In each period, diet samples and complete faecal samples for 5 d were collected to analyse phytate and mineral contents. Mineral concentrations in diet and faeces were measured by inductively coupled plasma–atomic emission spectrometry. Linear regression analysis was used to examine the associations between faecal phytate and mineral excretion. The degradation rate of dietary phytate was about 77 % for young women, which was significantly lower than that of elderly women (86 %) (P < 0·05). Faecal phytate excretion was positively correlated with mineral excretion (Ca, P, Fe and Zn) in both the HP and LP diet groups in young women (P < 0·05). The linear relationship tended to be greater during the LP diet period compared with the HP diet period in young women. However, no association was found between phytate excretion and mineral excretion in elderly women. In summary, undegraded dietary phytate (10–20 %) had a negative effect on mineral absorption in young women, and the relationship between faecal phytate and mineral excretion was affected by both dietary phytate and age.

Dietary Mg restriction is generally considered to contribute to the prevention of struvite urolithiasis in cats, but its effects on faecal and urinary excretion of Ca and P have not been systematically investigated. The present study seeks to fill the gap. In a 4×4-week crossover study, ovariectomized cats were fed on purified diets containing either 0·40, 0·79,1·59 or 3·17 mmol Mg/MJ (0·19, 0·38,0·76 and 1·52 g Mg/kg diet). Increasing the dietary Mg level from 0·40 to 3·17 mmol Mg/MJ by the addition of extra MgCO3 raised urinary and faecal excretion of Mg from 0·14 to 0·68 mmol/MJ and from 0·28 to 1·66 mmoI/MJ respectively. The 8-fold increase in Mg intake significantly raised urinary excretion of Ca from 0·06 to respectively when the dietary Mg level was raised from 0·40 to 3·17 mmol/MJ. A dietary level of 0·40 mmol Mg/MJ (0·19 g Mg/kg diet) was found to be sufficient to maintain Mg balance in the adult ovariectomized cats fed on the purified diet.

The effects of dietary P restriction to half the recommended minimum level on growth, bone and renal mineralization and urinary composition were studied in female kittens. In two separate experiments, 8-week-old weanling kittens were fed on purified diets containing either 4·6 or 9·2 mmol P/MJ (2·8 or 5·6 g P/kg diet). In the second experiment there was an additional low-P diet in which the Ca concentration was reduced from 9·5 to 4·8 mmol/MJ (7·5 v. 3.8 g Ca/kg diet). P restriction slightly but systematically reduced weight gain (to a maximum of 16%) and growth of the tibia (by 1–4%); the former effect was statistically significant (P < 0·05) between the ages of 15 and 20 weeks in Expt 1 only, and the latter did not reach statistical significance at any time point (P g 0·13). No adverse effect of P restriction was found on mineralization of femur at the age of 39 weeks. Kidney Ca concentrations were significantly lowered (Expt 1, 6 v. 20/μmol/g dry weight, P < 0-001; Expt 2, 7 v. 16/μmol/g dry weight, P < 0-01) in cats fed on the low-P diets, this effect not being affected by the dietary Ca:P ratio. Urinary P concentration was significantly depressed (by 50–96%) after feeding the low-P diets (P < 0-001). P intake did not influence P, Ca and Mg retention during the period of 15 to 39 weeks of age.