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The influence of ovarian steroids on food intake (FI), water intake (WI) and body weight (BWt) was measured under various conditions. Ovariectomy results in an increase in FI and BWt, which plateaued around one month after surgery. Daily injection of 1.5 μg oestradiol benzoate (OB) initiated at this time significantly reduced both FI and BWt. This effect of daily OB treatment on FI is only transitory since the FI returns to normal during OB treatment although the effect on BWt is maintained throughout and beyond OB treatment. Following ovariectomy, WI gradually falls, but is returned to normal by daily OB treatment. When oestrogen treatment is initiated at the time of ovariectomy, the increase in FI and BWt is prevented. In additional ovariectomized rats, 3 μg OB was injected every fifth day with either progesterone or oil administered on the intervening days. Although no influence of progesterone injection (either with OB or alone) was detected, the intermittent injection of OB induced cyclic suppression of FI, and the pattern of FI approached that of the intact cycling female. Adaptation to the intermittent injection of OB was not observed. Finally, OB treatment was found to decrease the increased FI seen during pseudopregnancy by a proportion similar to the effect of oestrogen in the long-term ovariectomized animal. These results suggest that oestrogen, but not progesterone, is the ovarian hormone active in the regulation of intake parameters and body weight in the female rat.

Introduction  Metabolism cages play a pivotal role in nutritional science as they are often used in experiments to determine nutrient requirements of animals, dietary nutrient digestibilities, endogenous excretions, glomerular filtration rates, mineral balance, 24‐h urinary excretion rates, etc. Such cages are a convenient way to obtain accurate data on the amount and frequency of excreta produced by animals. The accuracy of the procedures and equipment used for the measurement of excreta production, however, is often neglected, casting doubt on the results obtained. Recently, Wamberg et al. (1996b) showed that the recovery of urine collection from mink (Mustela vison) housed in a standard metabolism cage ranged from 68 to 88% in the fed state and 62–78% in the fasted state. This magnitude of under‐collection of urine will have a significant impact on data where quantitative urine collection is paramount, such as endogenous urinary excretions, and 24‐h urinary excretion rates. The main reason for the incomplete collection of urine in mink was attributed to the cross‐contamination of faeces with urine (Wamberg et al. 1996b). The domestic cat is a strict carnivore and has been noted to excrete relatively concentrated urine (Chew 1965; Anderson 1982). Under‐collection of urine, therefore, has a major impact on the measurement of excretion rates of urinary constituents and any subsequent derived data. The cat, furthermore, has been noted for oliguria, anuria and spraying of urine while held in metabolism cages (Worden et al. 1960; Klatt et al. 1975; Matandos and Franz 1980; Russo et al. 1986), making the domestic cat a difficult animal from which to collect excreta quantitatively. The main objective of this study was to validate quantitative urine collection from cats housed in specially designed metabolism cages fitted with a urine/faeces collection system when fed a nutritionally balanced diet and in the feed‐restricted state. Furthermore, the accuracy of water balance measurements using the metabolism cages and urine/faeces collection system was assessed in adult cats.

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Twenty-eight varieties of commercially-available cat food (23 canned, 5 dried) were analysed for iodine. The iodine concentration varied from less than 0.37 micromol/kg to 41.8 pmol/kg, wet weight (less than 1.48 micromol/kg to 167 micromol/kg, dry weight). Excessive or insufficient iodine intake or wide swings in iodine intake over prolonged periods may contribute to thyroid disorders in cats.