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Euthanasia of chickens, young and mature rats, and mice was assessed using chloroform, carbon dioxide and ether. Behavioural patterns were recorded to give some indication of the stress involved. Carbon dioxide induced collapse faster (11.2 +/- 0.4 s) than chloroform (18.9 +/- 0.4 s) or ether (greater than 60 s). With regard to the time taken to death, in carbon dioxide mice had the shortest time (48 +/- 10 s) and mature rats had the longest time (135 +/- 10 s). In chloroform, the only difference was the delayed onset of death (127 +/- 10 s) in the chicken. Behavioural patterns were similar for the chicken in carbon dioxide and chloroform, except for wing flapping, even when unconscious, in carbon dioxide. Chloroform is recommended as more aesthetically acceptable for euthanasia of chickens. Carbon dioxide is recommended for the euthanasia of both rats and mice, considering behavioural criteria. Ether is unsuitable as a euthanasia method as it is dangerous, slow acting and an irritant.

A total of 40 individually-penned British Friesian male calves were offered milk substitutes ad libitum from 2 days until 12 weeks of age. Ten milks were reconstitued from either liquid or spray-dried skim milk and a fat-filled (500 g fat per kg) powder and contained 80, 110, 140, 170 or 200 g dry matter (DM) per kg liquid. A further six calves were used in a randomized-block experiment to measure the digestibility, absorption and retention of the diets containing 80, 140 and 200 g DM per kg.There are no significant differences in the intake, growth rate, digestibility, absorption or retention between calves given milk substitutes reconstituted from liquid or spray-dried skim milk.At all ages, as the DM concentration of the milks increased, liquid intake decreased but DM intake and live-weight gain increased. The mean live-weight gain was 0·99, 1·13, 1·16, 1·28 and 1·27 kg/day for calves given the milk substitute diet at concentrations of 80, 110, 140, 170 and 200 g DM per kg, respectively. The DM intake to live-weight ratios were constant at all ages when live weight was expressed to the power of 0·61.No significant adverse effect of the diets was evident from the fortnightly monitoring of jugular blood samples for packed cell volume and concentrations of glucose, urea-N, Na, total protein, albumin, globulin and haemoglobin; nor from faecal consistency, rectal temperature, heart rate and respiration rate.There was no indication that age affected digestibility, except that digestive efficiency was reduced in calves with diarrhoea, particularly at 2 to 4 weeks of age; nor that dietary concentration influenced digestion or absorption. The true absorption of N, Ca and P from the milk diets was high with mean coefficients of 0·99, 1·01 and 0·95 respectively. The main endogenous losses of N and P occurred through the urine and of Ca through the faeces.

I . Experiments are described in which the food intake and the water intake of sheep at a single meal were measured. The sheep were offered lucerne chaff ad lib. for z h only each day. 2.Following the peritoneal infusion of physiological saline the food intake increased, while the injection of a diuretic before feeding caused the food intake to be decreased.3. In eight experiments the osmolality of the ruminal liquor was increased by the addition to the rumen of NaCl, KCl or the salts of volatile fatty acids in 250 ml water. The decrease in food intake was related to the osmolality, but not to the energy content, of the added electrolyte solution. In a further experiment, sheep receiving a highly digestible lucerne chaff, containing I yo (w/w) NaCl, increased their food intake when water was added to the rumen.Other workers have concluded that gastric osmolality is an important variable in the control of food intake in monogastric animals. The results of the eight experiments now described suggest that ruminal osmolality is of similar importance in ruminants. 4.It is suggested that all these observations are consistent with the theory, which has been proposed for non-ruminant animals, that the food intake at a single meal may be related to the degree of tissue hydration at the beginning of the meal.In some previous experiments with sheep, Ternouth (1968) found that soon after the ingestion of lucerne chaff there was a 10 % reduction in the extracellular volume, but this volume returned to the prefeeding size 3 h later. In contrast, the osmolality and the concentration of sodium and chloride in the plasma increased, the increase beginning I h after the start of feeding and reaching maximal values 3-5 h later. These results suggest that a reduction of extracellular volume rather than an increased plasma osmolality causes satiety in the ruminant. If this hypothesis were correct, then the food intake of sheep at a single meal should be increased by increasing the extracellular volume and be decreased if the extracellular volume is decreased. The first part of this paper describes the effects upon the food intake of sheep, during a single meal, of increasing the extracellular volume by the infusion of physiological saline into the peritoneal cavity and of decreasing the extracellular volume by the use of a diuretic.During eating, the ruminant animal secretes copious quantities of saliva; this salivation is likely to be the major cause of the reduction of extracellular volume recorded by Ternouth (1968). During and shortly after the ingestion of food, the osmolality of the ruminal liquor rises above that of plasma (Warner & Stacy, 1965) and plasma fluids move across the ruminal wall (Engelhardt, 1966) causing a further reduction in the extracellular volume. In experiments in which the osmolality of the ruminal liquor was increased by the addition of NaCl to the food (Wilson, 1966) or by intraruminal infusion of volatile fatty acids or their salts