1. The ash content of the skeleton of Cheviot ewes fed a daily ration containing about 4·5 g. of phosphorus fell by 18·8% between mid-gestation and mid-lactation, and 2 months after the end of lactation the loss was fully replaced.

2. In ewes fed a daily ration containing about 1·5 g. of phosphorus the loss of skeletal ash was 39·9% at mid-lactation, and this was not replaced 2 months after the end of lactation. When the phosphorus intake was raised in mid-lactation from 1·5 to 4·5 g. repair was greater but was still not complete.

3. Resorption was greater in bones rich in cancellous tissue, such as the cervical vertebrae, than in those rich in compact tissue, such as the shafts of long bones, but when severe resorption took place significant losses were found in the shafts of long bones as well as in other bones.

4. Whole blood inorganic phosphorus values were very low, particularly during lactation, in ewes fed on the low-phosphorus ration. When extra phosphorus was fed from mid-lactation onwards blood phosphorus values rose to normal in less than four weeks, a much more rapid recovery than that which took place in the skeleton.

5. Resorption of the skeletons of ewes on both moderate and low-phosphorus rations could be detected using radiographs taken of the radius in the living animal at mid-lactation, and severe resorption found in ewes fed on the low-phosphorus ration could be distinguished readily from the milder resorption found in ewes fed on the moderate-phosphorus ration.

1. The energy exchange of two sheep closely clipped at weekly intervals was determined at three feeding levels and seven environmental temperatures, using a respiration apparatus in which radiant temperature was equal to ambient temperature. All measurements were made under conditions in which the animal was in equilibrium with its environment and heat storage was zero.

2. Body weight and fleece growth were both markedly reduced at the lowest feeding level. Weight losses were most marked at the lowest temperatures.

3. The energy lost in faeces decreased slightly as environmental temperature increased from 8 to 38° C. Urine energy losses also fell. Losses of energy as methane were maximal in the temperature range 23–28° C. As a result of these changes, the metabolizable energy of food increased with environmental temperature by 7 Cal./24 hr./° C.

4. The environmental temperature of the sheep at which their heat production was minimal, i.e. the ‘critical’ temperature was 39–40° C. for the lowest feeding level, 33° C. for the medium feeding level and 24–27° C. for the highest feeding level.

1. The heat emission of two closely clipped sheep was studied in forty experiments in which three feeding levels were employed and in which environmental temperatures ranged from 8 to 38° C.

2. The sheep shivered at temperatures below 23° C., but the first reaction to cold was a corrugation of the skin referable to contraction of the fascial muscles.

3. As environmental temperature increased voluntary water consumption and urinary volume increased markedly. Only a small degree of cooling resulted from this warming of large quantities of water through a relatively small temperature gradient.

4. The basal loss of heat by vaporization of water was 316 Cal./m.2/24 hr. in one sheep (3) and 307 Cal./ m.2/24 hr. in the other (23). Increased vaporization occurred at environmental temperatures of 31° C. for the experiments at the low-feeding level, 27° C. at the medium level and 26° C. at the high level. The water-vapour loss increased subsequently by 87 Cal./m.2/24 hr./° C. change in environmental temperature in sheep 3 and by 88 Cal./m.2/24 hr./° C. in sheep 23. Respiratory frequencies increased with increasing heat loss by vaporization. Some evidence suggests that when the water-vapour loss was high the excretion of potassium through the skin was increased.

1. Fifteen calorimetric experiments were made with three sheep which had fleeces varying in thickness from 2·5 to 12 cm. All sheep received a constant ration, which corresponded in amount and kind to that given to closely clipped sheep in previous experiments (Graham et al. 1958).

2. The metabolizable energy of the food increased with increasing environmental temperature by 2–3 Cal./24 hr./° C.

3. Heat production remained constant throughout the range of 15–35° C. environmental temperature. Above 35° C. an increase occurred. At 11° C. a slight rise in heat production occurred in the sheep with a 2·5 cm. fleece. These results show that sheep with fleeces, in contrast to closely clipped sheep, have very wide thermoneutral zones.

4. Heat losses by vaporization of water converged to an identical value irrespective of fleece length at 40° C. The rate of increase of vaporization with environmental temperature at lower temperatures decreased as the fleece length increased.

5. Respiratory frequencies for given total watervapour losses were the same whether or not the sheep had a fleece.

1. Three female calves (Shorthorn, Zebux Australian Illawara Shorthorn, and American Brahman) of about 7–8 months old were exposed to different combinations of wet- and dry-bulb temperatures in the psychrometric chamber at the Physiology Department of the University of Queensland.

2. A capsule method has been developed for measurement of cutaneous evaporation from limited areas. This method has been described in detail.

3. Cutaneous evaporation from the shoulder area of the Zebu cross was significantly higher than that of the Shorthorn. There was, however, no difference between the two animals in their cutaneous evaporation from the belly area.

4. In the Zebu cross the cutaneous water losses from the shoulder area, on the average, increased linearly with increase in skin temperature. In the Shorthorn, there was no important increase in the cutaneous evaporation from the shoulder area, although the skin temperature increased by about 2–3/ F.

5. The Zebu cross had lower skin temperatures of the shoulder area when compared with that of the Shorthorn. These lower skin temperatures were associated with higher cutaneous evaporation.

6. Increase in rectal temperature was not accompanied by increase in cutaneous evaporation in all the three animals studied.

7. In all the three calves the cutaneous evaporation increased with increase in air temperature.

Two calves (Zebu × Australian Illawara Shorthorn and Shorthorn) of about 7–8 months of age were exposed to controlled atmospheric conditions. Cutaneous evaporation from the belly area of these calves was measured by the capsule method. Records of the temperature of the skin under test and that of the air passed over the skin was also maintained.

The amount of water passing through the cattle skin was proportional to the difference between the saturated water-vapour pressure at skin temperature and the water-vapour pressure in the air. Tests were made for the water-vapour pressure difference varying from 9 to 25 mm. Hg.

Two calves (Aberdeen Angus and American Brahman) were used exposed to different combinations of wet- and dry-bulb temperatures in a psychromatric chamber at the Physiology Department of the University of Queensland. These animals were 7–8 months old when first exposed to heat.

Effect of various drugs affecting the sympathetic nervous system (adrenaline, noradrenaline, Dibenamine, Priscol, atropine and acetylcholine) on the rate of cutaneous evaporation in calves was tested. Cutaneous evaporation was measured by means of a capsule before and after the administration of these drugs.

Cutaneous evaporation increased with the introduction of adrenaline and was suppressed by the administration of Dibenamine. Noradrenaline and Priscol had no appreciable effect. Acetylcholine failed to stimulate sweating and atropine did not block the sweat glands.

Sweat glands of cattle were, therefore, found to be functional and their innervation adrenergic. Cattle use sweat to prevent body temperature from rising, yet the amount of sweat secreted is not large enough to allow cattle to maintain thermoneutrality at high air temperatures.

1. The volume of rumen liquor in milk-fed calves at different ages up to 32 weeks was estimated by injecting polyethylene glycol into the rumen and subsequently determining its concentration in the rumen liquor. This volume increased progressively with age in relation to unit body weight. The increase xswas approximately fourfold between 4–8 weeks on the one hand and 28–32 weeks on the other.

2. The amount of milk entering the rumen during a feed was estimated at different ages up to 32 weeks by the subsequent determination of the volume and fat content of the rumen liquor. In the majority of cases less than 5% of the milk fed entered the rumen. There did not appear to be any increase in the quantities of milk entering the rumen as the calves got older.

3. An estimate of the rate of flow of fluid into and out of the rumen (other than milk at feeding) was made by measuring the rate of disappearance of polyethylene glycol from the rumen. A mean figure of 255 ml./hr./100 kg. body weight s.d. ± 50 was obtained in this way. It is suggested that this value probably represents the rate of flow of saliva.

4. Magnesium, in a concentration up to about 8 mg./100 ml. in the rumen liquor, did not appear to be absorbed to more than a small extent through the rumen wall.

1. The peripheral metabolism of thyroxine in sheep in pregnancy was investigated by measuring the rate of disappearance from blood of injected 131I-thyroxine. Only limited changes in thyroid metabolism during pregnancy were observed. The rate of turnover of thyroxine slightly increased, but this was not accompanied by increased levels of plasma protein-bound iodine (PBI), or thyroxinebinding protein.

2. In a 3·5-month foetus, the thyroid was active, and a marked concentration of iodide by the foetus was observed. The significance of this activity could not be assessed in the absence of knowledge on the placental passage of iodide or thyroxine in the sheep.

3. Knowledge of thyroid metabolism is inadequate at present to explain any correlation between animal productivity and either hormone supplementation, or PBI concentration.

1. Thirty-four lambs varying from 1 week old up to 22 weeks have been treated with: (a) p.m.s. alone; (b) Progesterone + p.m.s.; (c) p.m.s. + chorionic gonadotrophin (c.g.).

2. At 1 week old the lamb's ovaries were unresponsive to treatment (a).

3. At 4 weeks follicular growth was obtained in groups treated with both (a) and (b).

4. At 8 weeks of age follicular stimulation was obtained from treatment (a), follicle luteinization from (b), and ovulation from (c).

5. At 10 weeks luteinization was observed in (b) and ovulation in (c).

6. At 12 weeks luteinization occurred following treatment (a) and ovulation followed treatments (b) and (c).

Since the introduction of silos and associated techniques of ensilage production in the late 1870's, maize has been the principal silage crop in the United States. Many British authorities agree that maize is a ‘splendid silage crop, highly nutritious, heavy yielding and easy to cut and handle’ (Bond, 1948, see also Watson & Smith, 1956; Woodman & Amos, 1944) but, nevertheless, it is very rarely grown in Britain for silage. In this country, as in most countries of Western Europe, the predominant aim of maize cultivation has been to produce succulent green fodder for direct feeding to animals during time of drought and consequent grass shortage. The acreage grown in England is small, but in Western Germany in 1955 there were about 100,000 acres of fodder maize (Becker, 1956), while in France, in 1954, the acreage exceeded 500,000 (Desroches, 1955). Recently in Western Europe considerable interest has been shown in the possibilities of maize as a silage crop, and within the past few years preliminary results have been reported from Holland (Becker, 1956; Anon. 1954, 1955); Denmark (Bagge & Hansen, 1956); Belgium (Lacroix, 1955; Ledent, 1955); Germany (Jungehulsing, 1955; Schell, 1954); France (Desroches, 1955), and Switzerland (Bachmann, 1952).

Quantitative aspects of skin follicle population growth and maturation in post-natal life from birth to 16 months have been studied in four groups of N-type and non-N New Zealand Romneys. The following characters were observed on skin biopsy specimens from a standard position on the mid-side in all cases: total and primary follicle population density; ratio of secondary to primary follicles ; primary and secondary fibre diameter; primary/secondary fibre diameter ratio ; and the incidence and degree of primary and secondary fibre medullation.

No important differences were found between the genotypes examined in any of these characters except primary fibre diameter , the primary/ secondary fibre diameter ratio ; and the incidence and degree of primary and secondary fibre medullation. These characters individually, but especially in combination, appear of great diagnostic value at all post-natal ages in discriminating N-type from non-N genotypes, in terms which reduce the number of assumptions necessary on the relations between the fibre types of the staple and the follicles of origin in the skin.

Data concerning a random sample of flocks in Yorkshire and Lancashire were collected, in the form of answers to a questionnaire. Information was received from 88% of the 272 farms approached.

The present survey, a more detailed repetition of one performed in 1952–53, has extended the information already collected and enabled deductions to be made regarding the relationship between disease losses, breed and husbandry methods. The advantages and disadvantages of this type of survey are discussed.

1. The technique for assessing rejection and acceptance thresholds for gustatory sense in goats is described.

2. Quinine dihydrochloride is rejected at a level of 125 mg./100 ml. and accepted at 12·5 mg./100 ml.

3. Sodium chloride has a rejected threshold of 5·0 g./100 ml. and an acceptance threshold of 1·25 g./100 ml.

4. Acetic acid is rejected at 5 ml/100 ml. but is accepted at 1·25 ml./100 ml.

5. Glucose does not provide data for the assessment of thresholds, since all the goats consume solutions containing the highest concentration of glucose offered, viz. 40 g./100 ml.