Partial regression analyses have been used to calculate mean values for the cation exchange capacities of the clay and organic matter from five groups of soils.

It has been found that figures obtained for exchange capacities of the clays were in accord with what was known of their mineralogical composition. The corresponding figures for humus differed widely, the differences approaching significance, and were related to the mean pH of the soil group concerned.

The data on which this paper is based were obtained when the authors were at the Agricultural Chemistry laboratories of the University of Sydney, to the Research Grants Committee of which they are greatly indebted for generous financial assistance. They are particularly indebted to Dr G. Wilkinson, C.S.I.R.O., Division of Statistics, Adelaide, for helpful discussions, to Miss H. V. Rayner and Miss J. Walker for certain of the analyses.

1. The age changes in carcass composition of female kids killed at birth, 9, 16, 25 and 30 lb. are described.

2. The organs and tissues of the kids were weighed both wet and oven-dried, allowing the dry-matter percentages at different stages of growth to be calculated. The total dry-matter percentage for day-old kids averaged 26·5%, rising to a maximum of 40·5% at the 25 lb. stage. The greatest increase in dry-matter percentage was between birth and the 9 lb. stage, which was reached at approximately 1 month. This increase in dry matter is chiefly due to a steady rise in the dry-matter content of the muscular and skeletal tissues; from 20·2 to 25·4%, and from 34·3 to 59·6%, respectively, between birth and maturity.

3. The various joints of the kid were weighed and recorded separately, and the changes in the proportions of the joints illustrated centripetal growth. At birth, the joints were present in the following proportions: thorax 30%; legs 40%; head 20%; pelvis 10%. As the kid developed, there was a marked increase in the proportion of thorax and pelvis, accompanied by a corresponding decrease in the proportion of the head and foreleg.

1. Methods of investigating denitrification in soil are critically discussed with special reference to methods based on total-N analysis.

2. A modified Kjeldahl method of determining nitrogen which includes nitrate and nitrite and is applicable to waterlogged soil is described and the use of this method in studies on denitrification in soil is illustrated and discussed.

3. It is shown that rapid denitrification of nitrate in soil can be induced by incubating the soil under waterlogged conditions with organic materials such as glucose and that denitrification can be followed by total-N analyses if the organic material used to induce denitrification is not added in such excess that it also promotes significant fixation of atmospheric nitrogen.

4. The percentage of added nitrate-N lost by denitrification on incubation of waterlogged soils with different amounts of nitrate and sufficient glucose for denitrification was found to be the same whatever the level of application of nitrate.

5. Denitrification of nitrate in waterlogged soil containing glucose was found to be accompanied by a rapid but temporary accumulation of large quantities of nitrite and by the formation of smaller amounts of ammonia. Hydroxylamine could not be detected during denitrification, but it was found that this compound was rapidly decomposed in the soils examined by a process which appeared to be purely chemical.

6. It is shown that denitrification of nitrate in soil is a microbiological process and that the viability of the micro-organisms responsible for denitrification is not affected by air-drying and storage of the soil.

1. The factors affecting denitrification in soil have been studied by determining loss of nitrogen from soil under various conditions by total-N analysis.

2. It was found that the rate of denitrification of nitrate in soil was dependent upon various factors such as the pH, temperature and water content of the soil and that, under conditions conducive to denitrification, 80–86% of nitrate-N added to Rothamsted soils was lost by denitrification in 5 days.

3. The rate of denitrification was greatly affected by the pH of the soil. It was very slow at low pH (below 4·8), increased with rise in soil pH and was very rapid at pH 8·0–8·6.

4. The rate of denitrification increased rapidly with rise in temperature from 2° to 25° C. The optimum temperature for denitrification was about 60° C.

5. The degree of water saturation of the soil had a profound influence on the rate of denitrification. Below a certain moisture level practically no denitrification occurred; above this level denitrification increased rapidly with increase in moisture content. The critical moisture level was about 60% of the water-holding capacity of the soil.

1. In eight experiments on main-crop potatoes in 1953–4 placing 0·5 cwt. N/acre in a band beside the seed tended to give higher yields than broadcasting the dressing; when 1·0 cwt. N/acre was applied, broadcasting tended to be superior to placement. There were no consistent gains from placing 1·5 cwt. K2O/acre.

2. Four other potato experiments in 1954–6 tested all combinations of placing and broadcasting two levels of nitrogen and potassium. There was no clear relationship between the effects of broadcasting or placing one nutrient and the way in which the other nutrient was applied. When 0·5 cwt. N was applied, placing gave higher yields in seven out of ten possible comparisons (one effect was significant). With 1·0 cwt. N/acre there were also seven of ten comparisons in favour of placement (three significant effects), but in two other comparisons broadcasting gave significantly higher yields. Placing potassium gave higher yields than broadcasting in sixteen out of twenty comparisons (six significant effects), in one of the remaining comparisons broadcasting potassium was significantly superior. Placing of the potassium and, to a lesser extent, the nitrogen components of a complete potato fertilizer is likely to be beneficial.

3. In two experiments each on green peas and broad beans placing of phosphorus and potassium separately and together gave consistently higher yields than broadcasting these nutrients. When nitrogen was used in addition to phosphorus and potassium there were small gains in yield of broad beans provided the mixture was placed. There were no gains in yields of green peas from nitrogen however the mixture was applied.

1. An experiment with dairy cows is described in which the production per animal and per acre obtained in three methods of grazing management were compared during 2 years.

(A) An intensive method. Strip-grazing daily on heavily fertilized grass sward.

(B) A modified intensive method. Continuous, free-range grazing on a heavily fertilized grass sward.

(C) An extensive method. Continuous, free-range grazing on a grass and clover sward receiving a basic application of phosphate and potash only.

The intensively fertilized swards received a total of 212 lb. fertilizer nitrogen per acre, together with adequate amounts of phosphate and potash throughout the grazing season. No supplementary foods of concentrate type were fed to the cows during the experiment.

2. For the comparison of production per animal 3 × 3 Latin-square experimental design, with twelve Ayrshire cows and periods of 3 weeks' duration, was used. Two separate trials were conducted during the grazing season of 1955 and a third trial during 1956.

3. The different methods of grazing management and intensive use of fertilizer had little influence on the milk yield and butterfat percentage of the milk of the cows.

1. Fifty buffalo-cows were used for studying the pH of the vaginal secretion at different stages of the sex cycle.

2. Highly significant differences were found in the pH value of the vaginal secretions during the different stages of the sex cycle. The average was 7·3 during oestrus, 8·1 during dioestrus and 8·3 during pregnancy.

1. Two groups of Rhode Island Red × Light Sussex pullets were housed respectively in batteries and in a fold unit.

2. Samples of the eggs produced were collected monthly and weights of egg fractions, quality tests on yolk and thick white, and porosity coefficients were determined.

3. The tests were continued for a 9-month period and no consistent differences were found in the quality of the eggs produced under the two systems of housing.

4. Colours of yolks produced by battery pullets were paler than those produced in the fold unit on grass. Yolk colour was improved by increasing the proportion of grass meal in the diet of battery birds.

1. Five out of six sheep ruminated more in terms of the total time spent ruminating when fed their food (dried grass) cut into approximately 2 in. lengths, than when fed the same quantity and quality of food in the long (uncut) state or when ground to a meal.

2. Grinding to a meal markedly reduced rumination times as compared with the same quantity and quality of diet fed long or chopped.

3. It is postulated that these effects may be related to the stimulation of rumination.

1. Two adult sheep were housed and fed once a day. The time of feeding was advanced round the clock by 4 hr. periods, one advance was made each week. The jaw movements of both sheep were simultaneously recorded for 48 hr. after the sheep had become accustomed to each time of feeding.

2. The time when rumination occurred was found to be independent of any time-relationship with eating.

The course of pregnancy was followed in three groups of Peppin-strain Merino ewes. Group 1 of seven ewes, maintained on a high plane of nutrition, all lambed; the mean birth weight of lambs was 8 lb. 6 oz. The six ewes in group 2, kept on a low plane of nutrition, all lambed; the mean birth weight of their lambs was 1 lb. 9 oz. lower (P<0·01). The seven ewes in group 3 kept on a low plane of nutrition and subjected daily to temperatures of 112° F. dry bulb, 92° F. wet bulb, produced only four lambs; the mean birth weight was 4 lb. 6 oz. less than those from group 1, and 2 lb. 13 oz. less than those from group 2 (P < 0·001).

Scale photographs of the lambs, and X-rays and measurements of their long bones, after dissection, showed that the lambs of group 3 were miniatures: their skeletons were much reduced in size, whereas low nutrition alone (group 2), caused little skeletal reduction.

The mechanism of dwarfing is not clear. However, fore-cannon bone lengths and liver weights, considered in relation to lamb birth weights indicated that it was not a nutritional effect.

This study was undertaken at the Physiology Department, University of Queensland. It is a pleasure to thank Prof. W. V. Macfarlane for the valuable facilities, and for his help and encouragement.

The literature specifically related to the effect of vitamin B12 on methyl group synthesis and its relationship to protein utilization in experimental animals is discussed.

The techniques and results of nitrogen balance experiments on control A.P.F.-deficient chicks and vitamin B12-treated chicks are presented.

Results show that vitamin B12 administration does not result in any direct effect on nitrogen retention or efficiency of utilization when control and B12-supplemented chicks are pair-fed. This finding is discussed in relation to the response of A.P.F.-deficient chicks to vitamin B12 and the significance of appetite as a factor in the response is suggested.

1. Dried molassed sugar-beet pulp was fed to dairy cows grazing abundant intensively managed pastures in two trials (spring and autumn), each of 8 weeks' duration. A change-over design (four 14-day periods) with twenty-four cows was employed in each trial. Apart from six changes for the autumn trial, the same cows were used throughout.

2. In the spring trial (May–July) 8 lb. beet pulp were fed daily. The herbage dry matter consumed contained, on average, 16·8% crude protein, and the general mean milk yield was 38 lb./cow/day. The milk yield of the supplemented cows was 1·3 lb. (3·7%) greater than that of the control animals (P < 0·05).

3. In the autumn trial (August–October) 10 lb. beet pulp were fed daily. The herbage dry matter consumed contained 23·8% crude protein and the general mean milk yield was 27 lb./cow/day. The milk yield of the supplemented cows was 2·9 lb. (11·3%) greater than that of the control animals (P < 0·001).

1. The metabolic interactions of casein and starch or other carbohydrates are measured by estimating the concentrations of volatile fatty acids, ammonia, lactic acid and amino acids in the rumen after administering the protein and carbohydrate supplements alone or together.

2. The ammonia concentration is reduced (i.e. its utilization is probably increased), by the carbohydrate materials; levan and starch achieve this slightly more effectively than glucose or xylan and the effect of cellulose is very slight.

3. Under conditions when the normal ration fed is not of high quality a small supplement of casein stimulates the rate of fermentation of starch and other carbohydrates.

4. The findings indicate that the best utilization of protein supplements is probably obtained when a carbohydrate is also present that can be fermented at a comparable rate, conditions which stimulate microbial synthesis in the rumen.

An investigation has been made on the changes in the haemoglobin index with age in four breeds of indigenous African and two breeds of European cattle.

1. Support is given to previous findings that the haemoglobin index was high and variable at birth and fell to an individual more stable adult level at between 2 and 3 years of age.

2. The haemoglobin levels for mature animals of the four tropical breeds are higher than mean figures quoted for other tropical cattle, but still fall within the ranges quoted.

3. The haemoglobin levels for the Friesian agreed with those quoted from temperate regions, but those for the Jersey were higher, agreeing most nearly with Jamaican figures. A reason for this is advanced.

4. The haemoglobin levels of the tropical breeds were significantly higher than those of the two temperate breeds examined.

5. Confirmation was given to the association of a high haemoglobin index with a high heat toleration coefficient.

1. The effect upon the carcass characters of indigenous steers of supplementing veld grazing with two levels of salt with and without protein in the dry season has been investigated.

2. The feeding of 1 oz. of salt, found in part I (Walker, 1958) to speed up growth to a significant degree, was shown also to have speeded up maturity in carcass characters.

3. No benefit was obtained from adding a dry season protein supplement to the salt; the feeding of protein without salt produced only slight insignificant effects.

4. The addition of 2 oz. supplementary salt noted in part I as having an inhibitory effect on growth by comparison with the lower salt level has been shown to extend to the carcass characters.

5. Additional evidence has been found in the carcass characters to give further support to the suggestion that the tropical indigenous animal possesses the capacity for stopping growth during adverse nutritional conditions and continuing again afterwards.