1. An experiment was carried out from 1 August 1953 to 31 July 1955 to compare strip grazing with rotational grazing on the basis of the total animal production obtained from dairy cattle on irrigated pasture.

2. The same overall stocking rate was used for both treatments. Herbage surplus to grazing requirements at any time was conserved as hay and fed back to the appropriate group of cows at the end of the grazing season.

3. The aim was to manage the area under each technique as efficiently as the technique permitted.

4. The average production from the rotationally grazed group during the main pasture season of 260 days was 8740 lb. milk per acre (including 354 lb. of butterfatand 766 lb. of solids-not-fat) and from the strip-grazed group 8867 lb. milk per acre (including 358 lb. of butterfat and 766 lb. of solidsnotfat).

The average weight of pasture nutrients utilized per annum by the rotationally grazed group was 5887 lb. starch equivalent per acre and by the stripgrazed group 5896 lb. starch equivalent per acre.

None of the treatment differences in animal production was significant.

5. The differences between the results of this experiment and those obtained by other workers are discussed.

1. The effect of treating mineral soils with hydrofluoric acid to decompose clay minerals on the extraction of soil organic matter by alkaline and neutral reagents has been investigated.

2. It was found that treatment of soil with hydrofluoric acid had little effect on the extraction of organic matter by alkaline or neutral reagents, but that it released considerable amounts of ammonium and organic matter. More than 90% of the nitrogen in Rothamsted soils was dissolved by repeated treatments with dilute solutions of hydrofluoric acid and sodium hydroxide.

3. It is shown that treatment of clay minerals with n-HF:n-HCl solution at room temperature for 24 hr. effects quantitative release of fixed ammonium from clay minerals and that similar treatment of soil is not likely to cause significant decomposition of organic nitrogen compounds to ammonium. It is suggested that a method based on this treatment may prove useful for the determination of fixed ammonium in soil. Results obtained by this method indicated that 4–8% of the nitrogen in surface soils and 19–45% of the nitrogen in subsoils examined was in the form of fixed ammonium.

4. It is concluded that some mineral soils contain a significant quantity of ammonium and organic matter intimately associated with clay minerals and that this clay-bound material is not dissolved by neutral and alkaline reagents used for the extraction of soil organic matter, but is released by hydrofluoric acid.

1. A method of determining fixed ammonium in soil based on estimation of the difference in the amounts of ammonium released on treatment with N-HF:N-HC1 and with N-KCI has been investigated and compared with the hydrofluoric acid method of Rodrigues and the alkaline distillation method of Barshad.

2. Results obtained by the N-HF:N-HCl procedure with profile samples of various soils indicated that 3–8% (average, 5·6%) of the nitrogen in the surface soils and 9–44% (average, 21·5%) of the nitrogen in the subsoils examined was in the form of fixed ammonium. Rodrigues's method gave much higher values and Barshad's method gave much lower values.

3. Studies on the forms of nitrogen in soil profiles showed that the proportion of soil nitrogen released by acid hydrolysis as total-N and α-amino-N decreased with depth in the profile, whereas the proportion liberated as ammonium by acid hydrolysis increased with depth. They also showed that a considerable amount of the ammonium released by acid hydrolysis was derived from fixed ammonium in clay minerals.

4. It was found that the proportion of soil nitrogen dissolved by N-HF:N-HCl increased with depth in the profile, whereas the proportion dissolved by neutral and alkaline reagents used to extract soil organic matter decreased with depth. On the average, 23·2% of the nitrogen in the surface soils and 47·4% of the nitrogen in the subsoils was dissolved by a single treatment with N-HF:N-HCl at room temperature for 24 hr.

5. The reliability and significance of the results obtained by the N-HF:N-HCl method are discussed.

The response of S. 123 extra-late-flowering red clover in the year of sowing to three sprayings of gibberellic acid (GA) given at 28-day intervals is described. Plants in both soil and vermiculite cultures were used.

1. The first effects, noticeable in the basal rosette, were an increase in petiole length and a parallel increase in leaf area.

2. Fewer stems were formed on the treated plants but their thickness and the number and length of the internodes were increased.

3. Secondary branching was not significantly increased but the GA-treated plants produced a large number of tertiary branches from axillary buds on the secondary branches. Tertiary branching was not frequent in the control plants.

4. Cauline leaves showed an increased length/breadth ratio at each node with treatment, elongation tending to be most marked at those nodes where leaf formation coincided with GA sprayings. Leaf thickness was also increased by GA treatment.

5. Treated plants produced nearly 80% more heads, and flowering after GA treatment was up to 14 days earlier than the control.

An American Brahman calf of about 7–8 months age was placed in a hot chamber with a temperature of 108° F. dry bulb and 92° F. wet bulb. Sweat droplets were detected by preparing sweat prints on tannic acid papers applied closely to shaved skin areas smeared with ferric chloride solutions. The distribution of sweat spots on the sweat prints is similar to that of sweat glands.

An experiment is described in which sixty-four individually-fed pigs were used to investigate the effects of dietary protein status and administration of aureomycin on growth, efficiency of feed utilization and carcass conformation.

The main features of the results obtained were:

1. Pigs fed a ‘standard’ protein diet showed superior performance in terms of growth and economy of feed utilization in comparison with a ‘substandard’ ration. Appreciable differences in carcass quality including reduction in backfat and total body fat, concomitant with an increase in the lean meat content also resulted from variation in ration protein content. These results have been discussed in terms of the possible significance of both dietary crude protein status and amino acid content.

2. The administration of aureomycin at a ‘nutritional’ level had no apparent effect on any of the indices of pig productivity subject to analysis.

3. The high killing percentages noted over-all, have been discussed in relation to dietary energy and fibre levels.

1. The availability of iron in three species of grass has been investigated using the rat as the experimental animal.

2. Two procedures, namely, the increase in blood haemoglobin concentration, and the gain in total gramme of haemoglobin by nutritionally anaemic rats were employed.

3. Inorganic iron, as ferric chloride, was shown to be significantly more available than the iron contained in the three grasses.

4. The iron in the grass timothy was found to be significantly more available than that in ryegrass or cocksfoot.

5. Possible reasons for the differences in iron availability were discussed.

Quantitative and qualitative bacteriological comparisons were made between complementary samples of cud and rumen contents using five fistulated cows receiving various diets; no marked differences were observed between samples taken from the same animal at the same time. This, with the method of collecting cud described, simplifies bacteriological evaluation of the rumen contents of intactanimals.

1. The desirability of employing the genetic variation present in diploid and tetraploid wild species for the improvement of the cultivated hexaploid species stimulated an investigation into the synthesis of various amphiploid forms in Avena.

2. Five amphiploids at the hexaploid level have been produced, but the present investigation is limited to the amphiploids developed from the cross A. barbata (2n = 28)×.A. strigosa subsp. hirtula (2n= 14), their hybrids with the natural hexaploid species and with other amphiploid types.

3. These amphiploids, like their parents, possessed black paleae, with hairs and a fairly strong geniculate awn on both the lower and upper grains. The bases of both the lower and upper grains possessed the articulation surfaces characteristic of A. fatua. Their hybrids with A. fatua were similar in spikelet morphology, but the A. sterilis type of spikelet was dominant in both the amphiploid 6x × A. sterilis and amphiploid 6x × A. byzantina. Partial dominance of the cultivated type base over the shedding type was evident in crosses with A. sativa and A. nuda but the naked caryopsis and multiflorous spikelet were recessive in the latter cross. In crosses between the A. barbata/A. hirtula 6x amphiploid and the A. abyssinica/A. strigosa 6x amphiploid (Cc 4387) the hybrid exhibited a reversal of dominance relationships, with the cultivated base type of Cc4387 being completely recessive to the shedding base.

1. Seven experiments on spring barley and five on spring wheat carried out in 1955–7 compared dressings of ammonium sulphate and calcium nitrate applied to the seedbeds at 0·3 and 0·6 cwt. N/acre. The fertilizers were tested both when broadcast and when drilled with the seed.

2. Consistently higher yields of barley were produced by drilling than by broadcasting ammonium sulphate. Drilling calcium nitrate at 0·3 cwt. N/acre was superior to broadcasting for barley but when applied with the seed at 0·6 cwt. N/acre this fertilizer retarded germination and early growth and gave smaller yields than were obtained by broadcasting. Broadcast dressings of both fertilizers gave higher yields of wheat than combine-drilled dressings. There is a considerable risk of fertilizer ‘scorch’ when compound fertilizers containing all their nitrogen in nitrate form are combine-drilled at rates sufficient for maximum yield. This risk may be discounted when adequate rain follows drilling but the check to germination may be sufficient to reduce yields in dry springs, on light soils, and on badly prepared seedbeds. Fertilizers containing all their nitrogen in ammonium form appear to be quite safe at the rates of dressing tested in this work.

3. Calcium nitrate and ammonium sulphate gave similar yields and nitrogen contents of both crops when the fertilizers were broadcast on the seedbed. Nitrates applied at sowing-time to cereals grown in the drier parts of the country do not appear to be leached out of the root-zone before they can be taken up by crops.

1. Fractionation experiments have been described in which powdered bone materials were extracted with dilute acids using three different techniques. Ethylene diamine tetracetic acid (EDTA) was also used in one series of experiments.

2. The results suggested that the magnesium of bone is present in two main forms, one relatively soluble and the other relatively insoluble in dilute acids.

3. It appeared that a large proportion (at least 70%) of the total bone magnesium was located on the surfaces of the bone crystals either as Mg2+ or MgOH+ ions adsorbed at the primary cation adsorbing centres (the surface phosphate ions of the apatite crystals) or as Mg2+ ions replacing surface Ca2+ ions of the crystal lattice.

4. Evidence that magnesium carbonate does not occur in significant amounts in bone salt was obtained.

5. These results were discussed in relation to the hypomagnesaemia of lactating cows.

6. The carbon dioxide of bone also appeared to be present in two main forms, one relatively soluble and the other relatively insoluble in dilute acids.

The effect of environment on the production and size of eggs, feed efficiency and mortality of New Hampshire hens in individual cages was studied simultaneously in five areas of Guatemala having temperatures covering a range of 0°–45° C. with variable humidities.

While birds housed in the tropical lowlands did show visible signs of thermo-stress, there were no significant differences in egg size, production, feed consumption, mortality and body weight between areas or between groups within areas. The inconsistency of these data with other published reports is explained on the basis of the observed extremely wide diurnal range for temperatures and humidities. An attempt is made to present accepted physiological phenomena in the form of a working hypothesis wherein the diurnal temperature range is related to the fowl's tolerance to thermo-stress.

1. Results are reported of an experiment carried out under commercial conditions to obtain information on the effect of four different levels of allmeal feeding on the performance and carcass grading results of fattening pigs.

2. There were four treatments. All pigs were given the same meal mixtures and were fed dry and ad lib. up to four different daily maximums, namely, 6½, 6, 5½ and 5 lb. meal/pig/day. There were five pens of nine group-fed pigs on each treatment, involving a total of 180 pigs. The pigs were on experiment from approximately 8 weeks of age to bacon weight. Comprehensive carcass measurements were made on all pigs.

3. The results showed that as the level of feeding was decreased, the growth rate of the pigs, back fat thickness and belly thickness were reduced, and the depth and breadth of eye muscle were increased, while the efficiency of food utilization, carcass dressing percentage and carcass length were not markedly affected. Commercial grading results similarly improved as the level of feeding was reduced.

4. It was concluded that under the conditions prevailing, the maximum daily meal allowance should be of the order of 5½ lb./pig in order to obtain relatively satisfactory carcass grading.

5. Subdivision of the carcass measurement and commercial grading data according to sex of pig showed that in general at each level of feeding the carcasses of the female pigs were superior to those of the male animals.

The possibilities of segregating pigs according to sex during fattening as a means whereby undue retardation in the growth rate of the females might be prevented without adversely affecting their carcass grading, was discussed.

1. Four varieties of marrow stem kale, three of thousand headed kales, Hungry Gap Kale and Rape-Kale were grown at three centres in mid-Wales. They were sampled in the early winter period and separate leaf and stem samples analysed for the proximate constituents and minerals.

2. Leaf to stem ratios were measured on both a green and dry matter basis and the latter values used to calculate whole plant values for the chemical constituents.

3. The leaves of the marrow stem kales were higher in dry matter than the stems, except in the case of the Purple Stem Kale. This variety resembled the thousand headed and rape-type kales in having a higher dry matter in the stems. On a dry matter basis, the leaves of all the varieties were richer than the stems in ether extract, crude protein, total ash and all the minerals except potassium and sodium. These elements occurred to a greater extent in the stems of the fleshy stemmed marrow stem kales than in the leaves. The stems were higher in crude fibre and nitrogen-free extractives.

4. The leaves of the rape-type kales were higher than those of the other varieties in silica, phosphorus and potassium. They were the best source of phosphorus on a whole plant basis. The marrow stem kales had considerably higher leaf and stem values for sodium and were markedly superior to the other varieties as a source of the element.

1. Three varieties of giant rape, two broad leaved Essex rapes, Hungry Gap Kale and Rape-Kale, were grown at two centres in mid-Wales. They were sampled in the early winter period and the samples divided into separate leaf and stem samples. These samples were used to calculate leaf to stem ratios on a green and dry-matter basis.

2. The levels of the proximate constituents, silica, calcium, magnesium, phosphorus, sodium, potassium, chlorine, total sulphur, sulphate sulphur and ‘organic’ sulphur were determined in the dried samples. Whole plant values were calculated from the leaf and stem values with the appropriate leaf to stem ratios.

3. The leaf values for ether extract, crude protein, silica-free ash, silica, calcium, phosphorus, magnesium, chlorine, total sulphur and ‘organic’ sulphur are higher than the corresponding stem values. For dry matter, crude fibre, nitrogen-free extractives and sodium the reverse is found, whilst for sulphate sulphur there is no definite distribution.

4. There are no significant differences in composition between the main groups of varieties, and the rape-type kales are very similar to the other rapes in this respect.

Small doses of oxalic acid were given to sheep and typical results in sheep receiving 3 and 6 g. per day are given in detail. Little was excreted in the faeces, although sufficient calcium was present in the faeces to combine with 12 times the amount of oxalate present. The blood urea value rose, the blood calcium fell and there was an increase in the CO2 combining power. Only very small amounts of oxalic acid were found in the tissues after death. Sheep receiving the larger dose showed typical acute changes in the kidneys with deposition of crystals. Nevertheless, little evidence of renal failure or actual obstruction was obtained, the volume of the urine being maintained and the urea concentration remaining normal.

Subacute oxalic acid poisoning was reproduced by the administration of varying doses of oxalic acid. The amount needed varied according to the nutritional status of the animal immediately prior to the experimental period. If lucerne was present in the diet or if calcium or strontium was added much larger doses were tolerated. Such an animal excreted large amounts of oxalic acid as oxalate in the faeces, and as carbonate and oxalate in the urine. In animals which failed to survive the blood urea rose, while the amount of carbonate in the urine did not. In many such animals there was a decrease in blood calcium. It is considered that the major portion of the oxalate is decomposed by bacterial action in the rumen and that the primary factor in subacute oxalic acid poisoning in sheep is rumen dysfunction due to its effect on the pH of the rumen.

Field experiments are described comparing the yield of herbage on a series of grass-clover plots which were irrigated after various deficits had developed. In addition to the irrigation treatments, different rates of nitrogen were applied.

The maximum yields were obtained when only small deficits were allowed (maximum pF 3·3). This applied particularly to grass-clover swards to which no nitrogen fertilizer was applied.

There was not much reduction in yield on predominantly perennial ryegrass swards liberally supplied with nitrogen when larger deficits were allowed to develop (pF c. 4·0).

Estimates of soil water deficit from meteorological data using Penman's method agreed very well with direct measurements.

1. Six methods of diluting chicken's blood prior to counting erythrocytes and leucocytes in haemacytometers have been studied. No difficulty is found in recognizing erythrocytes. The most satisfactory method of counting leucocytes was the method described by Natt & Herrick (1952) in which the diluent contains methyl violet. Formulae are given which enable standard errors of estimates to be calculated.

2. Three methods of staining blood smears for the differentiation of the various leucocytes have been studied. The method using Leishman's stain appeared to result in good differentiation and was simple to use. However, an experiment to study sampling errors has shown that there may be considerable differences between observers in the percentages of lymphocytes and heterophils when the latter are high, showing that the estimates of these quantities may be biassed. These differences may have been caused by a tendency for heterophils to concentrate to the edges of the smears and for the observers to select different fields for their counts.

3. Although blood counts varied only slightly during the day, there were considerable differences from day to day. The average erythrocyte count for ten chickens fluctuated between about 2·9 and 3·5 millions per mm.3 during the first 3 weeks after hatching and was more steady for the next 4 weeks at about 2·9 millions per mm.3. The average leucocyte count rose from about 10,000 to 35,000 per mm.3 during the first 7 weeks of life, the rate of increase being greatest when the chickens were youngest; the rise was mainly due to a rise in the number of lymphocytes.

4. There were also considerable differences in blood counts between chickens even though environmental and genetic conditions were standardized as far as possible.