When pre-harvest foliar applications of growth regulators were made to vines of Dioscorea esculenta cv. Chinese Yam and D. alata cv. White Lisbon there were no obvious effects on tubers of D. alata, but dramatic effects on tuber development, storage and germination were obtained with D. esculenta tubers. Gibberellic acid caused marked extensions in tuber dormancy, 2,4-dichlorophenoxyacetic acid resulted in marked callus development, delayed germination and abnormal shoot and root development and indole acetic acid resulted in fingering of the tubers. It was concluded that there was potential for commercial exploitation of pre-harvest gibberellic acid treatments in extension of dormancy in Chinese Yam tubers and that the lack of response of D. alata tubers to foliar application of growth regulators warranted further investigation.

The study has comprised a detailed analysis of twelve samples of soil, ten of which were samples of typical peat soils, the other two being samples of normal soils. The degree of humification of the organic matter of the samples varied, that in the wet peats being high and low in the dry peats.

Extracts of the soil were obtained by the use of boiling hydrogen peroxide, 20 per cent, hydrochloric acid and 2·5 per cent, caustic potash.

Hydrogen peroxide extracted roughly 70–80 per cent, of the soil nitrogen, 60–70 per cent, of this soluble nitrogen appearing as ammonia through the oxidising effects of the reagent. The nitrogen compounds of wet peats were more easily oxidisable to ammonia.

Cowpea and sorghum grain crops, fertilized with 26 kg of phosphorus (P) per ha from either a P-soluble (SP) or a slightly P-soluble fertilizer (Kodjari, a natural rock phosphate (RP) indigenous to Burkina Faso), and cowpea and crotalaria (Crotalaria retusa) green manure crops, either unfertilized or fertilized with 26 kg P/ha from RP; were studied for their effects as preceding crop treatments for maize. The experiment was conducted in semi-arid West Africa (SAWA) at Farako-Bâ in Burkina Faso in 1983–86. Nitrogen (N) and soluble P fertilized and unfertilized subtreatments, applied to maize the following year, allowed the effects of the preceding crop treatments in improving soil fertility and the direct effects of P and N fertilizers applied to the maize crop to be assessed. Maize productivity was increased both by P fertilization and by soil improvements following cowpea and crotalaria; N fertilization in excess of 60 kg N/ha was not beneficial. Cowpea grain crop treatments, especially when fertilized with a P-soluble source, maximized maize yields, whereas cowpea and crotalaria green manure treatments were either similar to the cowpea grain treatment fertilized with RP or were intermediate between the latter and the sorghum treatment fertilized with SP. Sorghum, regardless of the source of P-fertilizer used, appeared not to be a suitable preceding crop for maize in SAWA.

The effects of N, P and K fertilizers on the yield and N, P and K contents of grass cut for conservation, measured during 1958–63, were again measured during 1964–7. Grass given 38 kg N/ha per cut needed 31 kg K/ha per cut for full yield, grass given 75 or 113 kg N/ha per cut needed twice as much K. With sufficient K, at least 75 kg N/ha per cut was justified. The grass responded little to P.

Percentage N in the grass, though greatly increased by N fertilizer, was little altered by K fertilizer. Percentage K, whilst greatly increased by K fertilizer, was decreased by N unless 62 kg K/ha per cut also was given. Percentage P in the grass was little increased by P fertilizer.

Exchangeable K in the surface soil (0–20 cm) was maintained with time where the grass was given either 38 kg N plus 31 kg K or 75 kg N plus 62 kg K/ha per cut, corresponding to an N:K ratio of 1:0·82. Percentage K in the grass decreased with time throughout. Whereas a N:K ratio of 1:1·66 best maintained % K in grass during 1958–63 it was no better than an N:K ratio of 1:0·82 during 1964–7.

Although exchangeable Mg in the surface soil decreased markedly between 1958 and 1967 (Mg fertilizer was not applied), % Mg in the grass did not. Mg in the grass was increased by N, but decreased by K fertilizer, and exceeded 0·2% (in dry matter) only in 1967 and then only where 75 or 113 kg N/ha per cut was applied.

The aim of the current work was to investigate the possibility of modifying the existing mean stage by weight (MSW) system for evaluating the average development stage in alfalfa. The modification was performed with the aim of providing a simplified system that may be used to evaluate the alfalfa development stage and to predict its nutritive value for ruminants. The suggested modification consists of designating an MSW value on the basis of the fresh weight of all morphological stages in a fresh green plant, as opposed to the original method which is based on weighing all morphological stages dried at 65 °C. The investigation was done on 141 samples of one alfalfa cultivar, collected from the same location during the first three growth cycles: spring growth, the first and the second regrowth. On all collected samples the following characteristics were determined: MSW, modified MSW (mean stage by fresh weight (MSFW)), crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), crude ash (CA) and in vitro organic matter digestibility (IVOMD). For these characteristics of chemical composition (apart from CA) and nutritive value the regressions were calculated for their prediction based on MSW and MSFW. The regressions were derived for individual growth cycles and all cycles combined. A trend for an increase in the coefficient of determination (R2) was identified as well as a decrease in root-mean-square error (RMSE) for all equations derived for all investigated characteristics from the spring growth to the second regrowth. A deviation from this trend was observed only in equations derived for IVOMD. A very high correlation was observed between MSW and MSFW (r=0·999). The determined R2 and RMSE were very similar within the same growth cycle in all regressions for prediction of chemical composition and nutritive value derived for MSW and MSFW. Based on the results of this investigation the MSFW appears to be a quick and accurate method for determining the average development stage in alfalfa which can therefore be recommended for both scientific research and practical field use, as well as for prediction of its chemical composition and nutritive value.

Experiments testing the effects on leafless peas of aldicarb, triazophos and a mixture of benomyl with zineb, were made on clay-with-flints soil at Rothamsted and on sandy loam at Woburn in 1977 and 1978.

The crop was shown to be susceptible to a wide range of pests and pathogens including the pea and bean weevil Sitona lineatus, the migratory nematode genera Pratylenchus, Tylenchorhynchus and Tylenchus, the pea moth Cydia nigricana, the aphids Acyrihosiphon pisum and Macrosiphum euphorbiae, the bean leaf roll and pea enation mosaic viruses and the powdery mildew fungus Erysiphe polygoni.

The mean yield of the four experiments when none of the treatments was applied was 3·6 t grain/ha, increased to 4·3 t/ha when all were applied. Aldicarb had the largest effect and increased mean yield at Rothamsted by 0·3 t/ha, attributed mainly to control of S. lineatus, and by 0·8 t/ha at Woburn attributed to control of S. lineatus and perhaps also to migratory nematodes, particularly Tylenchorhynchus. Triazophos and benomyl plus zineb did not individually increase yield but at Woburn when both aldicarb and triazophos were applied benomyl plus zineb increased mean yield by 0·7 t/ha.

All crops lodged severely, irrespective of treatment but perhaps because of experimental conditions. We suggest that susceptibility to lodging under field-scale conditions requires further study.

The joint action of two pyrethroid insecticides with several foliar fertilizers against the fourth-instar larvae of Spodoptera littoralis was determined. The rate of development of tolerance throughout three successive generations to insecticides alone and their combinations with fertilizers was also assessed. The results indicate that the toxicity of the insecticides tested was greatly enhanced by using fertilizers in admixture with each of them. Moreover, the inclusion of such fertilizers in spray emulsions slows down the development of tolerance to both insecticides. The synergistic action of fertilizers and the decrease in the induction of tolerance to insecticides can be attributed to the presence of inorganic ions and to decreasing the pH of both acidic experimental insecticides resulting in increasing the penetration rate of the internal membranes of the cotton leafworm.

1. Blood copper data are reported on ninety-four sheep divided into four experimental groups on a “border-pining” hill-side in Northumberland in 1940, in comparison with more extensive findings reported in 1939.

2. The mean value for comparable sheep was 0·080 mg. % in 1940 as compared with 0·086 mg. % in 1939, the overall range, 0·013–0·210 mg.%, being even wider than before.

3. Variations between animals comprising a group were as wide as between groups, and blood levels were not affected by moderate variations in Cu intake. Only in young sheep was there any evidence that a mineralized cake supplement, containing copper sufficient to double the natural grazing intake, had any elevating effect on blood copper.

4. Variations between values for the same individuals in 1939 and in 1940 were as wide as between different individuals in either year. Over 25% of the sheep showed Cu levels in 1940 falling within ±0·01 mg. % of their 1939 values, but nearly 20% showed figures differing by more than ± 0·05 mg. %, irrespective of differences in group treatments.

5. The significance of the figures, for normal. Northumbrian ewes is discussed in relation to those reported for Derbyshire ewes bearing lambs affected with “enzootic ataxia” or “swayback”.

On the Abu-Ghraib Experiment Station, milk production was investigated in 31 Awassi ewes of different ages and 12 newly imported Hungarian Merino ewes, two years old, together with the effect of age, lactation period, number of lambs born and reared and stage of lactation on milk production in the Awassi ewes. The relationships between milk production, birth weight and weaning weight of lambs were also investigated.

First-lactation milk yield during the suckling period (90 days) based on 12 h milking interval was 114·58 kg in the Merino and 75·29 kg in the Awassi.

Age had no significant effect on milk production in Awassi ewes although first-lactation yield was lower than that from subsequent lactations. Ewes that produced and nursed twins gave significantly more milk than ewes that produced and nursed single lambs.

Milk yield in Merino and Awassi ewes increased with the decrease of milking interval from 12 to 4 h. The correlation coefficients between milk yield during 12 and 4 h were positive and significant.

Correlation coefficients between birth and weaning weights and milk production were positive in both breeds. The correlation coefficient between weaning weight and milk production was 0·78 in the Awassi (P <0·01) and 0·65 in the Merino (P <0·05). The multiple correlation coefficient between weaning weight and birth weight and milk production was 0·67 in the Awassi and 0·43 in the Merino.

1. In metabolism experiments undertaken to study the channels of elimination of copper under varying conditions, the rabbit was chosen as experimental animal for convenience of manipulation. This choice, although not defeating the main objects of the work, accidentally added valuable informationon the little-known habit of “physiological faecal refection”in this animal.

2. On a normal diet of bran and oats, containing the usual traces of copper, the rabbit is in copper equilibrium, excreting as much in faeces and urine as is taken in the food. Urinary elimination is of the order of 0·07–0·38 mg. per litre, but this is very subsidiary to faecal elimination of about 2·5 mg. per 100 g. of dry matter, which may account for even more than 96 % of the total food copper.

3. Increase of food copper is not reflected by material increase of urinary output, the higher quantities appearing almost entirely in the faeces. Of 50 mg. of copper or nearly 200 times the normal food intake, as the dissolved sulphate dried on to the food, only 0·1 mg. appeared in the urine, the remainder being slowly excreted in the faeces over the unexpectedly long period of 4 or 5 weeks.

1. The reaction between lime sulphur and acid lead arsenate is shown to be small and to have little effect on the chemical properties of either material as a spray.

2. It is shown that the oxidation of lime sulphur proceeds according to the empirical formula:

CaS.Sx + 30 = CaS2O3 + Sx-1

and that the calcium sulphides are hydrolysed in aqueous solution.

3. The addition of lead arsenate has no effect on the amount of sulphur precipitated from the lime sulphur by oxidation or by the action of carbondioxide.

4. Lead arsenate is only slightly decomposed by lime sulphur or by the oxidation products of lime sulphur, the main decomposition being due to the action of sulphuretted hydrogen formed by the hydrolysis of the calcium sulphides. This decomposition becomes marked in the presence of carbon dioxide which reacts on the calcium sulphide to form sulphuretted hydrogen.

5. The fungicidal value of the mixed spray—as judged by the mildew killing properties of the polysulphides—is not less than that of lime sulphur alone. Additional fungicidal properties may be expected from the presence in the spray of soluble arsenates and thioarsenates.

6. Judging by the chemical changes which take place in the mixed spray the insecticidal value of the lead arsenate would not appear to be greatly affected by the addition of lime sulphur.

7. There is an increased amount of soluble arsenic formed by the action of carbon dioxide on the mixed spray which may prove sufficient in amount to cause spray injury.

8. The A.O.A.C. method for the determination of sulphate sulphur in lime sulphur solutions is shown to be inaccurate. A method yielding more concordant results is proposed.

Some years ago my colleague, Mr E. T. Halnan, suggested the construction of the present instrument for the purpose of determining figures for domestic fowls corresponding to those of Kellner for ruminants.

Owing to the activity of the fowl, it is essential that an instrument for this purpose should be capable of recording accurately a heat output which may be varying with some rapidity.

From this point of view the advantages of the indirect method were considered but were eventually rejected for the following reasons: (a) the advantage accruing from our greater experience of the direct method in this laboratory, (b) the work of Adams & Poulton (1933, 1934, 1935) calling in question the fundamental bases of the indirect method, and (c) the very variable R.Q.'S obtained in earlier work by numerous investigators working with birds.

That the decision was wise soon became apparent when work on birds was begun. It is certain that no ordinary apparatus of that kind could possibly take account of the variations caused by the constant changes in activity.

The principle of a “compensatory” or “balanced” calorimeter more or less as developed by Noyons (1927), Benedict (1927) and Heyster (1933), was selected as the most likely to give promptness in registration, and this choice has been amply justified in the result. Such instruments can be very lightly constructed, although where living animals are concerned, since their movements cannot be controlled, as can those of a human being, a greater margin of strength has to be provided, which naturally increases the heat capacity and lag and reduces sensitivity to small changes in heat evolution.

Concentrate diets supplemented with 5, 20 and 40% of a high- and a low-quality hay were given ad libitum to British Friesian steers from 9 weeks of age to slaughter. The intake of dry matter and metabolizable energy was studied over weight ranges from 91 to 363 kg live weight. The quality of hay did not significantly affect the drymatter intake at any of the weight ranges studied. From 91 to 182 kg live weight the daily dry-matter intake decreased as the proportion of hay in the diet increased. Over the weight range from 182 to 272 kg live weight, intake was maximum at the 20% level of hay supplementation, while from 272 to 363 kg live weight, intake increased with increasing levels of hay in the diet. The supplementation of high-quality hay significantly increased the intake of metabolizable energy by animals weighing 91–182 kg. Increasing proportions of hay in the diet significantly affected the metabolizable energy intake at all stages of growth studied.

At 18 and 36 weeks of age digestibility and N balance studies were carried out. The metabolizable energy expressed as a percentage of the gross energy and the mean retention time of the diets were significantly affected by the age of animal, quality of the hay and the level of hay supplementation. Nitrogen retention was also affected by the age of the animal but not by the quality of the hay.

The relationships between the voluntary intake of dry matter and the metabolizable energy of the diet expressed as a percentage of the gross energy, for different stages of growth, are also presented.

The change in the digestibility and the mean time of retention of the diets in the digestive tract with age and the effect of this on the point where physical regulation to intake gives way to physiological regulation are discussed.

Cold dehardening responses of seedlings of three cultivars of Lolium perenne L. (Premo, S.23 and Grasslands Ruanui) were studied in different temperature regimes following hardening at 2 °C. Seedlings of the three cultivars dehardened rapidly at 15 °C after partial hardening for 4 days, whereas there was a lag before dehardening occurred in seedlings of Premo and S.23 which were hardened for 28 days. At 10 °C dehardening did not occur in Premo and S.23 and occurred only slowly in Grasslands Ruanui. Alternating temperature regimes of 15 °C(day): 2 °C (night) gave increased levels of hardiness when the daily period of exposure to 15 °C was 8 h but only maintained the level of hardiness when it was extended to 16 h.

A tentative scheme of threshold temperatures for hardening and dehardening is proposed.

1. The effects of CCC, (2-chloroethyl)-trimethyl ammonium chloride, on the grain yields of wheat and barley in Britain were studied in field experiments in 1964 and 1965.

It has been shown that dried sugar-beet pulp contains a high percentage of pectose. A number of successive digestions of 1 hour each with 0·5 per cent. ammonium oxalate at 100° C. extracts an amount of pectin equal to 34·5 per cent. of the weight of dried beet pulp, basing the determination on the weight of crude pectin precipitated when the extracts are run into 95 per cent. alcohol. A single prolonged digestion gives a yield of crude pectin equal to 32·2 per cent. of the dried beet pulp.

Digestion with acidic reagents, such as 0·5 per cent. oxalic acid, 0·6 per cent. tartaric acid, N/20 hydrochloric acid, etc., leads to a quicker extraction of pectin, owing to a speeding up of the pectose to pectin hydrolysis. The yield of pectin, however, is not thereby necessarily enhanced, since under such conditions the pectin undergoes a slow secondary hydrolysis during the extraction with the formation of reducing substances not precipitated by alcohol.

Prolonged digestion at 100· C. of dried sugar-beet pulp with water alone also leads to a satisfactory extraction of pectin.

The object of the present investigation, was to compare the supplemental value of the microbial proteins in dried brewers' yeast with the animal proteins in white-fish meal when incorporated in a barley meal-fine bran diet containing a little lucerne meal and suitably adjusted as regards minerals. The investigation was carried out both by the nitrogen-balance method and by the statistically controlled growth method, using the individual-feeding technique. The main problem was to find the minimum percentage of yeast that had to be included in the cereal diet so as to sustain the same rate of growth and economy of food conversion, and to enable retention of nitrogen to take place at the same rate, as is obtained on a standard diet containing 7% of white-fish meal, the total digestible nutrients in all diets being kept approximately constant.

In the first nitrogen-balance trial a comparison was made between the standard diet containing 7% of white-fish meal and a similar basal diet supplemented with 15% of dried brewers' yeast. The percentage crude protein in the yeast diet was 15·39 as compared with 15·12 in the standard treatment, the total digestible crude protein being 12·34 and 12·29, respectively. The supply of total digestible nutrients was almost alike on both treatments.

After about 6 weeks on experiment, the two hogs on the yeast diet became subject to vomiting at rather frequent intervals, although they were always eager for their food and their faeces remained normal. It is unlikely that vomiting was caused by the presence in the yeast of any toxic substance and the possibility that it was due to the presence of live yeast cells is also remote for reasons given. The most likely hypothesis is that it was due to the animals ‘bolting’ their food with great avidity, since the pigs found the yeast diet to be highly palatable and they always appeared to be hungry.

The two hogs on the yeast diet made average daily live-weight gains of 0·85 and 0·80 lb., the figures over a corresponding period for the hogs on the standard treatment being 0·67 and 0·71 lb. Economy of food conversion was also better on the yeast treatment. The average daily retention of nitrogen was also higher on the yeast treatment the figures being 9·28 and 9·01 g. as compared with 8·07 and 8·90 g. on the standard diet. It is evident therefore that when yeast is incorporated in a cereal diet so as to bring the digestible crude protein content to the same level as in the standard treatment containing white-fish meal, maximum storage of nitrogen takes place, even with young pigs.

In the second nitrogen-balance trial the amount of yeast in the diet was reduced to 12% so as to investigate whether this amount would also support maximum retention of nitrogen and maximum growth. The percentage of digestible crude protein in the diet was 12·56 on the standard treatment and 11·29 on the yeast treatment, the total digestible nutrients being 64·47 and 64·18%, respectively. Over the 63 days that the pigs were in the metabolism crates the two hogs on the standard treatment made slightly higher live-weight gains and retained rather more protein in their tissues, the average retention of nitrogen being 9·43 g. on the standard diet and 8·3 g. on the yeast diet.

It appeared from these results that a cereal diet supplemented with dried brewers' yeast so as to bring the crude protein content to 14·18% (15·95% on the basis of dry matter) does not supply quite enough protein to support maximum retention of nitrogen. In the first experiment, however, when the yeast diet contained 15·39% of crude protein (17·37% on the basis of dry matter) the results were fully equal to the standard treatment containing 15·12% of crude protein (17·21% on the basis of dry matter). These conclusions were tested further by means of a growth trial with ten individually-fedpigs on each treatment.

In the growth trial the ten pigs on treatment A received a supplement of 9% of dried brewers' yeast, those on treatment B were on the standard diet containing 7% of white-fish meal and those on treatment C received a supplement of 12% yeast. The percentage of crude protein on the mean moisture basis was 14·62 in treatment A, 16·15 in treatment B and 15·4% in treatment C. It was concluded from the results of this growth trial that when approximately one-third of the total crude protein in the diet comes from either dried brewers' yeast or white-fish meal, complete supplementation of the proteins in the basal diet of barley meal and fine bran occurs, so as to enable maximum retention of nitrogen or maximum growth to take place without wastage of aminoacids. The results for treatment A suggest that the proteins in yeast may even be superior in supplemental value to the proteins in white-fish meal.

The deductions made from both methods of experimentation are therefore in close agreement and the results show that a basal diet of 2 parts of barley meal and 1 part of fine bran with a little lucerne meal and minerals when supplemented with dried brewers' yeast so as to bring the crude protein content of the mixture to about 15·5% enables the young pig to store the maximum amount of protein in its tissues and to grow at a maximum rate in conformity with the net energy content of the diet. The distribution of essential amino -acids in the proteins of yeast and in the proteins of whitefish meal, when based on equal weight of crude protein, is not significantly different, any differences being slightly in favour of the yeast proteins.

A comparison is also made between the results obtained with dried brewers' yeast and those obtained with extracted decorticated ground-nut meal used in previous trials.

Rice is the major food crop grown on black soils of southern India and these soils have problems of high zinc fixation due to high clay content, high pH and dominance of smectite minerals causing zinc deficiency problems. The addition of zinc fertilizers to these soils has often been ineffective as the element is transformed to unavailable forms particularly under flooded rice conditions. Studies on the distribution of fertilizer zinc among different pools of soil zinc (Viets, 1962) could be useful in formulating methods of zinc application for higher efficiency of utilization. An attempt was therefore made to study the transformations of added zinc in soils in field experiments conducted in a rice-rice sequence involving the use of 65Zn as a tracer.

1. The data used in this study were the estimated 210-day weights of 2351 calves born on eight farms in the years 1958–61. In each year data were only used from herds which recorded at least five calves of each sex in that year. One hundred such herd years were included in the study.

2. The mean 210-day difference in weight between male and female calves was 27 lb. 1202 male calves had a mean weight of 380 lb. and 1149 female calves had a mean weight of 353 lb.

3. The response of calf weight to age of dam was different in the two sexes. The weight of the female calf was found to increase with dam age in a linear fashion, whereas the response of male calves was best described by a quadratic relationship with the maximum response at a dam age of 8 years.

Six white clover genotypes that were easily distinguishable from each other on the basis of leaf lamina marks and morphology were grown at Lodi, Italy, during 1990 and 1991 in dense swards, under field conditions and a mowing regime, as (i) pure stands, (ii) a complex mixture of all genotypes, (iii) binary mixtures of each genotype with each of two ryegrass varieties, and (iv) complex mixtures of all clover genotypes in binary association with each grass variety. The grass components were of known, different vigour. The study assessed both intergenotypic and interspecific interference and related dry matter yield responses to morpho-physiological traits of the clovers, and also determined whether a high level of morpho-physiological heterogeneity conferred a yield advantage on clover populations.

Greater heterogeneity (i.e. a complex mixture of clover genotypes) did not produce higher clover yields either in the presence or absence of interspecific interference from grass; thus, the use of blends of varieties or the development of varieties with a fairly high degree of heterogeneity was not recommended for short-term meadows in environments with relatively low spatial and temporal variability. Interactions for yield occurred between clover genotypes and the presence or absence of intergenotypic interference (P<0·001), and between clover genotypes and the presence or absence of interspecific interference from the grass variety characterized by greater vigour and aggressiveness (P<0·01). The variance of the former interaction tended to be consistently larger than that of the latter interaction, indicating that competitive effects were greater between clovers than between the clover and grass components. A lower Spring [ratio ] Summer yield ratio and taller canopy tended to confer a competitive advantage under intergenotypic interference. Relatively better performance under interspecific interference was related to higher stolon density, suggesting that selection for this trait may increase the general ecological compatibility of large-leaved white clover types grown with vigorous grass companions.