The primary growth of eight varieties from three species—white clover (3), red clover (4) and lucerne (1)—was sampled at fortnightly intervals during 2 years and the percentage N, P, K, Ca, Mg, Na and in vitro dry-matter digestibility (IVD) were determined.

Differences between species, date of sampling and years were highly significant for all constituents. Clover was significantly different from lucerne for all constituents except P, and white from red clover with the exception of Ca. There was a steady decrease in N, P, K, Na and IVD with advance of date of cutting but no marked trend in Ca and Mg. Some constituents changed considerably from first to second year, decreasingin the case of Ca, and increasing for N, P andNa; the remainder K, Mg, and IVD changed only 4–8%.

The varieties did not give the same relative results in the 2 years for P, K and Ca content, but there was no interaction for N, Na, Mg, IVD content. Species differences accounted for mostof these interactions.

Percentage composition is discussed in relation to the needs of cattle and it is concluded that these herbage legumes provided sufficient Ca, Mg, N, K, and Na (white clover, and the firsttwo cuts of S. 123 red clover and lucerne only) for milk production and growth. The level of P fell below the quoted needs of a 20 kg/day milking cow but was adequate for growth.

An artificial rumen technique which simulated in vivo conditions was applied to the study of the effects of non-protein nitrogen on fermentation and nitrogen distribution in the rumen. Using this technique it was possible to reproduce in vitro a series of biochemical and other effects on fermentation that had been produced in vivo by the addition of various sources and levels of non-protein nitrogen to the rumen. It was shown that with a basal diet of cellulose, protein was synthesized from urea both in the presence and absence of starch over a period of 24 h and a typical rumen fermentation pattern was maintained.

Results from three trials are presented. The main variables were date of harvest, plant density and variety. Measurements were made of whole-crop yields and yields from plant fractions (leaf, stem, cob). Quality components—digestibility, acid-pepsin solubility, water-soluble carbohydrates, nitrogen and ash—were estimated for whole crop and fractions. There were successive samplings for quality components.

Whole-crop yield from fractions and yield of quality components increased with density. Whole-crop yield differed significantly with harvesting date as did all fractions except cob, although the proportion of cob increased with time. The earlier harvesting date gave greater yields of quality components.

There was no effect of density on the dry-matter content but later harvesting resulted in higher dry matter.

The only quality component affected by density was nitrogen content but there were large effects of harvesting date on digestibility and the acid-pepsin components.

Regressions were computed for quality components on dry-matter proportion of cob and the dry-matter content of the whole crop. Regressions were significant for the acid-pepsin soluble components and the water-soluble carbohydrate component on the proportion of cob. Regressions of digestibility and pepsin-soluble components (total and organic) on dry-matter content were significant.

The implications of these findings to the breeding of maize varieties are discussed.

Crosses between eelworm-resistant tetraploid red clover plants varied significantly in corolla tube length and in the distance between the top of the nectar and mouth of the corolla tube. Variability between plants in height of nectar above the base of the corolla was positively correlated with corolla tube length but a significant residual variance in nectar height was independent of corolla tube length.

Tetraploids had higher nectar but longer corolla tubes and greater distances for bees to reach than those in related diploids which were previously reported.

The implications of the findings are discussed in relation to the improvement by breeding of the attractiveness of tetraploid red clover to honey-bees.

Winter wheat grown on a sandy-loam and on a clay-loam soil was given ammonium sulphate alone or treated with the nitrification inhibitor, 2-chloro-6-(trichloromethyl)- pyridine, drilled with seed, in autumn. In spring, dressings of treated or untreated ammonium sulphate or of calcium nitrate, were broadcast. 75 or 150 lb N/acre were given on the sandy loam and 50 or 100 lb on the clay loam. Plants were sampled during growth and grain yield was measured.

Without fertilizer-N, the wheat yielded 17 cwt/acre on the sandy-loam and 46 cwt on the clay, and with the double dressings given in spring yields were 52 and 56 cwt/ acre. On the light soil, treated ammonium sulphate given in autumn increased yield by 3–5 cwt/acre with the single dressing and by 5–4 cwt/acre with the double one.

On the heavy soil the inhibitor had no effect on yield. Dressings of 50 lb N/acre in autumn or spring increased yields equally, but with 100 lb N/acre the spring dressing increased yield slightly more than autumn dressings. Calcium nitrate at 75 lb N/acre was significantly better than ammonium sulphate on the light soil.

The inhibitor did not affect the speed with which N was taken up, or the total uptake, from fertilizer given in spring.

In tests with seedlings in the glasshouse, significant differences in susceptibility to downy mildew, caused by Peronospora farinosa f. sp. betae, were observed between individual stocks of sugar beet. The resistance of a particular stock in glasshouse tests was not always a reliable guide to its resistance in the field. There were also serious discrepancies between the results of tests with seedlings and those with mature plants in the field, suggesting that the resistance of certain stocks, relative to one another, may vary with increasing age of the host plant. This contention was supported by evidence from a field experiment in which the susceptibility of several sugar-beet stocks was compared throughout the growing season. It also appears that changes in environmental conditions affected resistance to downy mildew more in some stocks than in others.

Progenies of selected plants that had not shown severe symptoms of downy mildew, after exposure to natural inoculation with P. farinosafor more than 3 months in the field, were much more resistant than the parent stocks. This showed that a single generation of selection under suitable conditions can significantly improve the resistance of sugar-beet breeding stocks to downy mildew.

An inbred sugar-beet line of American origin showed exceptional resistance to downy mildew in experiments under glass and in the field. Inoculated plants of this line usually showed no symptoms of the disease and P. farinosa did not produce conidia on them. These results show that sources of extreme resistance are present in cultivated sugar beet and suggest that an excellent control of downy mildew in Britain may eventually be achieved through the use of resistant varieties.

Twenty-six soils from different parent materials were exhaustively cropped with ryegrass in the glasshouse. Soil and crop measurements revealed inter-relationships similar to those observed with Rothamsted soils (Part I) generally, except that 12 of 20 soils, ‘poor’ in K (as defined by the K intensity of the uncropped soil and the change in soil K intensity with cropping), gave patterns of K uptake by the ryegrass crop similar to those of soils ‘rich’ in K. This indicates that these soils contain some K reserves not differentiated from those accumulated by K-manuring in Rothamsted by laboratory measurements.

The cumulative K yield of ryegrass was very significantly related to the K intensity of the uncropped soil. The relationships were improved slightly by allowing for differences in soil pH and organic carbon content. The cumulative K yields at 16 weeks and at 60 weeks were better related to the total clay (<2 µ) content than to the fine clay (< 0·2 µ) content of the soil. The K intensities of the cropped soils decreased to nearly 10–3 (AR) units after 16 weeks cropping (except the Harwell soil which took 3 years to do so), although large differences in K yield persisted until much later.

Potassium-buffer capacity per unit clay content of the soil (by a laboratory method) was inversely related to the K intensity of the uncropped soil and to K uptakes at 16 and 60 weeks. The rea⋅ons for this apparent anomaly are discussed and a more correct basis for the units for K-buffering capacity is suggested. The buffer capacities of ‘rich’ soils in the laboratory and glasshouse experiments were significantly related but not of ‘ poor ’ soils.

Soils exhausted by cropping released more K to ryegrass after a. drying-and-wetting cycle in amounts proportional to the clay content of the soil. This points to the need for caution in measurements to assess status after air-drying soils.

Results are reported of twelve experiments—over a period of 11 years—on the effects of date of sowing on development and yield of maize at the Oxford University Field Station, Wytham. Information was obtained on 14 varieties, representative of the range of types likely to be considered for commercial cultivation in England, and sowing dates ranged from mid-March until the end of June.

All varieties gave excellent emergence from May and June sowings but, from sowings made in March or early in April, some American varieties (e.g. White Horsetooth, Wisconsin 255) were slower and poorer in emergence than varieties of northern European origin. For northern European varieties emergence exceeded 70% from March sowings and approached 90% from mid-April sowings. Sowing date markedly affected speed of emergence. More than 40 days elapsed from March sowings until mean date of emergence; about 25 days from mid-April sowings; 18 days from late April sowings and 8–9 days from late May or June sowings.

Plants from sowings made in March or early in April were not significantly earlier or more productive than plants from sowings made in late April. For grain production, however, any further delay in sowing time usually led to lower yields, even with the earliest varieties tested. In contrast, final production of dry material from the shoot was higher, on average, from mid-May sowings.

Provided growth was not arrested by autumn frosts before flowering was completed, plants from later sowings were taller and had more leaves than plants from earlier sowings. The causes of these changes in plant development following variations in sowing date are discussed in the light of published information on the effects of temperature and of length of day on growth of maize.

The practical conclusion drawn from the experiments is that the end of April is an appropriate time to sow maize in central and southern England. No further delay is warranted for grain production. The effect of sowing date on the value of fodder or silage maize requires further information.

The production of herbage dry matter harvested from a mixture of S. 24 perennial ryegrass, S. 37 cocksfoot and S. 48 timothy is compared with the yields of the same species sown alone. Various levels of fertilizer nitrogen were applied to the grasses which were harvested by cutting fourteen times over a 3-year period.

The possibility that the mixture produced a greater yield than swards of pure species (after taking into account that the three species are not present in equal proportions in herbage harvested from the mixture) was examined using the concept of ‘the sum of the relative yields’. There was no evidence of a beneficial or antagonistic effect of one species on another; rather, the species seemed to be ‘mutually exclusive’ (de Wit & van den Bergh, 1965).

The botanical composition of the mixture changed through the course of the experiment, e.g. cocksfoot became increasingly dominant, particularly at the highest level of nitrogen. Changes in composition accounted for any tendency for the yield of the mixture to deviate from the mean of the pure-sown swards.

Some of the advantages and disadvantages of using mixtures are discussed and it is concluded that a rational approach to grassland husbandry should be based on swards sown to a single grass variety.

Three field experiments in 1963–5 compared the effects of three methods of fertilizer application, each at four rates, on the growth and yield of main-crop potatoes. Solid fertilizer was broadcast over the furrows and then concentrated round the seed tubers by splitting the ridges during machine planting. Liquid fertilizer was injected immediately after planting either 2 in below and 2 in to the side (shallow placement), or 6 in below and 2 in to the side of the seed tubers (deep placement). Solid and liquid supplied the same quantity of nutrients.

In two years deep placement of liquid gave larger yields than the solid fertilizer and in all three years larger yields than shallow placement of liquid. Results from growth analysis of the 1963 crop indicated that deep placement of liquid gave the largest yield after a dry period. Growth analysis on an additional experiment in 1964 showed that when the soil moisture deficit was limited by irrigation to 1-6 in, both the yield and nitrogen uptake from shallowly and from deeply placed liquids were similar. However, without irrigation deep placement gave a larger yield and nitrogen uptake than shallow placement. An artificial 'dry climate' emphasized that the magnitude of the response to deep placement was related to the soil-moisture regime. It is concluded that the deepplaced fertilizer was in a region of the soil which remained moist, whereas the shallower fertilizer was in drier soil where it was less available to the potato roots.

A Bolex S1 ciné camera, Kodachrome II colour reversal 8 mm film and a Specto analysis projector provided acceptable records of heifer behaviour from dawn to dusk throughout the year. Films are available on application.

Two groups of heifers showed logical and persistent behavioural responses to clement and inclement weather. Their daily behavioural routine was a response to, and in turn was modified by, the weather. Their group behaviour was readily recorded by time-lapse photography but an easy study of the more individual reactions of sheep was not possible from time-lapse film due to problems of identification and flock turbulence.

Heifers responded to bright sunshine predictably but differently in summer and winter, a definite response to a change in the direction of the incident wind being recorded in warm summer sunshine. A hitherto unrecorded reaction to unusually cold, strong, dry wind, viz. vigorous, non-stop grazing in the absence of effective upwind obstructions— requires verification.

Shelter usage was largely related to the incidence of wind-driven rain and, on the area of study, the slope of rainfall and the direction and strength of the wind which brought heavy rain were the main factors affecting sheltering activity. This unfortunately meant that shelter usage was synonymous with the fouling and poaching of sheltered ground.

Citric acid and three antibiotic-type substances—zinc bacitracin, tylosin and formosulphathiazole—were included in dry-meal diets for early weaned pigs up to 20 kg live weight. Two experiments were carried out and in each copper sulphate as 0.1 % of the diet was tested.

In the first experiment the diets were supplemented with citric acid, copper sulphate or both citric acid and copper. The pigs given the diet containing both citric acid and copper tended to have the greatest daily live-weight gains and there was a similar trend in favour of the diet containing copper sulphate alone, but these advantages did not reach significance.

In the second experiment diets with or without copper sulphate were supplemented with either Zinc Bacitracin, Tylosin or formosulphathiazole. All three ‘antibiotics’ had beneficial effects on rates of gain and feed-conversion efficiency, resulting in average. increases of 15% and 10% respectively. Copper sulphate did not improve the performance of the pigs when included in the basal diet with or without an ‘antibiotic’ and there was no interaction between the copper supplement and any of the other supplements.

The performance of the pigs after 20 kg live weight under standard conditions showed little evidence in these experiments that the beneficial effects of feed additive use before this weight persisted during growth to 90 kg live weight or that any of the major measures of carcass quality were affected by the early treatment.

After establishing a permanent omasal fistula in a ram, solutions containing histamine with or without formic or acetic acid were introduced directly into the omasum. It was found that histamine, together with formic or acetic acid, stopped feeding and rumen motility, but formic acid and histamine, infused separately, had no effect on food intake.

A co-ordinated trial has been carried out at sixteen centres to compare the following three feeding methods for growing pigs: (1) ‘sow and weaner’ type meal up to 120 lb live weight, followed by ‘finishing’ type meal to slaughter; (2) ‘sow and weaner’ type meal from start to slaughter; (3) as (2), but the cereal and supplement components given separately (not mixed).

Using the sow-and-weaner type meal throughout, rather than changing to a lower protein diet at 120 lb live weight, resulted in slight improvements (less than 2½%) in over-all growth rate and feed conversion; these improvements were not sufficient to compensate for the higher feed costs. None of the carcass measurements was significantly affected.

Lack of mixing of the cereal and supplement components did not harm the performance of the pigs and so farmers who produce their own cereals and buy concentrates may reduce costs by the elimination of mixing.

A standardized butcher-type method (B) in which anatomical reference points were used to determine cutting lines was compared with a semi-anatomical method (A) in which the jointing was based still more closely upon the anatomy of meat animals. Thirty-two lamb carcasses were split by hand sawing and the sides prepared for quartering, quartered and finally jointed into five hindquarter and five forequarter joints by one or other of two operators by either method A or method B according to a pre-arranged plan. Operator bias in the preparation of the sides for quartering was only noteworthy for the removal of internal fats.

Method A proved to be more consistent than method B, but the degree of advantage varied for different joints. In terms of the coefficients of variation for different joints by the two methods, method A had an advantage in consistency over method B for eight of the ten joints into which each side was divided.

The reproducibility of the semi-anatomical method (A) could be further improved by adopting more fully anatomical methods of joining.

The application and implications of an anatomical method in the excision of sample joints is noted.

Initial pH of buffalo semen as measured electrometrically is 7.2 ± 0.025 and the buffering capacity 1.40 ± 0.026. Sulphamezathine in glucose–egg yolk–bicarbonate diluent depressed fructolysis in buffalo semen. This depression is considered to be a factor in the better maintenance of motility in this than in other media investigated. The more alkaline pH of this medium also appears to be beneficial in preserving motility on storage.