1. The efficiency with which Ayrshire calves digested the dry matter of fresh grass was measured over two trial periods extending from the third to the tenth week of age.

2. A statistical method for determining digestibility coefficients is outlined and its advantages over the conventional procedure, particularly for young growing animals, are discussed.

3. The mean coefficient of digestibility of the dry matter of the grass for four calves was 74·6%.

4. This digestive efficiency was attained immediately the grass was fed and did not vary throughout the experiment.

5. Simultaneous feeding of milk in the first trial period did not affect the digestion of grass.

1. A spring top-dressing of 0·5 cwt.nitrogen/acre was applied to winter wheat as urea or ammonium nitrate in a single spray at 30 gal./acre or as solid fertilizer applied to the soil. A weed-killer, 2,4-dichlorophenoxyacetic acid, was applied in the nitrogen spray or separately in spray to plots that received solid fertilizer.

2. Uptake of nitrogen by the crop from solid fertilizer was about twice that from fertilizers applied in sprays. Solid fertilizer increased yield slightly more than did sprays.

3. Ammonium nitrate and urea had the same effects, both when applied in sprays and when applied as solid to the soil.

4. 2,4-D decreased the amount of weed slightly, but had no effect on yield of wheat.

5. The interactions between weed-killer and method of applying nitrogen were small; the response to nitrogen in dry weight of straw, including weeds, in one experiment, and of shoots in another experiment, was decreased by 2,4-D when nitrogen was applied in spray but not when it was applied as solid fertilizer.

Experiments are described which give some basic information on the rate and pattern of marker excretion by sheep on pastures ranging in digestibility from 70 to 80% and on hay of barely 50% digestibility.

The faeces output of individual sheep varied from 100 g. to more than 400 g. daily, and the estimated feed intake from below 400 to over 1,900 g. daily.

Despite these wide ranges a typical pattern for the passage of single doses of markers was quite consistently repeated in the trials on pastures:

1. Markers first appeared in the faeces 5–8 hr. after dosing.

2. Concentrations rose rapidly to peak values about 10–18 hr. after dosing.

3. Concentrations fell thereafter by about 50% each 6–10 hr. until 60–70 hr. after dosing when marker content could no longer reliably be determined by the methods used.

Factors affecting the basic pattern

1. The overall quality of the feed was of prime importance, in that peak concentrations occurred progressively later on poorer pastures and on hay.

2. For any given feed a high level of (estimated) feed intake was often associated with earlier appearance of marker in the faeces, an earlier peak of concentration, and slightly faster fall in marker concentration.

3. There was evidence that the time of administration might slightly affect rate of passage, presumably through its relation to grazing periods, for doses given at or near times of greatest feed intake were passed rather more rapidly.

4. It did not appear that there was any considerable retention of either marker within the tract beyond 72–96 hr. after dosing.

1. The experiment described confirmed earlier findings that a folding management across wormfree pasture was capable of preventing infection of the lamb by all species except Strongyloides papillosus.

2. The growth and productivity of lambs infected at five different levels were compared with those of ‘worm-free’ controls grazing with them.

3. Live-weight gain of the total infected group was significantly depressed; within the infected group only level 5 differed significantly from the control group.

4. Loss of productivity was, in this experiment, associated with egg counts between 30 and 57 e.p.g.

5. The problem of definig a ‘tolerance’ level below which no appreciable damage occurs is discussed in relation to the results obtained.

1. This paper reports a study of the behaviour of five strains of ryegrass (Devon Eaver, Irish S. 24 and New Zealand certified mother perennial ryegrass and H.I) under three different conditions of spacing and two types of management. Strain performances are compared on the basis of green and dry-weight data of total herbage, and green weight of sown strain contributions under the three techniques of evaluation.

2. Under both managements, the total annual production per unit area was greatest from broadcast and least from single-plant areas. Some individual cut yields were, however, greater than those from broadcast plots, with the drill-row production intermediate.

3. Yield differences between the four perennial ryegrasses were greatest as spaced plants and least in broadcast plots. Single plants and broadcast plots of H. 1 were outstanding compared with the perennial strains. Under neither management were there significant interactions between strains and sowing method in 1952, though such interactions were detected in both cases during 1953.

4. The relative yield performance of strains under similar spacing conditions were almost identical under both managements.

In 4 consecutive years, 1948 to 1952, combined varietal and manurial trials were carried out to obtain information on the yields of marrow-stem kale, thousand-head kale and cattle cabbage in the presence and absence of sulphate of ammonia applied as a top-dressing at the rate of 6 cwt./acre.

Yield and composition of all crops were apparently affected by differences in weather conditions. In most years, and particularly for cabbage, the yield declined with successive harvests.

Increased green crop, dry matter and crude protein yields resulted from the application of nitrogenous fertilizer in 3 years, but in the other year, a very dry season, the response to the top-dressing was negligible.

Marrow-stem kale both with and without the additional fertilizer, yielded more, in terms of fresh crop, dry matter and crude protein, than thousandhead kale with the same manurial treatment. Cabbage yields often approached those of marrowstem kale at the first harvest, but were nearer to those of thousand-head by the last harvest of each year.

1. A study has been made over two growing seasons of the volatile fatty acid production from ley grass obtained from a single area of one field, under the action of rumen liquor in vitro.

2. The acida estimated were acetic, propionic, butyric, valeric and caproic. On only one occasion did the last named appear in measurable amount.

3. The main acid produced in early stages of the year is acetic acid, but as the season advances propionic acid becomes the acid of major production.

4. In parallel cellulose runs it was found that propionic acid was invariably produced in greater amount than any other acid.

5. An attempt has been made to eliminate, by using cellulose as a standard, the effects of using different rumen liquor samples.

6. The dried samples, corresponding to the fresh material, were invariably found to yield acetic acid in greater proportion than propionic acid. The average percentages of acids obtained from the dried grass were similar to those found by other workers. It is suggested that the variations between the fresh and dried grass results are due to changes in carbohydrate content resultant upon storage of the latter.

In a co-ordinated experiment involving twenty centres and 558 pigs it was found that the growth rate, efficiency of food conversion and carcass quality of the pigs were not affected when one after-noon meal was omitted each week throughout the fattening period, provided the amount of meal thus saved was distributed between the remaining feeds during each week.

Limited evidence is presented to show that similar results may be obtained when two afternoon feeds are omitted each week.

A field experiment to test effects of cultural treatments on eyespot (Cercosporella herpotrichoides Fron.), lodging and yield of winter wheat, begun in 1952 (Salt, 1955), was continued on the same site in 1953. In 1952 only eyespot and lodging were severe, but in 1953 take-all (Ophiobolus graminis Sacc.) and weeds were severe also.

Squareheads Master 13/4 and Cappelle, each sown at 1½ and 3 bushels/acre, were top-dressed at four different dates with ammonium sulphate at 0, 2 and 4 cwt./acre. Sulphuric acid (12½% b.o.v. at 100 gal./ acre) was sprayed on four of the eight blocks of ten plots in March to control eyespot.

Halving the seed rate decreased the percentage of severe eyespot from 63 to 52%, decreased the area stunted by take-all from 36 to 14% and increased yield by amounts ranging from 8·3 cwt. in nitrogendeficient plots to 2·6 cwt./acre in plots well supplied with ammonium sulphate. The fertilizer applied to Squareheads Master at 0, 2 and 4 cwt./acre had little effect on the incidence of eyespot lesions at harvest, but increased the area lodged from 23 to 53 and 60% respectively; it decreased the area stunted by takeall from 47 to 19 and 10% respectively, and increased yield from 13 to 17 and 18 cwt./acre. Cappelle did not lodge and the fertilizer decreased take-all patches from 51 to 28 and 18% respectively, and increased grain from 15 to 20 and 21 cwt./acre. The time when nitrogen was applied to either variety had no important effect on disease incidence or yield.

Sulphuric acid sprayed in 1953 on blocks unsprayed in 1952 and so having a higher initial infection of eyespot and weeds, decreased the area lodged and the area covered by weeds, but did not decrease the percentage of straws with eyespot below that in unsprayed plots.

1. Three contrasting varieties of spring oats were grown at six centres in England and Wales for three seasons, at two levels of manuring. They were harvested at two stages of ripeness, and both straw and grain were analysed for all treatments.

2. Varietal differences in composition between samples of straw grown under similar conditions and harvested at comparable stages of ripeness were negligible. In this respect there was no relationship between quality of straw and that of grain.

3. Differences in composition attributable to environment were very large. Crude protein content ranged from 1·9 to 7·6%, and crops grown under cool and wet conditions always yielded a better quality straw than those grown under the warmer and drier conditions in the south of England.

4. The chemical composition of oat straw changed very little between the early ‘binder-ripe’ stage and the fully ripe ‘combine’ stage, although physically it tended to become more brittle and less attractive in appearance. The grain also showed little change in composition between the two times of harvesting.

5. A spring dressing of 2 cwt. per acre of nitrochalk increased the protein content of the straw very considerably, but the response varied widely with conditions. The average increase at all centres over three years was 20%.

6. Under cool and moist conditions the composition of oat straw was comparable with that of meadow hay.

1. Sixty Large White pigs in ten blocks of six litter-mates were individually fed on six different planes of feeding. Three groups were fed according to live weight and according to three different scales, and in the other three groups the pigs were given as much food as they would eat in 30 min. at two feeds daily up to a maximum of 7·0, 6·5 and 6·0 lb./day respectively. All pigs received the same meal mixtures.

2. Although the groups being fed according to the various scales took slightly longer to reach bacon weight, they utilized their food more efficiently than the groups fed on the ‘to appetite’ systems. Thus the pigs fed according to the scale shown in Table 1, but up to a daily maximum of 6½ lb. meal/pig, required about 35 lb. less meal to reach bacon weight than those pigs fed ‘to appetite’ up to a maximum of 7 lb. meal/day. The saving in food costs at present-day prices was approximately 10s. per pig.

3. The percentages of grade A carcasses were very high in all groups, but there was a marked tendency for the ‘to appetite’ fed groups to have thicker midback and loin fats, the latter being reflected in the poorer commercial grading results.

4. The importance of interpreting the results in the light of the influence of the strain of pig, environment and type of diet fed on the question of plane of feeding, was emphasised.

1. Free amino groups in humic acid preparations isolated from 0·5M-sodium hydroxide and 0·1M-sodium pyrophosphate (pH 7·0) extracts of various soils have been estimated by the nitrous acid method of Van Slyke (1929) and the fluorodinitrobenzene technique of Sanger (1945).

2. The results obtained by the Van Slyke method using a reaction time of 15min. indicated that from 12 to 30% of the total nitrogen in the preparations examined was in the form of free amino groups. No free amino groups could be detected by the fluorodinitrobenzene technique.

3. It is shown that lignin interferes with the estimation of amino groups by the Van Slyke method, and it is suggested that lignin or ligninderived material may be largely responsible for the high apparent amino-nitrogen values obtained with humic acid preparations by this method.

4. The reaction of humic acid with nitrous acid resembles the reaction of lignin with nitrous acid in that it is accompanied by the fixation of nitrogen and the destruction of methoxyl groups. The reaction of lignin with nitrous acid is similar in many respects to its reaction with nitric acid.

5. Only about one-third of the nitrogen fixed by lignin in its reaction with nitrous acid is removed by prolonged hydrolysis with 6N-HC1, and most of the nitrogen so released is in the form of ammonia. A small amount of the nitrogen liberated by acid hydrolysis is in the form of hydroxylamine.

1. Experiments to assess the effects of grazing management on the persistence of a lucerne-cocksfoot ley are described and the results discussed.

2. The work confirms the general opinion, based on other experiments in which lucerne was defoliated by cutting, that frequent defoliation causes a reduction in the persistence of the lucerne.

3. Defoliation at 8-weekly intervals maintained a satisfactory balance between the sown species in a lucerne-cocksfoot sward, irrespective of whether defoliation was by cutting or by grazing or by combination of the two.

4. Grazing at 4-weekly or 2-weekly intervals led to serious reductions in the proportion of lucerne in the sward.

5. The provision of a rest period, either early or late in the growing season, had little effect on the amount of lucerne present after 2 years on plots subjected to grazing at 4-weekly or 2-weekly intervals.

In two experiments, each involving 200 pullets, sunflower meal as a protein concentrate was compared with high quality fish meal, at two levels of protein intake. Since production was not reduced by the low protein intakes, it was concluded that the quality of the protein in sunflower meal was satisfactory for egg production. When 25% of sunflower meal was included in the mash, the consumption of mash was not reduced but the birds appeared to be unable to maintain high egg production and to maintain body weight at the same time. From this it was concluded that such percentages of sunflower meal gave an undesirably high fibre content and too low an energy value to the diet.

The apparent digestibility of crude protein by cattle and sheep of different breeds and types, both temperate and tropical, has been studied by means of an analysis of the results of feeding trials with herbages and mixed feeds in many parts of the world. No matter whether herbages or mixed feeds are used the digestibility coefficient (y) is shown to be related to the percentage crude-protein content of the feed (x) by means of an expression of the form y = a + b log x. The particular equation y= 70 log x − 5 is shown to give a reasonable fit of all the available data.

The digestibility of crude protein in the feed is shown to increase very rapidly at low protein levels (from about 2 to 9%), and there after it rises more slowly as the crude-protein content increases.

There is close agreement between the equations for herbage fed alone and for mixed feed which suggests that the total percentage of crude protein in the feed, irrespective of its nature, determines the digestibility of the protein.

The general equation, y = 70 log x − 15, connecting y, the digestibility coefficient, to x, the percentage of crude protein in the dry matter of the feed of ruminants, which was proposed in an earlier paper, has been shown to fit all the directly determined world data for cattle, sheep and goats which have been published by Schneider (1947). It is applicable to rations composed of both single and mixed feeds for it is the total percentage of crude protein in the ration which determines its digestibility.

The equation is of general application, irrespective of climate or feed, and for the first time a link is provided between the large bulk of data from temperate regions and those hitherto neglected and apparently aberrant data from the tropics and subtropics.

The equation adequately explains a large part of the variability of results obtained by the ‘by difference’ method. In particular, attention is drawn to its value in explaining ‘associative effects’ in mixed feeds.

It would seem to have several practical applications; one being the ready determination of the average digestibility of crude protein in rapidly growing grasses and herbages at different stages of development; another being the evaluation of average crude protein digestibility of single or compound feeds in those parts of the world where adequate facilities for digestibility studies are not available. It can also be used in computing maintenance and production rations for meat and milk.

The digestibility of the crude-protein equivalent (N × 6·25) of rations containing urea conforms with the general equation, y = 70 log x − 15, correlating the dry-matter crude-protein content (x) with its coefficient of digestibility (y), irrespective of whether the urea nitrogen is absorbed as ammonium salts or converted to microbial protein prior to digestion.