Crops of lucerne and cocksfoot of high moisture content were ensiled without additive and with the addition of formic acid at up to 0·91% of the fresh crop weight in test-tube silos and in silos containing about one tonne of crop. Silages from the larger silos were fed to sheep for measurement of voluntary intake and digestibility.

Silages made without formic acid were badly preserved and contained large quantities of acetic acid, butyric acid and ammonia. The addition of formic acid reduced the production of acids and ammonia. With test-tube silos differences between the minimum pH measured during the storage period and the final pH after 155 days were not significant for silages made from both crops with addition of 0·45% or more of formic acid: these silages were considered to be stable.

Silages from the larger silos were generally not as well preserved as those from the test-tube silos, particularly at the higher levels of formic acid application. This difference was attributed to less effective application of additive to the larger silos and loss of formic acid in the effluent which was released from these silos but not from the test-tubes. Organic matter intake increased with increase in formic acid level, but organic matter digestibility was not significantly correlated with formic acid levels. Intake was closely related to the quantity of ammonia in the silage and it is argued that formic acid affected intake by influencing the pattern of fermentation in the silo rather than by a direct effect of formic acid itself.

Experiments were done to determine the fate of soluble mucins in the gastrointestinal tract of sheep. Incubation of a soluble mucin with liquor from large intestinal contents resulted in loss of mucin. Some of this loss was due to soluble enzymes. The loss of mucin was less when incubation was with rumen liquor and variable when with ileal liquor.

The mean amounts of nitrogen in a soluble mucin fraction which was soluble in trichloroacetic acid (T.C.A.-soluble mucin) were 2·5, 7·3 and 20·0 mg per 100 ml in rumen caecal and faecal liquors respectively. These amounts were only a small proportion of the total soluble nitrogen in these fluids.

Amounts of T.C.A.-soluble mucin, measured by sugar content, were greatest in contents from the small intestine. When the amounts of T.C.A.-soluble mucin were compared with the amounts of lignin in the samples, there was an increase between the abomasum and the first part of the small intestine and then a decrease to the caecum. Amounts relative to lignin were low in other parts of the gastro-intestinal tract.

The greatest ratio of fucose to rhamnose in T.C.A.-soluble mucin from gastro-intestinal liquors was in ileal liquor. The presence of the two methyl pentoses, fucose and rhamnose, indicates that the T.C.A.-soluble mucin is derived from mucus and bacteria.

Wool samples from 47 Barki yearlings were taken from five positions during two years to study the variability in the fleece, the cause of variability and associations between different fleece traits. Statistical analysis has indicated the following significant points.

An antero-posterior gradient occurred in the different traits under study. When medullation was discarded, though it was of a low magnitude (3·9%), a reduction of 5·89% in the mean fibre diameter and of 18·33% in its standard deviation occurred.

The position most representative of the whole fleece varied with the trait. It is recommended to take three sampling positions forming a triangle, withers, mid-side and hip, to represent the Barki fleece.

The animals contributed the major part in the variability of mean fibre diameter (1), the standard deviation of fibre diameter (S.D.1), percentage medullation, mean fibre diameter after discarding the medullated fibres (2), the standard deviation of fibre diameter after discarding the medullated fibres (S.D.2), the contribution of medullation to the total variability, percentage fine fibres and percentage coarse fibres. The positions were the main contributor to the variability of percentage kemp fibres, staple length, medullation index and to a certain extent to that of the kemp score. The year played a significant part in the variability except for 2 and S.D.2.

The highest correlations with the standard deviation of fibre diameter were those of percentage medullation and kemp score. These three variables when considered separately accounted for 0·47, 0·35 and 0·31 respectively of the variability in S.D.

Equations were obtained to predict the standard deviation from both the mean fibre diameter and the percentage medullation and to predict the mean fibre diameter from the staple length and the kemp score. The coefficient of determination of the first set of equations ranged from 0·47 to 0·56 while that of the second set ranged between 0·07 and 0·51 for different positions.

Grasses of widely differing maturity have been extracted by two chemical and two enzymic methods in order to prepare cell wall materials with low nitrogen contents. These methods involved extraction, with neutral detergent or phenol-acetic acid-water (1:1:1), or digestion with the proteolytic enzymes pepsin or pronase. Wide differences were noted between these methods with grasses at different levels of maturity, both in the nitrogen content of the residue and the actual yield of cell wall preparation. The more efficient of these methods for removing nitrogenous materials, namely neutral detergent extraction and digestion with pepsin and pronase, were also examined for their effect on the structural carbohydrate and lignin content of the cell wall. In all respects, a method involving incubation with the enzyme, pronase, gave the most satisfactory cell wall preparation.

Comparative slaughter was used to assess the effects of body-weight loss on Brahman cross (BX) and Africander cross (AX) steers of the F3generation with respect to gross dissected carcass composition and the distribution of these components over the dressed carcass. Animals were slaughtered at design body weights of 325, 341, 358, 374 and 390 kg, some while during positive body-weight growth (Group A), and others during weight loss from 390 kg at a rate of approximately 0–5 kg/day (Group B).

Gross composition was similar in the two breeds, irrespective of the body-weight loss treatment. Body-weight loss resulted in muscle and fat approximately reversing the path of development, while bone and fascia and tendon remained approximately constant. No evidence of proportionally early loss of fat and later loss of muscle was found. Of the fat components, kidney and channel fat showed the highest relative loss. The distribution of muscle was different between the breeds, the most statistically significant differences being that AX had heavier muscles around the spinal column and lighter shin muscles, at the same total muscle weight. Bone weight distribution differences also occurred, with AX tending to have lighter leg bones, at the same total bono weight. A breed difference in intermuscular fat distribution meant that the AX animals were earlier developing in the forequarter and later developing in the hind quarter in respect to its intermuscular fat, than the BX animals.

Body-weight loss affected muscle-weight distribution, the most marked effect being that the relative proportion of abdominal muscles fell during body-weight loss. Boneweight distribution was affected to a minor extent, the effects mainly being in the leg bones rather than the axial skeleton. The distribution of neither fascia and tendons nor subcutaneous fat was affected by the body-weight loss treatment, but the distribution of intermuscular fat was affected.

Twelve experiments in the East of Scotland tested a hypothesis that the smaller yield responses to salt in Scotland than in England shown by previous work was due to the adverse effects of soluble salt concentration brought about by ridging, and also to test a wider range of salt and potash than used previously. All combinations of three rates of salt (0, 315, 630 kg/ha) and three rates of muriate of potash (0, 315, 630 kg/ha) were applied in four ways: (1) ploughed down in winter, (2) on the furrow in February, (3) in the seed bed and (4) half as (1) and half as (3). Plant emergence was decreased by salt and potash in only three experiments and then only when the larger amounts of both fertilizers together, along with nitrogen and superphosphate, were applied in the seed bed prior to ridging. Both experiments were in a year when the weather was dry while the plants emerged. Yield of sugar was greatest with the February application on the furrow and smallest with the ploughing down method. At equal weights, salt and muriate of potash had similar effects on sugar yield. Equations derived from the response surface gave the most profitable dressing as 377 kg/ha of salt plus 127 kg/ha of K2O which gave a £4.90 greater margin per hectare over costs than the best potassium application without salt.

Four of five ‘hairy’ Wiltshire lambs had fibre type arrays (as defined by Dry, 1965) of Plateau (P0 and P1) type, whereas in five ‘woolly’ lambs there was only one Plateau (P3) array, the arrays of the remaining lambs being Ravine or Saddle. In terms of Dry's theory that the severity of pre-natal check determines persistence of wool growth in adults, it appears that the amount of checking in these Saddle and Ravine arrays was insufficient to prevent the casting of the adult coat.

A mixed sward of grasses and clovers, previously established with adequate Ca, N, P and K on deep acid peat, was used for a factorial experiment to determine the amounts of nutrients required to produce herbage for conservation. The treatments consisted of all combinations of 0, 117and 234 kg N, 0, 29 and 58 kg P and 0, 156 and 312 kg K/ha, and their effects on the botanical composition of the sward, the yield and mineral composition of the herbage, and the nutrient status of the peat were measured over a period of five years. Three cuts were taken annually, one third of the N dressings being applied for each cut.

Tall fescue became the dominant grass species while cocksfoot persisted much better than either ryegrass or timothy. The proportion of clover in the sward was reduced to practically zero by applying N, but without N it was maintained at about 20% by applying K.

Yields of dry matter were greatly increased both by N and by K and there was a marked positive interaction between these two nutrients. Due to the marked suppression of clover by applied N there was no response to the first increment of N in 1959, but with this exception, 1 kg N/ha with adequate P and K produced between 15 and 30 kg dry matter/ha. The effect of K increased from 1958 to 1962, the first increment consistently producing most of the response. Applying P had little effect on yield until the fifth year when a significant response was obtained.

The mineral composition of the herbage varied during the season; the percentages of N, Ca, Na and Mg were generally higher in autumn than in early summer whereas the percentage of K showed the opposite effect.

The N, P and K treatments had large effects on the percentages of N, P, K, Na, Ca and Mg in the herbage and on the amounts removed in the crop. Without applied N, but with adequate P and K, percentage of N varied according to the amount of clover in the sward. With applied N there was less variation and the average percentage of N was about 1·7 with 39 kg N and 2·0 with 78 kg N/ha/cut. Percentage of P ranged from 0·14 to 0·54 and percentage of K from 0·5 to 3·5. Apparent recoveries up to 74, 65 and 96 % were obtained from the N, P and K treatments, respectively.

For continuous production by cutting and removing the herbage, a mixed sward containing clovers appears to require, without applied N, about 120 kg K/ha/year. With applied N, an additional 0·3 to 0·5 kg K/kg N appears to be needed. The amount of P required will depend mainly on the concentration desired in the herbage and on the rate of N used. To produce herbage with 0·3 % P in the dry matter about 15 kg P/ha/year, plus approximately 0·1 kg P/kg N applied seems to be needed; for 0·4 %P the corresponding quantities are about 40 kg P/ha plus 0·3 kg P/kg N applied.

Field trials were carried out for three years in the savanna zone of northern Ghana to determine the fertilizer requirements of yam (Dioscorea rotundata). Under the conditions of the experiment, K was not important in yam fertilization. Release from the exchangeable reserves was adequate in meeting the crop demand. A small positive response to P applied at low levels (33·6 kg/ha) was observed and averaged only 5·6% increase in yield. N was the most important nutrient element and its application increased yields highly significantly. On the average, application of 33·6 kg/ha gave an increase of 13·5% and 67·2 kg/ha gave a 22·1% increase in yield. More N did not further increase yield.

Four digestibility and balance experiments were carried out in which 33 growing heifers were fed basal diets of low dry matter silage offered ad libitum, supplemented with various levels of barley and/or groundnut meal or urea.

Voluntary intake of the silages was low although apparent digestibility of D.M. was high (66–75%). There was a significant linear negative relationship between the intake of D.M. as supplement and silage D.M. intake.

Apparent digestibility of crude fibre in the silages was high (74–83%). It was depressed significantly by addition of barley but not by addition of groundnut. There was a highly significant linear relationship between the digestibility of D.M. and G.B. in the mixed silage concentrate diets used.

Metabolizable energy (M.E.) values for the silages varied from 2·04 to 2·52 Mcal/kg (8·5–10·5 MJ/kg) D.M. Supplementation with barley at approximately 1% of live weight, increased M.E. values of the mixed diets to 2·57–2·85 Mcal/kg (10·8–11·9 MJ/kg) D.M. Additional N had little effect on these values.

Nitrogen retention was significantly increased in all experiments by barley supplementation. It was further significantly increased by groundnut in three experiments and by urea in one experiment.

Multiple regression analysis showed that N retention was significantly related to both M.E. intake and intake of absorbed N, and to M.E. intake and intake of supplementary N.

Apparent availabilities of Ca and Mg in silage based diets were low and the availability of Na varied with Na intake. Supplementation with either energy or nitrogen increased apparent availability and retention of Mg but did not exert consistent effects on availability or retention of Ca or Na.

There was a highly significant linear relationship between ingested and digested Na but not for Ca or Mg. There was a highly significant linear relationship between absorbed and retained Ca and Mg, but not for Na.

Animals fed second cut silages had rather low blood glucose levels and higher than normal levels of blood ketones.

Experiments were carried out to assess the effects of silage diets given with and without supplementary energy as barley and/or nitrogen as groundnut meal or urea on rumen fermentation in growing heifers.

Silage based diets resulted in a stable pH and a high molar percentage of acetate in rumen liquor. Total V.F.A. concentrations were significantly increased by supplementary energy plus protein but were not consistently increased by energy only, and were linearly related to M.E. intake but not to D.M. digestibility. Effects of energy and nitrogen supplementation on the molar percentage of rumen V.F.A. were small and not always significant.

Rumen NH3-N levels were normal on the basal silage diets and were linearly related to N intake. Levels were significantly reduced by energy supplementation but significantly increased by protein supplementation. Results are discussed in relation to energy and nitrogen utilization on silage based diets.

Response of wheat to fertilizer-P on soils low and medium in available P increased with increasing doses up to 26 kg P/ha; responses were proportionately greater on medium-P soils. Application of 39 kg P/ha increased the response slightly on low-P but decreased it drastically on medium-P soils. The relatively small response on low-P soils may be due to fixation of fertilizer-P. The results indicate that the maximum response to fertilizer-P may be obtained only when P fixing capacity of the soil is satisfied so that sufficient P for the crop remains in the soil solution. The results of this investigation suggest that fertilizer should be applied on the basis of soil test data of individual fields instead of following regional recommendations.

The results of a field experiment on winter wheat are presented in which the effects of the soil physical properties produced by different cultivation systems were studied in relation to root development.

The extension rate of the seminal root axes was slower in undisturbed or shallow (5 cm) cultivated soil than in ploughed or deep (20 cm) cultivated soil leading to earlier lateral branching and the production of an effectively shallower seminal root system which persisted throughout the season. During the first four weeks after drilling the soil in the ploughed and the deeper cultivated plots was of lower bulk density and there were more pores of a diameter suitable for unimpeded root extension. It is suggested that seminal root development in uncultivated soils, which are less readily deformed than cultivated ones, is related to the probability of the extending seminal axes contacting pores of suitable dimensions.

The implications of shallower rooting are discussed and related to field experience with cereal crops drilled directly into uncultivated soils where success has consistently been achieved on free-draining, open-textured soils.

Forty-four full-sib families from a diallel cross between 10 Lolium ((multiflorum × perenne) × perenne) clones were planted in the autumn at 0·6 × 0·6 m and 0·l × 0·l m spacings. Fresh weight of individual plants was measured on three occasions during the following spring and summer. The analysis of the diallel cross was extended to account for combining ability × spacing interactions, and to estimate between-spacing combining ability correlations and their sampling errors.

Family × spacing interactions became increasingly significant at successive harvests and always contributed substantially to the total phenotypic variance. Much of the family × spacing variance was due to the general combining ability (GCA) × spacing component. Despite these large and significant interactions, the correlation between GCA values at the two spacings was high and positive at each harvest, so that selection for yield at wide spacing should lead to a correlated increase in yield at close spacing. Although the experiment was of relatively short duration, the results suggest that recent criticism of the conventional technique of selection among widely spaced plants in pasture plant breeding programmes may not have been entirely justified.

The weight of the ruminal mucosa of breeding Blackface ewes and its total DNA and RNA content rose after parturition to reach a peak at 45 days post partum. There were no constant significant changes with time in the concentration of the nucleic acids.

It was found that there was a positive correlation between the amount of food eaten during the final week of life and the weight of the ruminal mucosa and the length of ruminal papillae. The mitotic index of the ruminal epithelial cells was very variable but most of the higher values occurred between 7 and 80 days post partum. The mitotic index could not be correlated with the amount of food eaten in the week before slaughter, but high values were not recorded when the food intake of lactating ewes was restricted to that of non-breeding controls. It is suggested that the most likely explanation for these findings is that in the ruminal epithelium of lactating ewes fed to appetite, oell division occurred in waves or bursts.

Hyperkeratosis of the ruminal epithelium occurred in pregnant and control animals but regressed during lactation and reappeared in the post-weaning period. The inverse relationship between the hyperkeratosis and the rate of cell division is of great interest when considering the aetiology of ruminal disease.

Fatty acid composition of tail fat (TF), kidney fat (KF) and subcutaneous fat from the rumps (SCF) of docked and intact fat-tailed Awassi sheep was studied.

Docking had no effect on the composition of KF. Kidney fat possessed harder characteristics due to its relatively higher content of saturated fatty acids as compared with SCF or TF.

The mean yield of field beans grown for three consecutive years on a site infested with migratory nematodes was 1540 kg grain/ha in untreated soil and 1870 kg/ha in soil treated with dazomet.

Fertilizer nitrogen in amounts up to 250 kg N/ha decreased yield to 990 kg in untreated soil but increased it to 2220 kg in soil treated with dazomet. Fertilizer nitrogen did not affect nematode numbers or root blackening but decreased nodulation and increased mycorrhizal infection by Endogone sp. in untreated soil. Dazomet greatly decreased migratory nematodes of the genera Tylenchorhynchus and Trichodorus and eliminated Pratylenchus. It had little effect on root blackening in the top 10 cm of soil but decreased it in the next 10 cm. Infection with Endogone was almost eliminated.

Radiographs were taken, of the medially sectioned half heads and flesh-free mandibles of 32 pigs serially slaughtered between birth and 120 kg live weight. From these radiographs, measurements were taken of the length of the skull, the depth of the cranium, the length and depth of the brain cavity, and five separate measurements of the mandible. Observations were made of the changes in configuration of the skull as a whole including sinuses. The patterns of development and eruption of the deciduous and permanent teeth were examined. It is suggested that the elongation of the mandible and the maxilla necessary to accommodate the full permanent dentition, together with the increasing size of the frontal sinuses, has an important influence on the shape of the skull as a whole. The results are discussed in relation to other published descriptions of the chronological development of the teeth.

A series of digestibility trials was conducted with non-lactating cows and adult castrated male sheep given diets of hay and dried or high-moisture maize grain in various physical forms. Sheep were able to digest all forms of maize well and to a greater extent than cows. In cows considerable variation in digestibility of maize was associated with the particle size of the maize and the individual animal. Maximum digestibility of dried maize in cows ensued when the modulus of fineness lay within the range 4·7–3·0 and with high moisture maize from 5·4 to 5·1. A study was made of the effect of particle size on the rate of digestion of maize suspended in nylon bags in the rumen. Evidence was presented showing the importance of rumination in ensuring the digestion of intact kernels. Possible causes of differences between cows in their ability to digest intact maize kernels are discussed.

The fen silts bordering the Wash are among the most important soils for crop production in eastern England. Derived from marine alluvial deposits occurring naturally or as a result of reclamation, they form deep almost stoneless soils containing little coarse sand but much fine sand and silt.

Seven textural classes, ranging from loamy fine sand to silty clay, can be distinguished, but these can be grouped into (1) light silts, typically deep very fine sandy loams with a large available water-holding capacity but weakly developed structure; (2) medium silts, silty loams; and (3) heavy silts, silt loams or silty clay loams, less porous and more retentive of moisture than the light silts.

Formerly under grass, the silts were at first capable of growing good crops of potatoes with P fertilizer alone, but as their organic-matter content decreased, potatoes became increasingly responsive to N.

In 18 potato manurial experiments on silt soils in Holland, Lincolnshire, done between 1953 and 1963, the mean response to N was much larger than on most English soils, but response differed greatly from site to site and year to year; in most trials N was particularly effective in increasing tuber size and yield of ware. With long-continued use of P fertilizer, residues have accumulated and, particularly on light and medium silts, responses were quite small and differed little between sites; P tended to increase tuber numbers, and so to decrease ware percentage. Most silt soils are rich in K, and only small responses to K fertilizer can be expected, but on a few sites on the light silts, identified by soil analysis as being comparatively poor in K, potatoes responded well. Using these experimental results, recommendations are given for the manuring of potatoes on silt soils.

Cooking tests showed little consistent effect of manurial treatment on the amount or degree of tuber blackening.