1. Semen was collected from bulls by means of the electro-ejaculation method developed by Thibault et al. (1948).

2. A copious sperm-free fraction of the ejaculate, produced in the early phase of stimulation, was examined for its chemical composition.

3. This secretion was found to have a low protein content, but its chloride concentration was higher than in the sperm-containing fractions of the ejaculate. Fructose and citric acid occurred in very low concentrations, and 5-nucleotidase was absent in the pre-sperm secretion. This indicates clearly that the secretion does not originate either in the seminal vesicles or in the ampullar glands; it is probable that it represents a discharge from the urethral glands.

4. The effect of the pre-sperm ejaculate fraction upon bull sperm fructolysis and motility was examined; both were unaffected by a considerable excess of this secretion.

5. The chemical composition of the pre-sperm secretion makes it unlikely that under physiological conditions it could play a role in the nutrition of the spermatozoa; presumably, its chief function is the clearing of the urethral passage prior to the descent of the semen proper.

Study of the nutritional requirements of sugar cane on a Jamaican estate necessitated simultaneous experimentation with five manurial factors: sulphate of ammonia, superphosphate, muriate of potash, bagasse, and filter press mud. By adopting a one-third replication of a 35 factorial scheme, each factor could be tested at single and double levels for comparison with the absence of the factor.

The structure and confounding system of the design adopted have been described and the method of computing the analysis of variance has been explained. Fractional replication introduces special problems of interpretation, and this experiment illustrates how they may be resolved. Each fertilizer clearly benefited the crop, and several interactions appeared; some ambiguity of meaning is an inevitable concomitant of fractional replication, so that care was needed in order to assign effects to the right causes. The most clearly marked effects were:

(i) Without phosphate, nitrogen failed to produce any response; where phosphatic manuring was adequate the crop responded well to nitrogen.

(ii) Superphosphate and filter press mud were practically interchangeable as sources of phosphate.

(iii) Bagasse appears to act as a source of potash; the interaction of responses is not very clearly established, but little extra response to artificial potash occurred when bagasse was given.

(iv) No evidence was obtained that the double level of any fertilizer was superior to the single.

There was also a suggestion of a reduced superphosphate response in the presence of bagasse.

If a recommendation on manuring were to be based on this experiment, it would be that a maximum of 3 cwt. sulphate of ammonia per acre be used with either 4 cwt. 18% superphosphate and 1 cwt. muriate of potash per acre or 10 tons filter press mud and 20 tons bagasse per acre. In reality, of course, no attempt ought to be made to determine a general manurial policy from results of a single year of experimentation on plant cane at one place.

The experiment should be regarded rather as typical of what can be done than as a complete investigation of manurial needs.

Cytological stvidies did not show any detectable structural changes which could be related to the spermhead deformity in a series of sterile bulls described by Hancock. The deformity according to Hancock consists of a deeply stained (in iron haematoxylin) area placed askew at the apex of the spermhead.

In spermateleosis it is connected with persistence of the shallow apical groove of the nuclear membrane observed only in earlier stages of development in normal cases. There is also a formation of vacuoles in the developing spermheads in the region of the apex and of the equatorial belt. The apex of the abnormal spermhead treated with Feulgen reagent appears to be cut off askew.

Formation of vacuoles in the developing spermheads may be related to some unknown changes in the nucleic acid metabolism of the spermhead. The absence of any chromosomal aberration, whether of quantitative or structural nature, may lead to the conclusion that the changes observed are due to a gene mutation.

1. Unlike many other mammals, the calf is capable of responding to pituitary injections almost from birth. Age has little effect on the ability of the follicles to develop during a series of a.p.h. injections, the follicular response generally being as good 3 weeks after birth as in calves 6–8 months old.

2. Ovulation can occur spontaneously in the a.p.h. treated calf before the end of the first month of post-natal life.

3. Ova obtained from such ovulations are capable of fertilization, although the percentage becoming fertilized is very low. This is thought to be due to the infantile state of the Fallopian tube and the difficulty in inseminating into the uterus, rather than faulty maturation of ova.

4. Although many follicles (10–60) can develop during a series of a.p.h. injections, superovulation was not consistently obtained either by intravenous injections of a.p.h., l.h. or p.u., or combinations of any of these three.

5. Superovulation can generally be obtained, with the formation of many corpora lutea, if the a.p.h. treatment is repeated a second time after a period of luteal activity.

6. The inhibitory effect of a corpus luteum on ovulation in cattle can be overridden in tho a.p.h. treated animal if suitable quantities of a.p.h., l.h. or p.u. are intravenously injected when the newly formed follicles are approaching maturity.

7. Ovulation in the calf at all ages up to 8 or 9 months of age, either in the presence or absence of luteal tissue, is unaccompanied by oestrus. Oestrus, when occurring during a series of a.p.h. injections, commenced after 90–100 hr. of treatment. In such cases slaughter has always revealed the presence of luteal tissue, indicating that ovulation during a ‘silent heat’ had occurred before the commencement of pituitary treatment.

8. Great individual variation exists in the ability of the ovary to respond to pituitary injections. This insensitivity to gonadotropins is not confined to young calves and has been observed in calves 4–6 months of age.

The extent to which early environment affects wool production of Romney sheep was studied by means of measurement of skin growth, and of fibre numbers and dimensions, of lambs reared to 52 weeks on contrasting planes of nutrition.

Measurement of skin growth revealed a series of gradients which generally conformed with growth and development principles. A great degree of individuality among animals in skin growth on various regions was expressed, and it was not possible to prove that plane of nutrition caused differential skin growth among regions.

An initial low plane of nutrition had a retarding effect on fleece development and fibre growth, but it could not be decided whether there was a permanent effect on fibre numbers. It seems that this is of little practical importance, since a low plane of nutrition during the major part of the follicle development phase does not appear to impair subsequent unit area production, providing immediate nutrition is good.

Examination of fibre attributes, and quantitative fibre growth characteristics on various regions of the body, showed a series of orderly gradients. Large differences existed between the body regions for quantitative production per unit area and this suggests a widely differing nutrient supply of various skin regions.

The importance of immediate nutrition is emphasized. It appears that permanent effects of early environment on future productivity take the form of a lesser area on which wool is produced. The efficiency of the processes, apparently, is not affected.

Records for milk, fat, solids-not-fat and fat percentage over forty-eight complete lactations were used as uniformity data to determine the relative efficiencies of a variety of experimental designs used in dairy husbandry experiments.

In general, it was found that:

1. Experiments conducted during the earlier part of the lactation are more efficient than those conducted during the later part.

2. Three-weekly periods are generally more efficient than 5-weekly periods.

3. If 3-weekly periods are used, then extending the time of the experiment over four such periods instead of three reduces the error. The converse is the case with 5-weekly periods since the experiment is carried over into the highly variable later part of the lactation.

4. Grouping the animals according to the yields recorded during the first 40 days of lactation does not appear to reduce the error.

An analysis of covariance using the pro-experimental records of the performance of the animals has been carried out on ordinary group trials and it is hoped to publish the results at a later date, but investigations on the data have shown that both reversal and Latin square designs are more efficient than ordinary group trials even when such an analysis is performed.

1. The relationship of semen age to conception rate was studied at two artificial-insemination centres and a subcentre of one of these. Data relating to 50,213 first inseminations were included in the analysis.

2. It is shown that external conditions can affect the rate of decrease of conception rate with semen age.

3. Records giving c.r.'s for each day of semen age may reveal centre differences that cannot be detected in records giving mean c.r.'s only.

4. Information may be lost if data are grouped by months rather than recorded by collections.

5. The rate of decrease should not be used for comparing centres until the various factors affecting it (e.g. breed differences) are more fully understood. Further investigations should not be limited to one centre.

1. The extraction of leaf protein from autumn-grown perennial ryegrass is described.

2. The composition, chemical analysis and rate of feeding of two mashes compared in the experiment are given. The same basal cereal mixture was used in each ration, with fish meal added to one and leaf protein and minerals to the other.

3. Two groups of three birds were kept on each ration. Nine-month-old Brown Leghorn × Light Sussex pullets, in full lay, were used.

4. The birds were given a 6 weeks' preliminary period on a uniform ration to accustom them to the experimental conditions and to ascertain their potential egg production.

5. In a 10-week feeding trial no difference occurred in the number of eggs or the total weight of eggs laid by the birds fed on either ration.

6. A small loss of body weight occurred in the birds in both treatments.

7. Egg-quality determinations indicated that the specific gravity of the eggs was not affected by the differential feeding. Yolk height was greater in eggs from birds fed on the ration containing fish meal. This ration also resulted in a higher number of eggs with rough shells and containing a higher content of foreign bodies.

8. The eggs from both treatments had low ‘Yolk-colour indices’, showing that the leaf xanthophylls were not present in quantities in the leaf-protein extract.

1. Two live-weight gain experiments using dayold chicks are described. A mash containing a basic ration with leaf protein was compared with a control mash containing the basic ration plus fish meal.

2. Details of the source of the leaf protein, its extraction and chemical analysis are given.

3. The composition and analyses of the mashes are recorded, together with their rate of feeding.

4. The live-weight gains at fortnightly intervals are discussed and the results adjusted for sex of chicks, weight at day-old and level of protein in the mash.

5. In the first experiment some of the pullets from each treatment were fed on a commercial growers' ration from 6 weeks old to maturity.

6. The birds on both treatments in the two experiments were equally healthy. The mortality rates were normal. The leaf-protein chicks had deep yellow pigmentation.

7. The results of the experiments are compared. In the first the leaf-protein mash was as valuable as the fish-meal mash; in the second experiment the fish-meal mash proved to be superior.

8. A new method of measuring the biological value of the protein of herbage plants is suggested, using extracted protein fed to chicks or rats.

9. It is concluded that a mash composed of homegrown cereals plus leaf protein with vitamin supplements, a balance of minerals and additional aminoacid if necessary, would be suitable for rearing chicks.

The partition of carotenoids and vitamin A in the colostrum of nine cows and six goats and in the milk of three cows and two goats was determined using chromatographic and spectrophotometric methods. The following were the main results:

1. The content of β-carotene and vitamin A in the colostrum decreased rapidly during the first nine milkings in both the cow and the goat. The rates of decline were logarithmic. Logarithmic regressions also showed that the decreases in β-carotene were more rapid than those of vitamin A.

2. The heifers secreted more vitamin A in their colostral fat than did cows on the same ration. The vitamin A content of the colostral fat of goats was greater during the first lactation than in later lactations. There was no difference in the rates of decrease of the vitamin A content of heifer and cow colostrum, but the difference between the rates of decreases of colostral vitamin A of first and later lactation goats was significant.

3. The colostral fat of cows at pasture contained more vitamin A than that of cows on winter rations. There was no difference between the logarithmic rates of decrease in the two groups during the first nine milkings. The colostral fat of four goats receiving winter rations was richer in vitamin A than that of three cows treated similarly, and this superiority of the goat over the cow persisted throughout lactation.

4. There was no difference between the carotene content of the colostral fat of the first and later lactation cows. The yield of fat and β-carotene of the heifers was smaller than that of the cows. Cows at pasture secreted more β-carotene in their colostrum than the cows on winter rations. The presence of β-carotene was demonstrated in goat colostrum, although mature goat milk was free from any measurable quantity of carotenoids.

The normal course of mammary development has been briefly described, in sheep from 2 months of foetal age to 4 months after birth; and in dairy cattle from the 3-month foetus to calves 6 months old. Observations were also made on a series of udders from ewes during their first pregnancy. A small group of beef calves and a number of freemartins of various ages were also examined.

Development was found to be closely similar in the two species, and in both, sex differences were marked.

Experimentally it was found that in males of either species castration at birth had little effect on mammary growth, while prolonged treatment with oestrogen gave rise to enlarged teats, dilated cisterns and ducts, and to a certain amount of secretion. Little gland tissue was formed in oestrogen-treated males, and there was no increase in the spreading of mammary tissue from the neighbourhood of the teat.

Females of the two species showed a striking difference in their response to experimental treatment. In sheep, removal of the ovaries at birth had no apparent effect on mammary development up to 4 months, while treatment with oestrogen stimulated gland formation in both spayed and intact lambs and also restricted the normal spread of mammary tissue into the udder. In cattle, on the other hand, heifers spayed at birth showed almost complete cessation of mammary development, while implants of oestrogen, in addition to inducing gland formation, promoted the spreading of tissue into the udder pad of the spayed animal.

Udder development of freemartins appeared to be similar to that of normal heifers from 5 months foetal age to about a month after birth, but thereafter was more like that of a spayed animal. Removal of the abnormal gonads shortly after birth had no effect, while oestrogen treatment induced development of teats, ducts and glands exactly as in a normal heifer.

Comparing small numbers of calves of the two types, it was found that heifers of the beef breed in general showed slightly poorer mammary development than dairy heifers that had been treated in the same way, with more connective tissue and numerous leucocytes in the mammary zone.

1. The use of the technique of gas-partition chromatography in the investigation of the formation of volatile acids in minced grass/water slurries is discussed.

2. Slurries kept anaerobically at 17, 37 and 62° for 13 weeks have been examined, and the amounts of the different volatile acids formed have been estimated. It has been noted that butyric acid forms most readily in the slurry at 37°, while in aerated slurries at 17°, the formation of volatile fatty acids is more speedy than under anaerobic conditions.

3. Only acetic, propionic and butyric acids have been noted so far, and the highest concentrations of the acids observed in any slurry were 5, 1·25 and 4% respectively.

1. Further studies were carried out during 1950 on the effects of different ground water-levels upon the productivity and composition of Italian ryegrass grown on a calcareous light peat soil. The season was an unusually wet one, in contrast with the dry season experienced in 1949.

2. Seven successive cuts were taken during the season from each of two crops of ryegrass, one following a crop of marrow-stem kale, and the other a crop of celery. Different amounts of a general compound fertilizer had been applied.

3. Generally, the findings confirmed those of the previous year's investigation. High ground waterlevel (approximately 18 in. below ground surface) had a deleterious effect upon the yield and quality of ryegrass as reflected by its protein content, compared with the medium and low water-levels (23 and 30 in. below ground surface, respectively).

4. The high water-level also had a depressing effect upon the percentage of potassium and magnesium in the grass, but had no consistent effect upon calcium and phosphorus. The silica content rose steadily in all cases as the season advanced, as occurred in the previous year.

5. Residual manuring effects were well marked in the crop following celery. The total yields of dry matter from the medium and low water-levels considerably exceeded those of similar plots following kale, and the protein contents were also appreciably higher. This demonstrates the advantages of a high soil nutrient status, under conditions of suitable water-levels, for a crop of fenland grass.

6. A high water-level inhibited growth and quality, irrespective of the nutrient status of the soil.

The follicle population of the Blackface breed (‘double-coated’) was followed in skin samples taken from four lambs at eight intervals between 3 days and 43 weeks of age. The follicle population differs greatly from that of the Romney and Leicester breeds previously studied (Burns, 1949).

1. At 1 month old the secondary/primary follicle ratio (S/P) was slightly lower than the Leicester and much lower than the Romney, and the difference became accentuated with age.

2. Fewer secondary follicles are developed after birth than in the Leicester or Romney, although the period during which they can be developed is longer, extending at least to 12 and possibly to 17 weeks after birth.

3. The follicle density is less than half that of the Leicester, but the difference in S/P ratio is not sufficiently large to account for this, which is mainly due to the Blackface having a much lower density of primary follicles at birth.

4. The possibility is suggested that the secondary follicles arise as a result of ‘induction’ by ‘follicle organizer’ coming from primary follicles in a quantity which decreases with advancing age. It may be that when the primary density is high the areas affected by organizer from each primary overlap, providing sufficient organizer to permit of numerous secondary follicles developing at a late post-natal stage, as reported in the Merino.

5. The Blackface contrast with the other breeds in that its primary follicles are conspicuously larger than its largest secondary follicles. All primary fibres are medullated except when about to shed, but many secondary fibres are free of medulla. Kemps are produced only by primary follicles, some of which however produce long ‘hair’ fibres.

6. Many fibres which grow strongly medullated fibres during summer change to the production of non-medullated fibres in winter. The shedding of the kemps in spring should probably be looked upon as physiologically an autumn moult, since the fibres cease growth and produce ‘brushes’ during the autumn.

1. A digestibility trial is described using sheep fed on the product remaining after herbage leaf-protein extraction.

2. The material gave an analysis of 25.7% dry matter, 16.2% crude protein, 0.26% phosphorus, 1.26% potassium and 1.13% calcium.

3. The animals showed no loss in body weight during the feeding period.

4. The material was of low palatability, and the sheep consumed a maximum of 2½ lb. of dry matter per head daily.

5. The average digestibility coefficient of the dry matter was 52.1% and that of the crude protein 67.6%.

6. Nitrogen balance determinations indicated a sufficiency of protein in the feed.

7. The material barely supplied sufficient potassium and was inadequate in its supply of phosphorus and calcium.

1. The data from a survey of beef production in West Wales has been subjected to analysis by the various regression equations deduced by Callow. The calculations have elucidated the quantitative proportions of fatty tissue, muscular tissue and bone tissue as well as the calorific values of the beef carcasses derived from animals of the various grades.

2. It is suggested that the method can be used as a basis to determine the controlled prices of fat cattle. The scale of prices thus obtained might encourage a better finish of the cattle and would tend to modify the seasonality of deliveries.

3. The process of fattening cattle alters the proportions of fatty, muscular and bone tissues in the carcass meat, but the increase in the quantity of muscular tissue is always greater than that of the fatty tissue. At all grades, the quantity of muscular tissue in the carcass is always greater than of fatty tissue.

A simple method to determine the expectation of selected minimum rainfall has been developed on the assumption that monthly or seasonal rainfall is normally distributed over a period of years. Although it is realized that a perfectly normal distribution cannot be obtained, practical experience has shown that the assumption leads to no serious discrepancies and the advantage of simplicity is considerable. A detailed example of its use to forecast the agricultural potentialities of dry lands is given.

1. A survey of the trade in fat cattle, calves and sheep through the collecting centres of the Ministry of Food has been made for the counties of Anglesey and Caernarvon.

2. The results show that the Anglesey stock are invariably heavier and in better condition and marketed slightly earlier in the year, than those of Caernarvon.

3. The imported fat cattle were heavier and more uniform than the home-bred.

4. A check has been made of the variations in live-weight of fat cattle according to colour. Invariably the Black cattle (Welsh) have been lighter, and the Red/White (Hereford) heavier than the average live weight of all cattle of both sexes.

5. The bulk of the meat produced in the two counties is delivered during the autumn months, confirming the experience that the winter fattening of cattle is not now widely practised.

6. In sheep husbandry the two counties are complementary. The small draft mountain ewe, crossed with a heavier type ram, is capable of rearing a fat lamb practically equal to her own body weight in less than 6 months.

7. Losses in mature ewes and rams are suspected to be high because of the small proportions of them, in relation to the population figures, that are delivered to the collecting centres.

As part of the overall programme of research directed towards an understanding of fertilizer needs of crop plants in East Africa a study of the nutrition of maize in sand culture has been made.

The purpose of the work was to study growth and yield in relation to changes in the proportion and concentration of the major nutrients, nitrogen, phosphorus and potassium, and if possible to relate the results to the field behaviour of the crop in fertilizer trials conducted by another section of this organization. Simultaneously studies of the uptake of nitrogen and phosphorus were also undertaken. These latter are discussed in the second paper of this series.

This first paper deals only with growth, yield and nutrient content in relation to the nitrogen phosphorus balance, though the methods now to be described were common to all experiments.

An experiment, designed to test different ways of using straw with fertilizers, and involving a three course rotation of crops, was carried out at Rothamsted between 1933 and 1951. The methods of analysis developed for this experiment are described in the present paper and demonstrated using yields of potatoes.

Treatment effects of interest are given by the mean yields over all years and the linear regressions of yield on time. These estimates are straightforward but the evaluation of their errors is complicated by the existence of correlations due to the recurrence of treatments on the same plots. Further complications are introduced when, as frequently happens in long-term experiments, treatment effects show real variation from year to year. A method is given for estimating standard errors which include a contribution from this variation.

The various relationships between yields and the uncontrolled seasonal factors can also be examined; in the present experiment there is some indication that the effects of treatments on yields of potatoes are influenced by the dates of planting.

In other circumstances the analysis requires modifications, some of which are briefly considered.