1. The characters of the semen of twenty-one bulls were compared with their fertility as expressed by the service rate—the number of services required for each conception.

2. It was found that, on the basis of the density of the semen, the total number of spermatozoa ejaculated, the motility and change in pH of the semen on incubation at 37° C, the animals could be divided into a higher fertility group with service rates from slightly more than 1·0 to about 3·5, and a lower fertility group with service rates from above 3·5 to ∞. Totally sterile animals could be detected.

3. It is suggested that other factors than the quality of the semen can vary fertility so as to give service rates at different levels from 1·0 to about 3·5. Below a certain level of semen quality fertility appears to be impaired no matter what other factors operate.

4. No relationship could be detected between the percentage of abnormal spermatozoa ejaculated and the service rate.

5. Standards for use in diagnosis of fertility are suggested.

1. Data for the composition and digestibility of certain by-products of the ryegrass seed cleaning industry are presented in amplification of data already published.

2. It is shown that the ‘hairgrass’ fraction of ryegrass seed cleanings has a starch equivalent somewhat superior to that of pure ryegrass seed or oats, and that this may be ascribed in all probability to its content of ratstail fescue seed.

3. It is shown that the ‘flatweed’ fraction, consisting chiefly of buttercup seed, has a starch equivalent, on a dry-matter basis, about three-quarters that of oats or pure ryegrass seed, and that it is, in spite of a relatively high content of digestible oil, among the least valuable constituents of the cleanings, apart from dust, straw and other worthless material.

4. Commercial Yorkshire fog seed is shown to have a feeding value comparable to that of pure perennial ryegrass seed.

5. Some data are presented regarding the inorganic constituents of ryegrass seed and ryegrass seed by-products.

An analysis of the data from the continuous manurial experiment in Woodlands Field, Craibstone Experimental Farm, Aberdeen, has demonstrated the effects of fertilizers and of rainfall on the yields of various crops grown on a six-course rotation plan with a basal application of dung to the roots. The soil is a dark brown medium loam of which the parent material is ‘drift’ from the grinding down of granite and metamorphic rocks and is typical of a large class of glacial soils in the north-east of Scotland.

Of the three major nutrients nitrogen gave the largest mean response on every crop except hay. The hay yield was benefited least by nitrogen and most by potash. The effect of nitrogen was to depress slightly, but not significantly, the total production of the ley for the 3 years. Potash, on the other hand, significantly improved the yield of hay as well as of the aftermath and the following ‘pastures’. The phosphate and potash responses were approximately equal in respect of barley, oats and potatoes. Turnips, swedes and potatoes responded similarly to potash, but in terms of dry matter the response was markedly higher for potatoes.

Superphosphate proved more effective than ground mineral phosphate on every crop except turnips. Further study of the data revealed interesting differences between the crops in respect of their capacity for utilizing ground mineral phosphate. Oats gave negligible responses to mineral phosphate throughout the experiment.

1. Losses of incorporated non-protein nitrogen compounds from stored cubes have been determined. The loss of incorporated urea was very small provided moulding did not occur. The loss of incorporated ammonium bicarbonate was large, amounting in all to some 50–60%.

2. The effects of the size of the cubes and of the nature of the container on nitrogen losses are discussed.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm it has been impossible to control bacillary white diarrhoea of chicks (pullorum disease) by blood testing when foods of c. 20% protein content have been fed as the sole diet of chicks.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) has occurred in brother chicks when fed foods of c. 20% protein content and that epidemic bacillary white, diarrhoea has not occurred in sister chicks which have been fed crushed oats for the first 72 hr. and thereafter have been fed a diet of c. 14% protein intake.

Evidence is presented, based on feeding tests, that at Hanns Hall Farm epidemic bacillary white diarrhoea (pullorum disease) not only did not occur in sister chicks in which B. pullorum had been demonstrated to be present in one of their number, but also epidemic bacillary white diarrhoea failed to develop despite the lack of hygienic precautions when these chicks had been placed in an uncleansed brooder from which the survivors of a severe epidemic of this disease had just been removed, and when they were brooded adjacent to chicks which suffered severe mortality from the disease, thereby undergoing all the chances of infection by wide dissemination of B. pullorum within a small area.

1. Experiments were made on the respiration of bran at different moisture levels using a continuous absorption apparatus in which the humidity of the air-stream was adjusted to be at equilibrium with the respiring bran. The rate of respiration was accelerated with increasing moisture content and was very rapid deterioration due to the high respiration rate and microbiological damage.

2. Experiments were made on the storage of bran at known moisture contents in closed tins in the laboratory and also in sacks kept under farm conditions. The total nitrogen content of the bran stored in the tins appeared to increase during storage. From similar increases in total phosphorus, it is clear that the increase in total nitrogen was caused by a loss of dry matter from the stored feeding stuff, a fact which was further demonstrated by the loss in dry weight of the sacks of bran with attributed to two causes: (1) the respiration of the plant cells still active in the bran itself, and (2) the respiration of developing micro-organisms. It is evident from these experiments that fresh bran, free from insect infestation and stored at a moisture content of less than 13%, will have a very low respiration rate and will, therefore, not be liable to heating. Bran of 15–19% moisture content respires at a much faster rate and the time for which such material can be stored with freedom from heating or other types of deterioration will be limited.

1. Experiments were carried out to determine the period of survival of spermatozoa in the genital tract of the cow.

2. No reliable results were obtained by searching, post-mortem, the genital tracts of two cows and three heifers killed at various intervals after insemination.

3. An attempt to induce ovulation at a definite time to which insemination could be related, in order that the survival time of the spermatozoa might be determined by the recovery of the ova post-mortem, was not successful. Of four cows and one heifer given pregnant mare's serum followed by pregnancy urine, one ovulated. To one animal, where a large follicle was present in one ovary, pregnancy urine was given. Ovulation occurred but could not be definitely attributed to the pregnancy urine.

1. The fertility records of two groups of bulls, one group used for controlled service, and one group used for free service, were compared over a period of one year.

2. The fertility of the free-service group was consistently better except during the months of December, January, February and March.

3. The difference in fertility between the two groups was correlated with the varying length of the oestral periods of the cows at different seasons of the year.

4. It is suggested that the higher fertility in the free-service group was due to a closer relationship of service to the end of heat and thus to ovulation.

The bacterial syndrome encountered in epidemic bacillary white diarrhoea of chicks (pullorum disease) is initially one of invasion by faecal type organisms, this is followed by invasion by anaerogenic B. pullorum.

Evidence is presented to show that ostensibly pure cultures of anaerogenic B. pullorum, consist of two organisms, a true aerogenic B. pullorum in symbiosis with an anaerobe, morphologically of the welchii type.

Evidence is presented to show that variation in fermentation reactions of ostensibly pure cultures of anaerogenic B. pullorum depend upon the degree of symbiosis exerted between the anaerobe and the aerobe and this degree of symbiosis is greatly affected by methods of cultivation on solid media.

It is proposed that the ovarian blight peculiar to adult hens which are carriers of bacillary white diarrhoea infection is caused by putrefaction of ovarian material in vivo by the activities of a morphologically welchii type organism.

It is proposed that B. pullorum exists in one form only, namely, the aerogehic form, and that this organism is a potential pathogen only.

The average numbers of females of all ages (herd size) in pedigree herds of Jerseys, Guernseys, and Red Polls in 1939 were found to be 25, 22 and 42 respectively. Of the herds listed, 15–20% made no herdbook entries and were of much smaller than average size. Excluding these, the average numbers become 29, 26 and 49. The number of females entered in the herdbook during 1939 was about 20% of the total number of females of all ages. The same proportion was found in all herd size groups except the smallest where it was lower. As a general guide, therefore, to breed and regional differences in herd size in all the major breeds, the average number of herdbook entries of females has been multiplied by 5.

The main object of the present investigation was to test the inference from the results of previous trials that a diet composed substantially of cereal and weatings, with a small percentage of lucerne meal or grass meal, and supplying 7% of white-fish meal up to 90 lb. live weight and no protein supplement at all thereafter, should provide all the protein needed for the maximum rate of growth in bacon pigs and the production of carcasses of satisfactory quality, when fed at the rates shown in the feeding chart in Table 3.

Two separate trials were carried out, and both the individual-feeding and group-feeding techniques were employed. In Trial I the control treatment A supplied the standard allowances of high-protein supplement, consisting of 10% of white-fish meal from weaning to 150 lb. live weight, and 5% of extracted soya-bean meal from 150 lb. to slaughter at about 200 lb. The white-fish meal in the rations of the pigs on treatment B was restricted to 7% up to 90 lb. live weight, and from this stage onwards the high-protein supplement was entirely omitted from the diet. The rest of the diet in both treatments consisted of barley meal and weatings, with a small percentage of lucerne meal, care being taken also to safeguard the animals against mineral deficiencies.

Carrots of Chantenay type wefe grown in cultures of a black fen soil shown by analysis to be deficient in phosphate but normal as regards potash. When phosphate was absent, the cotyledons, and sometimes the whole of the foliage, were dark bronze in colour. There was a statistically significant increase in yield following applications of phosphate, but a tendency for applied nitrogen and potash to diminish yield.

We thank F. Shaw, Esq., N.D.H., of the Cambs. C.C. Staff for Agricultural Education, for his assistance in obtaining the fen soil used in this experiment.

Average lactation curves have been prepared from selected animals in a group of heifers treated for 60 or 100 days with stilboestrol or hexoestrol tablet implants. A treatment period of 100 days appears to give poorer results than one of 60 days. The optimum duration, on the average, is probably about 75 days, but seems to depend upon the way lactation develops—which bears no obvious relationship to the amount of oestrogen absorbed.

A rise in yield follows tablet removal whether this is done while the yield is still rising or after it has begun to decline. Yield in an induced lactation may fall very far short of the animal's inherent capacity, but comparison between induced lactations and those at subsequent calvings shows that it may very nearly approach what would be a normal yield.

A heifer which was treated twice did rather less well in her second induced lactation.

Breeding histories of a number of implanted heifers are outlined. They were all animals which had failed previously to get in calf. 5–10% (without further treatment) did not return to an ovulatory cycle. About 70% of anatomically normal heifers got in calf, the service rate being about 2·6. A rather high incidence of abortions may be a feature of a recovery period from treatment, but may have been due to selection of animals with such a tendency.

The fatty acid composition of the back fats of pigs whose basic diets were buttermilk or skim milk have been determined by ester-fractionation, and the results are compared with those of previous workers. Pigs whose diets were supplemented with copra contained up to 13 mol. % of myristic acid, with smaller amounts of lauric acid.

Experimental evidence supports the view that dietary linoleic acid is assimilated to a greater extent by slow-growing than by fast-growing pigs. Dietary lauric and myristic acids, however, appear in greater proportions in the depots of fast-growing, as compared with slow-growing pigs.

The di-, and polyethenoid C18 acids of the fat of unsupplemented milk-fed pigs appeared not to contain appreciable amounts of linoleic acid.

Trichlorethylene-extracted palm-kernel meal is not an essential factor in the production of six-day disease.

A comparison of the results of tests 1, 2 and 3 clearly indicates that under the same conditions and with similar chicks, some diets tend to produce six-day disease and some do not.

A feeding test performed on Hanns Hall Farm chicks demonstrates that a diet conducive to intestinal putrefaction fed to chicks after 14 days from birth initiates an epidemic of bacillary white diarrhoea (pullorum disease).

If is proposed that measures for the control of epidemic bacillary white diarrhoea of chicks (pullorum disease), which consist of the detection and removal of reacting hens from the flock by means of a diagnostic and sensitive antigen, cannot be effective unless accompanied by an alteration in nutrition for the purpose of reducing intestinal putrefaction.

Experiments at this laboratory show that the agglutination test for bacillary white diarrhoea cannot differentiate between fowls which produce diseased chicks and fowls which produce chicks resistant to disease.

Experiments at this laboratory show that B. pullorum as a potential pathogen does not remain viable to an extent that it is able to produce bacillary white diarrhoea in chicks from an incubator or brooder which has held diseased hatches or broods, respectively.

In his observations on six-day disease, Taylor (1944) reported that the chicks which died on his preliminary experiments gave negative results on bacteriological examination.

Many workers hold that for routine examination of poultry, a quick, convenient and inexpensive method of detecting certain specific bacterial infection is to inoculate slopes of nutrient agar with liver or other tissue, and incubate at 37° C. It is claimed that some organisms often grow in pure culture from diseased chicks, and that this method is especially suitable in the detection of S. pullorum or S. gallinarum infections. The resultant growth can be washed off in saline solution and tested by specific agglutinating sera or by testing on certain carbohydrates.

Consideration of the composition of pig depot fats from the point of view of Callow's growth-rate theory (Callow, 1935a,b), shows that the theory appears to explain the iodine values of fats both of groups of animals and of depots of an individual pig. When, however, the fatty acid compositions of the fats are considered, the theory is untenable in respect of the depots of an individual pig. Differences in unsaturation between outer back fat, inner back fat, and perinephric fat are essentially determined by differences in the ratio of oleic acid to stearic acid, differences in linoleic acid content being inconsiderable.

It can equally be shown that the growth-rate theory does not explain the results obtained by Hilditch & Pedelty (1941) for depot fats of sheep. Differences between different depots both of the pig and of the sheep seem to be characteristic of the species and cannot readily be altered by altering either the quantity or the quality of the diet.

An experiment involving twelve pens of twenty-five pullets demonstrated that two types of dried potatoes compared favourably with cereals, as regards their effects on egg production, when up to 42½% of each product was included in the mash.

The records of the experiment, as regards (a) the number of eggs laid in 12 months, (b) the mean weight of eggs during the year, and (c) the change in live weight during the year, were studied by analysis of variance, using the approximate method of Yates (1933) for obtaining standard errors of pen means from the variance within pens. Similar analyses of the number of eggs laid in the month were carried out for each month separately. The latter analyses indicated the months in which increased production was obtained from the superior rations, and showed that duplicate pens had reacted similarly to the experimental feeding. The results of the statistical analyses are set out in some detail as an example of method.

A method is presented for the preparation of a sensitive and diagnostic stained antigen for the detection of fowls suspected of infection by the organisms found in epidemic bacillary white diarrhoea (pullorum disease).

Evidence is presented that an antigen prepared from organisms grown in a medium which provides for the peculiar growth requirements of the anaerobic organism associated with anaerogenic pullorum, is more sensitive than antigens prepared from organisms grown on media which lack these peculiar growth factors.

A stained antigen has been prepared which is agglutinated by pullorum antisera in 15 sec. at 4°C. and in 6 sec. a t 15°C. and which is not agglutinated by normal sera in 5 min.

The author wishes to thank the Directors of Messrs J. Bibby and Sons, Ltd., for permission to publish these papers.

In particular he would thank Mr J. Pye Bibby for his keen interest in the investigations and for his loyal support throughout.

In addition he wishes to thank Miss Margaret Davies for her assistance in the bacteriological investigations, and Miss Margaret Shafto for laboratory work and the compilation of relevant data.