Showing papers in "The Journal of Agricultural Science in 1952"

Studies on the breeding season and reproduction of the ewe Part I. The breeding season in different environments Part II. The breeding season in one locality

Abstract: A knowledge of the exact length of the breeding season for improved breeds under different environmental conditions in this country is lacking. Such knowledge is of importance so that the lambing season can be arranged according to farm conditions. Such knowledge, apart from providing the necessary background for the successful application of artificial insemination and administration of hormones, helps to explain certain problems of infertility. By selection it should be possible to build up strains, by extending the breeding season at one or both ends, so as to get lambing at any required time. As the results below show, crossbreeding and selection could lead to early sexual maturity, prolonged breeding season or restricted lactation anoestrus, which would undoubtedly increase the reproductive potentiality of the ewe.

Some chemical changes in the nitrogenous constituents of urine when voided on pasture

Abstract: 1. The chemical changes which take place in a urine patch have been studied using urine from wethers and to a small extent from cows.2. The sizes of individual urine patches vary considerably, depending mainly on the volume of the urination. The average from wethers is about 45 sq.in.3. The volume of urine per wether per day averages 2880 ml. with a nitrogen content of 0·92%, of which about 75% was in the form of urea; 4·1% as allantoin; 2·6% as hippuric acid; 1·5% as creatine-creatinine; and 12·4% as amino-nitrogen.4. Improved herbage growth results in twice the area actually wetted with urine. The total area affected averaged 100 sq.in.5. The probable area wetted with urine from cow urinations was about 650 sq.in. with a further 200 sq.in. affected indirectly.6. With wethers the average rate of nitrogen application on a urine patch amounts to 432 lb. of nitrogen per acre.7. The rate of hydrolysis of urea in laboratory experiments is affected by temperature and is increased by small amounts of hippuric acid but not by the other urinary constituents tried. The hydrolysis rate is greater at soil moisture content of 24% than at higher moisture levels.8. Urea hydrolysis in soil (both in laboratory and in the field) is accompanied by pronounced increase in pH (up to pH 9·2 with urea equivalent to that applied to a urine patch).9. The rate of nitrification is greatly affected by the pH changes. At pH values in excess of 8 nitrites accumulate and nitrate formation is retarded.10. Heteroauxin and allantoin were both found to stimulate nitrification in laboratory experiments when used at levels found in urine. Other urinary constituents were without effect.11. The hold up of urine on leaf surfaces of pastures was shown to amount to as much as 12·5% of the green weight of herbage.12. Ammonia in considerable amounts may be lost to the air both from herbage and from soil.13. Field experiments are in complete agreement with laboratory experiments and no essential difference of wether and cow urine was noticed.14. The fate of the nitrogenous constituents is briefly considered and shown schematically.

Studies on the breeding season and reproduction of the ewe Part III. The breeding season and artificial light Part IV. Studies on the reproduction of the ewe Part V. Mating behaviour and pregnancy diagnosis

Abstract: During the course of three breeding seasons, daily observations of oestrus were undertaken on the following groups of ewes, all of which were running with ochred rams. One hundred and twenty ewes (pure bred and first-cross) of different breeds and ages, running with vasectomized rams under natural conditions. Twenty-eight grade Suffolk ewes fed on a submaintenance diet. Eighteen grade Suffolk ewes running with a fertile ram. Twenty ewes of several breeds exposed to artificial light.The effects of heredity (breed and individual), environment (season, year and nutrition), age and artificial light on the breeding season and related phenomena have been investigated. The results and conclusions were as follows:1. (a) There are breed differences in the extent of the breeding season, cycle length, incidence of silent heat and duration of heat (Table 29). (b) The duration of the breeding season is related to the geographical origin (latitude and altitude) of the breed, (c) The duration of the breeding season of the first-cross is intermediate between that of the two parents, (d) Individual differences in the number of oestrous cycles per ewe per season were more marked in the mountain breeds.2. (a) Of the ewe lambs, 79% exhibited oestrus during the shortest days only of the first breeding season. Their breeding season is not spread evenly about the shortest day as it is with adults. (b) The occurrence and length of the breeding season in ewe lambs is associated with early birth dates or with higher growth rates.3. (a) Significant differences exist between breeds in the age at first oestrus. (b) Ewe lambs born early in the season showed their first oestrus at later age and heavier weight than those born late.4. Annual differences in the duration of the breeding season, cycle length, incidence of silent heat and occurrence of first oestrus were negligible.5. (a) Submaintenance diet had no effect on the onset of the breeding season, but it converted oestrus into silent heat. Conception occurred less frequently after periods of underfeeding. (b) At high latitudes nutrition has only a minor effect on the breeding season of the ewe.6. (a) A constant high ratio of artificial darkness (8 hr. light: 16 hr. darkness) hastened the onset of the breeding season some 57 and 27 days in the two experimental groups. (b) A constant high ratio of artificial light (16 hr. light: 8 hr. darkness) hastened the end of the breeding season some 104 days on an average (in one experimental group), (c) There were breed differences in the latency of initiation and of cessation of the induced breeding season, (d) In the induced breeding season cycles of ovulation preceded the first oestrus, (e) Two thresholds of pituitary activity are suggested, one for the onset of ovulation, and the other for the manifestation of oestrus.7. (a) A high frequency of cycles outside the normal range (14–19 days) was observed in the mountain breeds and in ewe lambs. (b) The shortest average cycle length coincided with the shortest days of the year.8. A high frequency of silent heats (during the breeding season) was observed in the mountain breeds, in ewe lambs and during the second half of the breeding season.9. Oestrus was of longer duration in adults and yearlings than in ewe lambs.10. (a) Post-partum heat occurred in 56% of Suffolk ewes with an average lactation anoestrus of 35 days. (b) There is a relationship between the early onset of the breeding season and the incidence of post-partum heat, (c) Conception post-partum is partly inhibited by lactation.11. Mating behaviour was observed in animals of several breeds and ages (three patterns were recorded for ewes and eight patterns for rams).12. Irregular columnar cells in the vaginal smear of the ewe characterized late pregnancy.In addition, the breeding season of wild and domestic sheep was reviewed in relation to the environment with special reference to the length of daylight.

Experiments on irrigation of sugar beet

Abstract: It is assumed that maximum growth requires maximum transpiration, and that maximum transpiration can be maintained by keeping the soil near to field capacity throughout the growing season. Transpiration rates can be calculated from weather data (the basic principles are outlined and an example of the calculation given), and the paper describes four field experiments in which attempts were made to control the water content of the soil throughout the growing season, by irrigation from overhead spray-lines.In spite of differences in season and soil, the four sets of data are consistent in showing that maximum sugar yield is obtained when the soil-moisture deficit (amount of rain or irrigation needed restore the soil to field capacity) does not exceed about 2 in. in mid-July, or about 4 in. in mid-September.

A study of the principal factors affecting the establishment and development of the field bean ( Vicia faba )

Abstract: 1. A survey of bean crops was carried out in the Oxford area in the years 1947–9 with the object of studying farmers' methods, and the factors affecting establishment and development of the crop in the field. 2. The season and the fertility status of the soil have a profound influence on the development of the crop, while plant density affects the growth of the individual plant. 3. Hard winters cause crop losses which may amount to more than 50% of the plants. Mortality continues throughout the season. 4. A warm dry spring and an equable summer temperature favour pod production more than hot, dry seasons. 5. High plant densities cause: (1) a reduced rate of pod formation on each plant over a wide range of conditions, but a greater reduction on poor land than under good conditions; (2) a reduction in stem formation on low fertility fields (but not on high fertility land); (3) a significant increase in pod production per acre on high quality fields. 6. A high level of fertility leads to significantly more pods/acre, owing to better plant survival and increased branching and podding. 7. Under conditions favouring vegetative growth, there appears to be some competition between stem production and pod production, for the correlation between stems/plant and pods/plant found on low fertility land and in dry seasons no longer holds under good growing conditions. 8. In an average crop, there is a very serious loss of flowers and partly matured pods, which may amount to 85% of the flowers formed. 9. This wastage may be due to (1) unsatisfactory pollination or self-infertility, (2) inadequate availability of certain plant nutrients, (3) unsuitable environmental conditions, particularly low light intensity in dense crops. 10. Botrytis cinerea can cause a high wastage of crop, but it did not figure prominently during the 3 years of the survey, and appeared to be associated with deficiency of potash and/or phosphate in the only two severe outbreaks that occurred.

The production of viable bovine ova

Abstract: 1. A comparison has been made between the effect of various forms of P.M.S. on the cow's ovaries by giving 3000 i.u. of: ( a ) processed P.M.S., ( b ) fresh whole P.M.S., ( c ) freeze-dried P.M.S.; the average follicle numbers produced being 13·9, 20·1, and 14·5 respectively.

The amino-acids of sheep and cow urine

Abstract: 1. Samples of sheep and cow urine have been analysed microbiologically for seventeen aminoacids.2. Over 90% of the total amino-nitrogen in hydrolysed urine was due to glycine.3. Bound glycine was present not only as hippuric acid but also in other forms as yet uninvestigated.

Studies in grazing management IV. A comparison of close-folding and rotational grazing dairy cows on intensively fertilized pasture

Abstract: 1. In continuation of experiments made in 1949 (Holmes et al. 1950) an experiment was carried out from 7 May until 23 September 1950, to compare close-folding and rotational grazing of cows on pastures which were liberally treated with nitrogenous fertilizer. With close-folding the cows were moved daily to an area of fresh pasture calculated to supply the day's feed requirements; the rate of stocking for the day ranged from thirty to sixty-five cows per acre. With rotational grazing the cows were stocked on pasture at the rate of seven to eight cows per acre and moved from one pasture to the other at intervals of 3–4 days. Two uniform groups of six Ayrshire cows were used in a double reversal layout with four periods each of 5 weeks. The same pastures as in 1949—a permanent pasture and a cocksfoot ley—suitably divided by electric fences were used. No supplementary feeding was given.2. The average yield per acre from close-folding was 241 cow-days, 732 gal. of milk and 320 lb. live-weight gain—equivalent to 632 lb. digestible crude protein and 4316 lb. starch equivalent. Rotational grazing on similar adjoining paddocks gave 181 cow-days, 557 gal. of milk and 285 lb. liveweight gain per acre, equivalent to 486 lb. digestible crude protein and 3371 lb. starch equivalent.3. The average daily milk yield per cow was 29·5 lb. for one group and 30·2 lb. for the other. For close-folding it was 29·6 lb. and for rotational grazing it was 30·1 lb., none of the differences being significant. Nor were any differences in the average live weight of the groups or in their live-weight gains significant.4. The increased production per acre from closefolding compared with rotational grazing—amounting to 20–40%—could be related to the increased efficiency with which the available pasture was consumed.5. Close-folding had no harmful effect on the pastures. Although the season was exceptionally wet, poaching occurred only in the gates and alleyways. 6. The frequent applications of nitrogenous fertilizer throughout the season maintained regular production of good herbage. In June and July, however, despite the fertilizer applied, the crudeprotein content dropped on some paddocks to 13% of the dry matter, a figure barely sufficient to maintain high milk yields.7. Comparison of the production per acre in 1950 with that in 1949 where close-folding was used, showed an increase of 34% in starch equivalent utilized on the permanent pasture. For each extra cwt. ‘Nitro-Chalk’ applied in 1950 over that in 1949, 190 lb. starch equivalent were produced. On the cocksfoot the response to additional nitrogen was reduced because of potash deficiency induced by cropping for grass-drying in 1948.8. The factors affecting the increased production from close-folding and the fertilizer requirements of pasture are discussed.

Control of reproductive and pelt changes in ferrets: some experiments with animals kept entirely upon artificial light

Abstract: The effects, on induction and maintenance of oestrus and on pelt changes, were compared for various schedules of entirely artificial light of constant intensity.A period of exposure to low environmental temperature was without effect on subsequent response to light treatment.In one experiment, after periods on 6 hr. artificial light or on daylight, groups were put upon, daily, (i) 7 hr. light as 6 hr. + 5 hr. dark + 1 hr. light, (ii) the same total amount of light but divided as 6 hr. + 1 hr. separated by darkness increasing by 5 min. each day, and (iii) light increasing from 7 hr. by 5 min. daily. Groups (ii) and (iii) became oestrous together, later than group (i).Subsequently all were placed on 7 hr. total light daily, applied in various ways. If given as a single continuous period daily, oestrus ended and moult into winter coat occurred. The latent period depended upon the treatment previously imposed. The duration of oestrus on treatment (i) was greater than normal.In another experiment females were put on, daily, (iv) 24 hr. light, (v) 14 hr. light, and (vi) 4 hr. light as 2 hr. + 10 hr. dark + 2 hr. light. First response was seen on (vi), but on the average the quickest was on (v) and slowest on (iv). Thus darkness contributes to the induction of oestrus.Possible interpretations are discussed.

Growth analysis of the domestic fowl I. Effect of plane of nutrition and sex on live-weights and external measurements

Abstract: 101 Rhode Island Red × Light Sussex chickens have been made to conform to four differently shaped growth-curves from hatching to 24 weeks, by control of their plane of nutrition. The four treatments HH, LH, HL and LL allowed comparisons to be made between birds of the same age but different weights.As the main concern has been to find the essential nature rather than the precise extent of the effects produced by different planes of nutrition, the treatment differences were made as extreme as possible without allowing the rations to become unbalanced.The conclusions reached are as follows:1. The treatments used have produced marked effects on the growth-curves of the birds, analysed on the basis of equal age. These effects have been shown to be statistically significant at all stages after 3 weeks.2. In body-weight and form, two types of bird were produced. The HH and LH birds were similar, with greater relative proportions of the late developing parts and secondary sexual characteristics, and the small differences that existed between them were not significant at 24 weeks. Likewise, the LL and HL birds formed a comparable group, exhibiting a more infantile body form similar to that of the HH and LH birds at an earlier age. The differencebetween the HL and LL birds, though generally not statistically significant, is greater than that between the LH and HH group.3. The treatments produced a small but consistent effect on the external measurements of the birds when comparisons were made on the basis of equal weight. Nine measurements were recorded. In the case of four measurements, no treatment effect was noted. Four skeletal measurements demonstrated a consistent effect of treatment, the LL and HL measurements exceeding those of the HH and LH at equal live-weights. This result was reversed in the case of the only muscular measurement, thickness of leg musculature. Opposite results are therefore indicated for the muscle and skeletal tissues. This finding will receive further discussion when the dissection analysis results are discussed in a later paper.4. The presence of definite growth-gradients from the body extremities towards the trunk is indicated by the external measurements.5. The two sexes differ in their live-weights at equal age and in their bodily proportions both at similar ages and similar weights. The most marked sex-difference in external measurement is noted in the length of the mid-wing, and a possible functional explanation is advanced. In general, the sex-difference is greatest for the late maturing characters.

The relationship between phosphate response and base saturation in acid soils

Abstract: In three groups of field experiments totalling fiftysix observations phosphate responses were found to be very significantly and inversely related both to the percentage saturation of the b.e.c. and exchangeable calcium as a percentage of exchangeable calcium plus hydrogen. The availability of the native soil phosphate was significantly and directly related to these values. The relationships between phosphate response or availability and the amounts of acid-soluble, adsorbed and water-soluble phosphate in the soils were much less conclusive. In acid soils considerable amounts of phosphate can be retained in a plant-available form associated with exchangeable bases, mainly calcium. Since practically all the soils from the field experiments lay within the range pH 4·7–6·3, it is believed that this form of phosphate is operative in these soils. The presence of such phosphate in the soil is, however, a function of the degree of base saturation in so far as this governs (probably through its influence on soil pH) the equilibrium distribution of the native soil phosphate between the available base-linked (saloid-bound) form and the less available colloid-bound form. With decreasing pH and base saturation increasing amounts of colloid-bound phosphate are formed at the expense of the saloid-bound phosphate. The degree of base saturation is therefore directly related to phosphate availability and, consequently, inversely related to phosphate response. In view of the significant regressions obtained, and the association of the exchangeable bases with a specific form of available phosphate, it is suggested that until methods are worked out for determining the amount of saloid-bound phosphate exchangeable base data may be used for assessing phosphato availability and response in acid soils. This method is contrasted with the more conventional methods of determining acid-soluble and adsorbed phosphates which are not always specific regarding tho form of phosphate extracted and the values for which, since they may represent the sum of a number of forms of different availabilities, aro difficult to interpret.

Histochemical studies on bovine sweat glands

Abstract: 1. Histochemical tests have been applied to the socalled sweat glands and their secretions of Zebu and Ayrshire cattle, the former to only a limited extent.2. For skin specimens of Ayrshire cattle positive reactions were obtained for ribonucleoprotein, arginine and alkaline phosphatase. Negative reactions were obtained for desoxyribonucleoprotein and acid glycerophosphatase.3. Neither the sweat glands of Ayrshire cattle nor those of Zebu cattle gave positive reactions for fats, lipids or cholesterol and its esters, although these were all present in the sebaceous glands of both breeds. Detectable amounts of phospholipid were not found in the sweat glands of the Ayrshire cattle and their secretions.4. The chemical composition of the secretion of bovine sweat glands differs markedly from that of human eccrine or apocrine sweat glands in not containing detectable amounts of glycogen, lipids and associated compounds or iron.

The availability of calcium in three legumes of grassland

Abstract: 1. The availability of the calcium in three grassland species, all legumes, has been investigated, with the rat as experimental animal. 2. Two procedures involving determination of the calcium balance, (a) by analysis of feed, faeces and urine, and (b) by a slaughter technique, were used. 3. The foregoing methods gave results, for any one species, which were without significant difference. It is considered that the slaughter technique would be the less laborious when any large number of determinations has to be made. 4. The calcium in both lucerne and late-flowering red clover was available to a significantly greater degree than that in wild white clover. In all three species calcium availability was high. 5. The possible significance of the high faecal calcium found in rats receiving wild white clover has been discussed. 6. It was concluded that the extension of availability studies to a wider range of grassland species and of their ash-components would be desirable.

Nutrition of the bacon pig XVI. The relative supplemental value of the proteins in extracted soya-bean meal and in white-fish meal

Abstract: In continuation of our work on the relative supplemental value of animal and vegetable protein concentrates (Woodman & Evans, 1951), a study has been made of the proteins in extracted soya-bean meal. It is probable that vegetable protein concentrates may vary among themselves in nutritive value and that the proteins of ground-nut meal, which were the subject of investigation in our previous experiments, could not for this reason be regarded as representative of vegetable proteins in general. The same basal diet, composed of roughly 2 parts of barley meal and 1 part of fine bran, together with a little lucerne meal and minerals, was again used in the present investigation.

Studies in grazing management V. Further determination of the nutrient intake of dairy cows under close-folding and rotational methods of grazing

Abstract: 1. The experiments started in 1949 to determine the weight and chemical composition of the herbage dry matter eaten by two groups of dairy cows grazing under a rotational and a close-folding system of management have been continued in 1950. 2. Good-quality herbage was fed in adequate quantity to both groups for 20 weeks, in four fiveweekly periods allowing a double change-over system for the groups. The weights of protein, fibre, other extractives, lignin and minerals eaten daily by the close-folded group were determined. Difficulty in obtaining truly representative herbage samples from the rotational paddock made such detailed analyses for the rotationally grazed cattle not worth while. 3. The weight of dry matter eaten by the closefolded cows was remarkably constant, the mean was 26 lb./cow/day and the standard deviation ±2·7 lb. The weight eaten by the rotationally grazed cows was more difficult to measure and appeared to vary considerably, the average being 31 lb. dry matter/ cow/day, and the standard deviation ±3·1 lb. Reasons are suggested why this figure of 31 lb. may be at least 5% too high. 4. The relationship between the chemical composition of herbage as cut for sampling and the probable composition of the herbage as eaten by the grazing animal is discussed. Correction curves are given to convert the protein and fibre contents of herbage as cut in these experiments to values corresponding to those in the herbage as eaten. 5. An attempt has been made to provide a balance sheet, in terms of D.C.P. and S.E., of animal production against nutrient intake. A deficiency of both protein and energy existed during the first spring period in both 1949 and 1950 (according to presentday standards), and although the protein balance became positive later in the season, the energy provided by the grass eaten was still barely adequate. 6. Mineral balances calculated for the closefolded cows showed deficiencies of both calcium and phosphorus during the period of high milk yield, with the balances becoming positive later in the grazing season.

Studies of the composition of sainfoin

Abstract: 1. Studies were made of the composition of Giant sainfoin cut successively at different stages of growth in two seasons under contrasting conditions of weather and soil.2. Cuts were taken at preflowering, early- and full-flowering stages of growth. Yields of both fresh material and dry matter substantiated the usual farming practice of taking two cuts at full flower in one season, and indicate that cutting sainfoin before it comes into bloom has a seriously depressing effect on productivity.3. Like most green fodder crops, sainfoin has a lower content of crude protein and nitrogen-free extractives, and a higher content of crude fibre as the plant increases in maturity. The mineral content is somewhat variable, and in particular the potassium content appears to reflect the status of this element in the soil.4. The ratio of leaf dry matter to total dry matter of the plant decreases with advancing maturity. The leaf composition is fairly constant, irrespective of stage of growth, number of cuts and season, the fibre content being remarkably constant in contrast with that of stem, where it increases with advancing maturity. Leaf is richer than stem in crude protein, ether extract and total mineral matter, particularly calcium. Thus changes which do occur in the composition of the plant are due to variations in stem composition and leaf-stem ratio.5. Analyses of sainfoin hay, made under both experimental and commercial conditions, are discussed, and the range of variation in the main constituents of thirty-five commercial samples is commented upon.6. The present investigations into the composition of sainfoin, both as green fodder and as hay, show figures that differ appreciably from those derived from earlier German work. Examination of the data available for the nutritive value of fresh and conserved sainfoin reveal anomalies which suggest that such data are not typical of the crop as grown in this country, and also suggest the need for more modern data.

Myoepithelial cells in bovine sweat glands

Abstract: 1. Spindle-shaped myoepithelial cells with longitudinal myofibrils have been demonstrated in the sweat glands of Ayrshire and Zebu cattle.2. The cells in both breeds are similar in structure, location and arrangement.3. Under the polarizing microscope they are birefringent as is characteristic of other fibrillar structures.

The storage of ware potatoes in permanent buildings I. Storage in bins in an uninsulated store, 1946–7

Abstract: Permanent buildings of a variety of designs have been in widespread use for many years as potato stores on the Continent of Europe and in the United States of America. (For a summary of recent literature, with references, see Rose & Cook, 1949.) There are examples of buildings being used as potato stores in this country (e.g. Keith, 1941), but the bulk of the crop is stored in clamps. Because the climates of the U.S.A. and the Continent of Europe differ markedly from that of Great Britain, it is not possible to use the types of store developed in those regions as models for British stores. Over much North America and the Continent of Europe the stores are designed to withstand severe winter frosts, and the main problem is to keep the temperature of the tubers high enough to prevent freezing, the metabolic heat being readily removed if necessary by a small amount of controlled ventilation. Under British conditions the mean daily temperature for most of the storage season, above the optimum for potato storage (40·42° F.), and therefore the main problem is that of keeping the tubers cool. This could, of course, be achieved by using a cold store, but cold storage is considered too expensive. To design a store, information is required about the temperatures attained by stacks of potatoes at different times of the year, the effectiveness ventilation in controlling the temperature, the relation of temperature in different parts of the stack to dimensions of the stack, and to the insulation both of the bin and of the building. To obtain this data a programme of work was initiated, and the results of the first year's work in a building of very low insulating capacity are described in this paper. The climatic conditions during this year, i.e. 1946–7, were very abnormal, a very cold winter followed by a hot spell in the spring which provided an abnormally severe test of an uninsulated store. Later papers will consider storage in an insulated building with adequate ventilation.

Experimental errors in laying experiments

Abstract: To amplify published information on the size of errors in annual egg records, results are presented for fourteen laying experiments and one flock under uniform management at the Agricultural Research Institute of Northern Ireland, Hillsborough. It is concluded that in laying experiments on a semi-intensive plant the egg records are seldom affected to any serious extent by differences between pens that are treated similarly. Non-random allocation of pullets to the laying pens does not appear to have seriously affected the results on which this conclusion is based. It is pointed out that the distribution of egg records from a high producing flock is likely to be extremely skew and leptokurtic.

The comparative seasonal output of ultra-simple and general-purpose seeds mixtures

Abstract: A comparison is made of the herbage production and animal output, as measured by live-weight gain, of temporary pastures sown to ultra-simple seeds mixtures with those sown to a more complex generalpurpose mixture. Herbage production was somewhat higher in the simple-mixture series on account of the inclusion of a lucerne-meadow fescue mixture. In total seasonal output, as reflected by live-weight gain of fattening stock, only small differences occurred. It is suggested that the value of simple mixtures lies in their ability to provide seasonality of grazing and a more even output of animal products throughout the season. This is not always possible when, using general-purpose competitive mixtures.

Fertility levels of bulls kept at an artificial insemination centre

Abstract: The present method of estimating preliminary results in artificial insemination practice bears a definite relation to calving percentages, and, with few exceptions, may be generally adopted as a true measure of fertility. Single factors, such as an individual bull with a low conception rate, a new and less efficient inseminator, or variations in the results obtained at the Sub-Centres, etc., do not noticeably affect the average monthly conception rate in a large A.I. Centre. The most important influencing factors have been found to be the choice of diluent, and in some cases the elimination of the use of stored semen. No significant variation in fertility occurs with the season of the year, the age of the bull or the area of operation; but, for a bull to work satisfactorily at a centre and at the same time achieve good results, it is necessary that he should be treated as an individual and his psychology closely studied. In view of results obtained, one is able to conclude that methods of evaluation at present in use (estimating initial motility, density, percentage of abnormals and a test of viability by storage of diluted and undiluted samples) are up to a point satisfactory. A dilutor or buffer may influence the conception rate considerably, and it is felt that the diluent in use at present has its own fertility level. With the Centre's team of forty-eight bulls it is obvious that there must be some variation in fertility levels between individuals; but it is seen that, whereas bulls in natural service fall obviously into categories of ‘high fertility’ or ‘low fertility’, this division tends to disappear in A.I. with the application of the various techniques.

Body weights of some New Zealand Jersey and Friesian cattle

Abstract: The mean body weights and standard deviations of body weights at monthly intervals of female Jersey and Friesian cattle on the Massey Agricultural College and Dairy Research Institute farms at Palmerston North, New Zealand, are presented in graphs. A summary of some of these mean weights is presented in the following table:

Report on an experiment to compare the fattening values, for beef cattle, of silages made from grass cut at different stages of growth

Abstract: 1. The method adopted for making three different grades of silage, from grass cut at different stages of maturity, is described. 2. A feeding trial is described including four groups of cattle fed on grades I–III silages and on swedes and straw respectively. 3. The live-weight gains made are recorded together with the rate of dry-matter intake. 4. A digestibility trial was carried out on the three grades of silage. The digestibility coefficients found are recorded. 5. It is shown that cattle fed solely on silage build up a bigger ‘gut fill’, to the extent of 40 lb. (± 11), than similar cattle fed on swedes and straw. 6. When an allowance had been made for a 40 lb. greater ‘gut fill’ in silage-fed cattle it was found that grades I and II silages produced a significantly greater rate of fattening than grade III silage and than swedes and straw. 7. It was found that the rate of total daily drymatter intake rose to a peak at the eighth week and then fell; it did not continue to rise beyond that point but the cattle continued to gain in live weight. 8. The efficiency of utilization of the dry matter of the rations fed increased during the latter part of the trial. 9. It is suggested that the increase in efficiency of utilization of the dry matter consumed may be attributed to an adaptation in the rumen microflora of the cattle which proceeded for up to 8 weeks after the cattle were put on to the experimental diets.

A method of assessing cutaneous pigmentation in bovine skin

Abstract: 1. Since the pigmentation of the skin cannot be assessed by visual examination of the hair or hide, a simple and convenient method of grading the cutaneous pigmentation of cattle based on the microscopic examination of skin sections has been described. 2. The degree of cutaneous pigmentation of the skin of twenty body regions of three Ayrshire cows, two Ayrshire bull calves, two Sudanese Zebu bulls, one Sudanese Zebu cow and one Jamaican Zebu cow have been assessed by this method. 3. The skin of the Zebu cattle was found to be much more heavily pigmented than that of the Ayrshire cattle. 4. The dorsal and lateral regions of both the Zebu and the Ayrshire cattle were more pigmented than the ventral and leg regions.

The nutritive value of common heather (Calluna vulgaris) I. The preparation of samples of Calluna vulgaris for analytical purposes and for digestibility studies

Abstract: 1. The methods employed by some of the earlier workers for separating analytical samples from heather, show little uniformity and are, in general, poorly defined. No procedure capable of separating the relatively large weights of material necessary for digestibility studies has hitherto been devised.2. Analytical samples prepared by (a) a method used by Thomas, and (b) a method suggested by Braid were compared. The results obtained were very similar, but the latter method was recommended as being the better denned.3. Two methods of preparing large samples for digestibility studies, one adapted for winter heather and the other for use in spring and summer, have been used. Both of these methods, when applied to winter heather, give samples which compare well with a sample obtained by the method of Braid.4. Samples separated in summer by method 5 were compared with samples of material similar to that observed to be eaten by sheep. It was found that the former were of appreciably lower crude protein content and contained slightly more lignin than the latter.5. No evidence of an adverse effect on digestibility by oven-drying for 24–48 hr. at 38° C. was obtained.

The potassium status of barley in relation to yields of grain

Abstract: 1. Various portions of barley plants were made available for chemical tests from manurial experiments which were designed to test the effects of K treatment (broadcast and placed with the seed) on grain yield. 2. The experiments were located at three centres differing in soil characters and K status. Centre A was severely deficient in K; centre B was moderately deficient and at centre C, K was adequate. 3. A comparison was made between the results of the following tissue test methods for K, Mg, Ca, P and Mn: (a) diffusion method, using young leaf, mid-stem leaf, and internode respectively; (b) Waring blendor, and (c) ash analysis. Mn was not determined by the blendor method. 4. The coefficients of variation for the quick tests compared favourably with those of ash analysis for K, Mg, Ca, P and Mn respectively. Variations in results in tissue tests for Ca were, however, significantly greater than those of ash analysis, at centre A (second sampling). 5. Correlation coefficients between results of ash analysis and the tissue test methods for K, Mg, Ca, P and Mn were positive and significant for totals, treatment and treatment × sites, except for Mn in young leaf by diffusion method. The error term for P was also significant for the quick methods, thus decreasing the value of the correlations for this nutrient. 6. Correlation coefficients of yields with ash analyses, Waring blendor and diffusion method (mid-stem leaf) analyses respectively were significant and positive for K and negative for Mg, Ca, P and Mn. This confirms an interaction of K with the other nutrients. 7. Minimum K levels, determined 5 weeks after seeding, above which no further increase in yields may be expected at the three centres, were: by diffusion method, using young leaf, mid-stem leaf and internode, 700, 500 and 600 μg. extracted per. g fresh weight respectively; by Waring blendor using ‘tops’, 2000 μg. extracted per g. fresh weight; by ash analysis of tops 1·5% K in dry matter. There is evidence that these critical levels fall later in the season, especially in mid-stem leaves, presumably through translocation of K to the ears. 8. Minimum levels of K required for optimum yields are above those associated with the onset of deficiency symptoms of the element. Thus chemical methods only can determine suboptimal levels of nutrients in relation to final yields.

Nutrition of the bacon pig XV. The relative supplemental value of the proteins in dried brewers' yeast and in white-fish meal

Abstract: The object of the present investigation, was to compare the supplemental value of the microbial proteins in dried brewers' yeast with the animal proteins in white-fish meal when incorporated in a barley meal-fine bran diet containing a little lucerne meal and suitably adjusted as regards minerals. The investigation was carried out both by the nitrogen-balance method and by the statistically controlled growth method, using the individual-feeding technique. The main problem was to find the minimum percentage of yeast that had to be included in the cereal diet so as to sustain the same rate of growth and economy of food conversion, and to enable retention of nitrogen to take place at the same rate, as is obtained on a standard diet containing 7% of white-fish meal, the total digestible nutrients in all diets being kept approximately constant.In the first nitrogen-balance trial a comparison was made between the standard diet containing 7% of white-fish meal and a similar basal diet supplemented with 15% of dried brewers' yeast. The percentage crude protein in the yeast diet was 15·39 as compared with 15·12 in the standard treatment, the total digestible crude protein being 12·34 and 12·29, respectively. The supply of total digestible nutrients was almost alike on both treatments.After about 6 weeks on experiment, the two hogs on the yeast diet became subject to vomiting at rather frequent intervals, although they were always eager for their food and their faeces remained normal. It is unlikely that vomiting was caused by the presence in the yeast of any toxic substance and the possibility that it was due to the presence of live yeast cells is also remote for reasons given. The most likely hypothesis is that it was due to the animals ‘bolting’ their food with great avidity, since the pigs found the yeast diet to be highly palatable and they always appeared to be hungry.The two hogs on the yeast diet made average daily live-weight gains of 0·85 and 0·80 lb., the figures over a corresponding period for the hogs on the standard treatment being 0·67 and 0·71 lb. Economy of food conversion was also better on the yeast treatment. The average daily retention of nitrogen was also higher on the yeast treatment the figures being 9·28 and 9·01 g. as compared with 8·07 and 8·90 g. on the standard diet. It is evident therefore that when yeast is incorporated in a cereal diet so as to bring the digestible crude protein content to the same level as in the standard treatment containing white-fish meal, maximum storage of nitrogen takes place, even with young pigs.In the second nitrogen-balance trial the amount of yeast in the diet was reduced to 12% so as to investigate whether this amount would also support maximum retention of nitrogen and maximum growth. The percentage of digestible crude protein in the diet was 12·56 on the standard treatment and 11·29 on the yeast treatment, the total digestible nutrients being 64·47 and 64·18%, respectively. Over the 63 days that the pigs were in the metabolism crates the two hogs on the standard treatment made slightly higher live-weight gains and retained rather more protein in their tissues, the average retention of nitrogen being 9·43 g. on the standard diet and 8·3 g. on the yeast diet.It appeared from these results that a cereal diet supplemented with dried brewers' yeast so as to bring the crude protein content to 14·18% (15·95% on the basis of dry matter) does not supply quite enough protein to support maximum retention of nitrogen. In the first experiment, however, when the yeast diet contained 15·39% of crude protein (17·37% on the basis of dry matter) the results were fully equal to the standard treatment containing 15·12% of crude protein (17·21% on the basis of dry matter). These conclusions were tested further by means of a growth trial with ten individually-fedpigs on each treatment.In the growth trial the ten pigs on treatment A received a supplement of 9% of dried brewers' yeast, those on treatment B were on the standard diet containing 7% of white-fish meal and those on treatment C received a supplement of 12% yeast. The percentage of crude protein on the mean moisture basis was 14·62 in treatment A, 16·15 in treatment B and 15·4% in treatment C. It was concluded from the results of this growth trial that when approximately one-third of the total crude protein in the diet comes from either dried brewers' yeast or white-fish meal, complete supplementation of the proteins in the basal diet of barley meal and fine bran occurs, so as to enable maximum retention of nitrogen or maximum growth to take place without wastage of aminoacids. The results for treatment A suggest that the proteins in yeast may even be superior in supplemental value to the proteins in white-fish meal.The deductions made from both methods of experimentation are therefore in close agreement and the results show that a basal diet of 2 parts of barley meal and 1 part of fine bran with a little lucerne meal and minerals when supplemented with dried brewers' yeast so as to bring the crude protein content of the mixture to about 15·5% enables the young pig to store the maximum amount of protein in its tissues and to grow at a maximum rate in conformity with the net energy content of the diet. The distribution of essential amino -acids in the proteins of yeast and in the proteins of whitefish meal, when based on equal weight of crude protein, is not significantly different, any differences being slightly in favour of the yeast proteins.A comparison is also made between the results obtained with dried brewers' yeast and those obtained with extracted decorticated ground-nut meal used in previous trials.