Showing papers in "The Journal of Agricultural Science in 1955"

Determination of ammonia and nitrate in soil

Abstract: 1. Methods for the determination of ammonia and nitrate in soil are described. The ammonia and nitrate are extracted at pH 1·0–1·5 with a mixture of potassium sulphate and sulphuric acid, and the ammonia is determined by distillation with magnesium oxide at 25° C. in a modified Conway microdiffusion unit. Ammonia plus nitrate is determined on a separate sample of the same extract by reduction of the nitrate to ammonia with titanous hydroxide and subsequent distillation with magnesium oxide, both the reduction and distillation being carried out in a modified microdiffusion unit at 25° C.2. The methods are applicable to coloured extracts and are not affected by substances found to interfere with other methods of determining ammonia and nitrate.3. It is suggested that the methods may also prove useful for the determination of ammonia and nitrate in plant materials.

Studies on milk production of Large White pigs

Abstract: 1 A review of the literature relating to the frequency at which pigs suckle under natural conditions was made The evidence indicated that the average interval between successive sucklings is approximately 1–1¼ hr2 A number of sows and their litters were continuously observed for varying periods of time under natural conditions and a similar average interval between sucklings was observed3 A review of the literature relating to the determination of milk production of sows was made This showed that the majority of previous workers imposed, during the periods when the litters were being weighed before and after every suckling, a suckling frequency that did not simulate the natural behaviour of the animals Evidence suggesting that the imposition of such unnatural conditions invalidated the findings, in so far as they might indicate the true milking capacity of the animals, was discussed4 An experiment to obtain direct evidence on the importance of the suckling interval in relation to the milk obtained by the pigs was carried out Conclusive evidence was obtained that when suckling was allowed every hour, both the quantity of milk obtained by the litters and their live-weight gain in 24 hr periods were much greater than was the case when suckling was allowed only every 2½ or 3 hr In addition, the pigs on the hourly suckling frequency utilized their milk intake more efficiently5 An experiment was carried out in which an attempt was made to obtain, under natural conditions, a valid estimate of the 56 days' lactation yield of three Large White gilts The method of weighing the individual pigs before and after suckling was used, and the animals were allowed to suckle every hour6 The estimated average lactation yield was 768 lb, with a range of from 882 to 655 lb, although it was suggested that the true yield might be some 5–10% higher The figures obtained in this work were shown to be very much higher than the yields reported by most of the previous workers7 The nursing and suckling behaviour of the dams and their litters was studied Observations of significance in relation to the variation in growth of pigs within a litter were made8 Data were obtained concerning the average amount of milk obtained by individual pigs at a suckling, the total amount ejected at a suckling, the effect of daylight and of darkness on the amount of milk obtained, the relative productivity of the individual mammary glands and the efficiency with which the milk intake was utilized by the individual pigs in the litter9 A close positive relation between milk intake and live-weight gain during the first 3 weeks of life was found During the last 5 weeks of lactation, when supplementary food was available, this close relationship was not seen10 The growth rate of the suckling pig, as related to the supply of food, was discussed The evidence available suggested that the supply of sow's milk was frequently insufficient to meet the requirements of the pigs for optimum growth11 The chemical composition of sow's milk in relation to the stage of lactation was studied

Inter-breed ovum transfer in sheep

Abstract: Fertilized ova have been transferred from Border Leicester to Welsh Mountain ewes, and vice versa. The oestrous cycles of the ewes were synchronized by progesterone treatment, and donor ewes were super-ovulated with PMS. 68–90 hr. after the onset of oestrus in the donors, thirty-seven ova, representing 58% of the ovulations, were recovered in vivo from thirteen ewes. Nineteen ova were transferred to eighteen recipient ewes and a total of eight pure-bred lambs were born to ewes of the opposite breed. Transfers resulted in pregnancy when oestrus in the recipients commenced from 16 hr. before to 20 hr. after that in the donors; two of the ova which developed to term were 4-cell, five were 8-cell and one was a 16-cell ovum at the time of transfer. Four out of seven and four out of eleven transfers, using blood serum and Ringer's solution respectively, resulted in the birth of lambs. Prior to transfer to the recipients seven of the ova which developed to term were exposed for 30–45 min. at room temperature, whilst one developed after exposure for 70 min.

Studies of the skeleton of the sheep I. The effect of different levels of dietary calcium during pregnancy and lactation on individual bones

Abstract: 1. Three groups of mature ewes were fed during pregnancy and lactation on rations differing in their calcium content. The mean daily intakes of calcium were 1·4 g. (group A), 4·5 g. (group B), and 7·4 g. (group C). Blood samples were analysed monthly for calcium and inorganic phosphorus. The ewes were killed at approximately 100 days after parturition and the skeletons isolated. Individual bones, either whole or divided into definite fractions, were analysed.2. The level of calcium intake was without effect on the number of lambs born, birth weight, or growth while milk fed.3. Blood calcium was significantly lower in group A than in groups B and C, but blood inorganic phosphorus was unaltered.4. The resorption of bone substance was greater in group A than in groups B and C.5. The severity of resorption varied between bones, and in regions within certain bones. Resorption was most severe in the vertebrae and pelvis, and only slight in the metacarpal, the metatarsal and the shafts of other long bones. Resorption of intermediate magnitude was found for the remainder of the skeleton.6. Resorption was accompanied by reductions in the percentages of ash in bones, but this effect was proportionately less than the ash weight reduction.7. Radiological observations made on flesh-free bones at the end of the experiment gave a picture of resorption similar to that presented by the data for ash weights and percentages of ash, namely that resorption was much greater in group A than in groups B and C.

Plane of nutrition and starch equivalents.

Abstract: 1. Experiments with two sheep are described in which energy retention was measured at different levels of food intake and the losses of energy incidental to food consumption measured. 2. Attainment of reasonably stable values for energy losses occurred after 72 hr. of fast. On realimentation stable values were not attained until 10 days had elapsed. Methane production was resumed relatively slowly. 3. The accuracy of the mean estimates of energy retention was high, and duplicate determinations of metabolism after lapses of time gave excellent agreement. 4. It is shown that the assumption of linearity of the relationship between energy retention and food intake expressed as metabolizable energy is incorrect. 5. An exponential relationship between energy retention, and food intake was employed to describe the data. This resulted in a reduction of the residual sum of squares compared with a linear regression. 6. It is shown that net energy values (starch equivalents) measured by Kellner, Armsby and Forbes have entirely different meanings, and that the correction employed by Wood reflects these facts. 7. The exponential relationship has been generalized to take into account body-size variation and has been examined as far as it affects concepts of efficiency of food utilization, and of nutritional plane. 8. Nutritional plane has been rigidly defined in such a way that it is independent of body size and of food quality, and it enables net energy values to be predicted at other planes of nutrition once the net energy value at one nutritional plane is known. 9. A simple and rational scheme for the feeding of livestock to take into account the decline in net energy value (starch equivalent) with nutritional plane has been devised. 10. Analysis of the energy losses in relation to nutritional plane shows that losses of energy in faeces, urine and as heat per unit food ingested tend to rise with increasing nutritional plane. Methane losses fall. These results suggest that the prediction of net energy values from measurement of energy losses in faeces, or from estimates of metabolizable energy, can give rise to extremely unreliable results. 11. The results have been discussed in relation to previous work in this field. It is pointed out that the exponential relationships employed are a convenient method of describing a very complex situation and facilitating its analysis.

The cytogenetics of the differences between some Secale species

Abstract: 1. The seed of crosses of Secale cereale with S. montanum and S. dalmaticum germinated only when S. cereale was the seed parent. 2. S. cereale was found to differ from S. montanum and S. dalmaticum by two large translocations involving three pairs of chromosomes, and a small translocation involving a fourth pair. The fertility of the F1 plants was low, and in ear morphology and perennial habit they were similar to the S. montanum and S. dalmaticum parents. 3. S. montanum and S. dalmaticum were found to be similar in gross chromosome structure and their hybrids were phenotypically intermediate and fertile. 4. The F2 of the cross S. cereale x S. dalmaticum consisted of three types, in terms of chromosome structural condition and plant morphology, those like one or other parent and those like the F1. 5. The genetic and evolutionary significance of this situation is discussed, together with the problem of the fixation of translocations in populations.

Studies on soil humic acids: I. The chemical nature of humic nitrogen

Abstract: 1. The chemical nature of the nitrogen in humic acid preparations isolated from 0·5M-sodium hydroxide and 0·1M-sodium pyrophosphate (pH 7·0) extracts of nine different soils has been studied by determining the amounts of acid-soluble-N, ammonia-N, amino-sugar-N and α-amino-N liberated by acid hydrolysis of the preparations and by paper chromatographic analysis of their acid hydrolysates. 2. Humic acid preparations isolated from alkali and pyrophosphate extracts of the same soil differ markedly in total nitrogen content and in nitrogen distribution after acid hydrolysis. The alkali-extracted preparations have a higher nitrogen content and a higher proportion of acid-soluble-N and α-amino-N. 3. A considerable fraction (20–60%) of the nitrogen in the preparations examined was not dissolved by acid hydrolysis. The major fraction of the nitrogen dissolved was in the form of amino-acids. 4. At least 31–48% of the nitrogen in the alkaliextracted preparations and 20–35% of the nitrogen in the pyrophosphate-extracted preparations was in the form of protein. From 3 to 10% of the nitrogen in the preparations was in the form of amino-sugars. 5. The results obtained by paper chromatographic analysis of acid hydrolysates of the preparations indicated that the protein materials in humic acids isolated from different soils by alkali or pyrophosphate are similar in their amino-acid composition. The following nineteen amino-acids were detected in every hydrolysate examined: phenylalanine, leucine, isoleucine, valine, alanine, glycine, threonine, serine, aspartic acid, glutamic acid, lysine, arginine, histidine, proline, hydroxyproline, α-amino-n-butyric acid, β-alanine, γ-aminobutyric acid and tyrosine. Two unidentified ninhydrin-reacting substances, oxidation products of cystine and methionine, and amino-sugars were also detected in every hydrolysate examined. A third unidentified ninhydrin-reacting substance and a substance provisionally identified as α,e-diaminopimelic acid were found in some of the hydrolysates.

Skin structure of Egyptian buffaloes and cattle with particular reference to sweat glands

Abstract: The structure, distribution and dimensions of skin strata and sweat glands have been investigated in Egyptian buffaloes and cattle Samples from sixteen body regions were taken from three adult bulls of both species Identical studies were also made on one buffalo calf and two buffalo embryos Serial vertical and horizontal sections were cut from each body region using the ‘terpineol paraffin wax’ method The following results were obtained 1 Buffalo skin is characterized by dermal papillae enclosing papillomatous epidermis The fibrous structure of the dermis is similar in both species In buffaloes, the average thickness of skin, main epidermis, papillomatous epidermis, and cornium is 6·5 mm, 50, 115, and 11μ respectively The epidermis coefficient is 12 for the main epidermis and 18 for the papillomatous epidermis In cattle, the average thickness of skin, epidermis and cornium layer is 4·3 mm, 51 and 5 μ respectively, while the epidermis coefficient is 8 2 The average number of hair follicles per sqcm of skin is 394 in the buffalo and 2633 in cattle Each hair follicle is accompanied by two large lobulated sebaceous glands in the buffalo, and one small bilobed gland in cattle 3 There is no species difference in the histology of the sweat glands Each hair follicle is accompanied by one sweat gland in both species In the buffalo, the body of the sweat gland is oval and convoluted, while the duct is twisted at its attachment to the body In cattle, the body of the gland is elongated while the duct is straight The number of sweat glands per sqcm of skin is 394 in the buffalo and 2633 in cattle The dimensions of the sweat glands are larger in buffaloes than in cattle The length, circumference and sweating surface of the gland is 0·58, 0·47, and 0·276 sqmm in the buffalo, and 0·47, 0·26, and 0·124 sqmm in cattle respectively The glandular surface of sweat glands per sqcm of skin is 1·07 sqcm in the buffalo and 3·08 sqcm in cattle 4 The type of sweat gland secretion is apocrine in both species In the buffalo, successive stages of apocrine secretion are observed, and the merocrinelike form is rare In cattle, the merocrine-like form prevails and the other stages are very rare The theory (Findlay & Yang, 1950) of intraluminal transformation, of secretory products from coarse granularity to fluid homogeneity is supported The effect of locality on the type of sweating activity is stressed 5 There are species differences in the distribution of blood vessels and capillaries In the subepidermal level, the arterial branches are more frequent and superficial in buffaloes than in cattle Capillaries are found in the dermal papillae of buffalo skin The capillary loops encircling the hair follicle are more frequent in cattle than in buffaloes The blood capillaries supplying the sebaceous glands are more numerous in the buffalo than in cattle The blood supply of sweat glands is poor in both species 6 There are age differences in the skin histology The number of hair follicles per sqcm of skin in a 5-months-old embryo, calf at birth, and adult buffaloes is 10560, 1248 and 400 respectively There are no skin glands in the 1-month and 5-months-old embryos The sweat gland in the calf is small in size and similar in structure to that of the adult Calves have fewer sweat glands than adults 7 The body conformation and the degree of pigmentation are affected by species, breed and locality 8 The secreting activity of the sweat glands may be affected by the locality 9 It seems that there are species differences in the mechanism of heat convection and radiation, insensible perspiration and sensible perspiration, due to histological differences

The intensive production of herbage for crop-drying Part VI. A study of the effect of intensive nitrogen fertilizer treatment on species and strains of grass, grown alone and with white clover

Abstract: 1. An experiment is described which lasted for 5 years and in which a comparison was made of twelve grasses or grass mixtures under different fertilizer nitrogen treatments and also when grown with clover. The herbage was cut 4–6 times in each season. Adequate amounts of mineral fertilizers (280–340 lb. K2O and about 100 lb. P2O5 per acre per annum), and the following nitrogen treatments were applied: (1) no nitrogen, no clover, (2) grass sown with clover, (3) 140–208 lb. nitrogen per acre per annum in four to six equal dressings, (4) 350–416 lb. nitrogen per acre per annum in five and six equal dressings. In 1951, 1952 and 1953 the clover dominant swards (treatment 2) were split between the following treatments; (X) as (3) above, (Y) 35 lb. nitrogen per acre in spring and again in late summer, (Z) no nitrogen as (2) above. 2. The average yields for the 4 years were 2180, 5940 and 8300 lb. dry matter per acre, and 290, 850 and 1460 lb. crude protein per acre for treatments 1, 3 and 4. With treatment 2 the average yields were 2830 lb. dry matter and 400 lb. crude protein in 1949 and 4270 lb. dry matter and 820 lb. crude protein in 1950. An approximate average yield for the 4 years from treatment 2 was 4630 lb. dry matter and 860 lb. crude protein. In 1951–3 average yields for treatments 2X, 2Y and 2Z were, 7240, 6340 and 5750 lb. dry matter and 1240, 1180 and 1100 lb. crude protein per acre. 3. There were considerable differences between grasses in nitrogen response and compatibility with clover. The highest yields with fertilizer nitrogen were given by cocksfoot strains, but, in the presence of clover, ryegrass and timothy strains gave the highest yields. There were also differences between strains within each species. 4. Mean crude protein contents were, for treatments 1, 3 and 4, 13·3, 14·3 and 17·6%, and for treatments 2X, 2Y and 2Z in 1951–3, 17·2, 18·6 and 19·1%. Differences between species were significant in only a few instances. 5. The distribution of yield over the season was most regular with treatment 4. Cocksfoot species gave the least variable yields from cut to cut, while those from timothy and ryegrass swards were the most variable. 6. Treatments 3 and 4 maintained a high proportion of sown grasses in the swards. In treatment 2 the clover percentage rose to a high level by 1950. A high percentage was maintained under treatment 2Z in 1951–3. Treatment 2Y depressed the clover content in some grasses, and treatment 2X further depressed it in those grasses. A fairly high clover content was maintained, however, even with treatment 2X with some timothy strains and meadow fescue. 7. The mineral fertilizers applied maintained the soil analysis at a satisfactory level. 8. The results are discussed with special reference to the relative merits of fertilizer nitrogen and clover nitrogen and to the differences between species and strains.

The effect of environmental temperature and humidity on the rectal temperature of calves

Abstract: 1. The rectal temperatures of three 4-month-old Ayrshire bull calves were measured in individual 6 hr. daily exposures to 15, 20, 25, 30, 35 and 40° C. dry-bulb temperature at low humidity (17 mg./l. absolute humidity) and to 30, 35 and 40° C. at high humidity (7 mg./l. saturation deficit). The experiments on each animal lasted 45 consecutive days and consisted of five replications of these nine environmental conditions. Measurements of rectal temperature were made every 5 min.2. The rectal temperatures of the animals rose with increasing environmental temperature and humidity.

Ovulation and the passage of the ova through the fallopian tubes in the pig

Abstract: 1. The rate of passage of ova down the Fallopian tubes in the pig has been checked on eighteen living sows by laparotomy and in fifteen sows and gilts at autopsy. 2. Both sets of observations suggest that the ova enter the uterus between 24 and 48 hr. after ovulation instead of 72 hr. as suggested by earlier workers. 3. It is suggested that the rapid passage of ova through the Fallopian tubes of the pig may be facilitated by the progesterone from the large number of corpora lutea in the ovaries of the pig.

The digestibility of the carbohydrate complex by birds of different ages

Abstract: 1. The digestibility of the carbohydrates in compounded poultry diets has been estimated, using both conventional and individual methods for certain components. 2. In the conventional analysis, crude fibre was apparently digested to the extent of 5%; this has been shown to be due to the comparison of different complexes in the food and the droppings. 3. Sugar and starch were digested by birds of all ages, and cellulose and lignin were indigestible. The digestibility of pentosan increased with increased age of the bird. 4. By deleting crude fibre and adopting available carbohydrate for the partition of the carbohydrate complex in foods, the nutritive ratio of a compound diet can be estimated from analytical data, and the amount of extra protein necessary when a diet is supplemented by fat can be calculated.

The effect of environmental temperature and humidity on the respiration rate of Ayrshire calves

Abstract: 1. The respiration rates of three 4-month old Ayrshire bull calves were measured in individual 6 hr. daily exposures to 15, 20, 25, 30, 35 and 40° C. dry bulb temperatures at 17 mg./l. absolute humidity and at 7 mg./l. saturation deficit at temperatures of 30, 35 and 40° C. in a planned sequence of environmental temperature. The schedule of experiments on each animal lasted 45 days consisting of five replications of these nine environmental conditions. Throughout the experimental programme the respiration rates of these three animals and of three control animals were measured in a holding room just before the experimental animal of each pair was transferred to the hot room.2. The frequency of respiration of all the calves increased with increasing environmental temperature and humidity.

The digestibility of the carbohydrate complex of barley, wheat and maize by adult fowls

Abstract: 1. The digestibility of the carbohydrates in barley, wheat and maize has been determined, using both conventional methods and individual methods for sugar, starch, pentosan, cellulose and lignin. 2. Sugar and starch were completely digested; cellulose and lignin were indigestible and the pentosan was about one-third digested. 3. Digestible pentosan accounted for about 3% of the total digestible carbohydrate. 4. The ratios of the available carbohydrate, i.e. the total of sugar plus starch expressed as starch, was almost exactly the same as that of the digestible carbohydrate and could be used as a measure of the relative amounts of digestible carbohydrate in the foods.

The storage of ware potatoes in permanent buildings II. The temperature of unventilated stacks of potatoes

Abstract: 1. Under normal English storage conditions, the heat production of mature potatoes drops rapidly from a value of probably about 150 b.th.u./ton/hr. immediately after harvest to about 30–50 b.th.u./ton/hr. Sprouting is accompanied by an increase in the rate of heat production. The initial heat production of immature potatoes may be of the order of 250 b.th.u./ton/hr.2. As a result of the production of heat, the temperatures in stacks of potatoes will tend to rise to levels above that of the outside air which are just sufficient to cause the convection and conduction necessary to remove the metabolic heat as fast as it is produced.3. The difference in temperature between the potatoes and the ambient air is a function of the heat production of the potatoes and of the height of the stack, and is practically independent of its other dimensions if these exceed twice the height. Under average conditions during the middle of the storage season, and for heights of storage of from about 6 to 12 ft. it may be taken as a rough practical guide that the average and maximum temperatures of the potatoes will tend to exceed the average temperature of the store air by about 2/3 and 1° F. respectively for every foot of height.4. Overheating is possible at both the beginning and end of the storage season, when heat production is high and the outside temperatures also possibly high. In general it is safe to store unventilated potatoes to a height of about 6 ft. if they are mature, though if they are harvested with a great deal of earth late storage should not be attempted. If there is no intention of storing late, and the potatoes are fairly clean, storage to aheight of 12 ft. may be permissible. Immature potatoes should not be stored to a height of more than 3 ft.

The chemical composition of oats I. The oil and free fatty acid content of oats and groats

Abstract: The petroleum-ether extractable oil content of native oats (dry-weight basis) ranges 3·0–8·5%, and is chiefly dependent upon variety and kernel content (which is itself a varietal characteristic). That of the kernel, which comprises 64–81% of the grain by weight, is 4–11% with a spread of about 2·5% within the variety. The kernel contains in addition about 2·5% of more complex insoluble fatty material which is released on acid hydrolysis. The husk, on the other hand, contains only a few tenths of one per cent of petroleum-ether soluble oil together with about 1% of more complex material that can be released by acid hydrolysis.Certain environments favour higher levels of oil content within all varieties whereas others favour lower levels; Scottish samples tend to be slightly higher in oil content than English samples of the same variety.The free fatty acid content of the oil in the kernel ranges 3–10% for sound, viable grain; the value for any sample is more dependent on environment during cultivation, harvest and storage than on the variety. After the grain is milled or pulverized the free fatty acid content rises to much higher levels within a few days.

Soil-sampling errors and advisory analyses

Abstract: 1. Twenty-four sampling units from 50 fields of differing soil type and past manurial history have been examined separately for pH and 1% citric soluble phosphorus and potassium to determine the errors which can occur in obtaining a representative sample for analysis.2. Soils which had received lime and fertilizers within 3 years of the sampling date showed appreciably greater sampling errors than those which had not.3. The sampling errors were greater than the analytical errors and were such that the common practice of classifying soils into six fertility groups was not justified. Three major groups are more reasonable and practical for routine advisory purposes.

Endocrine relationships in the induction of oestrus and ovulation in the anoestrous ewe

Abstract: 1. A total of forty-two Suffolk cross-bred and 230 stud Romney Marsh ewes were used in four experiments in which pregnant mare serum gonadotrophin (p.m.s.) was used in various combinations with progesterone and oestrogen in attempts to induce fertile mating in anoestrus.2. Groups of six Suffolk cross-bred ewes were injected with 1000 i.u. p.m.s. after pretreatment, commencing 4 days earlier, with 75 mg. progesterone administered in one of four different ways. Six twice-daily injections in oil resulted in oestrus in five ewes in each of two groups treated. Single injections in oil solution, aqueous suspension, and benzyl alcohol emulsion resulted in oestrus in two, nil, and four ewes, respectively. All were served within 48 hr. of injection of p.m.s.3. Ovulation was observed in five of six crossbred ewes which received six twice-daily injections of progesterone in oil, without subsequent injection of p.m.s. Three were served.4. Divided injections of progesterone commencing 4 days before 750–1000 i.u. p.m.s. failed to induce a satisfactory oestrous response in Romney Marsh ewes. An increase to 7 days in the duration of progesterone stimulation resulted in oestrus in all of eighteen ewes treated.5. The injection of a benzyl alcohol emulsion containing 75 or 150 mg. progesterone, given as a single dose 4 or 7 days before 750 i.u. p.m.s., failed to induce a satisfactory oestrous response. Of seventy-two ewes treated, only seven were served.6. Lambing results were most unsatisfactory when progesterone-p.m.s. treatment was followed by artificial insemination. Of 144 Romneys inseminated, only twelve lambed. Successful pregnancy appeared unrelated to the type of treatment or the occurrence of oestrus.7. On the basis of the oestrous responses observed after the injection of a variety of combinations of oestrogen, progesterone, and p.m.s., and by reference to quantitative data on progesterone-oestrogen relationships in oestrous behaviour in the spayed ewe, it is concluded that the developing follicle of the Romney Marsh ewe produces an amount of oestrogen approximately equivalent, in its physiological activity, to a single injection in oil of about 20 μg. oestradiol benzoate.

Seasonal variations in semen characteristics of sheep in the subtropics

Abstract: Semen samples were collected from twelve fattailed rams of two breeds (nine Ossimi and three Rahmani), by the use of an artificial vagina. They were kept under natural conditions at Cairo, Egypt (30° N.). Three collections were made each month throughout one year (1951–2).

The effect of environmental temperature and humidity on the skin temperature of Ayrshire calves

Abstract: 1. The skin temperatures at each of eight positions on the trunks of three 4-month-old Ayrshire bull calves were measured at 5 min. intervals in individual 6 hr. daily exposures to dry-bulb temperatures of 15, 20, 25, 30, 35 and 40° C. at 17 mg./l. absolute humidity, and 30, 35 and 40° C. at 7 mg./l. saturation deficit in a modified form of Latin square arrangement of environmental temperature. The schedule of experiments on each calf lasted 45 consecutive days and consisted of five replications of each of the nine environmental conditions.2. The skin temperatures of the calves all rose with increasing environmental temperature, humidity and time of exposure.

Studies on the milk yields of Scottish Blackface ewes.

Abstract: 1. Milk yields of thirteen Blackface ewes with single lambs were estimated over a period of 6 weeks at the hill farm of Glensaugh (Kincardineshire) and a further twenty-nine at Stanhope (Peeblesshire).2. The estimated average total milk yield over 6 weeks was 159 lb. at Glensaugh and 96 lb. at Stanhope. Recorded yields ranged from 86 to 220 lb. at Glensaugh and from 65 to 131 lb. at Stanhope.3. The average daily live-weight increase of lambs was 0·72 lb. at Glensaugh and 0·43 lb. at Stanhope. Daily live-weight increases ranged from 0·23 to 0·91 lb.4. At Glensaugh the average lactation curve reached a maximum 24 days after lambing. At Stanhope, the average lactation curve showed a peak 10 days after lambing and another peak 32 days after lambing. The lack of uniformity in this curve was attributed to changing conditions of nutrition.5. Linear regression was found between ewe milk yield and daily live-weight increase in lambs, and the correlation between ewe milk yield and ewe live weight was highly significant, though the regression coefficient is fairly small.6. Four samples of ewe's milk were analysed.7. The correlation between ewe milk yield and daily live weight increase in lambs persisted when figures representing other breeds of ewes (with single lambs) were included in the calculations.

The effect on yield and leaf area of wheat of applying nitrogen as a top-dressing in April or in sprays at ear emergence

Abstract: Nitrogen, at the rate of 0.5 cwt./acre, was applied to winter wheat as an April dressing of nitrochalk, or as eight sprayings of 2% NH 4 NO 3 solution applied either to the soil or to the leaves at about the period of maximum leaf area, before and during ear emergence. All three methods of nitrogen application caused similar increases in yield and nitrogen content of grain. April nitrogen gave a greater yield of straw than the later dressings. Late nitrogen application caused a small increase in leaf area index, first noticeable one week after ear emergence and persisting for another four weeks. L.A.I. of plots that received nitrogen in April was much larger than that of the other plots at the period of maximum leaf area, but by four weeks after ear emergence it was less than that of plots receiving the late nitrogen. Shoot number per metre and leaf area per shoot were increased by early nitrogen, but only the latter was increased by nitrogen applied at ear emergence. Leaf area duration after ear emergence was the same on all nitrogen-treated plots and the yield of grain divided by L.A.D. was nearly constant for all plots. Applying nitrogen late, after an April dressing, did not prevent the rapid fall in L.A.I. from the high value reached at the period of maximum leaf area and caused no greater increase in yield than when applied in the absence of an April top-dressing. A single urea spray applied in early June increased yield to the same extent as the ammonium nitrate sprays.

Nitrogen transformations during the biological decomposition of straw composted with inorganic nitrogen

Abstract: 1. Nitrogen transformations during the decomposition of straw composted with ammonium carbonate have been studied by following the changes in (a) the amounts of inorganic and organic nitrogen; (b) the amounts of ammonia-, volatile base-, α-amino- and amino sugar-N liberated by acid hydrolysis of the organic nitrogen complexes; and (c) the amino acid composition of acid hydrolysates of the composts.2. Synthesis of organic nitrogen during the biological decomposition of straw composted with ammonium carbonate is not accompanied by any gross change in the distribution of the forms of organic nitrogen. A large fraction of the organic nitrogen synthesized is in the form of protein; a smaller fraction is in the form of amino sugar.

A study of three breeds of sheep wintered in four environments

Abstract: A study has been made of the reactions of three breeds of sheep (Blackface, Cheviot and Wiltshire) to four different environments. Evidence was obtained that these breeds react differently to these different environments. No changes in rank occurred but the Blackfaces grew relatively faster on a good plane of nutrition than the other two breeds. Their wool production on a sample area was also relatively greater, due primarily to an increase in diameter of the non-medullated fibres. These differences indicate fundamental physiological differences in reaction to environment.

The nutritive value of roughages for sheep II. The relationship between the gross digestible energy and the chemical composition of silages

Abstract: 1. The relationship existing between the gross digestible energy content and the chemical composition of twenty-four silages has been studied with nine Cheviot wether lambs over a period of 8 months. 2. Silages were made from grassland herbage and varied widely in the chemical composition of the ingoing material. 3. Each silage was fed to a group of three lambs for a 10-day preliminary- and a 9-day collectionperiod. Faeces and urine were collected in metabolism crates. 4. The silages were analysed for volatile acids and bases, for proximate nutrients and for some of the more precise chemical constituents as suggested in the scheme of analysis of Ferguson (1948). 5. A close relationship existed between the gross digestible energy contents of the silages and the lignin (Ellis) content. 6. The most accurate prediction of gross digestible energy was obtained by taking into account the content of lignin (Ellis), cellulose (Crampton & Maynard) and crude protein, in the silage. 7. In the case of hays (Walker & Hepburn, 1955) no increase in the accuracy of predicting gross digestible energy was obtained by estimating the lignin and cellulose content, rather than crude fibre alone. However, with silages the results give support to the opinion of Mitchell (1942) and Schneider et al. (1951) that analysis for more precise chemical constituents will increase the accuracy of predicting digestibility. 8. Crude fibre and cellulose were not related in any fixed way with the digestibility of energy. Crude fibre itself was digested to some 80% compared with 62% in hays. 9. Metabolizable energy was closely related to digestible energy. 10. The starch equivalents of the silages were calculated by conventional methods and also from the content of gross digestible energy.

The effect of thermal stress on the acid-base balance of the Ayrshire calf

Abstract: 1. Two 4-month-old Ayrshire calves were subjected in a climatic room for periods of 2½–4½ hr. to an atmosphere having a temperature of 35° C. and an absolute humidity of 34 mg./l. 2. This treatment resulted in an increase in respiration rate, a decrease in carbon dioxide tension and carbon dioxide combining capacity of the venous plasma, an increase in the lactic acid concentration of the venous blood and an increase in the pH of the urine. The pH of the venous plasma showed only a slight tendency to increase. 3. It is concluded that thermal panting under the conditions described caused a carbon dioxide deficit which was just compensated for by the excretion of alkali by the kidneys, and that this compensation was not substantially influenced by the production of lactic acid resulting from an increased activity of the respiratory muscles.

The assessment of structure in tropical soils

Abstract: A comparison of methods of measuring the structural condition of cultivated surface soil was made for two important East African soil types.The soil samples were drawn from two field experiments: (i) a tillage trial in coffee on a porous red lateritic clay soil of recent volcanic origin; (ii) a rotation trial for cotton, on a red sandy lateritic loam of granitic origin.Of the measurements on soil cores, total porespace and field capacity (⅓ atmosphere) showed little change, while percolation rates, free-draining pore-space and a new rainfall acceptance test all reflected the observed field behaviour of the soils, and showed fairly close and highly significant correlation. Field sieving of dry clods gave highly significant differences in the lateritic clay, the stronger clods indicating the poorer soil condition. Drysieving for ½ mm. crumb was ineffective, as was wet-sieving after wetting under vacuum. Wetting by immersion gave some differences between treatments, but higher variability and no significant correlation with free-draining pore-space. Wetting by rainfall impact on dry crumbs gave the best wet-sieving tests on the clay soil. Different sieving techniques gave inconsistent results on the sandy soil. Crumb structure measurements are not efficient indications of structural conditions on these soil types, which are of wide occurrence in tropical countries.

Effects of nitrogen applied at different dates, and of other cultural treatments on eyespot, take-all and yield of winter wheat (field experiment, 1953)

Abstract: A field experiment to test effects of cultural treatments on eyespot (Cercosporella herpotrichoides Fron.), lodging and yield of winter wheat, begun in 1952 (Salt, 1955), was continued on the same site in 1953. In 1952 only eyespot and lodging were severe, but in 1953 take-all (Ophiobolus graminis Sacc.) and weeds were severe also.Squareheads Master 13/4 and Cappelle, each sown at 1½ and 3 bushels/acre, were top-dressed at four different dates with ammonium sulphate at 0, 2 and 4 cwt./acre. Sulphuric acid (12½% b.o.v. at 100 gal./ acre) was sprayed on four of the eight blocks of ten plots in March to control eyespot.Halving the seed rate decreased the percentage of severe eyespot from 63 to 52%, decreased the area stunted by take-all from 36 to 14% and increased yield by amounts ranging from 8·3 cwt. in nitrogendeficient plots to 2·6 cwt./acre in plots well supplied with ammonium sulphate. The fertilizer applied to Squareheads Master at 0, 2 and 4 cwt./acre had little effect on the incidence of eyespot lesions at harvest, but increased the area lodged from 23 to 53 and 60% respectively; it decreased the area stunted by takeall from 47 to 19 and 10% respectively, and increased yield from 13 to 17 and 18 cwt./acre. Cappelle did not lodge and the fertilizer decreased take-all patches from 51 to 28 and 18% respectively, and increased grain from 15 to 20 and 21 cwt./acre. The time when nitrogen was applied to either variety had no important effect on disease incidence or yield.Sulphuric acid sprayed in 1953 on blocks unsprayed in 1952 and so having a higher initial infection of eyespot and weeds, decreased the area lodged and the area covered by weeds, but did not decrease the percentage of straws with eyespot below that in unsprayed plots.

Studies on the nutrition of wool follicles in sheep: the anatomy of the general blood supply to the skin

Abstract: 1. Dissections were carried out on lambs, and the skin was found to be supplied by numerous small arteries fairly evenly distributed, but often in series along the body. In several instances these arterial trunks were traced back through the body muscles to various main arteries.

Observations on Merino × Herdwick hybrid sheep with special reference to the fleece

Abstract: 1. Observations, mainly concerning the fleece and pigmentation, were made on about 80 F1 Merino × Herdwick sheep. Of these, nine were used for intensive fleece studies, and skin samples were obtained from six.2. Pigmentation in all the F1 lambs was greatly reduced as compared with the Herdwick breed, the majority being entirely white on the main fleece area, with varying amounts of black and brown speckling on the face, legs and neck. A few were entirely white, like the Merino. The shade of colour of the Herdwick dam did not affect the amount of pigment on her half-Merino offspring.3. The fibre type array most frequently encountered was one not previously described, which has been named Incline. Fine Plateau arrays were also frequent, especially on the mid-side and britch positions. Other arrays which occurred were Coarse Plain, Fine Plain, Ravine, and Coarse Plateau.4. The hogg fleece weights averaged approximately 4·5 lb. for females and 5 lb. for males, which is about double the average weight of Herdwick hogg fleeces. In general appearance they showed some superficial resemblance to Romney and Corriedale fleeces, but there was much variation between individuals. None closely resembled either parental fleece type, but the Merino influence was much more manifest than the Herdwick. Kemp, if present, was usually long and fine, resembling hair.5. Growth of the experimental animals was normal. In an endeavour to assess conformation, measurements were taken on a few sheep, and compared with similar measurements on Herdwick and Swaledale.6. The follicle population showed characteristics of both parental breeds, and varied greatly between individuals. The highest S/P ratio was 9·0, with a follicle density of 3000 per sq.cm. In comparison with the British breeds previously studied, autumn and winter fibre shedding was delayed and reduced in the crossbreds.7. Thetotal number offibresper tattooed square remained stable after sample 2 (about 2 months old). There was no significant difference between sheep or between samples in percentage of coarse, medium and fine fibres, but there was a highly significant difference between positions S (shoulder), A (last rib), B (britch) and D (rump). Mean fibre density was approximately 3000 per sq.cm., and mean fibre quality proportions (by number) in the A position was coarse 10%, medium 24% and fine 66%.8. Nearly 85% of the total clean weight of wool produced was grown in the late spring and summer months. The total wool grown was divided into three qualities and the proportion of the total weight derived from each quality was coarse 23·69%, medium 41·21%, and fine 35·10%. The distinction between the three qualities was often quite doubtful and never as clear as in the Herdwick breed. There were significant differences in proportions of coarse, medium and fine wool, between regions, between seasons and between sheep.9. In the discussion, which concludes the series of studies of fleece and follicle population, the following topics are treated: error of estimate of proportions in work of this kind; time of development of post-natal secondary follicle, and theories of the possible influence of primary follicles on the development of secondary follicles; post-natal growth in size of follicles in Merino and other breeds; autumn moult; recapitulation in follicles during regrowth after fibre shedding; significance of fibre type arrays; origin of the Longwool breeds; protective birth-coats; pigmentation; ‘lift’ in British wools; and the possibilities of establishing a breed with the Merino type of fleece on British hill and mountain farming areas.