Article by van Tienhoven: ‘Metabolism of fowl sperm on different diluents.’

Tables 1–17: in column headed ‘Source’ read ‘replication’ for ‘respiration’.

In the communication: ‘Studies of the skeleton of the sheep. IV. The effects and interactions of dietary supplements of calcium, phosphorus, cod-liver oil and energy, as starch, on the skeleton of growing blackface wethers’, D. Benzie, A. W. Boyne, A. C. Dalgarno, J. Duckworth, R. Hill & D. M. Walker, J. Agric. Sci. (1960), 54, 202–221, Plates A1, A2 and B1, B2 have been interchanged on Plate 9. The letters A, B and C have been omitted from Plate 10, and should read top, middle and bottom respectively.

1. Twenty-two experiments on main-crop potatoes in 1955–7 compared calcium nitrate and ammonium sulphate applied to the seedbeds before planting. Urea was also tested in fifteen of the experiments in 1956–7. The three fertilizers were compared at rates that supplied 0·5, 1·Oand 1·5 cwt. N/acre.

2. Seven experiments on kale in 1955–8 compared seedbed dressings of calcium nitrate and ammonium sulphate. Urea “was also tested in. five of the experiments in 1956–8. The rates used were 0·6, 1·2 and 1·8 cwt. N/acre in 1955 and 1·0 and 2·0 cwt. N/acre subsequently. Single dressings applied to the seedbed were also compared with divided dressings applied partly to the seedbed and partly in mid-season.

3. Generally the potatoes gave only small responses to N; there was no worthwhile gain from applying more than 1·0 cwt. N/acre in 1955 and 0·5 cwt. N in 1956 and 1957. Nitrogen gave much larger proportionate increases in yields of kale, at several of the centres crops continued to respond up to dressings of 2·0 cwt. N/acre.

4. Calcium nitrate generally gave lower yields of potatoes than ammonium sulphate and the superiority of ammonium sulphate was greater with the higher dressings. Losses in yield with the nitrate were usually associated with a severe check to early growth occurring in dry springs and with dressings concentrated close to the seed, but lower yields were also obtained at some centres where early growth was not damaged. Calcium nitrate and ammonium sulphate were roughly equivalent for kale when the nitrate did not damage germination; heavy seedbed dressings of the nitrate reduced kale plant numbers severely unless there was adequate rain after sowing.

5. Granulated urea tested in 1956 contained 4·5% of biuret, it delayed emergence and reduced plant establishment seriously in several of the potato experiments; damage increased with the level of manuring and was accentuated when dressings were broadcast over furrows before hand-planting. Yields given by this batch of urea were less than with other N fertilizers and when 1·5 cwt. N/acre was applied they were less than with no nitrogen at all. Purer crystalline urea (having less than 1% of biuret) used in the 1957 experiments caused no damage to emergence of potatoes and gave yields similar to those obtained with ammonium sulphate. There were similar effects in the kale experiments; granulated urea containing much biuret damaged germination severely in 1956; the purer products containing little biuret used in later years reduced plant numbers at one centre in 1957 and at the single 1958 centre. Where there was no damage to the establishment of kale, urea and ammonium sulphate gave similar yields.

6. Dressings applied partly to the seedbed and partly in mid-season gave slightly higher average yields of kale than an equivalent total amount of nitrogen all applied before sowing.

1. The reliability of the Kjeldahl method for the determination of nitrogen in soils has been investigated using a range of soils containing from 0·03 to 2·7% nitrogen.

2. The same result was obtained when soil was analysed by a variety of Kjeldahl procedures which included methods known to recover various forms of nitrogen not determined by Kjeldahl procedures commonly employed for soil analysis. From this and other evidence presented it is concluded that very little, if any, of the nitrogen in the soils examined was in the form of highly refractory nitrogen compounds or of compounds containing N—N or N—O linkages.

3. Results by the method of determining nitrogen in soils recommended by the Association of Official Agricultural Chemists were 10–37% lower than those obtained by other methods tested. Satisfactory results were obtained by this method when the period of digestion recommended was increased.

4. Ammonium-N fixed by clay minerals is determined by the Kjeldahl method.

5. Selenium and mercury are considerably more effective than copper for catalysis of Kjeldahl digestion of soil. Conditions leading to loss of nitrogen using selenium are defined, and difficulties encountered using mercury are discussed.

6. The most important factor in Kjeldahl analysis is the temperature of digestion with sulphuric acid, which is controlled largely by the amount of potassium (or sodium) sulphate used for digestion.

7. The period of digestion required for Kjeldahl analysis of soil depends on the concentration of potassium sulphate in the digest. When the concentration is low (e.g. 0·3 g./ml. sulphuric acid) it is necessary to digest for several hours; when it is high (e.g. 1·0 g./ml. sulphuric acid) short periods of digestion are adequate. Catalysts greatly affect the rate of digestion when the salt concentration is low, but have little effect when the salt concentration is high.

8. Nitrogen is lost during Kjeldahl analysis when the temperature of digestion exceeds about 400° C.

9. Determinations of the amounts of sulphuric acid consumed by various mineral and organic soils during Kjeldahl digestion showed that there is little risk of loss of nitrogen under the conditions usually employed for Kjeldahl digestion of soil. Acid consumption values for various soil constituents are given, from which the amounts of sulphuric acid likely to be consumed during Kjeldahl digestion of different types of soil can be calculated.

10. Semi-micro Kjeldahl methods of determining soil nitrogen gave the same results as macro-Kjeldahl methods.

11. The use of the Hoskins apparatus for the determination of ammonium is described.

12. It is concluded that the Kjeldahl method is satisfactory for the determination of nitrogen in soils provided a few simple precautions are observed. The merits and defects of different Kjeldahl procedures are discussed.

A study, using the methods of growth analysis, is reported of the accumulation of dry matter in two Natal Common groundnut crops grown at Kongwa, Tanganyika under conditions of relatively low population (26,000 plants/acre) with phosphate fertilizer (F series), and at a higher population (56,000 plants/acre) without fertilizer (O series). The uptake and distribution of N, P, K, Mg and Ca was followed in the F series.

In the F series, the dry weight per plant at maturity was 32·7 g., of which 14·9 g. (45%) was kernels, while in the O series the corresponding figures were 20·6 and 10·4 g. The relative growth rates, net assimilation rates and leaf-area ratios were similar in the two crops, with small but consistent advantages to the F series. Nevertheless, the yields per acre were markedly higher in the O series, where total dry-matter and kernel yield were 2540 and 1290 lb./acre, respectively, against 1910 and 870 lb. in the F series. It is shown that this was the result of consistently higher leaf weights per acre and a higher total leaf-weight duration (4180 lb. weeks/acre) in the O series than in the F series, where total leaf weight duration was 2810 lb. weeks/acre.

The formation of the kernels continued to maturity in each case, largely at the expense of current assimilation rather than by net translocation from the vegetative parts.

The uptake of N, in the F series, reached a total of 63 lb./acre, of which 45 lb. was in the mature kernels. It went largely into the vegetative parts during the first two-thirds of the crop's life, but in the final stages most of the uptake went into the kernels and there was some evidence of translocation of N from the vegetative parts and the shells. N accumulation did not seem to be affected by rainfall fluctuations within the season. The net assimilation rate did not appear to be directly associated with the activity of the plant in accumulating N, but the leaf-area ratio, and the relative growth rate, were associated with the rate of N uptake per unit of plant dry weight.

The total P taken up was no more than 4 lb. (of the element) per acre of which nearly 80% was found in the kernels at maturity. There was considerable evidence of translocation of P into the kernels from the vegetative parts of the plant. P uptake (unlike that of N) was heavily reduced in a mid-season dry period, suggesting that P was largely derived from the upper layers of the soil.

The total amount of K found in the crop at maturity was about 26 lb./acre, mostly in the vegetative parts. Rather under a fifth was in the kernels, although they constituted 45% of the total dry weight. The data for Ca and Mg are incomplete, but it may be suggested that the maximum accumulation of Ca was around 10 lb./acre, almost all in the vegetative parts, and that of Mg about 5 lb./acre, of which 2 were in the kernels.

The grateful thanks of the authors are due to Dr M. T. Friend, of the East African Agriculture and Forestry Research Organisation, Muguga, Kenya, who determined N and P in the samples of the F series, and to Mr G. T. Chamberlain, of the same Organisation, who carried out the estimations of K, Ca and Mg. They would also wish to express their indebtedness to the members of the former Scientific Department of the Overseas Food Corporation who assisted with the work in laboratory and field, and in particular to Mr B. W. Culy, Manager of the Kongwa Experimental Station, who was responsible for the production of the crops.

Nitrification of urea and its loss through the volatilization of NH3 were studied under different soil conditions. Under all conditions less urea was nitrified and more time was needed for its nitrification in sandy than in sandy loam soil. Nitrification was favoured at lower concentration of urea, onethird moisture of the moisture-holding capacity and at neutrality or the alkaline pH.

Loss of NH3 was found to be twice as much from the sandy loam as from the sandy soil. It was also found that half of the total loss occurred during first drying. Loss of NH3 from urea was found to be proportional to its concentration. The loss increased with the increase in soil moisture and temperature; but it decreased with the decrease in pH on the acid side and the increase in depth of its placement.

1. Italian ryegrass, laid down for two years, was used to compare the value of casein and formalized casein, ammonium sulphate, calcium nitrate and urea for grassland production. Residual effects of these treatments were measured on a third-year crop of barley.

2. Single dressings of ammonium sulphate and casein were of similar value at each of three cuttings in 1956.

3. Casein treated with formalin released nitrogen much more slowly and was of little value in the early part of the growing season. Formalized casein produced significantly higher yields than casein at the later cuttings in both years, but aggregate increases from this material were much lower than those obtained from untreated casein in each season. Formalized casein increased yields considerably in the year following application.

4. Single dressings of formalized casein were also compared with ‘repeated’ dressings of ammonium sulphate, calcium nitrate and urea, in which the same total quantity of nitrogen was divided equally between cuttings. Formalized casein produced much lower yields than these ‘repeated’ dressings in the early part of the season, but was of only slightly less value at the last cut in 1956 and gave the highest yield at the final cut in 1957. Aggregate yields from repeated dressings of inorganic N fertilizers were higher than those given by single dressings of either form of casein.

5. Comparisons were also made between the yields given by ammonium sulphate, calcium nitrate and urea. Urea applied before sowing (at 0·5 cwt. N/acre) damaged germination and reduced plant establishment slightly. Under dry conditions both urea and calcium nitrate tended to give higher yields than ammonium sulphate but with adequate rain all three fertilizers gave similar yields.

1. The apparent cleanliness of the premises in which chicks are reared has little bearing on the growth rate of chicks within a given environment.

2. Bacterial counts of faeces from chicks reared under clean or extremely contaminated conditions showed no difference between the two sets of conditions.

3. Delaying feeding until 72 hr. after hatching retarded growth to at least 7 weeks of age. If the age of the chicks was calculated from the time at which the chicks were fed rather than the date of hatch, the weights of the chicks fed 72 hr. after hatching corresponded with those of the chicks fed immediately.

4. The contents of the duodenum and mesenteric intestine showed higher bacterial counts when feeding was delayed for 72 hr. than when feed was given shortly after hatching. This effect was no longer evident after the chicks were 1 week old.

5. Administration of penicillin in the water did not reduce the difference in growth rates between the chicks given feed immediately and those from which feed was withheld.

6. Antibiotics may decrease the thickness of the intestinal wall without stimulating growth.

Motility characteristics of bull spermatozoa in mixed ejaculates of different bulls were compared with those of the unmixed samples after 40-to 50-fold dilution with clarified standard egg-yolk—citrate buffer (pH 6·80 ± 0·05 at 37° C., 6·75 ± 0·05 at 22–23° C).

Using the photo-electric equipment described by Rikmenspoel (1957b) and by Rikmenspoel & Van Herpen (1957) the mean velocity , the number of spermatozoa passing by a constant spot per time unit n, the total number of spermatozoa moving normally N, the velocity decrease with time ( — d/dt), the half-life period of the number of passages per time unit t½(n) and the half-life period of the total number of spermatozoa moving normally t½(N) were determined. For none of these characteristics was any statistical difference found between the actual results and the expected values based on calculation from the data obtained with the unmixed ejaculates.

Acid production was investigated by accurate determination of pH change on incubation of samples diluted ten times with standard egg-yolk—citrate buffer containing 736 mg. added fructose per 100 ml. Again there was no statistical difference between the values found with the mixed semen samples and the expected values.

It is concluded that differences observed by other authors must be due to the effect of environmental factors, i.e. to the semmal plasma, for which there is analogous evidence in human sperm physiology.

1. Three levels of a nitrogenous fertilizer, supplying 0,104 and 208 lb. N per acre were applied in 1955 and 1956 to a rye-grass/white clover sward in its fourth and fifth harvest years on a loam soil overlying chalk.

2. Levels of animal production were measured using fattening cattle maintained on the plots at a stocking rate of 1⅓ per acre: excess herbage was conserved and fed back to them later.

3. Low rainfall in 1955 seriously affected yields of herbage and response to fertilizer, and severely reduced the clover content in all treatments.

4. Rate of live-weight gain per head was not reduced by the application of fertilizer at either level. Vigour of the sward was maintained by fertilizer application in a dry spring period in 1956, whereas, in the control treatment, which was low in clover, gains per head were markedly reduced because of inadequate dry-matter production.

5. By applying two-thirds of the fertilizer in late summer, a considerable extension of grazing time was obtained, particularly when rainfall was adequate. At the highest level of fertilizer application in 1956 the grazing season was extended from 6 months to 7½, and the cattle continued on conserved feed to a total of 8½ months. Response to the medium and high levels of application on grazed herbage only was 12 and 15 bullock-days per acre, respectively, in 1955. In 1956 the response was 46, and 67/59 (the two high nitrogen treatments). In terms of total live-weight gain per acre the response in 1955 to medium and high levels was 23 and 32% above control, up to 427 lb. per acre: in 1956 it rose to 51 and 52/55% with the highest treatment reaching 657 lb. per acre. Greater financial returns than are indicated by live-weight gain should result from the rising price per pound of carcass as the supply of fresh beef dwindles in early winter.

6. Carcass data indicated that both greater rate of gain and the extra time spent on fertilized herbage and conserved feed increased carcass weight and maturity in the normal pattern of development, fat most rapidly, muscle next and bone least. No significant differences in conformation due to treatment was detected by analysis of grouped joints.

1. Two methods were used to estimate the frequencies of nine morphological classes of spermatozoa in 257 ejaculates from one Guernsey, five Friesian and seven Hereford bulls at an insemination centre. In nigrosin-eosin stained preparations and in fixed wet preparations the respective mean frequencies (%) were: malformed heads, 1·08 and 0·98; malformed middle pieces, 0·88 and 0·89; bent tails, 3·92 and 4·56; coiled tails, 0·60 and 0·43; free heads, 3·72 and 2·63; free tails, 1·79 and 1·85; neck beads, 0·87 and 0·93; middle-piece beads, 4·91 and 6·83.

2. There were close correlations between the two sets of measurements, but the differences of means were significant for free heads, bent tails, coiled tails, neck beads and middle-piece beads.

3. The mean percentage of dead (eosinophil) spermatozoa was 21·0.

4. The variations in the frequencies of each morphological class and of dead spermatozoa were divided within and between samples, ejaculates, bulls and breeds. The frequencies of all classes differed significantly between ejaculates within bulls; all but broken necks differed between bulls within breeds, and the Friesian and Hereford bulls differed in the frequencies of malformed heads, free heads, malformed middle pieces, free tails, neck beads and dead spermatozoa. The frequencies of bent tails, coiled tails and dead spermatozoa declined significantly with order of ejaculate.

5. The interrelationships of the frequencies of each class were examined. Two new methods used to measure the dead-sperm content of semen were shown to give results significantly correlated with those obtained by the conventional staining method and with motility ratings.

6. The interrelationships of measurements of the individual characteristics and conception rate were examined. Within-bull variations in conception rate showed a significant positive correlation (P < 0·05) with the frequencies of malformed heads and free heads. The between bull variation in conception rate showed a negative correlation with the frequency of neck beads (P < 0·05).

1. The oxygen consumption of young pigs from 1 to 37 days of age has been measured in a closed circuit respiratory metabolism chamber, over the environmental temperature range 4–37° C.

2. The values obtained for single pigs alone in the chamber have been compared with the results of measurements on groups of pigs 3–6 days of age taken together.

3. It has been found that as environmental temperature falls below 30° C. and the grouped pigs huddle together, oxygen consumption per kg. for the group becomes smaller than values for single pigs of the same individual weight, and corresponds more with results from the larger single pig.

4. Rectal temperature is maintained in pigs of the group at a lower energy cost than that required for the single pig, the saving in energy expenditure becoming proportionately greater as ambient temperature falls.

5. These results are discussed in relation to body size and skin temperature.

1. The excretion of 144Ce in the faeces, urine and milk has been followed in two dairy cows receiving twice daily doses of 120 μc. with the feed over a 10-day experimental period. During the terminal 3 days, recoveries from the faeces amounted to 93–119% of the daily dose. From the urine and milk, respectively, 0·23 and 0·17% and 0010 and 0·016% of the total amount fed was recovered from the two animals.

2. The concentration of 144Ce in various parts of the gut was estimated after equilibrium conditions had been attained. The highest concentrations were found in the contents of the omasum and hind-gut.

3. The possible use of 144Ce as a marker in digestibility and similar trials is discussed.

Two calves (Zebu × Australian Illawara Shorthorn and Shorthorn) of about 7–8 months of age were exposed to controlled atmospheric conditions. Cutaneous evaporation from the shoulder and belly areas of these calves was measured by the capsule method. Density of the sweat glands in the shoulder and belly areas of these calves was measured, using a biopsy punch. Density was estimated by counting the hair follicles.

(1) The Zebu cross sweats more than the Shorthorn, at least from the shoulder area, and this is related to its higher sweat gland density as compared with that of the Shorthorn.

(2) In the Zebu cross cutaneous evaporation from the shoulder area is greater than that of the belly and this is associated with the differences in the number of sweat glands.

(3) In the Shorthorn cutaneous evaporation is the same from both shoulder and belly areas and the number of sweat glands in these regions is also the same.

1. The normal level of blood ammonia in the sheep seems to be somewhat higher than in nonruminants.

2. The toxicity of ammonium acetate, ammonium chloride or urea placed in the rumen follows different metabolic pathways. In the case of the chloride there is an uncomplicated metabolic acidosis which is not, however, adequate to account for the toxic symptoms. When the acetate is administered there is also a respiratory alkalosis and in the presence of urea the changes in the acid-base status, though interesting, do not account for the toxicity.

3. The toxicity is almost certainly due finally to a direct effect of the circulating ammonium ion level though in the case of urea, there is an earlier effect that may be of a pharmacological type and is less severe.

4. The organisms within the rumen rapidly reach a maximum level of adaptation (7 days) to handle large quantities of ammonia by a synthetic pathway.

5. The intravenous administration of L-arginine did not markedly ameliorate the ammonia toxicity.

The present work extends the information on the skin thickness of cattle and shows that generalizations made in previous work were only partly correct, for there are significant differences only between the skin thickness of the Zebu ‘races’ of tropical cattle and Bos taurus.

Again there appeared to be no significant difference between animals of different ages within breeds.

The work confirmed that cattle of eleven tropical breeds comprising four of the major ‘races’ of African indigenous cattle have a significantly thinner papillary layer than temperate breeds, and this was very strongly correlated with their superior heat toleration.

Further support based on wider premises was therefore given to suggestions made by Dowling regarding the importance of the histology of the skin in heat toleration.

An examination of the population density and morphology of the apocrine glands of four ‘races’ including fourteen breeds of African indigenous cattle has been completed.

Two types of gland were found, the club-shaped and the sac-like, and it is suggested that the former is the more primitive form.

Considerable differences in gland density and volume were found. In the thoracic-humped African Zebu both of these were similar to figures given for B. indicus sui generis.

Gland volume was found to be closely correlated to heat toleration, but it is suggested that secretory rate is probably of high importance in view of the fact that despite differences in gland volume, there were only small differences in heat toleration coefficient.

It is suggested that the heat toleration coefficient as presently defined may not be a reliable indication of the animals tolerance of prolonged high temperatures.

A suggestion is made regarding the mechanism of heat control by sweating in cattle.

1. A study was made of the effects of diet on the growth of the internal organs, and in particular the four stomachs of lambs.

2. A total of twenty-three lambs was reared from birth on various diets ranging from all milk to small amounts of milk and roughage ad lib. The lambs were slaughtered at various ages and the fresh wet weights of the parts of the alimentary tract and the other internal organs were recorded.

3. The growth rates of the four stomachs were influenced by the plane of nutrition, however, the type rather than the plane of nutrition was more important in determining the weights of the stomachs relative to each other and to live weight.

4. Lambs fed solely milk from birth had the development of their fore-stomachs retarded at about the level found in the 3-week-old grazing lamb. The abomasums of these lambs were abnormally heavy.

5. The rumens and reticulums, which were retarded in their growth by milk feeding, reached normal proportions very quickly once roughage was fed.

Two early weaning experiments are reported. When grazing young, high protein pastures, lambs weaned at 7, 10, 13 and 18 weeks of age grew equally well and there were no significant differences between their carcass weights, grades, and dressing percentages.

However, when grazing pastures in the preflowering and flowering stages of growth, lambs weaned at 8 weeks of age did not grow as well as unweaned controls. Their carcass weights, grades, and dressing percentages were also inferior. It is suggested that these differences were primarily due to an inadequate protein intake.

No difference in wool production was found either between the ewes of early weaned and control lambs, or between the lambs themselves.

1. Three completed series of laying trials involving the incorporation of calcium lactate in the diet are reported.

2. The addition of 1 or 2% calcium lactate to a layers mash results in a significant increase in egg production and/or the efficiency of the ration in terms of numbers of eggs per unit weight of food consumed. This effect has been obtained in birds at the onset of lay and also in birds that have been in lay for some 5 months.

3. The incorporation of 0·5% calcium lactate appears to be inadequate.

4. There is no evidence to date that the effect is attributable to dietary calcium, but the mechanism of action is unexplained.

5. Egg-weight, but not egg-quality, as judged by routine candling, is slightly lowered by feeding calcium lactate.

1. The digestibilities of the protein, oil and carbohydrate by chick in mash and pellets made from this mash have been determined at weekly intervals from 0 to 9 weeks.

2. There was no difference in the chemical composition of the food due to pelleting, not were there any differences in the digestibilities due either to pelleting or the age of the chick.