1. Floret samples of S321 perennial rye-grass (Lolium perenne L.), S215 meadow fescue (Festuca pratensis L.) and S352 timothy (Phleum pratense L.) were taken at 3-day intervals from inflorescence emergence to seed harvest. These were analysed for total chlorophyll content, chlorophyll a: chlorophyll b ratio and total anthocyanin content.

2. All varieties showed qualitatively similar patterns of total chlorophyll content. At emergence chlorophyll first increased on exposure to light and then fell as anther formation progressed. After fertilization a rapid increase in floret chlorophyll content coincided with early seed formation due to pigmentation of the expanding seed epidermis. Polymerization of carbohydrates to form endosperm starch resulting in increasing dry-matter content caused a concomitant fall in total chlorophyll when assessed on this basis. The final stages of seed maturation were accompanied by a further gradual decline to a very low level.

Canada's western prairies, lying within the confines of the provinces of Manitoba, Saskatchewan and Alberta, are generally recognised as comprising one of the largest and most important agricultural areas on the American continent. The immense acreage of their arable lands, the great depth and high fertility of their soils and the unexcelled quality of their wheat, have made them widely and favourably known throughout the civilised world. As yet but sparsely settled they will for many years offer a large and attractive field for agricultural occupation and development.

The luteolytic effect of prostaglandin F2α (PGF2α) during the confirmed luteal phase of the oestrous cycle was evaluated in ten Boran and ten Boran × Friesian cross-bred heifers. Following injection with 25 mg Lutalyse, animals were bled every 6 h for 96 h and plasma progesterone (P4) determined by the ELISA technique. Borans had significantly (P < 0·05) smaller corpora lutea (12·01±0·72 ν. 17·03±2·10 mm) and responded faster to PGF2α injection (65·57±1·40 ν. 78·27±2·18 h) than the cross-bred heifers. However, there was no significant difference in either the initial P4 values (6.24±0·98 ν. 8·00±1·71 ng/ml) or the rate of its decline following PGF2α injection between the two breeds. Values declined sharply to basal levels (11% of the initial pretreatment values) within 48 h in both breeds. All ten cross-breds and eight Borans showed standing oestrus within a week of treatment. However, oestrus was better synchronized (P < 0·05) in Borans than cross-breds. It was concluded that PGF2α is effective for oestrus synchronization in both breeds, but oestrus occurred earlier and was more precise in Borans than in cross-breds.

1. The soil temperatures in Egypt at a number of depths have been recorded by means of continuous recording thermometers. In general, the records show that the amplitude of the temperature wave at the surface of the soil is considerably greater than the air temperature wave. There is, however, a considerable damping of the wave with depth, no daily variation in temperature being observed at a depth of 100 cm.

2. No definite relation between the air and soil temperatures could be traced. The maximum air temperature was recorded in May and the maximum soil temperature in July.

3. The amplitude of the temperature wave decreases with increase in depth. The decrease in amplitude of the soil temperature wave is not regular owing to variations in the physical properties of the soil layers. Between any two depths, the ratio of the amplitudes of the temperature waves is constant throughout the year. The amplitude of the soil temperature wave bears no relation to the amplitude of the air temperature wave.

4. The time of maximum temperature at the soil surface is constant throughout the year at 1 p.m. The times of maximum temperature at depths below the surface lag behind the time of surface maximum, but they are constant throughout the year. When plotted against depth, the times of maximum at the various soil depths lie on a straight line.

The physical properties of hardness and dry matter and the histological characteristics of dermal and epidermal tissues were investigated in lateral and medial claws obtained post mortem from mature crossbred female cattle. Claws containing pigmented (n=22) or non-pigmented (n=22) coronary wall horn were studied. Impression hardness, measured on the dorsal border of claws, proximo-distal at intervals of 5 mm from the lower perioplic line was shown to increase to the 20 mm lower site. Similarly, in comparison with values for pigmented horn, pooled measurements for non-pigmented horn showed greater hardness from the lower perioplic line to the 40 mm lower site but were not different for subsequent measurements towards the distal edge. Differences in values recorded for sole and heel and for coronary wall horn measured under the distal edge were not different for claws varying in coronary horn pigmentation. The absence of differences in dry matter at measurement sites suggested that differences in impression hardness values were not caused by variation in water content of horn. Histological examination of pigmented claw wall horn and underlying soft tissue showed pigment-containing cells in the coronary epidermis but not coronary dermis or in dermis or epidermis of laminae. Pigmentation appeared concentrated in melanosomes in cells along the basement membrane and was present uniformly throughout the epidermis and in cells lining horn tubules. There was no pigmentation detected in the soft tissue epidermis of claws selected visually for non-pigmented wall horn. The presence of melanosomes in epidermal cells from the pigmented coronary region was demonstrated by electron microscopy. The results suggest that pigmentation in the coronary region is associated with reduced initial development of hardness. The possible antagonism between antioxidant properties of melanins and requirement for an oxidative environment for disulphide bond formation in the cytoskeleton of horn cells is discussed.

Ram semen was stored at 4° C. in a standard citrate-egg-yolk diluent, which served as a control, and in various diluents in which: (a) the citrate buffer was replaced by various concentrations of glycine in water (2, 3, 4 and 6%); (b) the ratio of semen to diluent was altered from 1:20 to 1:40; (c) the glycine buffer was augmented by the addition of fructose; and (d) the concentration of egg yolk in the diluent was reduced from 50% to 33·3 and 25%.

Replacing citrate buffer by 4% glycine considerably improved survival as against other concentrations of glycine and the citrate buffer control. Better survival in 4% glycine-egg-yolk buffer was obtained with a semen dilution ratio of 1:20 than with a ratio of 1: 40. The addition of fructose to the glycine buffer did not improve survival. The 50% concentration of egg yolk in 4% glycine buffer-eggyolk diluent was reduced to 33·3% without affecting either motility or survival, and to 25% with no effect on survival but with slight reduction in motility.

1. The effects of injections of oestradiol dipropionate, testosterone propionate and progesterone in immature pullets have been studied.

2. Oestradiol dipropionate evokes hypertrophy of the oviduct, and increases in serum calcium and serum riboflavin.

3. Testosterone propionate evokes hypertrophy and reddening of the comb and wattles, it acts synergistically with oestradiol dipropionate in evoking hypertrophy of the oviduct.

4. Progesterone antagonizes the effects of oestradiol dipropionate and testosterone propionate on the growth of the oviduct.

5. Progesterone and/or testosterone propionate increase the percentage of free riboflavin in the hypertrophied magnum from 18% of the total vitamin present to 35%.

Relationships between leaf expansion and MeOH-soluble (cytosol) and cell-wall fractions, and their sugar composition prior to silking in flint corn lines were studied. A greater husk leaf area of one genotype, X-15 is mainly due to prolonged and higher rate of expansion. Prior to rapid expansion of husk leaf area, neutral sugars in the cytosol fraction accounted for most of the non-starch carbohydrates (56–62%), while hemicellulose and cellulose fractions accounted for less than 20%. In mature leaf parts, however, sugars in the cytosol fraction decreased but those in hemicellulose and cellulose fractions increased by 30% and 42%, respectively. The predominant sugar in the cytosol fraction was glucose (Glc), while in the hemicellulose fraction xylose (Xyl) and arabinose (Ara) dominated. During rapid expansion of husk leaves, 13C was incorporated at a higher rate into hemicellulose than cellulose, and this process was more active in X-15 than in other genotypes. During an identical period, 13C atom % excess in Xyl increased markedly in the hemicellulose fraction, however it remained low in the cytosol one. The current results suggest that synthesis of Xyl and xylan plays an important role in renewal of hemicellulose, which may be required for expansion.

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

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

The methods usually employed for estimating calcium carbonate in soil are all subject to more or less serious practical difficulties when the percentage of lime falls below 0.5.

In gravimetric methods, in which the carbon dioxide set free by acid has first to be boiled out of solution and then perfectly dried before absorption by potash, a very small weight of carbon dioxide is estimated by the gain in weight of a comparatively heavy absorption apparatus.

Field experiments were conducted for three consecutive years during 1988–90 at a research farm near the Indian Institute of Technology, Kharagpur, West Bengal, India to study the influence of organic and inorganic fertilizers on the performance of rice and fish in a dual culture system. Under waterlogged conditions the grain yield and dry matter of the rice variety CR1018 was increased both when inorganic N fertilizer (50 kg N/ha) was supplied or when a combination of organic (lOt FYM/ha) and inorganic N fertilizer (25 kg N/ha) were applied as compared with an organic fertilizer alone (20 t FYM/ha). The recovery of N as well as grain yield response per kg of N applied was also greater when inorganic N was applied. On the other hand, the growth of the fish species Java punti (Puntius javanicus) when grown alone (monoculture) and Catla (Catla catla), Mrigal (Cirrhinus mrigala) and Java punti (Puntius javanicus) grown together (polyculture) in the rice field was found to be superior when organic fertilizer was applied either alone or in combination with an inorganic fertilizer. The total number of phytoplankton species as food for the fish under organic manuring was more than under inorganic fertilization. In low-lying waterlogged situations (15–45 cm water depth), the total productivity could be increased by supplying the appropriate nutrition to both rice and fish in such dual culture systems.

Relationships between milk fatty acids (MFA) and methane (CH4) emissions from dairy cattle were explored. Data from a total of 12 studies including 39 treatments were gathered in the database. Methane was expressed as daily emissions (g/d), relative to dry matter intake (g/kg), milk production (g/kg milk) and body weight (g/kg). The univariate correlations between MFA and CH4 were based on absolute means and on relative changes of each treatment compared with its corresponding control. Saturated fatty acids, odd- and branched-chain FA and long-chain poly-unsaturated FA were positively related to CH4, while cis- and trans-isomers of mono-unsaturated FA were negatively related to CH4. However, most of the coefficients of determination (R2) of these univariate regressions ranged from 0·2 to 0·7, indicating that individual MFA only explain a limited part of the variation in CH4. Significant relationships between MFA and CH4 varied depending on the unit in which emissions were expressed. Similarly, some MFA seemed more suited to predict relative changes in CH4 emissions rather than absolute amounts. The present findings contribute to the exploration of the potential of MFA as biomarkers for CH4 emissions from dairy cattle, although differences between studies in the detail of MFA analysis and hence the number of MFA reported in the current study, complicates this kind of literature survey.

Two sources of sulphur-coated urea (SCU) were compared with calcium ammonium nitrate (CAN) as sources of N for cotton and sorghum in the savannah zone of Nigeria. At the lowest rate of N application (30 kg/ha for cotton and 40 kg/ha for sorghum), SCU-11 with a dissolution rate of 11% in 7 days was found to be more effective than SCU-30 having a dissolution rate of 30% in 7 days and CAN. A single application of SCU-11 produced a higher sorghum yield than a divided application of CAN at the same rate. These results indicate that a slow-release nitrogen fertilizer might be useful for improved grain sorghum and cotton varieties.

A sheep-feeding experiment was carried out to assess the nutritional value of algae meal as a protein supplement in ruminant diets. The algae, mainly Chlorella, were grown in sewage ponds, harvested by flocculation with alumina (Al2(SO4)3.18H2O), and then drum-dried. Eight young rams, divided into two equal groups, were offered a basal concentrated diet, to which algae meal or soya-bean meal (SBM) was added to contribute 50% of the dietary nitrogen (N).

The digestibility values of dry matter (D.M.) were 69·3 and 79·3%, and those of organic matter (OM) were 75·3 and 82·2% for the algae diet and the SBM diet, respectively.

Nitrogen digestibility of the algae diet was 16% lower than that of the SBM diet and the calculated value of N digestibility in algae meal was 61·7%. However, there was no difference between treatments in the daily amount of retained-N or in the proportion of digested N which was retained in the body.

The algae meal contained 5·7% aluminium. This was probably the reason for the much lower P absorption in the algae diet (6·67%) as compared with the SBM diet (29·5%).

Ammonia-N concentration was lower and total volatile fatty acids (VFA) concentration was higher in the rumen of the algae diet-fed sheep. However, the VFA profile was similar for both diets.

Sewage-grown algae could perhaps be used as a protein supplement for ruminants, provided that the harvesting technology is directed to produce a low-mineral, low-aluminium, young biomass, which would be highly digestible and would not interfere with P absorption.

Rectal, external auditory meatus and skin temperatures and panting rates were measured in native fat-tailed Awassi and imported German Mutton Merino (GMM) sheep. The Awassi evolved under desert conditions, have a localized fat deposit, coarse carpet wool, long pendulous ears and long, spiral horns (males). In contrast, the GMM evolved under temperate conditions, have well-distributed fat, medium fine wool, short, straight ears and are polled. The study was carried out during the summer in the northern part of the Negev desert.

The mean daily rectal temperature fluctuation was higher (P < 0·01) in the GMM than in the Awassi (1·78 °C v. 1·08 °C). The external auditory meatus temperature was lower than the rectal temperature by 1·5 °C in the GMM and by 1·7 °C in the Awassi, indicating a cooler brain temperature. The maximum skin temperature was similar to the maximum rectal temperature in both breeds, thus sweating was of little importance. The panting rate of the GMM increased fivefold (40·6–199·4 pants/min) whilst the rate of the Awassi increased fourfold (35·3–135·0 pants/min). There was no between-breed difference in either the rectal temperature or panting rate until 25–30 °C ambient temperature and it is thought that the higher rectal temperature of the GMM at this ambient temperature might have triggered off the higher panting rate. It seems that the GMM use panting to a greater extent than the Awassi whereas the Awassi dissipate heat through the skin more efficiently than the GMM. It is concluded that both breeds are thermostable, much of the between-breed difference in rectal temperature can be attributed to their anatomical differences.

Determinations of sodium bicarbonate (pH 8·5) extractable P made on profiles of a sandy loam soil 7 and 8 years after fertilizer application to coconut in the Dry zone of Sri Lanka showed that the downward movement of P from concentrated superphosphate was greater than from rock phosphate (saphos). The surface layers (0–15 cm) of soil given concentrated superphosphate had higher P values (60 and 89 mg/kg for the 8th and 9th year respectively) than those given rock phosphate (3 and 16·5 mg/kg). At 40 cm depth the concentrated superphosphate treatment had 6 and 30 mg P/kg but the rook phosphate treatment had almost zero P at and below 40 cm.

Phosphorus in the soil profile 8 years after fertilizer application was fractionated by the method of Chang & Jackson. Concentrated superphosphate treatment increased the Al-P and to a lesser degree Fe-P and Ca-P. Rock phosphate treatment increased the Ca-P and to a lesser extent Fe-P and Al-P. Phosphorus concentration in the 14th leaf was significantly correlated with Al-P, Fe-P and NaHCO3-P but not with Ca-P and organic P.

The significance of the findings to phosphorus fertilizer application to coconut is discussed.

Cattle grazing buffel grass pastures during the dry season at Katherine lose large amounts of live weight during a short period following first rain. In Part 1 we showed that these losses were due mainly to reduction in gut contents. Part 2 examines the changes in pasture, diet and grazing behaviour to assess the probable change in nutritional status of cattle following rain.

During the dry season the most valuable pasture component, green leaf, was very scarce and had a nitrogen concentration of about 1%. Diets of oesophageally-fistulated cattle contained less than 0·5% N. Shortly after first rain diet N doubled owing both to rapidly increasing amounts of green leaf and to the increase in N concentration in young leaf to over 3%. Although intake was not measured, literature is cited to show that this increase in dietary N would be expected to increase rumen digestion rates with a resultant marked increase in D.M. intake and a reduction in gut contents.

Although availability of high quality herbage increased very rapidly following first rain, a period of increased nutritional stress immediately following rain could not be ruled out. However, any such decline in nutrition appears to be short-lived.

1. An experiment was carried out in which twelve Romney Marsh ewes were separated into two groups, one kept on a high plane of food intake and one on a low plane during pregnancy and lactation. Skin and wool samples were taken from the progeny at birth and weaning; the ratio Sf/Pf was determined for these ages as well as the proportion of follicles of various kinds and in different phases of activity. The results are compared with those of Ryder from an earlier experiment with Cheviots.

2. Differences in food intake of ewes of the order described affected live weight at weaning, but did not significantly affect the differentiation and development of secondary follicles in the foetus nor their number at weaning.

3. Lambs in the low-plane group shed secondary fibres at 12 months old much more than those which had been in the high-plane group.

4. A partial association of variation in birth Sf/Pf with variation in birth weight was demonstrated, but more than half the variation in this ratio is not accounted for in this way, and the same applies to the variation in birth S/P of the Cheviots in Ryder's earlier experiment. It is suggested that variations in foetal environment and in the early post-natal period affect the rate at which the secondary follicle population in a lamb develops towards its mature genetic maximum.

Results are presented from two experiments (1973 and 1974) in which high potato yields were obtained (60–70 t/ha). In both, Désirée and Maris Piper accumulated much more N and K (> 200 and 300 kg/ha respectively) than was applied as fertilizer (160 kg N and 189 kg K/ha). Increasing planting density (to levels above commercial practice) increased nutrient accumulation but had only small effects on yields. Thus, high yields are associated with but not necessarily caused by large accumulations of nutrients. As a general principle, increasing fertilizer rates above those shown to be optimal will not increase yields.

The calcium arsenate-lime-lime sulphur spray has been studied in the laboratory and from the results so obtained it is inferred

(1) That the formation of a stable tricalcium arsenate by precipitation from aqueous solution is improbable. The interaction of calcium hydroxide and dicalcium arsenate results in the formation of a continuous series of basic calcium arsenates which are hydrolysed in aqueous suspension.

(2) That through the formation of such basic calcium arsenates the addition of lime to dicalcium arsenate reduces the amount of arsenic in solution. This reduction is temporary and on exposure to atmospheric carbon dioxide the original solubility of the dicalcium arsenate is restored. The concentration of soluble arsenic in the dicalcium arsenatelime spray will not be as great as in the dicalcium arsenate spray and the risk of spray injury with the dicalcium arsenate spray is therefore reduced when lime is added.

(3) The concentration of soluble arsenic in the dicalcium arsenate and lime spray is reduced by the admixture of lime sulphur with a corresponding reduction of the risk of foliage injury.

(4) The precipitation of sulphur from the calcium polysulphides of the lime sulphur is unaffected by the addition of dicalcium arsenate. The addition of lime may result in a diminution of the amount of sulphur so precipitated but such a reaction is dependent on the rate of carbonation of the free lime on the leaf surface. The fungicidal activity due to the calcium polysulphides is therefore unaffected by the addition of dicalcium arsenate but may be adversely influenced if excess of calcium hydroxide be present.