1. By separating the sources of variability in an experiment involving haematological observations it has been shown how to estimate the usefulness of repeated observations on each animal.

2. In the illustration provided it is concluded that when monozygous twin calves are used, random variability accounts for so much of the total variability that a great improvement in accuracy can be achieved by taking repeated observations on each animal. When unrelated calves are used, little additional accuracy is obtainable by taking more than about three observations on each.

3. It is shown that, in consequence, the relative efficiency of monozygous twin and unrelated calves is likely to vary, depending upon the number of observations on each animal. Thus, to benefit fully from the increased efficiency offered by monozygous twins, more observations are required on each animal than in the case of unrelated animals.

4. Although the figures refer to haematological measurements on calves, the statistical method evolved is of wider application.

A method for determining the total exchangeable bases of carbonate soils is described. The carbonate in a known weight of soil is decomposed by acetic acid and the carbon dioxide evolved is estimated. By further extraction with acetic acid a solution is obtained which contains not only the bases originally in combination with the carbon dioxide but also the exchangeable bases. The amount of the latter is found by difference.

Biomass accumulation in cereals is an important determinant of grain yield (Green, 1984). However, when attempting to maximize dry-matter production a taller crop more prone to lodging may result (Boothroyd & Clare, 1984). While many contemporary triticale cultivars contain a dwarfing gene, most are very tall relative to wheat and barley (McDonald, 1984) and lodging is a particularly important factor in growing triticale crops.

1. The average electrode potentials of laboratory silages of various types have been measured.

2. The electrode potentials of ordinary and molassed silages tended to assume values of the order of –0·05 to –0·10 V. from about the third day; the pH of these silages lay in the range pH 4·0 to 5·5.

3. In a number of instances secondary increases of electrode potential were observed, frequently in association with secondary deterioration.

4. The electrode potential of silage prepared with hydrochloric acid and of pH 3·4 remained steady around +0·18 V.; the potential of silage prepared with formic acid and of pH 3·9 was about + 0·35 V. initially but declined towards + 0·23 V. at 35 days.

5. Curves for the ‘pure’ carotene content of laboratory silages displayed minima during the early stages of fermentation except in the case of formic acid silage.

The mechanisms responsible for moving K from soil to root were studied by growing perennial ryegrass in pots containing a flinty silt loam from Rothamsted and a sandy Woburn soil, with and without added K, at 0.75 water-holding capacity. More water was taken up from the Rothamsted soil than from the Woburn soil, and less was taken up when K was added without affecting dry-matter production. After 25, 52, 83, 122, 194 and 276 days, K uptake, water uptake and the K concentration in the soil solution were measured and the mass-flow contributionto K uptake calculated.

Without added K, mass-flow accounted for only about one-sixth of the K taken up from the Rothamsted soil and about one-third from the Woburn soil. Except at first, diffusion probably accounted for the remainder of uptake but was the rate-controlling step for uptake from the Woburn soil only. With added K, mass-flow became much more important relative to diffusion in both soils, and transported more than enough K to account for the measured K uptake. Root interception probably did not contribute to K uptake after the early part of the experiment, because the pots used were small.

The following paper is the first of a projected series on the results of work which has been in progress in the Animal Calorimetry Department of this Institute during the past five years. Subsequent papers will deal with body temperature variations, effects of environmental temperature, metabolism, energy expenditure, etc.

Bean cultivars Cargamanto (CIAT P590, indeterminate climbing, Type IV) and Puebla 152 (CIAT P498, indeterminate large vine, Type III) were grown at 20 and 60plants/m2 at two locations in Colombia; a cool, high rainfall, mountainous area (Popayan) and a hot, medium rainfall, valley (Palmira). The crop growth period was compressed and P590 failed to flower at Palmira.where plant shoot weights tended to be higher and root weights lower than at Popayan.

Midday soil temperatures at 10 cm averaged 7·8 °C lower and N2(C2H2) fixation rate and nodule fresh weight over ten-fold higher at Popayan than at Palmira. Increasing the plant population density increased yield but reduced seed weight per plant and the fresh weight of all other plant parts, with shoots more severely affected than roots. Density had little effect on carbohydrate concentration or N2(C2H2) fixation per plant. The cultivars accumulated carbohydrates in different amounts but had similar rates of N2(C2H2) fixation. Concentrations of ethanol insoluble carbohydrates were several times higher in all plant parts at Popayan. Soluble carbohydrates showed similar, but smaller, differences.

An experiment to study the effect of row direction on the light interception, growth and yield of three wheat cultivars sown at three different dates was conducted at Punjab Agricultural University, Ludhiana during rabi seasons 1982–3 and 1983–4. The results showed that sowing in a north-south direction resulted in 0·20 and 0·22 t/ha higher yield than sowing east-west. Bi-directional sowing gave further increases of 0·30 and 0·18 t/ha over north-south direction during 1982–3 and 1983–4 respectively. Late sowing significantly reduced yield.

Body-weight gain, protein efficiency ratio (PER), standardized protein efficiency ratio (Std PER) and gross protein value (GPV, GPV1 and GPV2) bioassays were compared with nitrogen incorporation efficiency (NTE) for their accuracy and precision to determine protein quality of fish meal (FM), groundnut cake (GN), mustard cake (MS) and cottonseed cake (CS) for poultry. Results showed that all the bioassays were significantly (P < 0·05) correlated with NIE and were equally effective in ranking the samples of FM, GN, MS and CS according to their protein quality although body-weight gain procedure was less sensitive.

In an intermediate deepwater situation (15–50 cm) at Cuttack, India, three improved high-yielding rice varieties, Utkalprabha (semi-tall), CR 292–8051 (intermediate tall) and Gayatri (semi-dwarf) were sown on 20 May, 30 May and 10 June in 1988 and 1989 with an application of either 0, 20 or 40 kg N/ha at sowing. Tall varieties performed better than the dwarf type but grain yield decreased with delay in sowing. The early-sown crops (20–30 May) germinated with pre-monsoon rains and were established well before water accumulated in the field from mid-June onwards. The late-sown crops (10 June), despite good initial germination, could not withstand immediate waterlogging. The tall variety, Utkalprabha, elongated faster with rising water level and escaped complete submergence; whereas the semi-dwarf Gayatri failed to withstand such extreme excess water stress. Application of N fertilizer up to 40 kg/ha proved beneficial to the crops sown by the end of May. However, with crops sown on 10 June, the application of N could not compensate for the loss in yield due to an inadequate initial crop stand. Therefore, early sowing of tall varieties by the end of May along with a basal application of N fertilizer is recommended for higher productivity of rice under excess water conditions.

Photosynthetic electron transport, osmotic volume changes and protein loss on osmotic shock were measured in isolated pea chloroplasts after treatment with a range of aldehyde concentrations at various temperatures and times. ADP+Pi-stimulated oxygen production was the most sensitive to inhibition by the aldehyde treatment. With suitable conditions, osmotic volume changes could be prevented and protein losses on osmotic shock reduced to about 1% of the control value, whilst NH3-uncoupled electron transport retained about 40% of its activity. Results showed that basal, ADP + Pi-stimulated and NH3-stimulated O2 production could be used together to indicate the extent of chloroplast fixation thus providing a way of assessing fixation in preparations where osmotic changes are difficult to measure.

Glutaraldehyde (M.W. 100) was found to be 60–80 times as effective as formaldehyde (M.W. 30), on a molar basis, in preventing osmotic volume changes and protein loss on osmotic shock.

The application of this work for the production of large amounts of glutaraldehyde fixed chloroplasts and of fixed herbage for use as a tool in nutritional studies in ruminant animals is discussed.

Two hundred and forty mature Merino ewes were used in a factorial experiment to investigate the effects of single injections of either 0, 40, 80 or 160 mg progesterone on the length of the subsequent oestrous cycle. Equal numbers of ewes (15 per group) received subcutaneous and intramuscular injections, and equal numbers were treated either on the day of oestrus or the following day.

Oestrous cycle length was significantly reduced in all treated groups, with a minimum cycle length of 7–10 days following treatment with 80 or 160 mg progesterone. Neither route of administration nor day of treatment significantly affected the response. The conception rate achieved by treated ewes at the first post-treatment oestrus did not differ significantly from that in comparable controls.

The results suggest that a single massive dose of progesterone on the day of oestrus is an effective means of shortening the oestrous cycle of the ewe without loss of fertility.

1. The influence of rainfall on the yield of mangolds is studied in this paper.

2. Analysis shows that the variation in the yield due to annual causes cannot be accounted for by a single weather element, rain.

3. An additional inch of rain above the normal, during the period extending from the middle of March to about the end of May, is harmful possibly because of the difficulty in securing a proper tilth and delay in sowing, which results in a shortening of the growing period.

The tubers of Dioscorea composita Hemsl. contain a high level of diosgenin, and hence there is economic interest in this plant. Levels of diosgenin vary greatly in different clones of the species. Vegetative propagation was studied with a view to obtaining plants with high levels of diosgenin. In this study cuttings from 1-year-old vegetative plants were used for propagation. The cuttings were treated with a single application of indole-3-butyric acid (IBA) and several applications of 6 benzyladenine (6-BA). Rooting was never observed in untreated cuttings. Cuttings treated with IBA produced callus and roots. Early application of 6-BA delayed senescence but inhibited callus and root formation. New plants were obtained with one application of IBA followed by applications of 6-BA at 48 h intervals initiated 2 weeks after IBA application. In some experiments, all cuttings treated this way produced new plants.

It has been shown in Part II that a glacial drift soil in a comparatively unweathered condition has a considerable power of absorption for ammonia, although it has sometimes been held that it is the weathered material in soils that is responsible for the absorptive power. Glacial drift, as exemplified in the Craibstone soil, however, though its weathering is geologically recent compared with that of many English soils, has been subjected to age-long weathering since the glacial period, and in the process of soil formation a certain amount of weathering with the resultant decomposition has necessarily taken place. Craibstone soil has also been shown (Table II, Part II) to contain a fairly large percentage of organic matter and it might be contended that the absorptive power was chiefly due to either or both of these factors.

Four of five ‘hairy’ Wiltshire lambs had fibre type arrays (as defined by Dry, 1965) of Plateau (P0 and P1) type, whereas in five ‘woolly’ lambs there was only one Plateau (P3) array, the arrays of the remaining lambs being Ravine or Saddle. In terms of Dry's theory that the severity of pre-natal check determines persistence of wool growth in adults, it appears that the amount of checking in these Saddle and Ravine arrays was insufficient to prevent the casting of the adult coat.

A 6 x 6 Latin Square balance experiment was carried out using six Friesian steers, each of which initially weighed about 304 kg. The six treatments studied were an all-hay diet and five other diets containing 20,40,60,80 and 100 % of rolled barley fortified with mineral and vitamin supplements, accompanied by correspondingly reduced proportions of hay. Each diet was fed at an estimated maintenance level of feeding.

The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in both digestible and calculated metabolizable energy. The actual increase in digestible energy was from 2·62Mcal/kg dry matter (59·3% of the gross energy) on the all-hay treatment to 3·42 Mcal/kg dry matter (79·5% of the gross energy) on the all-concentrate treatment. Use of the determined digestible energy values for the all-hay and fortified barley diets to calculate the digestible energy of the four mixed diets gave results in reasonably good agreement with the determined values, the maximum difference being 0·12 Mcal/kg dry matter, which represented 3·83 % of the determined value. The losses of energy in the urine expressed as percentages of the gross energy of the diets showed a small but significantly linear decrease (P < 0·01) with increase in proportion of barley in the diet. The molar proportions of steamvolatile acids in samples of rumen fluid taken from two animals on each treatment indicated that increase in the proportion of concentrate was associated with tendencies for increase in acetic acid, decrease in propionic acid and little change in butyric acid. The mean digestibility of the organic matter was 62·6 % on the all-hay treatment and 81·8 % on the all concentrate treatment. The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in digestibility of the organic matter. Although intakes of nitrogen decreased with increase in the proportion of concentrate due to a decrease in the amount of dry matter fed, the weights of nitrogen retained were well maintained and when expressed as percentages of intake showed a significantly linear increase (P < 0·01).

A study was made of phenotypic correlations between seed yield and some other traits of determinable value in two bred varieties of meadow fescue. Seed yield and such characters as time of flowering, plant height and dry-matter production of spaced plants in October and at the time of anthesis were found to be closely associated.

The method of path coefficient analysis was used to study the interrelationships of seed yield and its components in the causal system: fertile tiller and floret numbers, percentage fertility and thousandseed weight. This analysis corroborates the result of simple correlations in showing the importance of fertile tiller numbers and fertility as major determinants of seed yield.

A simple device for recording seedling emergence force was developed. In this device, the relationship between the bending moment and displacement of the free end of a cantilever beam is used to compute seedling emergence force. The growing seedling is forced to push the free end of the beam upwards and the displacement of the free end is recorded with a pointer on smoked paper tightly wrapped on a revolving clock drum.

Although considerable work has been done on basal metabolism and maintenance requirements of animals, maintenance needs in relation to total feed requirements for production have not received much attention in South Africa. Most workers have investigated production requirements, whilst the part of the total needs of the fattening of steers used for maintenance, has received very little attention.

This capital cost or ‘overhead’ expense is an item which constitutes a large proportion of the animals' fattening ration. In South Africa, only a small percentage of cattle is marketed under 4 or 5 years old. The maintenance cost of these animals must be considerable and the nett efficiency of beef production very low. As only the amount of a ration in excess of the maintenance requirements can be utilized for production, it follows that a level of nutrition well above the requirements for maintenance will facilitate a more efficient production system by narrowing the ratio between the part of the ration used for maintenance and that used for production. It is well known that differences in the efficiency of production between steers can only be due to the difference in the level of feed intake above maintenance needs—hence probably the strong correlation between rate of gain and efficiency of feed utilization. Apart from the actual determination of maintenance needs the object of this investigation was to determine the relationship between maintenance requirements and the total feed intake of beef steers when fed on fattening rations containing different ratios of concentrates to roughage.