Five male animals of each of the following species, zebu, eland, small East African goat, fringe-eared oryx and Dorper sheep, were penned, and their water intake measured and metabolic water production estimated. The figures for water input were compared with simultaneous measurements of body-water turnover by liquid scintillation counting of tritiated water in plasma, following dioxane precipitation. It was found that the resultant regression was sufficiently linear with the intercept near zero to justify the use of a ratio to predict input from turnover. The tritiated water turnover overestimated the water input by an amount approximately equal to the overestimate of the body water pool by the tritiated water space. Although there was a considerable amount of variation in individual ratios which could not be explained, there was no significant difference in the mean ratios between species.

The increase in dry weight of field lettuce from sowings made between March and August in 1973 and 1974 started exponentially but this did not persist throughout growth. Departures from exponential growth were most marked in the 10 days of growth prior to maturity and a logistic rather than an exponential curve gave a better overall fit to the data. The rates of increase in plant dry weight were similar from all sowings made between mid-May and early to mid-July, when air temperatures and total radiation during the growth period of these crops exceeded 11–12 °C and 250 mWh/cm2, respectively. Sowings made earlier than mid-May took longer to mature and in 1973 gave crops with lighter heads. Quadratic regressions of harvest date on sowing date gave good fits to data obtained in different years at different sites but separate equations were required for each site.

Experiments were made to evaluate the feeding value of undecorticated (UCS) and decorticated (DCS) cottonseed cakes and defatted DCS for egg-type starter, broiler starter and finisher diets for chicks. The results showed that UCS on average contained 22% crude protein, 0·06% free- and 0·33% bound-gossypol and 4·9% available carbohydrate. The corresponding values for DCS were 38, 0·04, 0·63 and 9·5%, respectively. Average metabolizable energy (ME) content of UCS, DCS and defatted DCS was 7·94, 11·77 and 9·42 MJ/kg, respectively. Apparent protein digestibilities of UCS, DCS and defatted DCS were 42, 47 and 36%, respectively. Although UCS had no effect on growth rate of egg-type and meat-type chicks when fed as 15% of the diet, feed conversion was adversely affected. Feeding DCS to broiler starter and finisher chicks as 30% of the diet, replacing groundnut cake (GN) had no effect on growth rate and efficiency of protein utilization but feed conversion was affected. The chicks of either breed were able to tolerate 0·02% free-gossypol of the diet derived from UCS or DCS without any adverse effect on growth rate and internal organs.

Cakes derived from Taramira (Eruca sativa), Raya (Brassica juncea), Toria (B. campestris var. toria) and yellow and brown sarson (B. campestris var. sarson) were evaluated for their contents of crude protein, true protein, essential amino acids, available carbohydrate and tannins. Feeding trials were also conducted to compare the suitability of these cakes with groundnut cake for broilers and White Leghorn chicks up to 4 weeks of age.

The crude protein content of Taramira cake was 33% whereas all the other cakes contained 37–38%. True protein accounted for 80–83% of crude protein in all the varieties and albumin and globulin constitutes the bulk of protein. The critical amino acid content of all the brassica seed proteins was found to be higher than that of other vegetable proteins although varietal differences were observed with respect to a few essential amino acids. The hulls accounted for 19% of whole Brassica seed and their removal raised the concentration of protein from 39 to 46% and reduced the crude fibre content from 15 to 6% in the defatted meal. Tannin content was higher in Taramira (1·74%) than in all other varieties (1·0–1·4%) and the major quantity of it was localized in the endosperm. The average metabolizable energy content of all the mustard cakes was 9·62 and 8·75 MJ/kg for meat-type and egg-type chicks, respectively. The nutritive value of Taramira cake was poorer than that of other Brassica cakes or groundnut cake for supporting growth rate of chicks of either breed.

The drying rate of fully exposed individual lucerne plants was substantially increased following brief immersion in 0·18 M potassium carbonate solution. The increase was maintained over a range of drying conditions, and at low moisture contents, but the use of more concentrated potassium carbonate solutions yielded no further increase. Changes in leaf:stem ratio had a smaller effect on the drying rate of potassium carbonate treated lucerne than on untreated lucerne.

Tests with diffusive resistance and viscous flow porometers support the hypothesis that potassium carbonate solution changes the water transmitting properties of the cuticular waxes.

In two field studies it was found that lucerne hay swaths sprayed with 3000 1/ha of 2% (w/w) aqueous potassium carbonate solution after cutting dried more rapidly than mechanically conditioned or control swaths; the ratio of drying rates being 2·17:1·43:1·00 respectively. Hay yields were increased in one of the two studies by the use of potassium carbonate.

The effect of different application rates was studied in a third trial using 200, 500 and 875 1/ha potassium carbonate solution, compared with mechanically conditioned and control swaths. After only 29 h of field exposure all swaths treated with potassium carbonate had dried to moisture contents below that required for baling (moisture: dry matter ratio < 0·3).

Field bean varieties were grown for 2 years on five plots varying in pH from 4·7 to 8·4. Non-aggressive Chocolate Spot infection was shown to be greater on plants grown in soil of pH 4·7 and 5·8 than on those grown in soil of pH 6·7, 7·7 and 8·4. Seed weight per plant was greater on soil pH 7·7 than on soil pH 4·7, suggesting that acid soil reduced plant vigour and consequently increased disease susceptibility. Varietal differences in infection were shown, although absolute resistance was not observed. Varieties differed in their susceptibility on soils of varying pH, and also showed different stability for susceptibility over the varying environmental conditions.

Previous work has shown a strong relationship between the mean soil temperature during the first 5 weeks of growth of a maize crop, and the final grain yield, warmer soils leading to greater yields. Trials were laid down in 1975 and 1976 to establish how early in the development of a maize crop higher soil temperatures would lead to increased yields. Soil temperatures were raised by polythene mulching applied at planting with six times of mulch removal: at crop emergence, 1, 2, 3, 4 and 5 weeks after emergence. Raised soil temperature led to a greater rate of development and leaf area production during early growth. Greater leaf area was due to greater leaf emergence rate rather than increase in leaf size, since increase in soil temperature was associated with a decrease in individual leaf size. This trend was reversed from leaf number 15 onwards resulting in no differences in leaf area, leaf weight or total dry matter at tasselling. In spite of this, yield differences were observed. Increase in soil temperature during germination alone had a beneficial effect on final grain yield, and this effect increased with duration. Increasing soil temperature for longer than 3–4 weeks from emergence caused no further yield increase. Yields increased from 133 and 172 g/ plant to 220 and 238 g/plant in 1975 and 1976 respectively. Yield increases were associated with more grains per plant rather than greater grain size. The period during which increased soil temperature led to increased yields coincided with the period when the apical meristem was below ground level. The mechanism involved is not yet clear.

Blood samples were taken from 172 Friesian bulls during 1973–5 on three or four occasions. The bulls were in Milk Marketing Board cattle breeding centres in England and Wales and were from 1 to 14 years of age.

The blood samples were analysed for packed cell volume, haemoglobin, erythrocytes, mean corpuscular volume and glucose, and samples of serum for the concentrations of albumin, total protein, urea-nitrogen, inorganic phosphate, Ca, Mg, K, Na and Cu.

Packed cell volumes and haemoglobin and K concentrations were higher in bulls than those previously recorded in dairy cows. There were significant age relationships for packed cell volume, haemoglobin, albumin and globulin (P < 0·001), inorganic phosphate and erythrocytes (P < 0·01) and Ca and Mg (P < 0·05).

Repeatability estimates were calculated and compared with estimates previously obtained for dairy cows.

On the basis of improved contemporary comparisons of the bulls, there was a significant relationship between the average milk yield of a bulls daughters and the concentrations of urea, inorganic phosphate and K (P < 0·05) in the blood serum of the bull.

In three experiments with mixtures of barley and oats, a combination of Midas barley and Karin oats gave consistently higher yields than the mean of the components and slightly higher yields than the better component. The performance of this mixture was maintained over different sowing patterns and seed rates, but where sowing was arranged to give an advantage to one component of the mixture at the expense of the other, mixture yields were less than where both components were closely mixed.

The increased yield of the mixture was attributed to the greater tillering of barley in mixture than in pure stand, brought about by less competition before heading, and to a higher weight per grain of Karin in mixture than in pure stand, a result of its greater height after heading and the favourable disposition of its panicles and upper leaves in the canopy.

The rectal temperatures of ten cows were measured each morning and their milk temperatures measured at each morning and afternoon milking for 40 days in order to study the value of these temperature measurements in determining the best time to inseminate, whether or not standing oestrus is exhibited. The best determination was based on the observation that a cow in oestrus had a milk temperature, taken at morning or afternoon milking, at least 0·1 °C higher than the corresponding temperature on any one of the previous 15 days. This method successfully detected 12 of 14 oestrous periods in the 10 cows (86%) and gave a false positive diagnosis on 6 days out of a total of 236 non-oestrous days (2·6 %).

Automatic mobile shelters were used to keep rain off a barley crop in a drought experiment. The treatments ranged from no water during the growing season to regular weekly irrigation. This paper reports the effect of drought on the harvest yield and its components, on water use and nutrient uptake.

Drought caused large decreases in yield, and affected each component of the grain yield. The magnitude of each component varied by up to 25% between treatments, and much of the variation could be accounted for by linear regression against the mean soil water deficit in one of three periods. For the number of grains per ear, the relevant period included tillering and ear formation; for the number of ears per unit ground area, the period included stem extension and tiller death; for grain mass, the period included grain filling.

The harvest yields were linearly related to water use, with no indication of a critical period of drought sensitivity. The relation of grain yield to the maximum potential soil water deficit did show that a prolonged early drought had an exceptionally large effect on both yield and water use.

Two unsheltered irrigation experiments, also on barley, were made in the same year on a nearby site. The effects of drought on yield in these experiments were in good agreement with the effects observed on the mobile shelter site.

When fully irrigated, the small plots under the mobile shelters used water 11% faster than larger areas of crop, because of advection. The maximum depth from which water was extracted was unaffected by the drought treatment. When 50% of the available soil water had been used the uptake rate decreased, but the maximum depth of uptake continued to increase.

Measurements of crop nutrients at harvest showed that nitrogen uptake was large, because of site history, and that phosphate uptake was decreased by drought to such an extent that phosphate shortage may have limited yield.

When two species are interplanted the interpretation of experimental data presents statistical difficulties because the yields of the two crops will not in general be independent. It is therefore desirable to have a method that will both allow significance levels to be determined and give full importance to the treatment means of the two crops. It is shown that a bivariate analysis of variance can be carried out with little difficulty and precise tests can be based upon it. If it would be helpful to combine the two crops in any way, e.g. on the basis of calorific value or price, the task is readily accomplished.

Field experiments were carried out in the early and late growing seasons in the rainforest zone of Nigeria to find out the relationship between lodging, morphological characters and yield of maize.

Morphological characters associated with lodging were plant height, ear height and length of basal internode. There was a negative correlation between lodging and yield. Much of the lodging recorded, especially in the early growing season, was due to weak stems. Earliness, diameter of stem and leaf area had no relationship with lodging.

A dry-block digestion system suitable for the estimation of total protein nitrogen in plant material has been evaluated. The method was found to be as accurate as Kjeldahl flask digestion, required much less fume cupboard space and enabled samples to be dealt with in large batches through weighing, digestion and analysis. The batch size can be designed to be compatible with the autoanalyser capacity. These advantages result in more rapid analysis with less chance of errors and accidents. A 45 min digestion period was found suitable for several crop species of widely different protein content, only field bean seeds required longer digestion time. Using the technique described samples are digested at a relatively low temperature (330 °C) for a short time and digests do not solidify on cooling. The autoanalyser method for determining ammonia concentrations in barley and malt digests (Micheson & Stowell, 1970) has been slightly modified for use with the plant materials studied. The dry-block and autoanalyser system is rapid, precise and compact, requires small amounts of tissue and is suited to the routine analysis of breeding material.

During the period 1962–73, the majority of the 92 lactations of imported British Friesian animals were initiated during the dry season (October–March). The following average values were obtained: lifetime number of lactations, 4·5; lifetime milk production, 9392 kg; age at producing first live calf, 39·6 months; milk yield of nine lactations, 2159 kg; lactation length, 336·5 days; daily milk yield, 6·3 kg; 305-day milk yield, 2012 kg; dry period, 173 days.

Milk production was highest in the fourth lactation when the animals averaged 7 years old. Differences in milk yield among lactations were small. Peak daily milk yield was greatest in the third lactation and was reached within the first 21 days of each of the first four lactations. A second but lower peak with the highest milk production persistencies at a later stage of lactation apparently depended on feed availability. The 305-day milk yield was reasonably predicted from the 100- and 200-day yields.

Lactations subsequent to abortions and stillbirths were slightly longer, gave less milk (P > 0·05) and were followed by longer dry periods than those initiated by normal births.

Agricultural research now has a long tradition of being served by statisticians, both those who are professionally trained and others who (in no derogatory sense) may be described as amateurs because their primary scientific training is in some other discipline. This paper urges that, as part of good research management, more attention be given to the numbers of statisticians needed and the responsibilities they should undertake.

Questions to be considered include not only ‘Who should analyse specified bodies of data?’ but also ‘Which data require full statistical treatment?’. Poor judgement here can mean that the pattern of statistical activity is governed by the forceful approaches of other scientists more than by the scientific content of a problem; moreover, statisticians may be left with no time for the vital tasks of collaborating with others in the planning of research and displaying initiative in new approaches to quantitative problems. Not all research institutes have yet made their statisticians collaborators and partners in research rather than technicians with sharply delimited duties.

Agricultural statisticians today should be deeply involved in research in cooperation with other disciplines, as innovators in statistical technique, and to some extent in development of statistical theory. They must be encouraged to publish, as partners in research teams and individually, to produce and document computer programs that implement methods required in agricultural research, and to improve statistical understanding among their colleagues in other disciplines. They are scientists whose responsibilities and rights are equivalent to those of other disciplines but need to be interpreted in relation to the research role of their subject. This paper asks for their proper integration into agricultural research, and not for special privilege.

The responses of Stylosanthes guyanensis (Stylo) to frequency and height of cutting and the effects of feeding increasing amounts of stylo meal on egg production, yolk vitamin A, yolk colour and percentage hatchability were studied. In the agronomic study, the higher the cutting height, the higher the total yield of dry matter, yield of crude protein, yield of carotene, percentage of crude fibre and the lower the carotene and crude-protein content. A highly significant correlation between the carotene content and crude-protein content (r = +0·91) was obtained.

The addition of stylo meal as more than 10% of the feed significantly (P < 0·01) depressed egg production. On the other hand, yolk colour, yolk vitamin A status and percentage hatchability were significantly improved with the feeding of stylo meal.

In t h e four production areas studied the gross energy contents of the biomass of the U.K. and Californian sugar beet crops were about 222 GJ/ha/year, while those for the Queensland and Transvaal sugar cane crops were about 682 GJ/ha/year. Recoverable sucrose constituted about 45% of the gross energy yield in the sugar beet crops but only about 29% in t he sugar cane crops, largely due to the bagasse (fibre) present in the cane. Since the sugar cane bagasse was used as fuel it provided nearly all the energy for the production of raw sugar from the sugar cane crops, but sugar beet by-products supplied no energy for t he production of sugar from sugar beet. This difference between the two species was the main reason why the support energy required for sugar production from beet, 28·8 GJ/t sugar, was greater than for production from sugar cane, 10·5 GJ/t sugar. The ratios, energy in refined sucrose:support energy required for its production, were 0·60 for sugar beet and 1·60 for sugar cane.

The efficiencies of conversion of the photosynthetically active solar radiation incident on the crops into energy in biomass (excluding fibrous roots) were 1·2% for sugar beet and 2·0% for sugar cane. This difference in efficiency did not appear to be due to a consistent species difference in the proportion of t he radiation intercepted by the crops, and may have been a consequence of the more efficient photosynthetic carbon fixation mechanism in sugar cane than in sugar beet. The efficiencies of conversion of incident photosynthetically active radiation into energy as sucrose recovered from the plants showed no consistent difference between species and averaged 0·56%.

External balances of water, sodium and potassium were examined in carpet wool Chokla sheep given water once in 24, 48 and 72 h during the hot months. There was a significant decline (P < 0·01) in feed intake on the third day of dehydration. The water intake of this group approached 30% of body weight and there was also a significant (P < 0·05) decrease in urine volume after 2 days of water deprivation. There was a large balance for potassium in all treatments and most especially when the sheep were given water every 72 h. It is argued that this unusually high balance of potassium was probably a characteristic of sheep adapted to a hot climate.