The optimal feeding time of microencapsulated sodium butyrate (SB) in whole milk (WM) and starter feed on growth performance and health in dairy calves was evaluated. Forty-eight newborn Holstein calves (body weight (BW) = 39.45 ± 2.48 kg) were randomly assigned to one of the four treatment groups (12 calves per treatment; seven females and five males) in a complete randomized block design and fed (1) WM without microencapsulated SB (CON) supplementation; (2) 4 g/day SB added to WM since days 4–32 (SB-4-32); (3) 4 g/day SB added to WM since days 61–74 and an equal amount was added to starter since days 75–88 (SB-61-88) and (4) 4 g/day SB added to WM since days 4–74 and an equal amount was added to starter since days 75–88 (SB-4-88). Total dry matter intake, starter intake, BW, average daily gain and gain-to-feed were similar between treatments. Calves fed SB-4-32, and SB-4-88 had lower faecal score during pre-weaning, and overall. In addition, calves in SB-4-32 and SB-4-88 groups had fewer numbers of days with scours during the pre-weaning period, and throughout the study. Calves fed SB-61-88 had greater serum total protein during post-weaning. Post-weaning and overall albumin concentrations were greater in SB-4-32 and SB-4-88 calves and tended to be greater in the pre-weaning period compared to control calves. In general, the time of SB addition had no remarkable effect on performance but better faecal score within the pre- and post-weaning periods.

The effects of crop density and fertilizer application on three varieties of marrowstem kale were investigated. The yield of stem, yield of leaf, components of leaf yield and plant height were studied separately. Varietal differences and effects of density and fertilizer application were significant for all characters, except for the effect of crop density on leaf and stem yield per ha.

Significant variety x treatment interactions occurred for a number of the characters measured. The possible importance of these is discussed.

The investigation bears out the conclusion of the Rothamsted experiments that leaching out may occur any time throughout the winter up to March, or rarely April.

The loss of nitrates is directly limited by the amount of drainage and so is indirectly determined by the rainfall, and by temperature—as it affects the rate of evaporation.

All three nitrogenous fertilisers are shown to lose well over 50 per cent, of a normal dressing by leaching out during the winter, but the loss is greatest in the case of sulphate of ammonia, least in the case of rape dust, calcium cyanamide being intermediate.

The writers wish to express their indebtedness to Miss N. Sugg who carried out the experimental work in the first winter.

The heavy wastage occurring in many dairy herds adds importance to the question of sex ratio in cattle, and it becomes an important factor in herds where it is desired to use only home bred cattle, as in herds free from tuberculosis and contagious abortion. The information required for the present investigation was obtained from Private Herd Books, particulars being taken as to sex of calf, month of birth and whether or not it was a first calf. Herds ravaged by contagious abortion were excluded, and also others if it was considered that there might have been neglect in entering births in the private herd book.

Many authors, for example, Settegast, Pusch, Kašpárek, Kraemer and Rostafinski, have attempted to draw conclusions concerning age, quality and breed of cattle from the type of hair produced. Exact investigations of the length and other features of the hair are, however, rare in the literature. Bilek has recently made some investigations of this kind under the direction of Professor Kašpárek, and has estimated the relation between the medulla and the fibrous layer, and has shown that the cross section of the hair is sometimes circular and at other times elliptical in shape.

The present method of estimating preliminary results in artificial insemination practice bears a definite relation to calving percentages, and, with few exceptions, may be generally adopted as a true measure of fertility.

Single factors, such as an individual bull with a low conception rate, a new and less efficient inseminator, or variations in the results obtained at the Sub-Centres, etc., do not noticeably affect the average monthly conception rate in a large A.I. Centre. The most important influencing factors have been found to be the choice of diluent, and in some cases the elimination of the use of stored semen.

No significant variation in fertility occurs with the season of the year, the age of the bull or the area of operation; but, for a bull to work satisfactorily at a centre and at the same time achieve good results, it is necessary that he should be treated as an individual and his psychology closely studied.

In view of results obtained, one is able to conclude that methods of evaluation at present in use (estimating initial motility, density, percentage of abnormals and a test of viability by storage of diluted and undiluted samples) are up to a point satisfactory.

A dilutor or buffer may influence the conception rate considerably, and it is felt that the diluent in use at present has its own fertility level.

With the Centre's team of forty-eight bulls it is obvious that there must be some variation in fertility levels between individuals; but it is seen that, whereas bulls in natural service fall obviously into categories of ‘high fertility’ or ‘low fertility’, this division tends to disappear in A.I. with the application of the various techniques.

The cost of developing and maintaining pangola grass pastures has been examined under a range of conditions. The direct cost of improving pastures to the stage where they were established as 5–10 acre, fenced, watered units of pangola grass was about £30 per acre. Under favourable conditions this cost could be reduced to £20, but with difficult land or poor techniques the cost could rise to £40 or more per acre. In addition to the direct cost of establishment there was an indirect cost due to land being out of use or stock numbers having to be reduced. This indirect cost appeared to be highest on lands where planting costs were least. It was suggested that there might be an inverse relationship between direct and indirect costs which tended to narrow the total range of establishment costs.

A plot trial tested the fertilizer value of dung and urine evenly spread on Hyparrhenia veld which was very deficient in N and was also deficient, although less seriously, in P.

In a field experiment on a typic hapludoll in 1983 and 1984, deep placement of urea supergranules at 40 and 80 kg N/ha proved to be the best N source, of five tested, for grain production, but at 120 kg N/ha it was similar to neem-cake-coated urea. The results showed that deep placement of urea supergranules can save fertilizer use by 60% compared with prilled urea to obtain the same yield. Shellac-coated urea and dicyandiamide-coated urea was more effective than prilled urea in 1984. Differences in dry-matter production and grain yield were directly related to N uptake by the plants. On average, apparent recovery of applied N increased from 35% for prilled urea to 55, 52·5,46·5 and 37·5% for urea supergranules, neem-cake-coated urea, shellac-coated urea and dicyandiamide-coated urea, respectively.

Four soils, sterilized by steam at 100° C, with unsteamed controls for three soils, were examined at intervals up to 62 days to study the microbiology in relation to the abundance of ammonia, nitrites and nitrates of all the soils, the C/N ratios of two, and the pH and moisture content of three. After steaming, the soils were flooded with sterilized tap water equivalent in amount to 3 in. of rainfall at intervals varying with the particular soil. The soil of the first trial remained under water until very near the end of the experiment. In all the soils, the production of ammonia up to 14 days after steaming was associated with increased biological activity, generally a multiplication of bacteria associated with multiplication of Protozoa. The production of nitrites and nitrates was associated with a similar biological activity. Those bacteria that survived steaming had simple growth requirements as compared with those of the subsequent microflora. The Protozoa showed a series of ‘pulses’ of maximum and minimum abundance and there was also a succession of species in all the soils. A predilection of Protozoa for certain bacteria was shown by the association of certain species with particular groups of bacteria identified by Gram's staining. In two of the soils, there were ‘pulses’ of maximum and minimum abundance of diatoms, and in one soil diatoms possibly affected soil texture. The investigation showed that despite the contrasting characters of the soils, the major chemical changes were almost wholly attributable to biological activity, and that after steaming the same general reactions occurred in all. The investigation proved the importance of considering the microbiology of steamed soils as a problem in ecology.

1. The sugar-cane in Trinidad is subject to blight, caused primarily by the sucking action on its leaves of a Cercopid, Monecphora (Tomaspis) saccharina Dist., commonly known as the “froghopper.” The intensity of the injury sustained by the cane appears to depend largely on the condition of the soil in which it is grown. An investigation has, therefore, been made of the extent to which certain soil factors are associated with the reaction of the cane to froghopper attack.

2. The data obtained show that the mechanical composition of the soil and its content of organic matter bear little relationship to the damage caused. The blighted soils differ from those blight-free, however, in that, whereas the former are devoid of calcium carbonate and, as a rule, markedly acid, the latter almost mvariably contain at least traces of this substance, and in general are alkaline or slightly acid only. These differences suggest that the lime status of the soil is a factor of primary importance.

1. Heat tolerance in nine hair-coated wethers on a maintenance diet was studied during the hottest period of the year near Salisbury, Southern Rhodesia.

The expected merits of the semi-hybrid variety, produced by bulk interpollination of two populations (Foster, 1971a, 6, c), are examined in relation to those of the synthetic variety. With diploid inheritance, the mean expression of both types of variety is seen to be the same. Any postulated difference in productivity must depend not only on the preferential establishment and survival of a small fraction of the total population, but on the existence of a correlation between characters determining productivity and establishment. For two populations producing a heterotic hybrid, a correlation due to loose linkage or gene association without linkage may result in the superiority of the semi-hybrid, but tight linkage or pleiotropy are more likely to favour the synthetic variety. It is concluded that superiority of the semi-hybrid mode of varietal production can only be established by means of a direct comparison with its synthetic counterpart, and not solely by the demonstration of upper-parent heterosis for productivity.

1. It is shown that results for the loss in weight of a soil on oven heating can be obtained to a very satisfactory degree of accuracy when a Hearson electrically controlled oven is used.

2. Results obtained by heating soils to temperatures ranging from 5° to 250° give smooth curves connecting loss in weight with rise in temperature; from which it is concluded that there is no sudden alteration in the structure of a soil when it is heated to 100°, and that the airdry moisture of a soil, as determined with sufficient accuracy by the usual methods, is a convenient empirical factor, but not a representation of any fundamental soil property.

3. An examination is made of the factors contributing to the observed total loss in weight when the soil is heated, and an explanation offered of the contributions made by the different types of soil water and by the soil colloids. It is found that the conclusions drawn from this discussion confirm views developed earlier with regard to the behaviour of the water in the soil, and the absence of any sharp dividing line between the different classes into which the soil water is usually divided.

Yields from lucerne cultivars grown on land infested with Verticillium albo-atrum, a cause of wilt disease, were studied over the period 1969–77. Field experiments established in 1969, 1971, 1972 and 1973 were maintained for periods of 4–6 years. Reactions by cvs Europe and Vertus were of principal interest. Europe is considered to be moderately susceptible, initially producing yields exceeding those of resistant types on uninfested land. In comparison cv. Vertus has considerable resistance derived from a polygenic system. In the first 2 cropping years on infested land, Europe yielded similarly to Vertus with only slight symptom expression. In year 3, Europe maintained comparable yields to Vertus but with increasing disease expression. During succeeding years Europe was badly affected by discase and yields were below those achieved by Vertus. Data from other cultivars indicated a positive correlation between symptoms in years 4 and 5, a negative correlation between dry-matter yield in year 5 and symptom severity in year 4, and a negative correlation between symptom severity and yield in year 5. Symptom expression and pathogen build-up appear to occur at similar rates in the latter years of a lucerne crop. Disease development in one season has a considerable effect on future productivity. These findings are discussed in terms of the primary (extra-vascular) and secondary (intra-vascular) determinants of resistance to wilt pathogens. It is suggested that the apparent moderate susceptibility of cv. Europe in seasons two and three relates to a rapid growth rate.

1. In the seeding year the total dry-matter yield in swards sown without a cover crop was increased by infrequent defoliation, but the yield of crude protein was decreased. The highest production of starch equivalent was obtained when a cover crop was used.

2. In the absence of a cover crop, the yield of red clover was higher under infrequent defoliation, but the yield of white clover was higher under frequent grazing.

3. Frequent grazing, and the use of a cover crop, reduced the ingress of weeds more than infrequent defoliation. Nitrogen applied to the cover crop also reduced the growth of weeds.

4. Nitro-chalk increased the total yield of herbage except when under a cover crop; it reduced the growth of red and white clovers, but this was not so marked under frequent grazing.

5. Nitro-chalk increased the annual yield of crude protein under frequent grazing, but decreased it in all herbage mixtures under infrequent defoliation; nitrogen had no effect when a cover crop was used. The increase in yield of starch equivalent due to the application of nitrogen and its apparent recovery was greater under frequent grazing than under the other two managements. Under infrequent defoliation, in the absence of a cover crop, the recovery of nitrogen was particularly low.

6. The ryegrass mixture and ryegrass-dominant general-purpose mixture made more growth, and suppressed clover and weeds to a greater extent than did the timothy and cocksfoot mixtures. This was modified by management in that ryegrass was particularly aggressive under frequent grazing (management 1) but not under managements 2 and 3.

7. In the autumn of the seeding year the yield of total herbage was highest under infrequent defoliation, particularly in the cocksfoot, and general-purpose swards. All undersown mixtures gave lower yields than when no cover crop was used.

8. Nitrogen increased the yield of herbage in May and June under frequent grazing, and in the August cut under infrequent defoliation, but in the autumn particularly it was reduced where a cover crop was used.

9. The application of nitrogen decreased the protein content in all herbage mixtures when a cover crop was used or when defoliation was infrequent. Under frequent grazing the nitrogen increased the percentage of crude protein in the first two grazings, but decreased it in the September grazing.

10. The production from the various mixtures was modified by management: under frequent grazing in May the ryegrass-dominant mixtures were higher yielding than the others, but in July the general-purpose and cocksfoot swards were the most productive. Under infrequent defoliation in August the timothy mixture had the highest yield and cocksfoot the lowest, and under this management cocksfoot and timothy swards had the highest yield in the autumn of the seeding year.

A theoretical model for the influence of plant size and age on plant protein content was tested against the results of 13 field experiments on vegetable crops grown with high rates of application of N, P and K fertilizers.

For each crop the protein contents of individual plants of similar age (but of different sizes) harvested at regular intervals during growth were found to bear a linear ln-ln relationship to their contents of nitrogen-free organic matter. The slopes of the lines of best fit were almost the same at each harvest date. The intercepts were similar irrespective of harvest date when growth was exponential but showed an approximately linear decline with length of growing period when it was not. These features are in agreement with the theory.

Maintenance respiration rates were deduced by interpreting the data in terms of the theoretical model. The values determined in this way were between 8 and 21 mg of glucose/g of protein/day for the above ground parts of the plant compared with values of between 8 and 87 mg that have been obtained by entirely different methods.

It is concluded that during the exponential phase of growth the critical protein and, thus, nitrogen contents depend primarily on plant size and on the chemical composition of the nitrogen-free organic matter, but that when growth is not exponential plant age and maintenance respiration are also of importance. The models should facilitate the determination of the critical nitrogen contents for crops grown under different conditions.

The joint scaling test of Cavalli (1952) and the six-parameter procedure of Jinks & Jones (1958) were applied to test the adequacy of the additive-dominance model and to estimate various main and interaction gene effects for five characters, namely, final plant height, ear length, number of spikelets per spike, number of grains per spike and yield per plant, in three wheat crosses (Kalyan Sona × Norteno 67, Norteno 67 × WL 212 and K. Sona × Moti). Goodness of fit of the model varied from cross to cross for the same character except for number of grains per spike and yield per plant for which the model was inadequate for all three crosses. The two methods were in complete agreement regarding the presence of epistasis in the material. Among the interaction parameters, the component [1] showed the greatest effect for most of the characters in all three crosses where there was evidence of epistasis.

1. The frequency of excretion of droppings by hens varied considerably over the day and much of this variation appeared to be related to the disturbance of the birds by attendants.

2. Data relating to dry-matter excretions by five birds for 17 days were used to study the influence of zero hour and length of the time unit on variations in this dry matter.

3. It was found that, in this experiment, 14.00 hr. appeared to be the best zero hour, but it was suggested that, considering the heavy excretion of material around 06.00 hr. when the birds are first disturbed in the morning, 07.00 hr. might be the ideal time. Data from an earlier experiment supported this.

4. There was a decrease in variation up to a unit of time equal to 3 days and times not multiples of days gave greater variations. There were, however, considerable differences between birds.