The results of experiments conducted on 156 swine, from time of weaning till bacon weights were reached, are reported. One hundred and twenty of these animals were subjected to complete dietary control as regards the quantity of food consumed and the composition of the diet.

Twenty-nine treatments, consisting of different amounts of Ca, P and vitamin D added to an otherwise adequate diet, were imposed.

The reaction of the animals to the treatments was studied in relation to growth (increase in weight), appetite, utilisation of the food, the blood picture (concentration of serum Ca, blood inorganic phosphate, serum phosphatase and blood Hb), and the morphology and chemical composition of the bone. The results obtained are summarised in Table XVIII.

A modified method of estimating the carotene content of plant material has been described in detail. The modifications include a combined aqueous and alcoholic potash hydrolysis of the original material before extraction is carried out.

A statistical analysis and a recovery test have shown this method to be relatively more efficient than methods similar to those described by other workers.

In northern areas of maize production in Europe and America, increasing use is being made of the association between accumulated temperature and stage of crop development. Temperature is accumulated either in terms of day-degrees above a given base temperature, taken to be 10 °CC in the U.K., or in terms of developmental units (‘Ontario Units’). Formulae for obtaining the daily contribution from recorded maximum and minimum air temperatures are available for compiling accumulated temperature totals for each of these methods, but the processing of long series of data is tedious, even with the assistance of computer programs. Results are presented from several locations in the central lowlands of England to suggest that very close approximations to the true monthly or seasonal totals can be obtained from the regression relations with corresponding mean monthly or seasonal temperatures.

For the sites considered the regression equations were sufficiently close to make joint, ‘regional’, regression equations appropriate. It is believed that the results will be applicable to other areas of England, and that the methods suggested might provide a suitable basis for supplementing the information available on accumulated temperatures elsewhere in northern Europe.

Eighty-nine lactating sows, which had farrowed at least once before, were given 140 injections with 2000, 1800 or 1500 i.u. pregnant mare serum hormone. Seventy sows served as controls. 124 injections with 2000 i.u. P.M.S. were followed by 113 oestrus reactions and 88 pregnancies, and 16 injections with 1800 or 1500 i.u. by eleven instances of oestrus and six of pregnancy.

Oestrus occurred in 69% of the positive reactors on the 5th day after injection, and in the rest either earlier or later. The interval between the P.M.S. injection and the onset of oestrus was similar to that between weaning and oestrus in the controls.

The difference between the pregnancy rate of 71% following injection with 2000 i.u. P.M.S. and that of 83% in the control sows from the first oestrus after weaning was found to be statistically highly significant.

Mean litter size and weight were not affected by different time intervals between farrowing and P.M.S. injection, nor were there any statistically significant differences in size and weight of litters at birth or at weaning at 8 weeks of age between those of hormonally treated sowsand the controls.

The shortening of the farrowing interval by P.M.S. injection had no after-effect on the sizeand weight of litters subsequently obtained with or without hormone application.

Injections with 1800 or 1500 i.u. P.M.S. were followed by a reduced pregnancy rate, but the few litters thus obtained were similar in mean size and weight to those obtained with 2000 i.u.or those of the controls.

Sows that did not come on heat or become pregnant following P.M.S. injection came into heat at the same times after weaning of their litters as the control sows.

The shortening of the farrowing interval by an average of 22 days was considered to be of sufficiently high economic value to warrant the introduction on the farm where the experiment wasconducted of the routine application of 2000 i.u. P.M.S. to all gilts and sows on the 28th day after farrowing.

Field experiments on crop compatibility and spatial arrangements in sorghum were conducted at the Indian Agricultural Research Institute, New Delhi in irrigated conditions in 1976 and 1978. Grain yield of sorghum increased when grown in association with the legumes greengram, groundnut, grain and fodder cow peas and soya bean, compared with sole sorghum. Planting of sorghum in paired rows (30:90 cm) with two rows of intercrop in the 90 cm space produced maximum yields of sorghum and intercrops.

Mn, Fe, Cu and Zn were determined in topsoil and herbage samples from sites in North West Pembrokeshire. Means and ranges for these elements are given and the distribution is shown throughout the sampled area.

There are no clear relationships between the total amounts of these elements in the soils and the amounts found in herbage but it is shown that soil drainage strongly influences both soil and plant concentrations, and pH has a strong influence on Mn concentrations in soils and plants.

Seasonal variation in plant uptake of these elements is discussed and the effect of soil contamination of herbage, especially on Fe content. It is hoped that data from this area can be used as a guide to the range of values found for Mn, Fe, Cu and Zn in soils and herbage of an area relatively unpolluted from industrial sources for comparison with more polluted regions.

Ethiopian mustard (Brassica carinata) genotypes with different contents of oleic acid (C18:1) in the seed oil could be useful for food and industrial applications. The objectives of the present research were to study the inheritance of high C18:1 in the seed oil of different lines of Ethiopian mustard and its relationship with erucic acid content (C22:1). The low C18:1/high C22:1 mutant line L-1806, the high C18:1/high C22:1 mutant line L-482, the high C18:1/low C22:1 mutant line L-2890 and the low C18:1/very high C22:1 mutant line L-1630 were isolated after a chemical mutagen treatment of C-101 seeds (about 94 g C18:1/kg and 450 g C22:1/kg). The high C18:1/zero C22:1 line L-25X-1 was obtained by interspecific crosses of Ethiopian mustard with rapeseed and Indian mustard. Plants of lines L-2890×C-101, L-482×L-2890, L-1630×L-25X-1, L-1630×L-2890 and L-482×L-1806 were reciprocally crossed and F2 and the BC1F1 generations were obtained. Cytoplasmic effects were not observed in any of the crosses. The segregation pattern in F2 and BC1F1 populations differed in the crosses studied. The inheritance of C18:1 content in crosses segregating for this fatty acid was that expected for one (crosses between L-482×L-1806), two (L-2890×C-101) or three (L-1630×L-2890, L-1630×L-25X-1 and L-482×2890) loci. Oleic acid segregation indicated control of accumulation by two segregating genetic systems, one acting on chain elongation from C18:1 to C22:1 and the other involving desaturation from C18:1 to linoleic acid (C18:2). Accumulations of C18:1 and C22:1 were influenced by the same loci (M1, M2, E1 and E2), which control the chain elongation steps leading from C18:1 to C22:1. In addition, C18:1 was influenced by one additional locus (tentatively named OL) involved in control of desaturation of C18:1 to form C18:2. The genetic constitution of the parent lines would be OlOlE1E1E2E2m1m1m2m2 for L-2890, OlOlE1E1E2E2M1M1M2M2 for C-101, ololE1E1E2E2M1M1M2M2 for L-1630, OlOle1e1e2e2M1M1M2M2 for L-25X-1, ol1ol1E1E1E2E2M1M1M2M2 for L-482 and Ol1Ol1E1E1E2E2M1M1M2M2 for L-1806. Transgressive recombinants were obtained from the cross L-1630×L-25X-1, with about three-fold increase of the C18:1 content of the parents (>643 g/kg) and free of C22:1 content, which represent a high potential for commercial exploitation.

Sixteen sheep were continuously fed diets based on straw, straw and barley grain, or NaOH-treated straw, each with adequate minerals and with or without additional urea (7·3 g N/day for the straw and straw and barley diets; 14·4 g N/day for the diet containing NaOH-treated straw) infused intra-ruminally. [14C] tracers were used to measure the rate of irreversible loss (i.e. synthesis) of plasma urea and its transfer to the rumen and to the remainder of the gastrointestinal tract in 4–6 sheep per treatment. [15N] tracers were also used to make these measurements in four sheep fed the straw, straw and barley and straw and barley with intra-ruminal urea infusions. Inclusion of the barley grain in the diet increased digestible organic matter intake by c. 70%. Replacing the straw with a greater amount of NaOH-treated straw increased digestible organic matter intake by 43% in the absence of additional urea, and by 65% when urea was infused intra-ruminally. Rumen ammonia concentrations were 37 and 31 mg N/l when straw or straw and barley diets respectively were provided and were reduced to 3 mg N/l when treated straw was given to the sheep. These concentrations exceeded 223 mg N/l when urea was infused intra-ruminally. Rate of irreversible loss of plasma urea measured using [14C]urea ranged from 3·7 g N/day in sheep given the treated straw diet to 16·8 g N/day when urea was infused intra-ruminally, while this rate was correlated with plasma urea concentration. In the three diets where it was measured, rate of irreversible loss of [15N]urea was on average 0·73 of the rate of irreversible loss of [14C]urea. Measurements made with 14C and 15N tracers of plasma urea transfer to the rumen were similar. This transfer measured with 14C tracers ranged from 1·4 to 2·4 g N/day for the three diets without additional urea, while providing urea by intra-ruminal infusions reduced the transfer to 1·1–1·4 g N/day. Transfer of plasma urea to the rumen was not changed by the higher digestible organic matter intake associated with either inclusion of barley grain in the diet or provision of a greater amount of more highly digestible NaOH-treated straw. These studies indicate that plasma urea transfer to the rumen is not always increased by greater organic matter fermentation in the rumen.

The production of biomass and its partitioning into stem, leaf, ear and dead material were monitored weekly in crops of wheat and oats from 16 May 1990, which corresponded approximately to ear emergence in the wheat, until ensilage on 29 June, 7 July and 19 July 1990 using the Ag-Bag system. An enzyme/inoculant additive was used on both crops on each ensilage date, although a portion of oats was ensiled without additive on the first two cutting dates, giving a total of eight silages. Changes in rumen degradability of dry matter were assessed for both crops throughout the monitoring period using the synthetic fibre bag technique. The digestibilities of gross energy, modified acid detergent fibre, organic matter and crude protein were determined in vivo using sheep.

Over the total period of monitoring, the daily rates of increase in dry matter (DM) yield were 15·1 (± 1·6) and 16·5 (±1·9) g DM/m2 for wheat and oats respectively. From 29 June to 19 July the rates of increase were 11·3 (± 3·1) and 23·1 (±6·0) g DM/m2. The increase in weight of the ears accounted for almost all of this increase and, by the end of the monitoring period, the ears contributed approximately half of the dry matter of each crop. In both crops the portion of dead material was small until 19 July, when there was a rapid increase in the amount of dead stem. The DM content of both crops remained < 30% up to day 33 (18 June) but increased from c. 33% to c. 52% between days 53 and 65 (8–20 July). Rumen degradability of both crops decreased rapidly from c. 66% on 16 May until 16 June, when it was c. 56% for wheat and 55% for oats; it remained constant at these values thereafter.

For silages made on the three successive ensilage dates, there was an increase in DM and starch contents but decreases in digestible energy, digestible fibre and digestible crude protein contents. Digestible organic matter was similar for the first two ensilage dates but lower in silage made on the third date.

The use of an additive with the oat crop resulted in decreases in the digestible energy, digestible organic matter and digestible crude protein contents of the silages compared with untreated oats.

Maximum yield of DM from wheat (18·6 t/ha) was obtained with the third cutting date, but optimum yield of energy (170 GJ/ha) and digestible crude protein (746 kg/ha) were found at the second cutting date. For oats, maximum yield of DM (17·3 t/ha) was again found with the third cut and maximum yield of energy (159 GJ/ha, untreated; 140 GJ/ha with additive) with the second cut. Digestible crude protein yield was greatest with the second cut of oats when no additive was used (708 kg/ha) but with additive it was greatest with the first cut (661 kg/ha).

It was concluded that, under these conditions, the optimum date for ensilage of wheat or oats was 7 July and that the use of the additive was detrimental to the quality of the oat silage.

An examination has been made of some of the extensive experimental data obtained by Bouyoucos and his associates on the freezing-point depression of soil solution at varying moisture contents, examined in situ.

These workers find that the soil solution in quartz sand and extreme types of sandy soil obeys approximately the same law as dilute solutions—the freezing-point depression varying as the concentration, or in the present case, inversely as the moisture content. In other words

where K is a constant, and Dn is the freezing-point depression, at a moisture content of Mn. Soils do not obey this law, the freezing-point depression rapidly increasing as the moisture content decreases.

Rates of commercial certified seed (CCS) use are low, but comprehensive upgrading of farm-saved seed (FSS) is also often neglected in northern Europe, represented in the present paper by Finland. In general, available growth resources are particularly underutilized in the northern and eastern parts of Europe, in contrast with the prime agricultural areas of western Europe. The present paper demonstrates the potential of increasing CCS use, and/or upgrading FSS, to boost yields at regional and national level. The assessment indicated that a substantial increase in CCS use in Finland, to correspond with that of Sweden and Denmark, is a basic, readily available and easily applicable means of sustainably intensifying northern European barley (Hordeum vulgare L.) production. Yield benefits averaged 440 kg/ha, corresponding to a 13% increase at national scale. Cultivar change contributed to about one-third of the benefit. At the national scale, an additional 20 000 tonnes of nitrogen (c. 8% increase) would be removed with the yields that would considerably exceed 2000 Gg annually compared with the present c. 1900 Gg total production of barley. Higher use of CCS represents a win–win situation for farmers, plant breeding companies and industry.

A tetraploid wheat breeding programme was initiated at the Plant Breeding Institute in 1970. Hexaploid × tetraploid wheat crosses were expected to contribute to the improvement of the tetraploid wheats but severe hybrid necrosis caused the death of the pentaploid Fxhybrid plants in most crosses. The genotypes of tetraploid wheat selections derived from crosses involving Rampton Rivet, a non-carrier of Neu were determined by test crossing to hexaploid wheat varieties which were known to carry the Neim allele. Similarly, hexaploid wheat selections which did not carry Ne2 were identified from crosses involving Maris Ranger by test crossing to durum selections which carried the Nef allele. By the careful choice of one parent, hexaploid x tetraploid wheat crosses were then made which avoided the hybrid necrosis problem. Segregation of the Ne% gene was as expected but selection for agronomic characters appeared to favour the retention of the dominant allele of the Ne1gene. Nevertheless, test crossing on a relatively small scale still identified many non-carriers.

Pot experiments in which cowpea and hyacinth bean were grown at 15–45% soil moisture showed that nodulation, nitrogen fixation and plant growth were poor at 15%. The weights of nodules and plants were lower in January (winter) than in June (summer). In June cowpea was more tolerant of dry conditions giving good nodulation at 25–35% whereas hyacinth bean required 35–45%.

Under field conditions the number and dry weight of nodules were affected by the irrigation interval whereas plant growth was affected by the amount of water applied. Applying 75 mm depth of water every 7 days gave the best combination of nodulation and plant growth.

1. Three fistulated cross-bred sheep were fed diets which consisted solely of lucerne, cereals or potatoes. Potatoes were fed both in the raw and in the cooked form.

2. A pre-feeding sample of the rumen liquid was examined for its content of protozoa and various chemical components and for its enzymic activity on glucose and on soluble starch.

Fourteen experiments were carried out in various parts of England to compare ammoniumsulphate, ammonium nitrate, calcium nitrate andurea applied to grassland in early winter, latewinter and spring at rates supplying 40 and 80lb./acre of nitrogen. Yield of herbage and of nitrogen were recorded at one cut in spring..

1. The availability of the calcium in three grassland species, all legumes, has been investigated, with the rat as experimental animal.

2. Two procedures involving determination of the calcium balance, (a) by analysis of feed, faeces and urine, and (b) by a slaughter technique, were used.

3. The foregoing methods gave results, for any one species, which were without significant difference. It is considered that the slaughter technique would be the less laborious when any large number of determinations has to be made.

4. The calcium in both lucerne and late-flowering red clover was available to a significantly greater degree than that in wild white clover. In all three species calcium availability was high.

5. The possible significance of the high faecal calcium found in rats receiving wild white clover has been discussed.

6. It was concluded that the extension of availability studies to a wider range of grassland species and of their ash-components would be desirable.

A field experiment was carried out in three wet seasons of 1982, 1983 and 1984 with various combinations of urea and organic nitrogen sources to investigate the nitrogen transformation and productivity of rice crop in a waterlogged situation. The treatments used were: (i) control (No), (ii) FYM + urea, (iii) Sesbania + urea, (iv) urea, the levels of nitrogen being 60 and 90 kg/ha and the proportion being 50:50 between organic and chemical sources where such combination was used. The soil samples were analysed for ammonium, hydrolysable and non-hydrolysable forms of nitrogen at 15, 30 and 45 days after transplanting. The release of hydrolysable and non-hydrolysable nitrogen was superior in the urea-Sesbania combination while the release of NH4·N was slightly better in FYM-urea combination. Yield of rice and apparent nitrogen use efficiency were highest in sole urea treatment and almost similar in FYM-urea and Sesbania + urea combinations. A statistical nitrogen-transformation model outlined the relationship among the various forms of soil nitrogen under submergence. The model suggested a strong correlation among the different forms of nitrogen during the earlier period of submergence.

(1) The edge rows give significantly higher yields than the inside rows, indicating thereby the inadvisability of using edge rows in yield trials.

(2) The variation between rows is very much greater than within rows. Different parts of the same drill row should therefore not be regarded as subject to independent error. The present investigation emphatically confirms Clapham's conclusions on this point.

(3) A slight advantage may be gained by the subdivision of the area to be sampled, without additional labour.

(4) In order to study the effect of the structure of a sampling unit of given size five types of unit have been examined. Of these, method (1), in which the “sampling unit” consists of four parallel half-metre lengths on adjacent rows, appears to be the most precise, and may be recommended on the basis of this trial. The half-metres within such sampling units appear to be negatively rather than positively correlated, and a significantly lower sampling error is obtained in consequence.

Eight feeds were treated with seven solvents and the proportion of seven mineral elements (Ca, Mg, P, Na, K, Cu, Zn) released was assessed. Six of the feeds were from Sri Lanka (Panicum maximum ecotype Guinea A, Glyricidia maculata, Artocarpus heterophyllus, untreated and urea-treated rice straw, and rice bran) and two from the Netherlands (maize silage and wheat straw). The solvents were water, tris buffer, rumen fluid from a cow deprived of (RF -) or fed (RF +) mineral supplements, neutral detergent solution with (NDS +) or without (NDS -) EDTA, and acid detergent solution (ADS).

Both the type of feed and the solvent significantly influenced (P < 0·01) the amount of dry matter loss and the proportion of minerals released. Maize silage released over 80% of its minerals, except Cu, in water and tris buffer, probably because of the low pH (3·7) during ensiling. The other feeds differed widely in their ability to release minerals. In general, P, Na and K. were more soluble in water than Ca, Mg and Zn.

Mineral concentration in RF influenced not only the amount of minerals released, but also the extent of sorption by the feed. The latter effect was more pronounced in feeds with low mineral concentration, maize silage being no exception.

Treatment with NDS+ and ADS removed all minerals except Cu. With all feeds, 12–34% and 5–34% of the Cu remained in the ND and AD residues, respectively, indicating its association with the cell wall. Results of the NDS- treatment showed that some of the Ca and Mg may be associated with the cell wall.

Comparison of the feeds across the different solvents tested indicated that, in terms of absolute quantity of mineral released, G. maculata could be a good source of Ca, Mg, K and Cu, and that rice bran is a good source of P and Zn. The variety of rice straw tested released high amounts of Na. A. heterophyllus is rich in available Ca.

Skin temperatures, deep body temperatures and respiratory rates have been measured in Southdown and Merino sheep following feeding, and during infra-red irradiation, rumen infusions of hot and cold water, and cold exposure induced by shearing. The increases in respiratory rate and skin temperatures induced by infra-red heating and the heat increment of feeding were reversed by addition of iced water to the rumen and were suppressed by shearing. These responses could not be systematically related to particular body temperatures in the sheep and appeared to be continuously variable rather than ‘all-or-none’ phenomena. Considerable overlap was observed between respiratory and vasomotor mechanisms of thermoregulation. Measurements of the surface area and weight of ears and legs showed that these regions contribute approximately 23% of the surface area and 8% of the body weight in Merino sheep. Calculations suggested that up to 70% of the additional heat produced in the 2 h after feeding in sheep may be stored in the tissues through increase in mean body temperature. Sheep kept in short wool throughout the winter appeared to establish a new thermoregulatory ‘set-point’ associated with lower rectal temperatures than those in sheep with a full fleece.