The tissue copper concentrations of Black Najdi sheep at the Hofuf Agricultural Research Centre (HARC) are reported. Lambs suffering from a delayed neonatal ataxia had low concentrations of copper in blood, liver and kidney, consistent with a diagnosis of copper deficiency, which was supported by histological examination of their brains and spinal cords.

Low concentrations of copper and high concentrations of molybdenum and sulphate in forages produced at the HARC appear to contribute to the high incidence of neonatal ataxia observed there.

The parenteral administration of 40 mg of copper to pregnant ewes improved the viability and weight increases of lambs over lambs born to untreated control ewes, even though all lambs had received an injection of 20 mg of copper soon after birth.

The provision of supplementary barley to the lambs running with their mothers and with access to lucerne hay increased their growth and blood copper concentrations over animals restricted to the hay diet.

The blood copper, haemoglobin and packed cell volumes of lambs born to ewes maintained on Rhodes grass were significantly lower than lambs born to ewes given lucerne, all ewes having received copper during pregnancy. This effect was attributed to the low copper and high molybdenum and sulphate content of Rhodes grass (Chloris gayana).

1. On storage under good farm conditions Calcium Cyanamide gained steadily in weight, the increase reaching about 10 per cent. after 27 months. The percentage of nitrogen decreased at a practically equivalent rate, so that there was little change in total nitrogen. The form of the nitrogen remained practically unchanged for the first 6 months; by 12 months there was a slight reduction in cyanamide nitrogen and a slight production of dicyanodiamide—less than 1 per cent. of the total nitrogen.

2. In a farm mixture of Calcium Cyanamide and superphosphate (1:3) cooled by spreading in a thin layer after mixing, 16 per cent, of the nitrogen was converted to dicyanodiamide in the fresh mixture and this increased to 25 per cent, after 1 month's storage. More dicyanodiamide was produced in a series of laboratory mixtures of Calcium Cyanamide and superphosphate, in which heating was allowed to take place. Dicyanodiamide production varied regularly with the composition of the mixtures, rising to a maximum of 50 per cent. of the total nitrogen in the mixture containing 20 per cent. of Calcium Cyanamide, and falling to below 20 per cent. of the nitrogen in the 50 per cent. mixture.

1. The value of the knowledge of the saturation capacity of a soil as an aid in its characterisation and classification is briefly stated.

2. A short account is given of the more important methods in use for determination of saturation capacity.

3. The theory underlying the method of Page and Williams, and the possible defects of the method are discussed.

4. The results of an investigation of this method lead to the following conclusions:

(a) Leaching the mixture of soil and calcium carbonate to 2 litres is in sufficient to displace from the soil all its exchangeable bases.

(b) In view of this, it is recommended that 3 litres or more of filtrate be obtained, or preferably, the amount of soil employed be reduced to 10 grm.

(c) The leaching solution remains in contact with the soil mixture for a period adequate for the normal sodium chloride solution to be saturated with calcium carbonate.

(d) The difference in the amount of calcium, derived by solution from the carbonate, in the first and second litres of filtrate, is sufficiently small to be neglected.

(e) The tardiness with which the reaction proceeds to completion is probably due to the difficulty experienced in displacing the final amounts of adsorbed ions, rather than to the presence of calcium ions in the leaching solution.

(f) The incompleteness of the reaction renders the method of Hissink inaccurate for the calculation of the saturation capacity.

(g) The variation in the character of the colloidal material of soils i s to some extent reflected in the value of the ratio of the calcium passing into solution through exchange reactions in the second litre, to that dissolved in this manner by the total volume of filtrate.

The above data on the sire's conformation and on the dam's conformation in relation to their daughter's production of milk are concordant in showing that with the possible exception of weight, there is no correlation of practical significance between the body type of the sire or the dam and the productive capacity of the daughter in milk, butter-fat or butter-fat percentage.

In a long-term experiment with maize-wheat rotation, no response to zinc application was observed, even after 13 years of cropping though the status of zinc had decreased to a deficient level (0.35 mg/kg; DTPA). A study was, therefore, planned to find the reasons for lack of response, and the zinc fractions in the soil were analysed to assess their contribution to plant growth. All the zinc fractions other than organic zinc decreased as a result of continuous cropping without zinc application. Depletion was from the 0-30 cm layer and mainly from acid-soluble and weakly adsorbed Zn fractions. Applied zinc remained mainly in the 0-30 cm layer as acid soluble and weakly adsorbed Zn pools. All the fractions were strongly related to each other. The acid-soluble zinc fraction contributed 54 % to zinc uptake by the crops. Thus release of zinc from this pool was perhaps the main reason for lack of response to zinc.

Twenty semen samples were collected by means of the artificial vagina from three Friesian and two Dexter bulls. In each sample, the head length and head breadth of spermatozoa which did not take up the nigrosin-eosin stain, and their percentage before and after 72 hr. of preservation in egg-yolk-citrate and egg-yolk-glycine, were studied. The following results were obtained from the study:

1. No significant variation was found in the two measurements of sperm head before and after preservation in E.Y.C.

2. Both the head length and head breadth of spermatozoa preserved in E.Y.G. were significantly less than those before and after preservation in E.Y.C..

3. The change in size of the spermatozoa head in E.Y.G.. dilutor may be due to an alteration in the acrosome.

Laboratory experiments were conducted in PVC columns to study the leaching and transformation of applied urea in sodic soils (Gharachon loam-Aquic Natrustalf and Domeli silty clay loam-Aquic Camborthid) reclaimed by gypsum application and kept submerged for 7 or 14 days after fertilizer application. The effect of different depths of irrigation water (5, 7·5, 10, 20 and 30 cm) on urea leaching was studied in a sandy loam sodic soil. In another experiment, the effect of time interval (0 or 4 days) between urea application and initiation of submergence with distilled water (for 7 or 14 days) was investigated involving two recently reclaimed sodic soils (Gharachon loam and Domeli silty clay loam). The results showed that the extent of urea leaching mainly depended upon soil texture. In Domeli silty clay loam, urea penetrated to 20 cm depth with peaks in concentration at 12·5 cm at both 7 and 14 days of submergence. In Gharachon loam urea-N moved to 25 cm depth after 7 days and to 35 cm after 14 days. In the sandy loam sodic soil peaks of urea-N concentration were observed at 12·5, 22·5 and 27·5 cm depths after infiltration of 5, 7·5 and 10 cm depth of water, respectively. Leaching with 20 and 30 cm depths of water moved urea deeper (below 50 and 70 cm, respectively). In recently reclaimed soils, leaching initiated immediately after fertilizer application displaced urea to slightly deeper layers compared with leaching initiated 4 days after urea application. Leaching may not be an important loss mechanism of urea-N in loam or silty clay loam sodic soils. However, in light-textured sandy loam sodic soils leaching beyond the root zone can be expected to create fertilizer management problems.

Recent amendments to European Economic Community Feed Additives Directive 70/524 have lowered the maximum permitted copper content of pig rations because of concern about the environmental pollution risks that may be caused by land application of slurry containing high copper concentrations. The inclusion of copper compounds in pig feed improves growth rates and food conversion ratios, but 80–90% of dietary copper is excreted (Unwin, 1977), although the concentration in slurry varies widely according to diet and water intake. Repeated applications of pig slurry to grassland may result in copper-induced phytotoxicity and, more importantly, toxicity to grazing livestock, particularly sheep. However, the experimental evidence regarding the accumulation of copper in soil and herbage is inconclusive, and there is some difficulty in identifying ‘safe’ levels, as these vary according to soil type, herbage composition and herbage contamination (Batey, Berryman & Line, 1972; Bremner, 1981). Results are presented here on an experimental investigation into soil and herbage copper contents under three different slurry application rates at two permanent grass sites.

Chemical analyses were carried out on the three main commercial varieties in the Sudan and some wild species of Gossypium. A genome-specific pattern was not found for either the oil content, fatty acids, amino acids or seed index. G. sturtianum differed significantly from the other species in oil content with a substantial amount of unsaturated fatty acids and of the essential amino acids. A breeding programme has been started to incorporate such desirable characters into the commercial varieties.

The effect on palatability of crossing Angus with other beef breeds has been studied. Purebred Angus and Jersey × Angus crosses were significantly more tender and of a higher general acceptability than the Simmental × Angus and Limousin × Angus crosses. The possible cause of tenderness differences amongst the cross-breeds is discussed.

For the purposes of this article the “food capacity” is taken to be the amount of total dry matter consumed when the animal is offered as much as it cares to eat. This has been estimated from the results of a variety of experiments collected by the author for the purpose.

The evidence quoted shows that the food capacity of steers is subject to a nearly uniform acceleration of 40 lb. per month per month from birth up to the age of 12 or 14 months, after which it remains approximately constant. It cannot therefore bear any simple relation to the live weight of the animal.

In the case of steers the average constant rate of consumption was about 18 lb. of total dry matter, per head, per day, throughout the period from 1 to 4 years of age; in the case of milk cows it is probably about twice as great, viz. from 30 to 40 lb.

The food capacity of steers has been much exaggerated by various scientific writers. In Kellner's tables it seems to be implied that the capacity varies as the live weight and that it may be as much as 64 lb. per head per day, i.e. 3½ times as much as was found in the experiments under review.

Ten Scottish Blackface ewes from each of three lines, a line selected for hairiness, a line selected for a fine fleece, and an unselected control, were fleece and skin sampled in April, June, September and December, during their 6J year life-span on the hill.

Fleece weight differed between individuals and between lines, and declined by 4% per year from 1·5 kg at 1 year, to 1·3 kg at 6 years. Fleece grade was inadequate as a method of denning fleece differences between the lines.

The height of the spring ‘rise’ in growth in April differed between years, and between lines, declining 2 mm a year from 26 mm at 1 year. Staple length was greatest in the Hairy group and least in the Fine group (P < 0·05). Growth in length was faster between September and December (autumn) than between April and June (spring). Staple length decreased by 14 mm a year.

The lines differed significantly (P < 0·05) in mean fibre diameter but not in modal fibre diameter. There was a highly significant decrease in diameter from summer to winter, ranging from 20% in the Fine line to 31% in the Hairy line, the greater decrease in the Hairy line being attributed to loss of medulla.

The selection had between 1954 and 1972 changed the S/P follicle ratio of 3·0 in the control to 2·8 in the Hairy line and 3·2 in the Fine line. Most seasonal follicle inactivity occurred in April, December came second, and June invariably had more follicle inactivity than September. The control line had the greatest values of primary follicle inactivity and the Fine least. Among the secondary follicles the Hairy line had most inactivity, and the control line least. Maximum primary fibre medullation occurred in either June or September, and medullation was at a minimum in December or April.

The present communication deals with the results of an inquiry into the possibility of utilizing dried penicillin felt, a by-product of the manufacture of penicillin, in the feeding of livestock. The availability of this by-product on a suitable scale afforded an opportunity of obtaining information about the digestibility and biological value of a mould protein. During the course of the investigation, digestion trials with both sheep and pigs, and a farm-scale feeding trial with bacon pigs, have been carried out.

The carcass characteristics of a total of 43 infertile bulls were oompared with those of 42 steers from five independent trials. In most cases there was no significant difference between the bulls and the steers for dressing percentage, or fleshing index. Bulls were generally found to have greater hide percentages than steers, the difference being very highly significant (P < 0·001) in one of the trials and significant (P < 0·05) in another. Eye musole area expressed relative to caroass weight was greater in the bulls, the difference being significant (P < 0·05) in three of the trials. The depth of fat over the eye musole and the hind to fore-quarter weight ratio were greater in the steer carcasses. Head weights were found to be significantly greater (P < 0·05) and caul and kidney fat weights less (P < 0·05) in bulls than in steers in the one trial where these parameters could be measured.

Carcass composition was estimated by the three-rib sample joint teohnique in four of the trials, and in these the bulls had a greater percentage of bone and muscle, but a lower peroentage of fat than the steers, the differences being significant in most oases. In the fifth trial composition was estimated by half carcass dissection. This, too, showed bulls to have a greater percentage of bone and muscle and a lower percentage of fat, the differences being highly significant (P < 0·01) and very highly significant (P < 0·001) respectively. On a fat-corrected basis the estimated retail value of the carcasses favoured the bulls by about $20.00 each.

The studies, conducted over a range of nutritional conditions, showed that non-castration favoured muscle growth while suppressing fat deposition, and that this advantage was more pronounced when growth rates were high.

The effects of plant population density, defoliation and removal of pods and apical buds on dry matter, nodulation and nitrogen accumulation in field bean (Viciafaba L.) were investigated in the field in 1973 and 1974.

In 1973 seed yield, dry matter and nitrogen accumulation were similar at 50 and 150 plants/m2 while in 1974 40 plants/m2 was significantly different from 80, 120 and 160 plants/m2 which were similar in these attributes. At similar densities, these crops generally had similar leaf areas and nodule weights/m2 during the early pod-filling period while at earlier growth stages leaf area and nodule development were greater at the higher plant population densities. Leaf area and nodule weight per plant were positively correlated as were absolute growth rate per plant and nitrogen assimilation rate per unit weight of nodule.

Substantial leaf removal reduced weight but not the nitrogen assimilation rate of nodules determined from plant nitrogen content. Leaf removal did not significantly reduce dry matter but reduced nitrogen yield by reducing seed yield provided that the removed leaves were accounted for.

Pod removal reduced dry-matter and nitrogen yield as well as nitrogen assimilation rate of nodules. Pod removal, however, substantially increased number and weight of nodules. Most of these late-formed nodules were located on the older parts of the lateral roots. Removal of the shoot apex had minor effects on nitrogen yield but reduced nodulation towards the completion of pod-filling.

Resistance to insects in cow peas was studied in a diallel cross and in a test cross. Number of pods and seed yield under unsprayed conditions, expressed as a percentage of their values under sprayed conditions, were confirmed as reliable characters for the assessment of resistance and as suitable for diallel analysis. Non-allelic interaction was not detected for these ratios despite its presence in yields. Resistance to flower damage by Maruca and resistance to all damage by post-flowering pests were both highly heritable and were controlled polygenically by alleles showing partial dominance.

The test cross was not as informative as the diallel cross in the analysis of the genetic control of resistance in a group of moderately resistant lines, but was useful in selecting the best of these for future crosses. The results from both schemes suggested that resistance should be accumulated by intercrossing resistant lines before attempting to transfer it to agronomically-preferred susceptible lines.

Two systems for integrated weed control in winter wheat based around the combination of herbicides with cultural control have been investigated and compared with conventional practice in experiments between 1993 and 2001. These systems were (a) an overall spray of a reduced herbicide dose followed by spring tine harrow weeding and (b) the combination of herbicide applied over the crop row with a novel vision guided inter-row hoe. The latter required wheat to be established with a wider (22 cm) inter-row spacing than standard (12·5 cm). Experiments over 10 sites/seasons indicated that this increased spacing could be achieved without yield loss. Trials to measure the accuracy of hoe blade lateral positioning using the vision guidance system indicated that error was normally distributed with standard deviation of 12 mm and a bias that could be set to within 1 cm. This performance could be maintained through the normal hoeing period and the crop row location and tracking techniques were robust to moderate weed infestation. In the absence of weeds neither overall harrowing nor inter-row hoeing affected winter wheat yield, 1000-seed weight or specific weight in 12·5 or 22 cm rows. When combined with inter-row hoeing, manually targeted banded applications of fluazolate, pendimethalin or isoproturon reduced grass weed levels and increased yields over untreated controls, though better results were obtained using overall herbicides. However, improvements would be possible with more accurately targeted herbicide applications and more effective inter-row grass weed control. The implications and costs of using such an integrated system are discussed and requirements for future developments identified.

First-harvest, precision-chopped Lolium perenne grass with a dry matter (DM) content of 132·0 g/kg and water-soluble carbohydrate (WSC) and crude protein (CP) contents of 24 g/kg and 106 g/kg DM, respectively, was ensiled in farm scale silos following the addition of formic acid (FA) (2·5 l/t) or molassed sugarbeet pulp (MSBP) (50 kg/t). Mature twin-bearing ewes (n=56) were allocated to one of seven treatments and offered either FA-treated silage or MSBP silage ad libitum. The trial commenced on day 91 of pregnancy, when the ewes were offered FA-treated silage (T1), FA-treated silage+soyabean meal (T2), MSBP silage (T3), MSBP silage+soyabean meal (T4), FA-treated silage+MSBP (T5), FA-treated silage+MSBP+soyabean meal (T6) or FA-treated silage+a barley-based supplement (150 g CP per kg DM) (T7, control). Soyabean meal supplementation was only offered in the last 3 weeks of pregnancy, with the objective of achieving a total CP intake of 220 g/ewe per day. Compared with the FA-treated silage, the MSBP silage had a higher nitrogen content (P<0·01) and a lower neutral detergent fibre (NDF) content, but the two silages did not differ in DM, acid detergent fibre (ADF) or gross energy contents. Silage DM intakes (SDMI) were higher on the MSBP silage-based diets (T3, T4) than for any other treatment (P<0·05). The addition of soyabean meal significantly increased SDMI in T2 in the last week of pregnancy (P<0·05), but there was no response in SDMI to soyabean meal supplementation in any of the other treatments. Ewe liveweight changes (kg) of −0·4, 4·1, 7·8, 10·2, 7·1, 9·6 and 10·8 (S.E.±1·2), body condition score changes of −0·96, −0·59, −0·42, −0·33, −0·37, +0·01 and −0·27 (S.E.±0·1) and total lamb birth weights (kg) of 8·0, 8·7, 9·2, 9·9, 8·6, 8·0 and 10·4 (S.E.±0·5) were recorded for ewes in T1 to T7 respectively.

The effects of white clover mosaic virus infection on the yield of two red clover varieties grown alone and in mixtures with either perennial or hybrid ryegrasses were examined. The spread of this virus within the pure clover plots was rapid. Clover drymatter yields were reduced and these losses were greater in the grass–clover mixtures than in the pure clover plots. Reductions in yield of about 70% were recorded at the first cut in mixtures of Sabtoron and Sabrina. The response of the clover to different levels of virus infection was best described by a negative linear relationship.

Yields of Sabrina hybrid ryegrass increased as the levels of virus infection in the clover increased. This compensated for the losses in yield of the legume, leaving total sward yields unaffected by the virus.