The use of cactus cladodes in animal feed is well-established in semi-arid areas. The cactus Nopalea cochenillifera (L.) Salm-Dyck cladodes (Nopalea) have high acceptability amongst dairy cows and are resistant to carmine cochineal insects (Dactylopius opuntiae Cockerell), a problem in semi-arid regions, but in regions of prolonged drought, it has lower productivity compared with the cactus Opuntia stricta (Haw.) Haw cladodes (Opuntia), which is also resistant to the insect. The objective of the current study was to evaluate the intake and content of digestible material of dry matter (DM) and its components, feeding behaviour, microbial protein synthesis, nitrogen balance, blood parameters, performance and milk composition of Holstein cows fed a control diet, containing either Nopalea or Opuntia associated with different concentrate levels (225, 275, 325 and 375 g/kg). Ten cows with an initial average milk production of 20 ± 2.1 kg/day were distributed into a double 5 × 5 Latin square design. Diets containing 775 g roughage/kg and 225 g concentrate/kg promoted similar responses to the analysed variables regardless of the cactus cladode used, except for digestibility of neutral detergent fibre. Diets containing higher proportions of concentrate (325 and 375 g/kg) promoted greater DM intake and 3.5% fat-corrected milk yield. The diet containing Opuntia at 775:225 g/kg roughage:concentrate proportion is as effective as the control diet for Holstein cows producing 20 kg of milk/day. To promote greater milk production, higher proportions of concentrate should be added to diets using Opuntia.

The suitability of stained food and [103Ru]phenanthroline-treated food as markers for measuring dietary retention time was examined in sheep. The digestibility of oat husk, assessed by incubation of samples contained in nylon bags in the rumen, was greatly depressed by staining with brilliant green, and slightly depressed by basic fuschsin. The latter effect appeared largely to be due to boiling rather than the stain itself.

When milled hay treated with both basic fuschsin and [103Ru]phenanthroline was introduced into the rumen, the mean retention time estimated with the stain was about 40% longer than that estimated with [103Ru]phenanthroline.

1. Over 3 years, different levels of first winter nutrition were imposed on groups of North and South Country Cheviot ewe hoggs (lambs). In 1956–57, three levels, high, mid and low, were fed indoors. In 1957-58, only two levels, high and mid, were fed indoors, with the low level being represented by hill wintering. In 1958–59, two levels were represented by away wintering and hill wintering.

2. Low-plane feeding was designed to simulate average hill wintering, creating a 10% loss in live weight. Mid-plane feeding was designed to maintain live weight at approximately the same level throughout the winter. High-plane feeding was designed to produce a live-weight gain of 15–20% in 1956–57 and the maximum gain possible in 1957–58.

A pot experiment studied the effect of gypsum and green manuring on equilibrium soil solution pH, pE, Mn concentration and Mn equilibrium in three sodic soils. Submergence decreased soil solution pH and increased Mn concentration in all the soils. Addition of gypsum with green manure further decreased soil solution pH and increased Mn concentration. Maximum Mn concentration in all the treatments was observed at 4 weeks of submergence in Kaheru soil and at 6 weeks of submergence in Jagjitpur and Langrian soil followed by a decline up to 12 weeks. In spite of wide variations in pH, pE and Mn concentration in soil solutions, the solubility of Mn after peak values appeared to be mainly controlled by the MnC03-Mn2+ system irrespective of the treatments, and the Mn2O3-Mn3O4 system appeared to operate after 2 weeks of submergence in the control and gypsum-treated soils.

In a previous paper(1) reference was made to the subject of seed disinfection, in particular to an investigation on disinfectant dusts containing mercury. It was shown that by the use of certain of these dusts the common seed-borne diseases of cereals (excluding the loose smuts of barley and wheat) could be controlled. The present observations record further work, chiefly greenhouse and field studies, that has been done on green peas. This crop would appear to be of increasing economic importance, since in the past ten years the acreage devoted to it has increased by approximately 49 per cent. Its successful cultivation is often much influenced by climatic and soil conditions, particularly during the first few weeks after sowing. If adverse weather conditions follow, poor germination may result although the seed sown may have been viable and not necessarily diseased. Failures of such a type are usually associated with the rotting of the ungerminated seed in the soil, but from the same bulks, samples sown under more favourable conditions may germinate well and produce a satisfactory crop. Ogilvie (2,3,4) finds that in the Western Advisory province Ascochyta Pisi and Mycosphaerella pinodes are two causes of the early failure of pea plants, and that “pea sickness” is associated with a strain of the eelworm Heterodera schachtii and with foot-rot caused by various species of Fusarium. Premature dying-off of the plants is accompanied sometimes with Heterodera schachtii and foot-rot and sometimes with foot-rot alone.

This article attempts to discuss the relations between the nitrogen sources in data from a large field experiment in which various levels of fertilizer nitrogen were applied to various grass mixtures in the presence and absence of white clover. It was seen that a number of effects occurred, among them the strong depression of clover nitrogen by fertilizer nitrogen (to the extent that equations predicting their contribution to grass nitrogen could not be produced directly by multiple regression but had to be constructed separately), a further apparent depression of clover nitrogen transfer effectiveness, a more significant relationship between grass nitrogen increase and the previous year's clover nitrogen than the current year's clover nitrogen, and apparent competition between grass and clover despite the latter's contribution to increased grass yield.

As some of the effects are counteractive, in each comparison made a balance appears to exist. This varies between sites and years in such a way that although the variation in grass nitrogen is always largely dependent on the clover and fertilizer nitrogen the relations are not consistent as shown by the mathematical equation representing them, and cannot be extrapolated or predicted for other sites. It is suggested that a mathematical model be constructed to simulate such an interactive system and that predictions when necessary be made using this, rather than using simple equations.

A study was carried out on the post-lambing normal and abnormal maternal behaviour of sheep using 237 Barki ewes of 2, 3, 4 and 5 years of age and their newborn single lambs.

Normal maternal behaviour was observed in 64·5% of the ewes as they immediately recognized their lambs after birth, readily accepted them and started grooming and helping them to suckle. The overall average time-interval from parturition until ewes stood, started cleaning and until lambs started suckling was 2·9 ± 0·5, 4·0 ± 0·8 and 20·5 ± 2·0 min respectively. The 2-year-old ewes and the ewes weighing 30 kg and less took longer to accept and nurse their new-born lambs than older and heavier ones.

Post-lambing abnormal maternal behaviour was observed in 30·4% of the ewes, among which 43·1, 45·8 and 11·1% were classed as fair, poor and very poor mothers respectively. Fair mothers failed to nurse their lambs, poor mothers deserted them and very poor mothers permanently deserted their lambs and were aggressive to them. The post-lambing abnormal maternal behaviour was more frequent among 2-year-old maiden ewes than older ewes.

(1) The colorimetric method is unsuited to the examination of heavy, alkaline soils owing to the turbidity of the suspension.

(2) Where the nature of the suspension permits of colorimetric determinations being made, they agree with those obtained electrometrically: with the latter method practically identical results are obtained using soil-water mixtures or moderately clear extracts.

(3) No disturbing effect is likely to be introduced by amounts of nitrate up to 500 parts per million of soil.

(4) Owing to the effect on the pH of a soil suspension caused by varying the proportion of water and time of extraction, these conditions should be fixed for routine work. We have found 1 hour's extraction with 5 parts of water satisfactory.

(5) On account of the amphoteric or buffer nature of clay, soil shifts the reaction of acids and alkalis in the direction of neutrality.

(6) The effect of sodium salts on a soil is to displace aluminium and so reduce alkalinity: the residual soil after leaching is found to be more alkaline.

(7) The effect of drying alkaline soil is to cause the pH of the extract to be lower than that obtained from the undried soil. If however the time of extraction is prolonged, the differences disappear almost entirely.

The technique of visual appraisal of intact sides of beef was used on most of the carcasses previously described in Parts I and II of this series. Tests of discrimination and consistency were carried out for each of the judges taking part, and their assessments were compared with the results of subsequent dissection of the carcasses.

It was found that visual appraisal of the subcutaneous fat content of a carcass was very good, especially with the aid of photographic standards, though a curious tendency to match the standards consistently to carcasses of a higher proportion of fat than those used for the photographs themselves was apparent. This did not materially affect the use that can be made of visual judgements in predicting fat content and it was found that expert judgement alone is capable of predictive accuracy roughly equal to that obtained from simple measurements, though not as good as that obtained by partial dissection, as described in Part II. Equations are given for the prediction of carcass composition, using visual appraisal in combination with other variables.

The appraisal of conformation was not so successful; reasons for this are advanced, and suggestions made for future improvement.

The efficiency of nitrogen fertilizer use is as low as 0·30–0·35 in most agricultural practices due to losses to the natural environment in many ways. Ammonia (NH3) volatilization is important in paddy rice fields. The present study investigated the effect of a surface film-forming material (SFFM) on NH3 volatilization from a paddy rice field, by model estimation using parameters from evaporative pan experiments. The modified Jayaweera–Mikkelsen (J-M) ammonia volatilization model was employed to simulate and elucidate the effect of SFFM in reducing ammonia volatilization from paddy fields. A parameter of kf value in the J–M modified model was introduced to represent the resistance of NH3 volatilization loss from SFFM. The simulated data fitted well with the prediction of the J–M modified model and field observations. The modified J–M model is suitable for screening and verifying the new SFFM, and merits further study.

The daily intake of dry matter by zebu steers between 400 and 600 lb. live weight when fed hay and hay-concentrate mixture was investigated and found to be 2·0–2·2% of body weight.

Preliminary results of the nutritional values of Rhodes grass and Star grass hays are discussed and these suggest that the local zebu cattle require less starch equivalent for maintenance than do European cattle in temperate climates.

Two trials were conducted to measure the herbage intake of South Devon cross calves suckling Hereford × Friesian cows and to test the validity of applying the relationships established between milk and herbage intake and milk intake and live-weight gain for artificially fed calves to suckled calves. In Expt 1 the milk and herbage intakes of eight calves were monitored. Their average milk consumption was 2250 kg and their growth rate was 1·14 kg/day. Both milk consumption and growth rate were higher than those recorded in other studies with artificially-reared calves. Nevertheless, it was possible to predict the herbage intake and growth rate of the calves from the relationship previously established for artificially reared calves. The nutrition of cows in Expt 2 was manipulated to induce changes in milk production and the consequent effect on the herbage intake of their calves assessed. Milk consumption was at a lower level and herbage intakes fell within the expected range. Herbage intake also responded to changes in the milk production of the cows. The observed herbage intakes and live-weight gains were similar to those predicted from previously established relationships with artificially fed calves.

The environment, design and methods of this 2-year Kedong grazing trial in the Rift Valley of Kenya were described in Part I.

Crude protein of grasses varied seasonally, usually between 3 and 6 %, while most shrubs and herbs, leguminous and non-leguminous, were in the 10–20 % range, although contributing only about 3 % by weight of the total sward, excluding large bushes and trees. Steers selected herbage of 2–3 % units higher C. P., more Themeda leaf and more herbs than the sward average. Treatment effects on sward and diet C. P., and their relationships, were generally small and inconsistent. Higher C. P. in post-burning ro-growth declined to average levels after 2–3 months, except when grazed at one steer to 4–4 acres, rotational (i.e. 1–5 acres available). At this pressure available herbage fell below 1000 lb D.M./acre (1120 kg/ha). In all other treatments 2500–4500 lb D.M./acre wore available at all times. Estimated herbage production varied from almost nil to 320 lb D. M./acre/month. Burning removed 3000 lb D.M./acre. Relationships between herbage C. P., diet c. p. (oesophageal fistula samples) and faeces N were determined.

Progeny tests for resistance to potato leafroll virus using true seedlings in a glasshouse in Scotland ranked progenies by the percentages of seedlings showing primary symptoms, in accordance with the known phenotypes of their parents. Symptoms were more obvious in seedlings grown under sodium lamps than in those grown under fluorescent strip lights. These glasshouse seedling progeny tests were then evaluated by comparing them with field clonal trials. The progeny tests were found to identify effectively those progenies most resistant to potato leafroll virus but were not effective for identifying the most resistant clones within progenies.

Seven out of ten chemical extractants were found to be promising for the evaluation of critical limit and response of wheat grown in pots to Cu application in Sub-Himalayan hill and forest soils of recent alluvium origin. The critical limit of available Cu using DTPA-CaCl2(pH 7·3), DTPA-NH4HCO3 (pH 7·6), EDTA-(NH4)2CO3 of pH 8·6, EDTANH4OAc (pH 7·0), n-NH4OAC (pH 7·0), n-NH4OAC (pH 4·8) and n-Mg(NO3)2 of pH 5·9, was 0·66, 1·73, 1·95, 1·38, 0·13, 0·20 and 0·47 mg Cu/kg, respectively. The amount of Cu extracted by these extractants was positively and significantly correlated with ‘Bray's percent yield’. Apart from ‘Bray's per cent yield’, the Cu extracted by most of these extractants was positively and significantly correlated with Cu concentration in the third leaf of wheat, Cu uptake by wheat shoots and organic carbon content of the soils, and negatively correlated with soil pH but the value of this relationship did not approach the 5% level of significance. n-Mg(NO3)2 of pH6·7, N-NH4NO3 and 0·1 n-HCl were found to be ineffective extractants. Among chelating agents, DTPA-CaCl2 was found to be most and EDTA-NH4OAc least promising extractant. N-NH4OAC (pH 4·8) proved to be better than N-NH4OAC (pH 7·0). The critical Cu concentration in the third leaf of wheat was 8·8 mg Cu/kg, below which responses in dry weight to Cu application may be expected.

During spring, perennial ryegrass tillers change from vegetative to reproductive growth in response to photoperiod and undergo irreversible morphological changes. The effect of latitude and meteorological factors on the timing of reproductive initiation and ear emergence (EE) were measured in the field on 40 vernalized spaced plants for each of eight cultivars. The measurements were made at two latitudes in Ireland (Moorepark 52°N, Crossnacreevy 54°N). There was a significant effect of site and cultivar on all the variables measured. Cultivar initiation responded to a specific photoperiod but detection through apical development incurred a small variation due to growing conditions affecting the time taken for a visible change in apical morphology to occur. When converted from photoperiod to initiation date this variance was minimal (±6 min). Timing of EE was dependent on growing conditions not photoperiod and so was specific to the studied conditions. As cultivar rank order for EE date was largely retained, there was a very strong correlation with published UK Plant Breeders Rights (PBR) heading dates for these cultivars, which in turn had a strong relationship with the ear initiation (EI) dates (R2=0·95). The latter relationship was sufficiently robust to allow estimation of photoperiod for any cultivar on the EU Common Catalogue based on its published heading date from Crossnacreevy, where the UK PBR trials are conducted. As photoperiod can be converted to calendar date by reference to latitude, this relationship can also be used to estimate the EI date for sites at latitudes other than those in the current study.

The nutritive value of a new forage pea (Pisum arvense), commercially available as ‘Rosakrone’, was assessed by feeding the seeds in ground form to laying hens as a supplementary source of protein in diets based on mixed cereals. Like other pulse seeds they were found to be relatively deficient in methionine. The effect of this on egg production was overcome by adding synthetic methionine to the diet.

However, there was also present an anti-nutritive factor, similar in action to that found in other pulse seeds, which caused live-weight loss and reduced the rate of lay to about 0·85 of normal in 20 weeks with 40% pea meal in the diet. This anti-nutritive factor appeared to be heat stable.

The possibility of using sustained lactation as a maternal character for the enhancement of lamb growth has been suggested by Doney & Peart (1976). Horák & Jakubec (1964) shows that Improved Valachian ewes had a relatively sustained pattern of lactation when lambs were suckled. This breed was developed by cross-breeding between the Texel breed and the original Valachian, a coarsewoolled, mountain breed used to produce milk for cheese. The process of breed development has been described by Laurinčík (1964).

1. Regression equations for the ratio of organic matter (O.M.) feed intake to O.M. faecal output on faecal N%, and the N% in the O.M. intake on faecal N% were established over a 52-week period by feeding caged Corriedale wethers on pasture cut from a Wimmera rye-grass (Lolium rigidum Gaud.), subterranean clover (Trifolium subterraneum) sward in a Mediterranean-type environment.

2. The regression equations and their application to grazing sheep together with the relation between O.M. intake and faecal N, are discussed.