In order to determine whether cereal crops require fertilizer sulphur (S) in areas estimated as receiving < 20 kg S/ha per year from the atmosphere, the effects of applying agricultural gypsum (10, 20, 30, 40, 60 and 80 kg S/ha), ammonium sulphate (24 and 48 kg S/ha) and foliar-applied elemental S (10 kg S/ha) fertilizers were compared with a nil-S control in replicated field experiments at 12 sites in England and Wales during 1987–90. Averaged across all S treatments, significant (P ≤ 0·01) positive yield responses of 0·4 t/ha were obtained in winter barley at three sites in 1990 on sandy soils in Wales (two sites) and in south-west England (one site). There was no yield advantage in applying > 10 kg/ha of S as gypsum at these sites. Yield responses were best predicted by a nitrogen: S concentration ratio ≥ 17:1 in leaf tissue at anthesis and a S concentration of ≤ 0·1% in the grain dry matter at harvest.

Significant increases in total S and sulphate-S concentrations in leaf tissue at anthesis were obtained from increasing the rates of gypsum applied at ten of the sites, but a significant increase in the concentration of S in the grain at harvest was obtained at only one site. There was no difference in effectiveness between gypsum and foliar-applied elemental sulphur when compared at a single rate of 10 kg S/ha. Comparison of the increases in leaf-S status from maximum application rates of ammonium sulphate and gypsum suggested that ammonium sulphate was the more effective Sfertilizer source. The results confirm that S deficiency is starting to appear in cereal crops in England and Wales.

The chlorophyll fluorescence parameters ΔF/Fm′ and Fv′/Fm′, related respectively to the quantum yield of photosynthetic electron transport and to the efficiency of excitation capture by the open centres of photosystem II, have been evaluated as possible indicators of drought tolerance in durum wheat. ΔF/Fm′ and Fv′/Fm′ measurements were carried out on excised leaves, both control and dehydrated, of 25 cultivars. ΔF/Fm′ and Fv′/Fm′ values were obtained at two times after the start of fluorescence measurement: at 14 s, i.e. during the induction curve (ΔF/Fm′14s and Fv′/Fm′14s) and at 200s, i.e. at steady state fluorescence (ΔF/Fm′200s and Fv′/Fm′200s).

In dehydrated leaves a mean significant decrease of 20% (P < 0·001) was observed in ΔF/Fm′14s values. In contrast, no great differences were observed between control and dehydrated leaves with regard to ΔF/Fm′200s, Fv′/Fm′14s and Fv′/Fm′200s.

The percentage decrease of ΔF/Fm′14s after dehydration was correlated with the drought susceptibility index (DSI) of the cultivars, evaluated on a yield basis and a significant correlation (r = 0·72, P < 0·001) was found.

Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of different winter wheat cultivars, halfat flag leaf emergence and halfat ear emergence, in factorial experiments in 1986, 1987 and 1988. There were no clear visual symptoms of S deficiency, but there was evidence from soil analysis, grain S concentration and grain N:S ratio that the crops were marginally deficient in sulphur. Disease severity was generally negligible. Leaf senescence at the end of grain growth was delayed by sulphur in two of the three years, both with and without urea in 1987, but only with urea in 1988. Sulphur, both alone and mixed with urea, increased grain S concentration from early grain growth in 1986 and 1987, but not until the end of grain growth in 1988. Urea alone reduced yield in 1986 and 1987, but mixing S with the urea compensated for this phytotoxic effect. Yield was not significantly increased by S when compared with plots receiving neither urea nor S.

Field experiments were carried out on six sites in eastern Scotland between 1987 and 1989 to determine the effect of nitrogen on the yield, N uptake and grain N concentration of spring barley grown for malting. The effects of fertilizer applications at rates from 0 to 150 kg N ha-1 and the timing of application were studied, using three fertilizer forms: calcium nitrate, ammonium sulphate and ammonium nitrate. Calcium nitrate applications significantly increased grain N concentrations (P < 0·05), and grain yields (P < 0·01 and 0·05) at two sites, above the values obtained with the other fertilizers, but there was no effect at the other sites. Split applications of calcium nitrate increased yields above those from single applications in some treatments at two sites. At low rates, recovery of 15N-labelled fertilizer was greatest when applied as calcium nitrate. Recovery fell at higher rates in calcium nitrate treatments, but rose in ammonium sulphate treatments. Uptake of fertilizer N, during the period of stem elongation in June, was significantly greater (P < 0·05) in the calcium nitrate and ammonium nitrate treatments. Maximum uptake was usually reached by the time of anthesis. Uptake of soil N was not as great during the early sampling periods, but continued up to harvest in most treatments. There was evidence of losses, between anthesis and harvest, of fertilizer N previously taken up by the crop. The uptake of soil N remained constant over the range of fertilizer treatments except with ammonium sulphate, where there was evidence of increased uptake at higher fertilizer rates, possibly due to ‘pool substitution’ of 15N-labelled fertilizer. The variation in soil N uptake between sites was greater than the variation in fertilizer N uptake caused by different forms of fertilizer and different application times.

Bahia grass (Paspalum notatum Flugge) plants were grown in growth chambers at Gif, France, and at Gainesville in Florida, demonstrating that the species is a long-day plant and greatly influenced by light quality during the photosynthetic period. Flowering occurred in all instances when the middle of the dark period was interrupted with red or red + far-red light. With nightly interruptions of farred light, flowering occurred only when a sufficient quantity of far-red was present during the photosynthetic period. Plants grown under short days with nightly interruptions of red, far-red or red + far-red light had less starch accumulation and greater leaf growth and dry weight than plants grown without nightly light interruptions, whatever the light quality during the photosynthetic period. The treatments did not affect the partitioning of assimilates and flowering in the same way.

Nitrate leaching was measured under three pastures – perennial ryegrass and white clover, a herbal ley comprising a mixture of legumes, non-aggressive grasses and deep rooting herbs, and perennial ryegrass fertilized with 400 kg N/ha per year as urea – from 1989 to 1991 at Palmerston North, New Zealand (latitude 40° S). The pastures were regularly mob-grazed by sheep at a stocking rate which varied with the amount of feed available. Drainage was estimated from a daily soil water balance and accumulated over 10 day intervals. Nitrate concentrations in the drainage were measured as the volume-averaged concentrations in the soil solution between 30 and 45 cm depth during these intervals. Although the N applied as fertilizer to the grass was 2·5 times greater than the N estimated to have been fixed by the clover-based pastures, the leaching loss from the former was 6–7 times greater than from the latter. The stocking rate on the grass pasture averaged over each year was only 1·2–1·4 times that on the two clover-based pastures. Leaching from urine patches was estimated to account for 55% of the total N leached from the clover-based pastures, but only 25% of the total leached from the N-fertilized grass.

The amount of NO3-N leached should be related to the cumulative drainage to determine whether the average nitrate concentration exceeds the environmental safety limit of 10 mg NO3-N/1. In 1989, when the total drainage was 215 mm, 21·5 kg N/ha would have had to be leached for the concentration to exceed the limit and none of the pastures did so. In 1990, when the total drainage was 270 mm, the critical amount to be leached was 27 kg N/ha which was exceeded by the Grass + N400, but not by either the Grass-clover (5.8 kg N/ha) or the Herbal ley (7·3 kg N/ha). The utilization of N was more conservative in the clover-based pastures than in the N-fertilized grass.

White clover cultivars Sacramento ladino, Sonja and Aberystwyth S.184 were assessed for dry matter (DM) yields, clover content and herbage quality in monostand and in 50:50 mixtures with grasses under cutting at Truro, Nova Scotia and Charlottetown, Prince Edward Island between 1986 and 1989. Grasses were: orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.) and reed canarygrass (Phalaris arundinacea L.). Dry matter yields ranged from 6158 to 11645 kg/ha and were highest in white clover/orchardgrass and white clover/timothy at Truro, and in white clover/timothy at Charlottetown. Sonja and Aberystwyth S.I84 outperformed Sacramento white clover in herbage DM and clover yield in all years at both locations. First-cut herbage contributed 39 and 29% of total yields at Truro and Charlottetown, respectively. Clover yield was highest in first-cut Sacramento/orchardgrass, but dropped by up to 73% in white clover/timothy associations over a 2-year period. Crude protein ranged from 14·4% in clover/timothy to 23·4% in clover/reed canarygrass and was positively correlated with clover content. It was concluded that choice of clover cultivar as well as grass is an important consideration in maximizing herbage yields and quality in the Atlantic region.

Leaf appearance of contrasting potato cultivars was examined in field experiments at Cambridge, UK, between 1985 and 1990. Three experiments examined the effects of N fertilizer on the appearance and growth of leaves. Four experiments examined leaf appearance over a wide range of planting dates and in two of these experiments different physiological ages of seed were compared.

Linear regression of rate of appearance of main-stem leaves on air temperature indicated a strong dependence of rate of leaf appearance on temperature in the cultivar Maris Piper with a phyllochron of c. 31 K d/leaf but in Estima variation in rate of leaf appearance was only partly explained by differences in air temperature. The phyllochron of main-stem leaves in Estima and Home Guard was shorter for old seed than young seed but there was little effect of seed age in four other cultivars. The phyllochron of main-stem leaves was longer without N fertilizer than with N but the difference in the phyllochron between rates of applied N was small. Leaf appearance on sympodial branches was slower and more variable than on the main-stem. Growth of branches differed between cultivars, particularly with no N fertilizer. In the determinate cultivars Estima and Diana there was restricted growth of branches but in the indeterminate cultivar Cara, significant leaf area was contributed by branches. The duration of leaf appearance and longevity of individual leaves is discussed in relation to N, temperature and cultivar.

Experiments were done during 1990/91 and 1991/92 at Bangalore to estimate the reduction in yield caused by powdery mildew (Erysiphe polygoni DC) on coriander (Coriandrum sativum L.) cultivars differing widely in time to maturity. Powdery mildew resulted in smaller reductions in yield in the early maturing than the late maturing cultivars. Although the results of this study suggest that even expensive control measures can be recommended for managing powdery mildew in late maturing cultivars, because a small increase in the severity of powdery mildew infection may cause a considerable economic loss, they also indicate that such measures may not be economically viable for early maturing cultivars.

Low quality chaffed meadow hay, containing 10·5 g N/kg dry matter (DM), was fed to four artificially reared sambar (tropical) deer (Cervus unicolor) and four red (temperate) deer (Cervus elaphus) confined indoors in metabolism crates at Palmerston North, New Zealand, during March and April 1994. Measurements were made of DM intake (DMI), apparent digestibility, nitrogen (N) retention and the time spent eating and ruminating. Voluntary food intake (VFI), measured over days 7–11, was substantially greater for red deer than for sambar deer (67 v. 36 gDM/kgW0·75/day). Dry matter intake of red deer was then restricted, so that apparent digestibility could be better compared between the two species. Eating and ruminating time/gDMI and chews during eating/gDMI were all greater for sambar deer than for red deer. Apparent digestibility of DM, organic matter (OM) and energy were low (c. 0·42) and not different between deer species. Apparent digestibility of neutral detergent fibre (NDF) and cellulose were highest for red deer, but lignin apparent digestibility was highest for sambar deer. Both deer species lost weight and were in negative N balance. However, despite their lower N intake, sambar deer lost significantly less N and liveweight per day (– 5·6 g and – 118 g) than red deer (– 12·2 g and – 258 g). It was concluded that red deer responded to a diet of low quality roughage by increasing VFI and cellulose digestion, whilst sambar deer responded with a lower VFI but greater chewing activity, improved lignin digestion and better N conservation. Rumen mean retention time should be measured in future experiments with sambar deer and red deer fed on low quality forage diets.

The chewing behaviour of red deer (Cervus elaphus) during eating and the effectiveness of chewing on feed comminution was studied in two experiments. In Expt 1, deer were fed long or chopped lucerne (Medicago sativa) hay, and feed intake and chewing activity were recorded. In Expt 2, the rumen was emptied and test meals of fresh chicory (Cichorium intybus cv. Puna), lotus (Lotus corniculatus cv. Grasslands Goldie), ryegrass (Lolium perenne cv. Ruanui) forage and long lucerne hay were given, chewing activity recorded and the ingested forage quantitatively removed from the rumen. In Expt 1, the chopped hay was eaten more quickly than long hay (11·4 v. 8·3 g dry matter/min), and required fewer chewing bites per g dry matter eaten. In Expt 2, the four forages were consumed at similar rates (mean 4·3 g organic matter/min) and there was no significant difference in the chewing required to consume either total organic matter (OM) or cell wall OM. Deer chewed more quickly when eating lucerne hay than when eating lotus, and it was estimated that a greater number of chewing bites were required to form a bolus of lucerne hay than to form a lotus bolus. The proportion of ingested OM which was comminuted so as to pass a 1 mm sieve (efficiency of chewing) was greater for lotus (0·485) and lucerne hay (0·.518) than for chicory (0·.267). The efficiency of chewing ryegrass (0·.366) was intermediate and not significantly different from any other forage. For all forages, the main effect of chewing during eating appeared to be the release of cell contents, rather than the comminution of cell wall. Physical breakdown to particles which passed a 1 mm screen but were retained on an 0·25 mm screen was low for fresh forages (0·074–0·086) but was slightly higher for lucerne hay (0·127). Deer reduced feed particle size during eating with a similar efficiency to sheep, but were less efficient than goats.

It is suggested that the chewing effort associated with forage consumption by red deer is related to the need to form a bolus. The amount of chewing may be as much influenced by the physical characteristics of the forage (e.g. leaf size and shape) as by its chemical composition, and the extent of comminution during eating may be determined by the processing needed to form a bolus and the resistance of the feed to bolus formation.

A multivariate linear model was developed to evaluate dairy cow body weight (BW) during lactation on a commercial dairy farm. The model was calibrated separately for first, second and greater than second parities, and also for winter and summer calvers, fed a total mixed ration of 65% concentrates. Average weekly BW was predicted using the following variables on a weekly basis: 4% fat-corrected milk (FCM) yield, time of conception (PREG), time from calving (w), initial body weight (1BW) measured within 2 days after calving, and weeks remaining until the end of the calving season (SWR). The ability of the model to predict mean BW along lactations was tested in the same herd following calibration and during the same period. The prediction capacity of the model for average BW of groups of cows was examined on two timescales: (i) time from calving (physiological timescale) and (ii) any time during the year (calendar timescale). Results indicated that predicted mean BW deviated from measured values either by 1–2% with a maximal deviation of c. 5% on the physiological timescale or by up to 2% on the calendar timescale.

The urinary excretions of creatinine, allantoin and total purine derivatives by Merino ewes were compared with predictions based on the assumptions that creatinine excretion scaled to liveweight (the creatinine coefficient) was constant and was not affected by diet. The creatinine coefficient varied between individuals and was found to be affected by diet (P<0·01). As a result, there were systematic deviations (p<0·01) in the predictions of allantoin and total purine derivative excretion. If predictions of purine derivative excretion are to be made for individual animals in the absence of total urine collections, prior determination of individual creatinine coefficients is required and predictions may be confounded by diet effects on creatinine excretion. Predictions for groups on the basis of general relationships between the creatinine coefficient and liveweight may be subject to errors between diets of > 10%.

Sixteen Blackface wether lambs (25–27 kg) were fed for 9 weeks on diets based on either barley (B) or sugarbeet pulp (S), with either a low or high protein content. A constant amount of metabolizable energy (ME) was given at twice maintenance level. At one stage the animals were fed frequently and blood was sampled over a 24 h period. Plasma was assayed for acetate, glucose and insulin. After slaughter, the metabolism of acetate to CO2 and lipid was investigated in perirenal adipocytes in vitro.

Frequent feeding helped to achieve near-steady-state conditions. Carbohydrate source influenced plasma acetate (P < 0·08) but not glucose or insulin. Level of protein in the diet influenced plasma acetate, higher concentrations of acetate were associated with lower levels of protein (P < 0·01). Acetate oxidation and incorporation into lipid was influenced by the concentrations of acetate, glucose and insulin in the incubation media (P < 0·001). Acetate oxidation was influenced by carbohydrate source (P < 0·05), whereas level of protein in the diet affected acetate incorporation into lipid (P < 0·05).

These results show how the balance of nutrients provided to a ruminant for metabolism may influence selected plasma parameters and the metabolism of acetate by adipose tissue, which may help to explain the reduced efficiency of ME utilization from more fibrous diets.

The badger culling component of the cattle tuberculosis (TB) eradication scheme has been controversial from the outset. Despite the apparent complexity of the issue, and ever expanding literature, it is perhaps worth highlighting several basic key aspects in need of an urgent reappraisal.