Concentrations of potentially indigestible cellulose (PIC) and acid insoluble ash (AIA) were determined in samples of feed and faeces in a study to determine their value as internal markers. PIC and AIA were then used to predict the organic-matter digestibilities (OMD) of samples of perennial ryegrass (Lolium perenne) and lucerne (Medicago sativa)of known OMD which had been determined using wether sheep. The mean values for OMD (%) measured in vivo were 67·2 and 62·8 for ryegrass and 58·0 and 55·8 for lucerne at intakes of 15 and 25 g D.M./kg live weight, respectively.

The in vitro digestibility technique, using rumen liquor, gave OMD values of 69·5 and 57·4 for ryegrass and lucerne which are in close agreement with the in vivo values at the lower level of intake.

The mean differences between OMD measured in vivo and that estimated using PIC were: -1·1 (± 0·65) and -1·6 (± 0·46) percentage units for ryegrass and lucerne respectively, and using AIA were: -1·4 (± 0·57) and -3·5 (± 1·61).

For the two feeds tested, OMD was predicted more precisely by PIC than by AIA or the in vitro digestibility technique. However, the PIC technique required the use of rumen-fistulated animals and 10 days to digest samples of faeces; this may make the technique impractical if large numbers of determinations of PIC are required.

A multifactorial experiment sown to winter wheat cv. Hustler in autumn 1978 tested the effects of combinations of the following eight factors, each at two levels: drill type, sowing date, amount of nitrogen, division of nitrogen, irrigation, autumn pesticide (aldicarb), summer aphicide (pirimicarb), and fungicide (carbendazim, maneb and tridemorph).

The mean grain yield of all plots was 9·7 t/ha and the best eight-plot treatment mean was 11·3 t/ha. The factors that had the greatest effect on yield were aphicide and fungicide, mainly from the control of Metopolophium dirhodum and Septoria spp. respectively. Both factors increased grain size and their effects were more than additive and greater with 250 than with 160 kg N/ha. Aphicide and fungicide also temporarily decreased the numbers of microbes on the developing ears. Autumn pesticide gave good control of aphids in the winter and some control in the summer: it also decreased nematode populations and slightly increased yields.

Precision sowing compared with random distribution of seeds along the row had little effect on growth or yield. Sowing on 21 September compared with 13 October greatly increased growth early in the season but had less effect after anthesis; it was the only factor that increased yield when aphicide and fungicide were applied. There was negligible infection by barley yellow dwarf virus in crops sown on either date. The amount and division of N fertilizer affected N uptake early in the season and had small effects on the production and survival of tillers. Three N applications instead of one slightly increased grain yields but did not affect total N uptake by grains plus straw, which averaged 190 kg N/ha. The larger amount of N always increased N uptake but decreased yield in the absence of aphicide and fungicide. Irrigation slightly decreased yield despite prolonging the duration of green leaf area.

One hundred and forty different varieties of grass, from seven species, were harvested in spring, in 1, 2 or 3 years, at a D-value of 67 and dried at 25 °C. Moisture content was determined every 3 h for at least the first 48 h and less frequently thereafter until the grass was about dry enough to store as hay.

Rate of drying was in the order tall fescue > Italian ryegrass = meadow fescue > timothy = cocksfoot > perennial and hybrid ryegrass. The perennial and hybrid ryegrass took twice as long to dry as did tall fescue. Tetraploid varieties of the ryegrasses took appreciably longer to dry than the diploid varieties. Apart from this there were some differences between varieties within a species in rate of drying. Differences in moisture content at cutting, in the proportion of leaf blade and in the number of leaf sheaths per ‘stem’ may have accounted for some of the differences between species and varieties in rate of drying. Further research is suggested.

Grain growth and final weight per grain were measured in 12 genotypes of spring barley, the parents and progeny of two six-row × two-row crosses. Weight of carpels or grains from node 10 on the main shoot ear was measured from shortly after meiosis until grains were at maximum dry weight. Similar measurements were made at representative node positions along the ear of Proctor and of Midas spring barley cultivars.

From about 10 days after anthesis grains grew at a constant rate for about 3 weeks. Amongst genotypes growth rate of the median grain ranged from 1·4 to 2'2 mg/day and there was a very highly significant positive correlation between growth rate and final grain weight. A similar relationship was found among grain positions on the ear. For about 10 days after anthesis growth was exponential and although relative growth rate did not differ between genotypes or grain positions there was a highly significant difference between caryopsis weights during this phase. There were significant correlations between final grain weight and carpel weight at anthesis and between final grain weight and husk weight at anthesis. In the period between meiosis and anthesis growth was exponential and the relative growth rate did not differ between genotypes or node positions on the ear. There were significant differences between carpel weights during this phase. Carpel weight at anthesis and carpel linear dimensions at meiosis were correlated.

These data suggest that the initial size of carpel is an important factor in determining growth rate and potential grain weight. Potential grain size in barley may be determined by physical limitations imposed by the lemma and palea or may be causally related to the size of the carpel. The relative size of the carpel is determined by the time of meiosis and potential size may also be affected by pre-anthesis conditions.

Digestibility trials were carried out using wether sheep, to determine the organicmatter digestibility of several forages. Acid detergent fibre (ADF) was isolated from samples of feed and faeces, incubated in buffered cellulase solution, and the ash-free residue remaining (IADF) was used as an internal marker to estimate the organicmatter digestibility (OMD) of the feeds. Estimates of the OMD value of the samples were also made using the standard in vitro digestibility technique.

IADF had reached a constant value after incubation for 4–5·5 days and predicted OMD more precisely than the in vitro digestibility technique.

It is concluded that IADF is a suitable internal marker and predicts OMD well. However, more work is required to test this technique over a wider range of herbage species and digestibilities.

Twenty-four Friesian cattle classed as large, medium or small and from 776 to 163 kg initial live weight (LW) were grazed over two successive 8-week periods. Two stocking rates were imposed and there were four replicates. Trios of animals, including one of each size, grazed in each paddock. Cattle changed stocking rate in mid-season. Herbage intake, live-weight gain and grazing behaviour were recorded.

The stocking rates resulted in large differences in herbage allowance and consequent differences in intake, live-weight gain and grazing behaviour. The large cattle were least able to compensate for the higher stocking rate by increasing grazing time or frequency of biting. Average herbage organic-matter (OM) intakes ranged from 13 g OM/kg LW for large animals to 28 g OM/kg LW for the small animals.

The digestibility and rumen metabolism of diets containing as 50% of their organic matter (OM), cotton straw (CS) untreated, treated with sodium hydroxide and treated with ozone, were studied in sheep cannulated in the rumen and at the duodenum with simple cannulae. The concentration of total volatile fatty acids (VFA) in the rumen of sheep given the ozone and NaOH treatments was higher than in the untreated diet; however, the VFA profiles were not different. The rumen dehydrogenase activity, suggested to reflect general microbial activity, was higher by 83 and 81% in the ozone and NaOH treatments respectively, than in the untreated.

Apparent digestibility of organic matter in the ozone-treated diet was 74·6%; 1·25 and 1·17 times higher than in the untreated and NaOH-treated diets respectively. The calculated values for organic matter and cell-wall digestibilities of the cotton straw in the complete diets were: 30·0, 20·0; 60·8, 60·0; and 39·6, 39·7%, respectively, for the untreated, ozone and NaOH-treated cotton straw. Nitrogen metabolism was not impaired by the presence of formic acid in the ozonated cotton straw; the apparent absorption of N from the intestine and the apparent digestibility of N were higher in the ozonetreated diet than in the untreated or NaOH-treated diet.

The proportion of organic matter and cell walls digested in the rumen was higher in the NaOH and ozone treatments than in the untreated, and the possible reasons for that are discussed. A positive relationship was found between cell-wall digestion in the rumen (% of intake) and the rate of passage (% per h) of particulate matter from the rumen. The interpretation of this relationship is discussed in general and in view of the results of the present study.

The effect of pesticides on nitrogenase activity in rhizosphere soil from rice fields was investigated. The differential response of insecticides on nitrogenase depended on the method of field application. Results also showed that the differential response to the pesticides of. specific groups of nitrogen-fixing micro-organisms depended upon the method of application.

Soil incorporation of carbofuran stimulated the rhizosphere nitrogenase, while endosulfan and hexachlorocyclohexane inhibited it. Carbofuran and hexachlorocyclohexane stimulated nitrogenase when applied to the standing water. Seedling root dips of isofenphos stimulated nitrogenase, while endosulfan, BPMC and carbaryl showed a variable effect. Quinalphos inhibited nitrogenase irrespective of method of application.

The effect of nitrogen and sulphur application and seed inoculation on the yield of beans (Vicia faba) was studied at two locations in 1979–80 and 1980–1. Nitrogen was applied at flowering, whereas sulphur was applied as foliar applications in elemental form, several times during the growth cycle of plants or only once at four different growth stages. Results showed high and significant increases in yield, particularly when the three treatments were combined. Results additionally suggested that a single application of sulphur at 45 days after emergence was as effective as four separate applications.

The digestibility of cell wall (CW) monosaccharides of diets containing as 50 % of their OM, untreated, sodium hydroxide and ozone-treated cotton straw (CS), was studied in sheep cannulated in the rumen and at the duodenum with simple cannulae.

CS contributed the major part of the dietary cell-wall glucose, xylose and uronic acid in the three diets. The digestibility of the diets' CW glucose was 38·2, 66·6 and 50·2 % for the untreated, ozone and NaOH-treated CS-diets, respectively. Ozone and NaOH treatments significantly increased the digestibility of cotton straw CW glucose by 108 and 42%, respectively. The highest digestibility of CW xylose in the whole diet was obtained in the NaOH treatment: 43·4% as compared with 19·1 and 31·2% in the untreated and ozone-treated diets. The calculated values of CW xylose digestibility in CS were lower than those of CW glucose. Ozone remarkably increased the degradation of CW uronic acids. The calculated value for ozonated CS was 68·7%, 4·09 and 1·47 times higher than in the untreated and NaOH-treated CS.

Irrespective of diet, the digestibilities of the minor CW sugars, i.e. arabinose, galactose and mannose, were high, and their degradation was largely completed in the rumen. The contribution of the hindgut flora was expressed mainly in degrading the residues of the potentially digestible CW glucose and CW xylose.

The digestibility values of ADF-cellulose and those of CW glucose were compatible, whereas those of hemicellulose (determined as NDF-ADF) and CW non-glucose polysaccharides (NGP) were clearly different. The digestibility of NGP was 16·8, 36·6 and 43·2% for the untreated, ozone and NaOH-treated CS, respectively. It is suggested that those values more closely represent the digestibility of the ‘true hemicellulose’ fraction.

Accessions of green and dry-podded Phaseolus vulgaris beans were tested for resistance to seven isolates of bean yellow mosaic virus (BYMV) originating from a wide geographical area. Based on their level of resistance, the beans could be divided into four groups, (i) accessions with a high level of resistance to most BYMV isolates; (ii) accessions containing previously known sources of resistance in germplasm derived from the cv. Great Northern, which were mainly susceptible to the BOS 25 isolate, but had high levels of resistance to most other isolates; (iii) and (iv) groups showing increasing levels of susceptibility with the accession Red Mexican (common) the most susceptible bean tested. The seven BYMV isolates induced distinct reactions when inoculated to arange of plant species, indicating that they possessed different pathogenicity genes.

Bunaji and Sokoto Gudali breeds of cattle were fattened and slaughtered at live weights of 250, 300 or 350 kg. After the carcasses were jointed into commercial cuts, the joints of the left side were dissected into lean, bone and fat. Dressing percentage was significantly higher in Bunaji carcasses (52·5%) than in Sokoto Gudali carcasses (50·3%). The lean percentage was nearly constant at 68·69% at all slaughter weights whereas fat percentage increased from 10·3 at 250 kg to 14·5 at 350 kg. Bone percentage was inversely related to fat percentage. The relative growth coefficients of muscle and fat were 1·28 and 1·80, whereas that of bone was 0·59. Significant changes in proportion of carcass parts and tissues were observed with increased slaughter weight. The proportion of hind decreased and that of back and belly increased, while chuck and shank remained relatively unchanged. Lean percentage was relatively unchanged by slaughter weight in all carcass parts except the chuck where it increased. The greatest increase in fat percentage was in the belly (7·6%) followed in decreasing order by the back (5·4%), shank (4·9%), hind (3·0%) and chuck (1·8%). The breeds did not differ in any of the traits except dressing percentage.

In Expt 1, four groups of seven hypocupraemic ewes were repleted with a semipurified diet containing 7·2 mg Cu, 3·5 gS and 0·5, 2·5, 4·5 or 8·5 mg Mo/kg D.M. as ammonium molybdate for 65 days. The first increment in Mo caused the largest reduction in plasma Cu repletion and the second completely inhibited repletion but the final increment led to a partial recovery. The highest Mo level caused marked increases in plasma Mo and reduced rumen sulphide concentrations.

In Expt 2, five groups of four hypocupraemic ewes were repleted with hays containing 7–8 mg Cu, 3–3·4 g S and 0·4, 2·8, 4·3, 14·2 or 18·7 mg Mo/kg D.M. for 21 days. The hays were made in June from pasture sprayed earlier with 0–800 g Mo/ha as sodium molybdate. Qualitatively the changes in plasma Cu distribution and Mo content showed the same curvature with increases in dietary Mo as those in Expt 1.

In Expt 3, four groups of five hypocupraemic ewes were repleted on pastures which had received a spring foliar dressing of 0–800 g Mo/ha. Herbage in the four plots was grazed in July, when it contained 0·7, 3·5, 5·9 or 12·4 mg Mo, 6'4 mg Cu and 2·7 g S/kg D.M. and again in September. Quadratic responses to Mo were demonstrated on both occasions, but, for a given Mo level, responses in caeruloplasmin synthesis were much lower than in Expt 2.

It is concluded that Cu absorption is inhibited most by 4–6 mg Mo/kg D.M. and that inhibition of S2- production at higher Mo levels may give rise to a recovery in Cu absorption. Semi-purified diets give responses which lie roughly between those for fresh herbage and hay.

Bean cultivars Cargamanto (CIAT P590, indeterminate climbing, Type IV) and Puebla 152 (CIAT P498, indeterminate large vine, Type III) were grown at 20 and 60plants/m2 at two locations in Colombia; a cool, high rainfall, mountainous area (Popayan) and a hot, medium rainfall, valley (Palmira). The crop growth period was compressed and P590 failed to flower at Palmira.where plant shoot weights tended to be higher and root weights lower than at Popayan.

Midday soil temperatures at 10 cm averaged 7·8 °C lower and N2(C2H2) fixation rate and nodule fresh weight over ten-fold higher at Popayan than at Palmira. Increasing the plant population density increased yield but reduced seed weight per plant and the fresh weight of all other plant parts, with shoots more severely affected than roots. Density had little effect on carbohydrate concentration or N2(C2H2) fixation per plant. The cultivars accumulated carbohydrates in different amounts but had similar rates of N2(C2H2) fixation. Concentrations of ethanol insoluble carbohydrates were several times higher in all plant parts at Popayan. Soluble carbohydrates showed similar, but smaller, differences.

Drinking regimes of Bedouin goats affect their feeding behaviour and the ruminal environmental conditions, as expressed by changes in osmotic pressure as well as in pH of the rumen content. The osmotic concentration of the rumen content of a goat drinking once daily was 330 m-osmole/kg just before drinking. After water deprivation for 4 days, the osmotic concentration reached 360 m-osmole/kg and, immediately after excessive drinking, decreased to 82 m-osmole/kg. After a short while, the osmotic concentration increased to 300 m-osmole/kg and after 13 h reached the peak of 440 mosmole/kg, mainly owing to the release of degradation products. The pH was also affected by food consumption. Just prior to drinking, the pH in the rumen of dehydrated goats was 6·9. It decreased to 6·0 after excessive drinking and feeding. Later, it ranged between 6·4 and 7·1.

Most of the micro-organisms in the rumen are attached to the fibres fraction. No difference could be observed in direct bacterial counts in the fluid fraction between dehydrated and goats drinking daily. However, the number of protozoa was reduced in dehydrated goats, especially after excessive drinking, as some species of protozoa seem to explode in a hypo-osmotic ambient.

The fermentation capacity of the fibres fraction was higher than that of the fluid fraction, indicating also the presence of more micro-organisms in the fibres. In addition, the osmotic changes occurring during the dehydration-rehydration cycles had no significant effect on fermentation capability of the rumen micro-organisms.

At a low osmotic concentration in an NaCl deficient ambient, there was some decrease in fermentation rate, but this could be nullified with the addition of NaCl, which is required for microbial activity. The decrease in fermentation rate is not due to its effect on the osmotic concentration. The micro-organisms in the fibres fraction were found to be less affected by NaCl deficiency in the ambient medium.

Twenty-seven Hereford weaner steers (mean age 11 months, and live weight 142±17 kg) were used to study the effect of supplementation of an energy-rich grain (sorghum), and/or a protein meal on the live-weight change of cattle on a basal diet of low-quality grass hay over 48 days (Expt 1). The basal hay had an estimated energy value of 6·2 MJ metabolizable energy (ME)/kg dry matter (D.M.) and a nitrogen content of 6·2 g/kg D.M. Corresponding values for the sorghum supplement were 12·4 and 14·4, and for the protein meal 9·6 and 65. The daily rates of supplementation in Expt 1 were (g/head) 0 (nil), 600 (P1) or 1200 (P2) of protein meal pellets or 0 (nil), 560 (S1) or 1120 (S2) of sorghum and all combinations of P1 or P2 with S1 or S2. The carry-over effect of such supplementation on subsequent growth was recorded in Expt 2 when the steers grazed a kikuyu grass pasture for 100 days.

In Expt 1, organic-matter intake of hay (HOMI) was increased (P < 0·01) by protein but decreased (P < 0·01) by the sorghum supplements. By 48 days, P1-supplemented steers were eating 29·5% more hay than non-supplemented steers, and P2 steers were eating 43·5% more hay than the non-supplemented steers. S1 supplemented steers were eating 29·5% less, and S2 steers 23% less hay than non-supplemented steers. Steers lost weight on the basal hay diet, and at the lower level of sorghum (S1) supplementation, but were able to maintain weight at the higher level (S2) of supplementation. In contrast, steers supplemented with protein gained weight (P < 0·01): 430 g/day on P1 and 700 g/day on P2 treatments. None of the steers offered combinations of P and S had live-weight changes as high as those offered only protein supplements. There was no evidence of compensatory gain by the smaller steers in Expt 2 when grazing and unsupplemented.

Glucose kinetics in plasma were studied in each steer on day 35 of Expt 1 by means of a single intravenous injection of [2-3H]glucose. The quantity of glucose in the sampled pool and the total rate of glucose entry into the pool (GER) were higher (P < 0·01) in steers that were protein supplemented, with GER being related to both ME intake and to N intake per unit ME intake.

Urea pool size and entry rate were also estimated on day 35 of Expt 1 using a single intravenous injection of [14C]urea. The quantity of urea in the sampled pool, and entry rate into the pool were increased significantly (P < 0·01) by protein, but reduced (P < 0·05) by sorghum, supplementation. Rumen ammonia concentrations were low in steers given the hay alone, and when supplemented with sorghum (10–15 mg N/l), but were significantly higher (70 mg N/l; P < 0·01) during protein supplementation.

It was concluded that growth of cattle on the basal ration was restricted by low voluntary intakes of hay. Intake was increased substantially by protein supplementation. The consequent increase in live weight was due to a greater intake of organic matter which was accompanied by a greater synthesis of glucose and availability of amino acids in the animals.

Field experiments made for 2 years on a deep vertisol under semi-arid conditions showed that soil-surface evaporation control by mulching with rice straw or transpiration suppression by foliar application of kaolin or atrazine increased the yield of grain sorghum. These materials decreased soil moisture depletion and thus increased water-use efficiency. Application of one irrigation at the boot-leaf stage was beneficial. No additional advantage was noted with two irrigations, one given 45 days after seeding and the other at anthesis.

In 1976 and 1977 late sprays of a urea-ammonium nitrate solution supplying 50 kg N/ha, and broad spectrum fungicides, were tested in factorial combination with 0, 50, 100 or 150 kg N/ha (as ‘Nitro-Chalk’) given either in April or in May to winter wheat. In 1976 leaf diseases were not assessed. In 1977 brown rust (Puccinia hordei) was prevalent and more severe than either mildew (Erysiphe graminis) or septoria (Septoria spp.). Its severity was decreased by the fungicides and by the late sprays of N. Yield and N content of the grain were increased by each increment of ‘Nitro-Chalk’; though % N in grain was larger, yield and N uptake were smaller when the ‘Nitro-Chalk’ was applied in May. The liquid N-fertilizer increased yield little after giving N in April and decreased yield after giving N in May; nevertheless it always increased N content of the grain. The fungicides increased yield only on plots given N in April; their effects on % N in grain were inconsistent.

In 1978 and 1979 isobutylidene di-urea (IBDU) supplying 63 kg N/ha in autumn, ‘Nitro-Chalk’ supplying 0, 50, 100 or 150 kg N/ha in April, late sprays of urea solution supplying 50 kg N/ha, sprays of broad spectrum fungicides and sprays of the rust fungicide benodanil were tested in factorial combination (4 × 24) in a ½ replicate design.

In both years septoria was more severe than either brown rust or mildew. The broad spectrum fungicides decreased septoria in 1978, but not in 1979. In 1978 (after wheat) 150 kg N/ha as ‘Nitro-Chalk’ was needed for maximum yield, but in 1979 (after beans) only 100 kg; N content of the grain was increased by each increment of N each year. IBDU in the seed bed was less effective than equivalent ‘Nitro-Chalk’. The urea sprays increased yield and most where the least N was given in spring; they always increased grain N content. In 1978 the broad spectrum fungicides increased yield only with 150 kg N/ha in spring, but in 1979 with each amount of N; they affected % N in the grain inconsistently. The rust fungicide little affected yield, but decreased % N in the grain.

The weight of 1000 grains was irregularly affected by ‘Nitro-Chalk’ during 1976–1979. However, in all 4 years, 1000-grain weights were increased both by the liquid N fertilizer and by the broad spectrum fungicides and were largest where both had been sprayed.

The variation in setting fruit and immature fruit abscission at successive nodes of an individual panicle, and in panicles at different directions of the canopy in an individual tree, were studied in cashew (Anacardium occidentale L.). The numbers of perfect flowers and fruits set increased from the proximal to the distal end with the maximum yield at the fifth or sixth nodes in a panicle of 8–10 branches. The productivity of an entire inflorescence or a whole fruiting branch was related to its orientation with respect to the sun. The numbers of nodes and fruits set and the percentage of fruit retained were maximal in panicles located on the western and southern sides of the canopy. Tea mosquito damage was also less on these sides of the canopy but the physiological disorder of ‘apple’ cracking was higher here than on the eastern and northern sides. These variations are discussed in relation to the differences in the incident photosynthetically active radiation on these sides.

In the Mediterranean region, chickpeas are traditionally spring-sown since humid winter conditions encourage the development of Aschochyta blight which often causes complete crop failure. Lines resistant to this blight have been selected at the International Centre for Agricultural Research in Dry Areas (ICARDA) and thus winter planting has become feasible. The best selection, ILC 482, was sown in both winter and spring at three locations in northern Syria with contrasting precipitation patterns. Crop growth and soil moisture analyses were undertaken on all treatments, and relevant meteorological data were collected at each location. At all locations maximum greenarea and dry-matter production of the winter-sown crop was nearly double that of the spring sowing. Large differences were also observed between sites, with green-area and dry-matter production decreasing with precipitation. Depth of profile recharge, amount of extractable moisture and crop evapotranspiration also decreased with precipitation, but only small differences in these moisture variables were observed between winter and spring sowing. Duration of green-area production, as determined by the onset of rapid leaf senescence, was closely related to the fraction of extractable moisture in the soil profile, rapid senescence occurring in all treatments when extractable moisture fell below 40% of its maximum value. Differences in the maximum rates of green-area production are discussed both in relation to the depth of profile recharge, hence the depth of rooting and moisture extraction and to the ambient evaporative demand. The differences observed in green-area and dry-matter production was clearly reflected in final seed yield. The components of yield, number of pods, percentage of empty pods and seed size are related to the variations in moisture stress experienced by the crop.