bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant density effects on growth, yield, leaf area index and light transmission on intercropped maize and Vigna unguiculata (L.) Walp. in Nigeria
Authors: Fawusi M. O. A. , Wanki S. B. C. , Nangju D.
Published: March 2009

In field experiments at the International Institute of Tropical Agriculture in Nigeria, two cow-pea cultivars, TVU-1209 and FARV-13 and a composite maize cultivar were intercropped at plant densities of 10000, 20000, 30000 and 40000 plants/ha in a split-plot design. There were four replications of each density. Results showed that increasing cow-pea plant density increased the number of days to flowering but decreased the numbers of branches and of leaves per plant in both monoculture and mixture. Different varietal responses to plant density were observed for other growth measurements. While TVU-1209 yielded the highest dry matter at 20000 plants/ha in monoculture and mixture, FARV-13 did so at 40000 plants/ha in monoculture and at 20000 in mixture. Some yield components decreased while others were unaffected by increasing plant density. Similar response pattern was observed for maize. Both leaf area index and light interception were greater in FARV-13 than in TVU-1209.
Assessing potato seedling progenies for resistance to the white potato cyst-nematode
Authors: Phillips M. S. , Dale M. F. B.
Published: March 2009

A bulk seedling test is described which can be applied shortly after completion of a crossing programme. The test assesses resistance to G. pallida in progeny derived from crossing programmes involving S. luberosum, S. vernei and S. tuberosum spp. andigena. It provides good estimates of both the mean level of resistance within progenies and the breeding value of the parents. The test was applied to a crossing schedule involving a half-diallel and a North Carolina 2 design utilizing a range of material. The results and their implications are discussed.
Effects of dietary N on lipids of rumen digesta, plasma, liver, muscle and perirenal fat in sheep
Authors: Gerson T. , John A. , Shelton I. D. , Sinclair B. R.
Published: March 2009

Two-year-old Romney wethers were fed diets with (a) varying proportions of N (0·5, 1·1, 1·4 and 3·4%) while on similar digestible organic matter (DOM) intake, and (b) the same proportions of N with different DOM intake.

The composition of rumen volatile and unesterified fatty acids, as well as of lipids and fatty acids of plasma, liver, muscle and perirenal fat, was determined.

When the proportions of dietary N were varied the findings were as follows: in the rumenahigh level of propionate (37%) was found on the 1·4% N diet, unsaturated fatty acids constituted between 20 and 30% of rumen unesterified fatty acids with diets containing 0·5 and 3·4% N, while sheep on 1·1 and 1·4% N diets had 70·80% unsaturated fatty acids. In plasma and tissues other than the liver there was a greater proportion of unsaturated fatty acids in sheep fed the 1·4% N diet. Total liver lipids were highest on the 0·5 and 3·4% N diets. Perirenal fat was highest on the 0·5% N diet.

With the exception of unesterified cholesterol, tissue and plasma cholesterol concentrations decreased with increasing dietary N content.

Increased DOM intake while the proportion of dietary N was kept constant caused few changes in lipid and fatty acid composition of rumen, plasma and tissues.
Low temperature growth in a controlled environment of Lolium perenne L. ecotypes from northern latitudes
Authors: Ollerenshaw J. H. , Baker R. H.
Published: March 2009

Nineteen ecotypes from northern Britain and selected genotypes of a cultivar of L. perenne were assessed in controlled environments for shoot growth at low temperature and irradiance and also short daylengths. The ecotypes were collected from a range of altitudes at sites experiencing estimated mean monthly temperatures in the coldest month between -0·1 and + 4·2 °C.

A clinal relationship between low temperature growth and the winter temperature at the place of origin of the ecotypes could not be found in these experiments. Low temperature growth was not generally associated with altitude of origin of the plants, but in this study some of the plants collected from mid-altitude were exceptional in leaf growth produced at 5 °C. Types of L. perenne which extended leaves quickly also produced heavier shoot weights than other types less able to show rapid leaf extension at low temperature. The exceptional ecotypes may provide useful basic plant material for breeding cultivars of L. perenne to grow at low temperatures, and irradiances and short daylengths. Several possible explanations are discussed for the differences in shoot growth found between L. perenne ecotypes at low temperature.
The use of titanium dioxide for determining apparent digestibility in mature domestic fowls (Gallus domesticus)
Authors: Peddie J. , Dewar W. A. , Gilbert A. B. , Waddington D.
Published: March 2009

The apparent digestibility of a diet can be calculated from the amounts of food eaten and excreta voided. This ‘total collection’ method is laborious because it requires a period lasting several days. It can be circumvented by the inclusion in the diet of a suitable reference substance (Kotb & Luckey, 1972). From the concentration of the reference substance (marker) in the diet and in the droppings, apparent dry-matter digestibility can be calculated.
Effects of short-term waterlogging on growth and yield of cowpea (Vigna unguiculata)
Authors: Minchin F. R. , Summerfield R. J. , Eaglesham A. R. J. , Stewart Katrine A.
Published: March 2009

When cowpea plants were grown in large pots under simulated tropical conditions, and were dependent on either symbiotic fixation or inorganic N for their total nitrogen requirements, short periods of waterlogging had adverse effects on vegetative growth and seed production. The effects of waterlogging were more acute as plants experienced stress at progressively earlier stages of development. In plants depending either on biologically fixed N or inorganic N, waterlogging before flowering reduced vegetative growth by about 50%. Although some compensation in vegetative growth occurred during the reproductive development of nodulated plants, seed yields in both cases were still 48% less than in unstressed plants. Depending on the stage of plant development, treatment effects were mediated largely through changes in branch, peduncle and flower production and/or abortion, which contributed directly to variations in the number of pods retained to maturity. Inorganic nitrogen stimulated vegetative growth but did not significantly improve seed yield compared with effectively nodulated plants.
The relative resistance to escape of leaf and stem particles from the rumen of cattle and sheep
Authors: Poppi D. P. , Hendricksen R. E. , Minson D. J.
Published: March 2009

In a study of the effect of animal species on the threshold particle size leaving the rumen, two grasses cut at two stages of growth and one mature legume were separated into leaf and stem fractions and fed to cattle and sheep. Samples of rumen digesta and faeces were used to determine the validity of using a 1·18 mm porosity screen to separate the rumen particles into large and small pools when studying escape of particles from the rumen. Samples of rumen digesta and faeces were collected for the determination of particle size by wet sieving and the calculation of resistance of particles to passage from the rumen relative to small particles retained on a 0·15 mm sieve.

Particles < 1·18 mm but > 0·5 mm had a mean relative resistance to passage of 2·0 and 2·6 for cattle and sheep respectively, compared with resistance values of between 10·9 and 31·2 for particles between 1·18 and 2·36 mm. It is suggested that there is no justification for using different threshold particle sizes for sheep and cattle and that a 1·18 mm sieve may be used to divide the rumen contents of both cattle and sheep into two pools of particles with high and low relative resistance to passage from the rumen.
Intrinsic antibiotic resistance in chickpea (Cicer arietinum) rhizobia
Authors: Garg F. C. , Beri N. , Tauro P.
Published: March 2009

More than 200 wild type isolates of chickpea (C. arietinum) rhizobia were screened for their drug resistance. Only 15 were found to be resistant to one or more antibiotics at a concentration of 5 μg/ml (units/ml). When tested for multiple drug resistance, some were found to be resistant to more than one antibiotic. In competition studies, rhizobia resistant to streptomycin were found to be more competitive than antibioticsensitive strains, while those resistant to penicillin could not compete even with antibiotic-sensitive strains.
Boran cattle maintained by chemoprophylaxis under trypanosomiasis risk
Authors: Trail J. C. M. , Murray M. , Sones K. , Jibbo J. M. C. , Durkin J. , Light D.
Published: March 2009

Reproductive performance, mortality, growth, and culling and replacement rates based on 20000 calving records were evaluated for grade Boran beef cattle maintained with trypanocidal drugs in an area of high trypanosomiasis risk in Tanzania. Under ranching conditions, over a 10-year period in this area of highGlossina morsitans morsitans, G. pallidipesandG. brevipalpischallenge, a calving interval of 15·9 months, pre-weaning mortality of 8%, annual cow mortality of 5·8% and 8-month weaning weight of 133·5 kg resulted in a herd productivity of 96 kg of weaner calf per cow per year. The proportion of heifers required as replacements (45%) and the generation interval (6·9 years) indicated scope for implementation of selection programmes on growth traits. The level of productivity achieved compared favourably with major data sets recently analysed from pure Boran cattle under trypanosomiasis-free ranching conditions in Kenya, and from trypanotolerant N'Dama cattle in West Africa. These results indicate the possibility of improving livestock production in tsetse-infested areas by the rational use of chemoprophylaxis as an integral part of management.

Year, season, cow age, calf sex and location on ranch had significant effects on practically all the traits of calving interval, pre-weaning mortality and growth, and cow productivity. Superior performance where bush clearance and tsetse fly control had taken place suggests that economic evaluation of these interventions should be attempted. The season of calving had a major effect on productivity. Cows of 5–8 years of age were the most productive, as were animals producing male calves, features well recognized in beef cattle production.

An average of 4·4 treatments with Samorin, a prophylactic, and 0·6 treatments with Berenil, a therapeutic, were required per year. The number of treatments varied from year to year and by area, being greater in the south of the ranch where the tsetse challenge was considered higher. However, the age and season of calving had little effect on the number of treatments required. Despite such extensive use of trypanocidal drugs, there was no indication that drug resistance had developed or evidence that repeated inoculation of Samorin had affected productivity.

Grading-up of small East African Zebu cattle to Boran over an 8-year period allowed annual comparison of birth weights, pre-weaning growth and weaning weights of two groups of calves, one having a higher level of Boran genes (varying from 12 to 6% higher annually) than the other. Those with the higher level of Boran genes performed better by 3·3% for all attributes studied, but as the percentage difference in Boran genes decreased, so did this difference. In an environment improved through bush clearance and tsetse fly control, the calves with higher levels of Boran genes were superior, but this superiority was not expressed in the unimproved environment.
On exogenous chemical imposition of ephemeral dormancy in cereal seed
Authors: Leshem Y. Y.
Published: March 2009

Chemical imposition of water leachable germination inhibition was attempted as a means of overcoming wheat seedling wilting after insufficient rainfall. Effective inhibition in aqueous solutions was imposed by abscisic acid, coumarin and by two ethylene releasing preparations, Ethrel and Alsol. Germination inhibition caused by the latter two compounds was found to be associated with effects of the carriers, other than pH, and was not a result of ethylene gas liberation. As evidenced by tetrazolium staining the dormant seed possessed respiratory activity, and imposed germination inhibition, even to the extent of 75%, was not lethal. Rainfall simulation effected by 30 h H2O leaching with a 200 mm precipitation equivalent was ineffective for reversal of germination inhibition caused by abscisic acid and Alsol, limitedly effective in the case of Ethrel, while the coumarin-induced inhibition was relieved to a greater extent.
A study of some wool traits in two coarse wool breeds and their reciprocal crosses
Authors: Guirgis R. A. , Kazzal N. T. , Haddadine M. S. , Abdallah R. K.
Published: March 2009

In a study of two coarse wool breeds (Awassi and Karadi) and their reciprocal crosses, data were obtained on the mean fibre length, mean fibre diameter, fibre type ratio, medullation and on the effect of some environmental factors on these traits. Reciprocal crosses showed intermediate values, in growth rate of fibres, percentages of fibre types and medullation, between those of the parental breeds. Sex exhibited a significant effect at weaning only, on fibre length. Heterosis in fibre length, at the two ages, was small and negative. Maternal influence on fibre length was small and not significant. Fibre length in Karadi sheep showed the highest frequency of bimodal distribution whereas Awassi showed the lowest. Awassi × Karadi was closer to Karadi and Karadi × Awassi had greater affinity to Awassi in the frequency of samples showing bimodal distribution.

Reciprocal crosses had larger diameter, at weaning, than those of the parental breeds. At 1 year of age they assumed an intermediate position between the pure bred parents.

At weaning, the two reciprocal crosses showed a highly significant heterosis in fibre diameter; its value decreased with advancing age and it showed no significant effect at 1 year of age.

Maternal influence on fibre diameter was very small and not significant.

Karadi × Awassi and Karadi samples had the highest percentage of samples showing bimodal distribution of fibre diameter.

Samples with bimodal distribution of both length and diameter, indicating two coats, had the highest frequency in Karadi followed by Karadi × Awassi; Awassi showed the lowest value.

Percentages of fine, coarse and kemp fibres were significantly affected by breed and age of dam. Type of birth showed a significant effect only on percentage of coarse fibres.

Karadi wool might be more suitable for carpet manufacturing. It excelled the other groups in the bimodal distribution of both length and diameter as well as in medullation. Cross-breeding increased the bimodality of fibre distribution.
Fruit and seed development in mung beans (Phaseolus aureusRoxb.)
Authors: Savithri K. S. , Ganapathy P. S. , Sinha S. K.
Published: March 2009

A study of fruit set at different nodes was made in mung beans,Phaseolus aureusRoxb., under field conditions. Flowering commenced on the fourth node from the base and the percentage fruit set showed a gradual decrease from the fifth node upwards. Yield analysis was carried out for each of the fruiting nodes. When the leaf and inflorescences at a node are taken as a functional unit it is seen that there was a decrease in the ratio of leaf area to fruit and seed weights from the base of the plant upwards indicating that at the upper nodes particularly, some other plant parts also contribute to the photosynthate pool of the developing seeds.

A quantitative study of the dry matter, proteins and starch in the fruit wall and seeds of fruits at different stages of development was made. It showed that the rapid increase in dry matter, proteins and starch in the seeds at the later stages of development is compensated, in part, by a decrease of these components in the fruit wall. Histochemical studies of the fruit wall further supported these observations. This indicated the contribution of substrates by the fruit wall to the developing seeds.
Effects of severe food restriction on growth rate, muscle distribution and muscle: bone ratio in pigs
Authors: Goenaga P. R. , Carden A. B.
Published: March 2009

In a previous experiment we investigated the effects of a restricted intake of dietary energy, protein or both on carcass anatomy in pigs (Carden & Goenaga, 1977). Contrary to results of Elsley, McDonald & Fowler (1964) and of Richmond & Berg (1971) we found several changes in muscle distribution, which gave rise to differences in the proportion of the commercially valuable muscles in the carcasses. The treatments had no effect on an important trait, the muscle: bone ratio.
Studies on nitrogen fixation by antibiotic-resistant mutants ofAzospirillum brasilenseand their interaction with cheena (Panicum miliaceumL.) genotypes in calcareous soil
Authors: Rai R.
Published: March 2009

Azospirillum brasilense was treated with nitrosoguanidine and five antibiotic-resistant mutant strains isolated. Variations in growth, N2-fixation, ultraviolet-dark survival and level of antibiotic resistance were found between the mutant strains. Mutant strains STR 112 and KR 2051 showed maximum nitrogenase activity, glutamine synthetase activity and hydrogenase activity (H2uptake) at 32 °C and 40 °C respectively. Inoculation of cheena genotypes withA. brasilenseand its mutants led to significant increase in associative nitrogen fixation, dry weight of roots and grain yield compared with the uninoculated control, with significant strains × genotypes interactions in calcareous soil. It was also noted that under laboratory conditionsAzospirilluminoculation may have produced its response by hormonal means and/or associative N2-fixation.
In vivocolonization of grass cell walls by rumen micro-organisms
Authors: Elliott R. , Norton B. W. , Ford C. W.
Published: March 2009

Cell wall preparations from stems of four mature grass species, pangola grass, setaria, sugar cane and barley straw were incubated in nylon bags in sheep fitted with rumen cannulae and fed chopped pangola grass at hourly intervals. After varying incubation times D.M. loss, and incorporation of35S into microbial cystine on the fibres, were measured. Pangola and barley straw were digested to a much greater extent (ca.48 and 44%) than sugar cane and setaria (ca.29 and 23% respectively) and digestion was still continuing after 60 h. With the exception of setaria, microbial colonization of the cell wall preparations peaked after 24 h incubation and then declined. In setaria only a small amount of [35S]cystine was measured, the level of which did not change appreciably after 18 h.

After 24 h incubation, microbial colonization on pangola fibre was about three times that on barley straw and sugar cane. Only on pangola fibre did cystine accumulation, and its subsequent rapid decline, coincide with the development and detachment of fungal sporangia. There was no relationship between the extent of microbial colonization and D.M. loss from the fibres. Sulphur concentrations, both in the plant fibres and rumen fluid, could not explain the greater fungal growth on the pangola cell walls in preference to the other species.
The effect of inclusion of mineral salts in the diet on dilution rate, the pattern of rumen fermentation and the composition of the rumen microflora
Authors: Thomson D. J. , Beever D. E. , Latham M. J. , Sharpe M. E. , Terry R. A.
Published: March 2009

The mixed buffer salts of artificial saliva were incorporated at three rates: 0 (diet 1), 5·7 (diet 2) and 11·4% (diet 3) (w/w) in pelleted diets prepared from60% ground flaked maize and 40% dried ground grass. The control and mineral-supplemented diets were fed to sheep hourly (Expt 1) or twice daily (Expt 2).

When the sheep were fed hourly or twice daily the pattern of fermentation in the rumen was altered from a predominantly propionate to mainly acetate fermentation. Dilution rate in the rumen increased from 0·036 to 0·053 to 0·064 when diets 1, 2 and 3 were fed hourly, and dilution rate was negatively related to the molar proportion of propionic acid (P< 0·05) and positively related (P< 0·05) to the molar proportion of acetic acid in rumen fluid, but these relationships were not apparent in Expt 2.

Nitrogen retention was higher for lambs fed diet 2 than for those fed diets 1 and 3 (P< 0·05) in Expt 1.

In sheep fed hourly, selenomonads and bacteroides were the predominant rumen bacteria associated with the control diet but the inclusion of mineral salts resulted in the bacteroides being replaced by large number of chain-forming cocci. Numbers of protozoa were variable. The relationship of these changes to the fermentation pattern is discussed. In sheep fed twice daily there was much variation between animals.
The interactions of water and fertilizer nitrogen in effects on growth pattern and yield of potatoes
Authors: Clutterbuck B. J. , Simpson K.
Published: March 2009

Three field experiments in 2 years were made in S.E. Scotland to investigate the effect of water (normal rainfall or irrigation to maintain soil moisture tension between pF 2·0 and 2·5) on the response of the potato crop to nitrogen fertilizer (0, 100, 200 or 300 kg N/ha).

Final tuber yield was closely related to leaf area duration. Addition of water reduced the delay in early haulm growth resulting from fertilizer nitrogen application. The beneficial effect of reducing moisture tension could not be related to water per se, nitrate, ammonium or conductivity levels in the fertilizer band or nitrogen uptake. Accumulation of nitrate in the roots and stems + petioles early in the season indicated that the rate of protein synthesis was reduced at high soil moisture tension in the presence of fertilizer nitrogen.

In a long growing season (1971, 153 days) there was a significant response of tuber yield to nitrogen, with an increase in yield even at the highest rate tested (300 kg N/ha) and irrigation enhanced this response.

In a normal season (1970, ca.130 days) there was a significant irrigation x nitrogen interaction on tuber yield. Irrigation increased the optimum rate of nitrogen from 100 to 200 kg N/ha in one experiment and from nil to 200 kg N/ha in another.

Addition of water increased the number of tubers at harvest but the effect of nitrogen was less consistent. Yield increases resulting from application of nitrogen or reduction in soil moisture tension were mainly due to increases in the proportion of large tubers.
Seasonal changes in the position of the shoot apex of winter wheat and spring barley in relation to the soil surface
Authors: Hay R. K. M.
Published: March 2009

In many field investigations of cereal growth, stages of crop development may be described adequately using the Feekes scale (Large, 1954) or the more recent decimal code (Zadoks, Chang & Konzak, 1974). For example, the onset of stem extension (Feekes stage 6; decimal code 31) is frequently taken as a field indication of the switch from vegetative to reproductive growth. However, in investigations of the influence of soil properties, especially temperature, on shoot apex and leaf growth, it is important to know (a) the position of the apex below the soil surface during the early stages of development and (b) the timing of the rise of the apex above the soil surface.
Studies on genotype × spacing interactions for herbage yield, using a modified diallel analysis
Authors: Sedcole J. R. , Clements R. J.
Published: March 2009

Forty-four full-sib families from a diallel cross between 10 Lolium ((multiflorum × perenne) × perenne) clones were planted in the autumn at 0·6 × 0·6 m and 0·l × 0·l m spacings. Fresh weight of individual plants was measured on three occasions during the following spring and summer. The analysis of the diallel cross was extended to account for combining ability × spacing interactions, and to estimate between-spacing combining ability correlations and their sampling errors.

Family × spacing interactions became increasingly significant at successive harvests and always contributed substantially to the total phenotypic variance. Much of the family × spacing variance was due to the general combining ability (GCA) × spacing component. Despite these large and significant interactions, the correlation between GCA values at the two spacings was high and positive at each harvest, so that selection for yield at wide spacing should lead to a correlated increase in yield at close spacing. Although the experiment was of relatively short duration, the results suggest that recent criticism of the conventional technique of selection among widely spaced plants in pasture plant breeding programmes may not have been entirely justified.
Growth analysis of the domestic fowl I. Effect of plane of nutrition and sex on live-weights and external measurements
Authors: Wilson P. N.
Published: March 2009

101 Rhode Island Red × Light Sussex chickens have been made to conform to four differently shaped growth-curves from hatching to 24 weeks, by control of their plane of nutrition. The four treatments HH, LH, HL and LL allowed comparisons to be made between birds of the same age but different weights.

As the main concern has been to find the essential nature rather than the precise extent of the effects produced by different planes of nutrition, the treatment differences were made as extreme as possible without allowing the rations to become unbalanced.

The conclusions reached are as follows:

1. The treatments used have produced marked effects on the growth-curves of the birds, analysed on the basis of equal age. These effects have been shown to be statistically significant at all stages after 3 weeks.

2. In body-weight and form, two types of bird were produced. The HH and LH birds were similar, with greater relative proportions of the late developing parts and secondary sexual characteristics, and the small differences that existed between them were not significant at 24 weeks. Likewise, the LL and HL birds formed a comparable group, exhibiting a more infantile body form similar to that of the HH and LH birds at an earlier age. The difference

between the HL and LL birds, though generally not statistically significant, is greater than that between the LH and HH group.

3. The treatments produced a small but consistent effect on the external measurements of the birds when comparisons were made on the basis of equal weight. Nine measurements were recorded. In the case of four measurements, no treatment effect was noted. Four skeletal measurements demonstrated a consistent effect of treatment, the LL and HL measurements exceeding those of the HH and LH at equal live-weights. This result was reversed in the case of the only muscular measurement, thickness of leg musculature. Opposite results are therefore indicated for the muscle and skeletal tissues. This finding will receive further discussion when the dissection analysis results are discussed in a later paper.

4. The presence of definite growth-gradients from the body extremities towards the trunk is indicated by the external measurements.

5. The two sexes differ in their live-weights at equal age and in their bodily proportions both at similar ages and similar weights. The most marked sex-difference in external measurement is noted in the length of the mid-wing, and a possible functional explanation is advanced. In general, the sex-difference is greatest for the late maturing characters.
A simple method for assessing the reliability of rainfall
Authors: Glover J. , Robinson P.
Published: March 2009

A simple method to determine the expectation of selected minimum rainfall has been developed on the assumption that monthly or seasonal rainfall is normally distributed over a period of years. Although it is realized that a perfectly normal distribution cannot be obtained, practical experience has shown that the assumption leads to no serious discrepancies and the advantage of simplicity is considerable. A detailed example of its use to forecast the agricultural potentialities of dry lands is given.
Physiological acclimatization of fowls to a hot humid environment
Authors: Hutchinson J. C. D. , Sykes A. H.
Published: March 2009

1. The resting heart rate of cocks and hens was measured in varying degrees of heat stress, and during acclimatization to heat.

2. When the rectal temperature was below 110°F. (43·3° C), the heart rate varied inversely with the severity of the climate up to an air temperature around 99° F. (37·2° C).

3. At air temperatures of 99° F. (37·2° C.) and above the heart rate was nearly constant over a wide range of rectal temperatures below 110° F. (43·3° C). It averaged about 50 beats/min. less than in an equable climate.

4. Above 110° F. (43·3° C.) there was an increase of about 30 beats/min./° F. (17 beats/min./° C.) rise in rectal temperature. The rate equalled that found in an equable climate, when the rectal temperature reached 111–112° F. (43·9–44·4° C). Over this zone of body temperature the fowls were often agitated.

5. In severe heat stress there was a slight fall in the heart rate on acclimatization, but this was small compared with the effect of climate.

6. In severe heat stress the heart rate during the day was slightly higher than that at night.

7. The relation of these findings to the mechanism of temperature regulation is discussed.
The effect of spacing on the growth of two genotypes of perennial ryegrass
Authors: Simons R. G. , Davies Alison , Troughton A.
Published: March 2009

Two clones of perennial ryegrass were planted along the radii of a fan in such a way that any group of four adjacent plants was approximately square, with spacings ranging from 3 to 30 cm. During the first year the amount of regrowth per vegetative plant was found to be related to the area available at the high densities, whereas at low densities there was little change in weight per plant with change in density. At high densities the number of tillers declined following defoliation, but at low densities it increased consistently. In the second year, the ratio of fertile to barren tillers was lower and ear emergence was later at high densities. Results indicated that the performance of the clones differed in each of three stages of regrowth. It appeared that early regrowth was better in the erect clone, but after the first week, and where the canopy remained open, the RGR of the prostrate clone was greater. In a dense sward the crop growth was greater in the erect clone indicating that better use was made of the available light.
Variation in muscle fibre diameter among sections and intrasections and between contralateral muscles in seven bovine muscles
Authors: Johnson E. R. , Beattie A. W.
Published: March 2009

Sectional and intrasectional variations in muscle fibre diameter over a restricted axial range were examined in seven bovine muscles from foetuses, calves and steers. Significant sectional variations were found in four muscles, while two muscles showed significant intrasectional variations. The results indicate that sampling sites require accurate definition in comparative studies of muscle fibre diameter.

Two extensor muscles of the foreleg, m. extensor carpi radialis and m. extensor digitorum communis showed neither sectional nor intrasectional variation in muscle fibre diameter and appear to be more satisfactory muscles for use in muscle fibre growth studies than m. longissimus thoracis et lumborum.

A comparison of mean muscle fibre diameter in 60 pairs of contralateral muscles showed that there were no significant differences in 52 of the muscle pairs.
The incidence of precipitins to Micropolyspora faeni in cattle fed hay treated with an additive to suppress bacterial and mould growth
Authors: Wiseman A. , Dawson Christine O. , Pirie H. M. , Breeze R. G. , Selman I. E.
Published: March 2009

The development of precipitins to Micropolyspora faeni in cattle fed hay treated with a bacterial and mould inhibitor is compared to that in herds fed untreated hay. The results indicate that, even when fed only treated hay, exposure to M. faeni was such that a considerable proportion of precipitin-free cattle did develop precipitins.
The effects of fatty acids on pure cultures of rumen bacteria
Authors: Henderson C.
Published: March 2009

The effects of fatty acids, at low concentrations (0–005-O5 g/1), on the growth of seven species of rumen bacteria were examined.Anaerovibrio lipolytica(strain 5 S),Peptostreptococcus elsdenii(type 2),Bacteroides ruminicola46/52 andSelenomonas ruminantium(strain 17) were unaffected by addition of oleic acid to the medium. Growth ofButyrivibrioB 835 was stimulated by low concentrations of oleic (< 0–01 g/1), lauric (< 0–1 g/1) or capric (< 0–1 g/1) acids while higher concentrations of these acids were inhibitory. Myristic, palmitic and stearic acids were inhibitory at all concentrations tested.Ruminococcus4263/1 was inhibited at all concentrations of the six acids. Production of methane by pure cultures ofMethanobacterium ruminantiumwas also inhibited by the additions of long-chain fatty acids. Oleic acid was the most inhibitory of the series of acids. These results are consistent with the reported effects of lipids on rumen function.
Effect of soil water potential on growth and yield of sunflower (Helianthus annuus)
Authors: Sionit N. , Ghorashy S. R. , Kheradnam M.
Published: March 2009

The effect of soil water potential of the root media on the vegetative growth, seed and oil yield of sunflower (var. Record) grown in containers under field conditions was investigated.

The weight of shoots and the total leaf area of plants before flowering significantly decreased with decrease in the water potential of the root media. There was a sharp reduction of shoot weight as the potential decreased from —0–32 to — 1–25 bars and then a further slow decline as soil water potential dropped to — 8'6 bars. There were no significant differences in the 100-seed weights and percentage. of oil among the treatments, but the total number of seeds was significantly different.

The data did not indicate the existence of a threshold water potential above which yield was independent of soil water potential, but rather that yield was a continuously decreasing function of soil water potential.
Pregnancy diagnosis in cows; changes in milk progesterone concentration during the oestrous cycle and pregnancy measured by a rapid radioimmunoassay
Authors: Heap R. B. , Gwyn Merle , Laing J. A. , Walters D. E.
Published: March 2009

The progestagen concentration of milk was measured in cows, at various times of the reproductive cycle by a competitive protein binding procedure and by radioimmunoassay. The apparent progesterone concentration was found to be significantly greater in milk (P <0–05) than in plasma, probably due to the presence of an unidentified metabolite(s). A simple, rapid radioimmunoassay was developed to measure directly the progestagen concentration in milk. A mean concentration of about 1 ng/ml at oestrus (or mating) increased, 20–24 days later, to 3–4 ng/ml in cows subsequently found to be non-pregnant and to about 7 ng/ml in pregnant animals. The possible application of this analytical procedure as the basis of a method of pregnancy diagnosis is discussed.
The effect of imposed light rhythms on semen production of Suffolk rams
Authors: Jackson G. , Williams H. LL. , Jackson G. , Williams H. LL.
Published: March 2009

The effects of two, symmetrically opposing, light treatments on the semen of Suffolk rams were investigated over two years. The light rhythm had an amplitude of 12 h and a cycle of 24 weeks. Data on semen volume, spermatozoa concentration, total spermatozoa per ejaculate, fructose concentration, seminal fluid fructose concentration and total fructose were collected during 38 semen collection periods. During the last 20 periods libido was assessed on the interval to mounting.

The effects of treatments were assessed by fitting Fourier curves with 24-week cycles to the observed fluctuation of the differences between treatments and with 52-week cycles to the means of treatments. From periodic regression analysis of the treatment differences it is concluded that the Suffolk rams were susceptible to the artificial light rhythms and that both groups adapted to the imposed rhythms. Some effects of the pretreatment photic environment appeared to persist during the first year of the treatment period. There appeared to be a lag between the fluctuations of the semen attributes resulting in a series of sequential changes.
Statistical analyses of some measurements of fertility in sheep
Authors: Goot H.
Published: March 2009

In dealing with fertility in sheep there are a number of initial difficulties. On the one hand, there is generally a lack of any uniform definition of such terms as ‘fertility’, ‘fecundity’ and ‘prolificacy’ (cf. Marshall & Hammond, 1947; Lush, 1938; Rice, 1942; Asdell, 1946; and others); on the other hand, investigators have been confronted with a real difficulty in procuring suitable information which would conform to the requirements of any single and adequate definition of fertility. Because of this, fertility figures have been calculated in different ways* and may differ by as much as 30%. The situation is at present so confused that reference to similar work, especially when the original papers are not available, or the terms not clearly denned, is often of dubious value if not altogether misleading. In the past the data analysed were mostly based on farmers' answers to questionnaires or on flock records. The limitations of such methods are only too obvious; yet it must be clearly realized that in commercial flocks there is no possibility of any basic departure from them, even though their accuracy could in many cases be improved. In other words, only such information is collected as the circumstances allow. This, for instance, may be the number of lambs docked per ewes put to ram in one flock and number of lambs docked per ewes lambed in another.
Efficiency of the utilization of the energy of food in piglets, after weaning
Authors: Burlacu G. , Băia G. , Ionilă Dumitra , Moisa Doina , Taṣcenco V. , Viṣan I. , Stoica I.
Published: March 2009

The efficiency of utilization of the energy of food by weaned pigs of the Large White breed was measured. Three diets based on maize (40–60%) had a metabolizable energy of 75·8±1·2% of the gross energy, and 78·2 ±3·4% of the metabolizable energy was present as net energy.

The maintenance requirement of metabolizable energy of pigs weighing 14·3 ± 2·1 kg was 143·6 kcal/kg°0·75/24 h (601 kJ/kg0·75/24 h).

The energy cost per g protein and fat synthesized by piglets was estimated to be 7·43 and 12·05 kcal (31·1 and 50·4 kJ) metabolizable energy, respectively.

Equations for calculation of metabolizable energy (Yl, kcal) and of the net energy (Y2, kcal), based on digested nutrients, were:

Y1 = 4·64×1 + 9·12×2 + 4·25×3'CV = ± 1·2%,

Y2 = 3·84×1 + 7·09×2 + 3·28×3'CV = ± 1·4%,

where X1 = g protein digested, X2 = g fat digested, X3= g carbohydrate digested (crude fibre × N-free extracts).
The yield of sugar beet in relation to weather and length of growing season
Authors: Scott R. K. , English S. D. , Wood D. W. , Unsworth M. H.
Published: March 2009

An experiment at Sutton Bonington in 1971 tested the effects of sowing and harvesting dates on yield of sugar beet. Seed sown on 28 March germinated slowly in the cold soil and crop establishment was poor. From early April until the beginning of May the loss in yield of sugar consequent upon delaying sowing by 1 week was 0·4 t/ha. For later sowings the yield loss was greater. During the harvest period the rate of increase in sugar yield was the same for all sowings. Yields of crops sown and harvested on different dates were closely correlated withthe amount of solar radiation intercepted by the leaf canopy.
Effects of weather conditions on the response of lettuce to applied fertilizers
Authors: Greenwood D. J. , Cleaver T. J. , Niendorf K. B.
Published: March 2009

Fertilizer experiments on lettuce were carried out over 5 years on adjacent sites of the same soil. The shapes of the response curves to both N and P varied considerably from experiment to experiment even though the amounts of those nutrients that could be extracted from the soil did not show this variation. Responses to N were of an ‘overturning’ type and the level of N at which maximum yield occurred ranged from 50 to 400 kg/ha. Responses to P were of a ‘diminishing returns’ type and the maximum increases in yield brought about by applying P ranged from 75 to 700% of the yields obtained with no application.

A mathematical model was derived which fitted the results from all the experiments satisfactorily. The parameter denning the response to P, and that denning the ‘downward’ component of the response to N were linearly related to the integral of cumulative rainfall with respect to time. Insertion of these relations into the model led to an overall model that predicted lettuce yields for each treatment in each experiment from the values of two weather parameters, the levels of N, P and K and a fitted value for seed weight. This overall model accounted for about 75% of the total variance due to fertilizer applications in the nine experiments. It is argued that most of the year-to-year variation in fertilizer response could be explained in terms of rain influencing the adverse osmotic effects on growth, the leaching of nitrate down the soil profile and dispersion of P from phosphate fertilizer granules especially in the early stages of growth.

The model was slightly improved by replacing the parameter ‘time’ with cumulative evaporation from an open water surface, but not with cumulative day degrees, or cumulative evaporation divided by vapour pressure deficit.
Weed control and its effects on yield ofPhaseolus vulgarisbeans in Malawi
Authors: Ayonoadu U. W. U. , Norrington-Davies J. , Edje O. T. , Mughogho L. K.
Published: March 2009

A number of herbicide treatments involving the use of trifluralin, preforan and igran were compared together with hand weeding as methods for the control of weeds in a cultivar ofPhaseolus vulgarissown on 19 January 1972.

Favourable increases in yield of beans were obtained by combinations of preforan and igran which were associated with an increase in the number of pods produced per plant. Hand weeding failed to give a significant increase in final yield.

Within 14 days from sowing there was an appreciable weed cover in the control and hand-weeded plots but little evidence of weeds in the herbicide-treated plots. At 41 days there were still no significant differences between the control and the plots to be hand weeded. There was, however, a considerable reduction in percentage cover of weeds on the herbicide treated plots. Trifluralin and preforan were equally effective in reducing weed cover.
Some mathematical aspects of the clover, grass, and fertilizer nitrogen relations
Authors: Stewart D. A. , Chestnutt D. M. B.
Published: March 2009

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.
Crossbreeding and the effect of certain environmental factors on body weights of Barki and German Merino sheep
Authors: El Kouni M. H. , Karam H. A. , Galal E. S. E. , Afifi E. A.
Published: March 2009

Body weights at birth, weaning, yearling and 2 years of age were studied on 710 lambs born from 1956 to 1967 and representing Barki, Merino and their F1 and backcross. Body weights ofthe lambs of the two cross-bred groups were intermediate between those of the two pure-breds at birth and exceeded them at weaning. Merino lambs were 0·61 kg heavier than Barki lambs at birth and maintained that advantage throughout the study.

Age of dam, type of birth, sex, and year of birth were significant sources of variation on the weights studied. The effect of age of dam and type of birth declined after weaning while that of sex increased.
An empirical model relating crop yield to weed and crop density and a statistical comparison with other models
Authors: Cousens R.
Published: March 2009

A hyperbolic model relating crop yield to weed density is extended to include crop density as a further variable. Other models were obtained from published sources, eight being originally applied to yield of above-ground biomass and six to marketable yield. Data were obtained from a field experiment in which spring wheat and spring barley were planted either in monoculture or together and at a range of densities. Further data were obtained from a published experiment onSinapis albaand barley grown in containers. The models were fitted to data using maximum likelihood estimation. Comparisons of residual sums of squares showed that for the wheat and barley field experiment biomass yield and marketable yield were sufficiently described by a three-parameter model. The Baeumer & de Wit (1968) equation proposed for replacement series experimental designs is considered reasonable for the analysis of field additive designs provided the parameters are interpreted in agronomic terms. For theSinapis albaand barley experiment more complex models could be justified.
A comparison of fungicides for the control of mildew on spring barley
Authors: Wale S. J. , Hunter E. A.
Published: March 2009

A series of 24 standardized, replicated field trials comparing 47 fungicidal treatments for the control of spring barley mildew have been analysed. The joint analysis has enabled stronger conclusions to be drawn about the relative efficacy of treatments than examination of individual trials. To increase sensitivity the trials were divided into those with high or low mildew pressure. Under high mildew pressure, the treatments which gave the greatest control of mildew also gave the highest yields. However, within any given treatment the yield response appeared not to be closely related to the degree of mildew control achieved. It is concluded that effective fungicides may have a phytotonic effect as well as a mildew control effect.
Heavy metal uptake from contaminated soils by six varieties of lettuce (Lactuca sativa L.)
Authors: Crews Helen M. , Davies B. E.
Published: March 2009

A replicated pot experiment is described in which six lettuce varieties were grown in four contaminated soils of different Cd, Cu, Pb and Zn concentrations. Webb's Wonderful absorbed least and All Year Round absorbed most Cd and Zn from all four soils. Uptake of both metals by all six varieties increased with increasing soil contents and leaf Cd and Zn concentrations were positively and significantly correlated. There was little evidence for a varietal control of the absorption of Pb and none for Cu, but a significant positive correlation between leaf Cu and Pb concentrations was observed.