bluuebunny/crossref_metadata_2025 huggingface dataset:
A note on the method of “differential regression” in analysis of variance
Authors: Hendricks Walter A.
Published: March 2009

Some time ago, the author (Hendricks, 1935a) pointed out a modification which may occasionally be desirable in the application of co-variance analysis to experimental data. It was suggested that, in some instances, it is more logical to base the analysis on the assumption that the slope of the line of regression varies from class to class than on the assumption that the regression coefficient has the same value for each class of observations.
The nature and variability of the carcass characters of Danish and English bacon pigs
Authors: McMeekan C. P.
Published: March 2009

1. The quality status of Danish and English Wiltshire bacon sides representative of the highest grades produced at the present time has been investigated by the use of carcass measurements. The data resulting provide “standards” for practical guidance in stock improvement work on bacon pigs, and for the evaluation of experimental treatments involving bacon quality.

2. The variability of the respective characters has been compared by means of the coefficient of variation of each. The results indicate that while selection on a basis of “external characters” and of such internal characters, as are readily measurable, leads to marked uniformity in respect of these characters, it does not necessarily involve similar uniformity in respect of important “internal characters” which are not taken into account in either stock selection or commercial grading practices.

3. External characters thus do not provide a reliable indication of the internal quality status of the bacon pig, and since it is the latter which largely governs the cutting value of the side, concentration upon addition to the former is desirable if still further improvement in the quality of the bacon pig is desired.

4. Variability appears to be affected also by the rate of development of the character concerned; late developing characters in general tend to be more variable than early.

5. The intimate association between nutrition and the rate of development of the various parts and tissues of the pig provides a method of control in addition to that of selection.
Investigations into the environment and nutrition of the cultivated Mushroom Psalliota campestris: I. Some properties of composts in relation to the growth of the mycelium
Authors: Pizer N. H.
Published: March 2009

Composts on which the mushroom mycelium fails to make normal growth are a common cause of poor yields and crop failures. No investigation into the matter appears to have been made, though other aspects of mushroom nutrition have received attention. A good deal of research has been directed towards the discovery of the principal mineral (3, 5, 6, 7, 11) and organic (1, 2, 4, 6, 7, 8, 9) nutrients required by the mushroom. Environmental factors such as temperature (2), partial pressures of gases (12), concentration of soluble materials (6, 7), hydrogen-ion concentration (10, 11) and moisture content (7) of the compost have been studied. But failures occur, of the kind described, when these factors appear to be favourable and when the compost contains ample food material. It has been suggested (l, 2) that poor composts may be unsuitable in physical condition or contain injurious compounds. The influence of the physical or physicochemical condition of the compost on mycelial growth deserves attention, since a compost is a colloidal system composed of solid, liquid and gas phases. In such a system it is possible, without changing the chemical identity of the materials, to bring about great changes in free surface energy, kinetic energy, interfacial tensions, dispersion and hydration of colloids, electrokinetic phenomena, diffusion and osmotic pressures—all of which are probably of vital importance in the nutrition of the mushroom. The properties of stability, swelling and degree of dispersion of most colloidal systems are determined by the nature of the adsorbed ions, especially the adsorbed cations.
On the spring cultivation of autumn-sown wheat
Authors: Garner F. H. , Sanders H. S.
Published: March 2009

Experiments have been conducted on heavy gault clay and on a gravelly loam to determine the effects of rolling and harrowing autumn-sown wheat in spring. It is concluded that rolling has no effect on yield on such soil types. In general, harrowing also had little effect on yield, although on three occasions it significantly increased the weight of grain per ear in excess of the increment to be expected from its effect on ear number.
Performance of two strains of laying fowl fed on diets containing field beans (Vicia faba L.)
Authors: Wilson B. J. , Teague P. W.
Published: March 2009

Fifteen hundred Thornber 808 and 909 female chicks were reared for 126 days from day-old on conventional diets or on diets with 200 g field beans/kg. From 127 to 490 days they were offered a control diet or diets with 100 or 200 g field beans/kg. When the diets fed from 127 to 490 days contained 0 or 200 g field beans/kg their food intakes were 45·4 and 44·6 kg/bird and they laid 235 and 233 eggs, respectively. The differences were not significant. Efficiency of food conversion to egg mass was significantly reduced from 0·310 to 0·303 when beans were increased from 100 to 200 g/kg of diet and mean egg weight was significantly reduced from 58·9 to 57·6 g when beans were included at 200 g/kg of diet in the 127- to 490-day period.
Investigations on certain toxic substances obtained from the wheat plant which inhibit the germination of the uredospores of various wheat rusts
Authors: Parker-Rhodes A. F.
Published: March 2009

A method is described whereby solutions can be obtained from wheat leaves which are toxic to the spores of rusts. Precautions designed to minimize unknown variable factors affecting the activity of the solutions are described.

It was found that the uredospores used germinated better in extracts from Little Joss wheat infected with Tilletia tritici than in that from healthy plants, this being correlated with the relative susceptibility of the two kinds of plant under field conditions. On the other hand, no correlation was obtained as between four different varieties tested in the healthy state.

A method is described, by which solutions are obtained in which enzymic activity in the course of preparation is reduced to a minimum. It is found that solutions prepared in this way are non-toxic, if obtained from healthy living leaves, though present in decaying leaves. It is deduced that the toxic substances studied are formed in the course of autolysis.

It is found that, using the second method of preparation, solutions obtained from rusted leaves are toxic. An experiment is described in which modifications of the degree to which such toxins are produced by a given amount of rust infection are brought about by different nutritional treatments, excess of potassium and deficiency of minor elements being conducive to the production of toxins.

Experiments are described which demonstrate that the toxins produced by infection with Puccinia glumarum are toxic only to spores of that species, and not to those of P. triticina, and vice versa.
Nutrition of the bacon pig: IV. The influence on growth, conformation and carcass quality of including meat meals of widely-differing fat content in the rations of bacon pigs
Authors: Woodman H. E. , Evans R. E.
Published: March 2009

The amount of oil in the diet and its degree of unsaturation are known to exert an important effect on the nature of the fat deposited in the body of the growing pig, foods of high oil content tending to give rise to bacon carcasses containing fat of an undesirably soft and unsaturated character. For this reason, authorities on pig nutrition are agreed on the desirability of excluding from the dietary of the bacon pig all foods containing more than a small percentage of oil. It has been stated that, in order to avoid the danger of producing carcasses with soft fat, the meal ration of the fattening pig should be made up so as to contain no more than about 3% of oil.

This prejudice against the use of feeding stuffs rich in oil has been transferred, somewhat unquestioningly perhaps, to feeding stuffs rich in fat. Feeding meat meal, for example, contains normally from 8 to 10 % of fat, and manufacturers complain of the difficulty of securing sales of this product for pig-feeding on account of the view generally held that its high fat content would occasion the production of soft fat in the resultant bacon or a carcass with an excessive amount of fat. To meet this prejudice, therefore, the meat meal as ordinarily produced is frequently submitted to a process of de-greasing with petroleum benzine at about 200° F. so as to give a meat meal containing about 3% of fat. This procedure, however, not only adds to the cost of the manufacture of meat meal, but may actually lead to a distinct lowering of the digestibility of the product (Woodman & Evans, 1937).
The influence of manurial treatment on the carotene content of poor pasture grass, and on the relationship of this constituent to the ash and organic Fractions
Authors: Moon F. E.
Published: March 2009

Sulphate of ammonia and nitrate of soda, applied at monthly intervals, produced increases in the carotene content of poor pasture grass amounting to 28%. Sulphate of potash, also applied monthly, produced an increase of 6·2%. A single dressing of carbonate of lime, which was sufficient to satisfy the lime requirement of the soil, produced no effect on carotene content, whilst monthly dressings of superphosphate also had no influence except in the month of June, when an increase of 14·5% was produced. All five manurial treatments significantly increased the yields of dry matter and carotene.

Carotene contents were very low during the drought experienced in April and May 1938, increased significantly in June, and showed very marked and highly significant increases in the autumn months.

Ash content was increased by the three non-nitrogenous manures, and protein content by nitrate of soda, sulphate of ammonia and superphosphate. Ether extract was increased by superphosphate and sulphate of ammonia, whilst nitrogen-free extract was decreased under all manurial treatments except carbonate of lime. None of the five artificial fertilizers had any effect on the mean fibre content of the grass, although various significant differences were observed on certain sampling occasions. Normal seasonal variations occurred in the percentages of ash and organic constituents.

Correlations of carotene with crude protein, fibre, nitrogen-free extract and ash have been computed for each manurial treatment and several significant differences have been observed. The physiological significance of these correlations has been briefly discussed.
The genesis and development of two profiles of a drift soil in the north-East of Scotland. (With Two Text-figures.)
Authors: Stewart A. B.
Published: March 2009

1. Two profiles of a drift soil at Craibstone, Aberdeenshire, have been examined in the field and in the laboratory. Both profiles have been derived from parent material of the same geological origin—a somewhat gravelly drift consisting of the granitic and metamorphic rocks of the district. One of the profiles was taken in uncultivated land and the other from arable land in the same area.

2. The chief results obtained in the present investigation may be summarised as follows:
A Statistical examination of the yield of mangolds from Barnfield at Rothamsted. (With Six Text-figures.)
Authors: Kalamkar R. J.
Published: March 2009

1. Series of yields (root weight) of twenty-five plots of Barnfield mangold field are analysed into components representing (a) deterioration, (b) slow changes other than steady deterioration, (c) annual fluctuations. The two first of these components are exhibited graphically from 1876 to 1930.

2. Yields are well maintained on the dunged strip, except for the last few years. This falling off does not appear in the other strips, and may be due to a falling off in the quality of the farmyard manure in the last five years.

3. On the strip receiving farmyard manure and on that receiving superphosphate the plots receiving nitrate of soda yielded more highly than any others; on the strips receiving complete minerals, and on that receiving superphosphate and potash, the two plots receiving rape cake in one case, and sulphate of ammonia and rape cake in the other, gave higher yields than nitrate of soda; on the strip receiving no minerals the result is intermediate, there being little to choose between these three plots. On all strips sulphate of ammonia is the least satisfactory of the four nitrogenous dressings tested.
Cohesion and viscosity of clays. (With five text-figures.)
Authors: Richardson E. G.
Published: March 2009

The variable viscosity which is shown by colloids generally as the rate at which they are sheared is varied leads to more striking anomalies in the behaviour of concentrated suspensions such as clay pastes when they are subjected to forces tending to make them flow. Bingham and Durham (l) first showed that when clay pastes were forced through capillary tubes, not only did the amount of clay squeezed out per second increase more slowly than the pressure applied, indicating a diminishing coefficient of viscosity, but also that there was evidence of a limiting shear, due to the consistency or cohesion of the particles, below which no flow would take place. It is the existence of this latter criterion that distinguishes clay from a weak suspension,e.g.of sand grains in water. This combined effect of cohesion and viscosity Bingham calls plasticity, and modifies Newton's law of viscous flow by the addition of a constant to allow for the cohesive force. Nevertheless, owing to the fact that the coefficient of viscosity is a function of the velocity gradient instead of being constant as in a homogeneous liquid, and that this velocity gradient is not known in the capillary tube viscometer, results as between one viscometer and another, or between two flow tubes of different size cannot be reduced to a common basis for comparison except by empirical trial. Keen and Scott Blair(2), Scott Blair and Crowther(3), and Schofield and Scott Blair(4) have repeated Bingham's experiments in an improved apparatus of the flow tube type, which they call a “plastometer.”
Investigations into the Intensive System of Grassland Management. By the Agricultural Research Staff of Imperial Chemical Industries, Limited. IX. The Digestibility of Artificially Dried Hay
Authors: Watson S. J. , Ferguson W. S.
Published: March 2009

Hay of excellent quality and high digestibility has been made by a process of artificial drying in which a current of warm air is blown through the grass in a stack. The air is heated by a system of hot-water pipes round which the stack is built.

The resultant product was of much greater feeding value than good meadow hay or seeds hay and was made at a season of the year when hay-making conditions were poor.

The economics of the process have not been worked out.
Studies on the Carbon and Nitrogen Cycles in the Soil. V. The Origin of the Humic Matter of the Soil. (With Three Text-figures.)
Authors: Page H. J.
Published: March 2009

The results so far recorded in this series of investigations are discussed in their bearing on the hypothesis according to which the humic matter of soil is derived from lignin.

This hypothesis is supported, but since the artificial product prepared from lignin is nitrogen-free, whereas the natural product contains nitrogen, further progress in the elucidation of the nature and origin of humic matter is dependent on a study of the part played by nitrogen in the formation of humic matter, and the form in which it occurs.
Response of S1 maize varieties and varietal hybrids to altitude and environments in Cameroon
Authors: Ayuk-Takem J. A.
Published: March 2009

S1 maize varieties and varietal hybrids were tested in six locations ranging in altitude from 236 to 1600 m in Cameroon. The grain yields of highland varieties were observed to increase with each increase in altitude while the yields of the lowland varieties decreased with increasing altitude.

The highland × lowland S1 varietal crosses yielded the same as the lowland parental varieties in highland areas and better than highland parental varieties in lowland areas.

Average yields of all varieties per location increased by about 1·1 t/km increase in altitude. Eberhart & Russell's (1966) stability method found no stable variety while Francis & Kannenberg's (1978) genotype-grouping technique found five highland × lowland crosses to be relatively stable.

Number of days from planting to tasselling increased with increasing altitude by about 20 days/km increase in altitude. Highland and lowland varieties performed poorly outside their zones of adaptation because of high incidence of foliar diseases like leaf blights and rusts.
Genetic control of the nuda character complex in the genus Avena
Authors: Atiyya H. S. , Williams Watkin
Published: March 2009

The inheritance of the units of the character complex which differentiates Avena nuda from Avena sativa was studied in F1 hybrids and in the F2 generation derived from inter-crossing five cultivars of A. saliva with four cultivars of A. nuda. The 14 derived F1 hybrids could be classified into four types depending on the level of dominance of the sativa or nuda character expression. Type-I hybrids involving the cultivar Milford as parent showed a high level of dominance of the sativa-type expression, whereas the F1 hybrid from the cross, Condor × China, type IV, had the character expression typical of the A. nuda parent. Segregation in the F2 generation indicated that the entire character complex was under the control of a major gene, and supported the suggestion from previous work that modifying genes interact with the major gene to alter the expression of the homozygous nuda genotype towards the heterozygous phenotype

Homozygous nuda and heterozygous genotypes were shown to exhibit a gradient in the expression of the nuda character complex from the apex to the base of the panicle, the nuda-type characters being most pronounced in the apical spikelets. It is suggested that the variation of character expression within single panicles of homozygous nuda and heterozygous genotypes indicates the operation of an inhibitor-type gene action rather than a mutation to loss of function.
Effectiveness of rhizobial strains with and without co-inoculants and phosphate on bengal gram (Cicer arietinum)
Authors: Maurya B. R. , Sanoria C. L.
Published: March 2009

That rhizobial strains belonging to pulses not only differ among themselves but also show differences in their effectiveness when Azotobacter isolates are used as co-inoculants has been shown by Sanoria & Ram (1979) and Sanoria & Mallik (1981). This has now been further demonstrated in trials conducted over 2 years using bengal gram. These trials also included a phosphate solubilizing bacterium (Pseudomonas spp.) as an extra inoculant but it had no effect on the responses obtained.
Enhancement of the efficiency of some insecticides against thrips and cotton leafworm by mineral oils
Authors: Moustafa Omayma K. , El Attal Z. M.
Published: March 2009

Field experiments were carried out to study the effect of a highly purified paraffinic oil on the efficiency of some insecticidal sprays used for the control of thrips and cotton leafworm. The results show that the oil used separately at the rate of 7·51/ha significantly reduced the population of thrips, but oil-insecticide combinations were superior to oil or insecticides applied alone. The mineral oil increased the efficiency of candidate insecticides against both thrips and cotton leafworm two-fold or more.
Influence of sudden temperature changes on oxygen consumption and heart rate in chickens in light and dark environments
Authors: Kampen M. Van , Mitchell B. W. , Siegel H. S.
Published: March 2009

Seven-week-old White Rock males were exposed to step-wise increases in ambient temperatures from 7·7 to 37·7 °C in light and dark environments. Heart rate decreased with increasing ambient temperature with a quadratic slope (P ≤ 0·0001). Heart rate was lower during the dark period than during the light period (P ≤ 0·06). There was a positive linear correlation between heart rate and oxygen consumption (γ = 0·997) for ambient temperatures from 7·7 to 37·7 °C.

Body temperatures began to increase significantly when ambient temperature reached beyond 27·5 °C. The increases followed a quadratic slope (P ≤ 0·0001). Body temperatures during the light period were significantly higher than during the dark period (P ≤ 0·05).
The apparent digestibility of maize grain when given in various physical forms to adult sheep and cattle
Authors: Wilson G. F. , Adeeb N. N. , Campling R. C.
Published: March 2009

A series of digestibility trials was conducted with non-lactating cows and adult castrated male sheep given diets of hay and dried or high-moisture maize grain in various physical forms. Sheep were able to digest all forms of maize well and to a greater extent than cows. In cows considerable variation in digestibility of maize was associated with the particle size of the maize and the individual animal. Maximum digestibility of dried maize in cows ensued when the modulus of fineness lay within the range 4·7–3·0 and with high moisture maize from 5·4 to 5·1. A study was made of the effect of particle size on the rate of digestion of maize suspended in nylon bags in the rumen. Evidence was presented showing the importance of rumination in ensuring the digestion of intact kernels. Possible causes of differences between cows in their ability to digest intact maize kernels are discussed.
A comparison of glutaraldehyde and formaldehyde fixation of isolated pea chloroplasts and its implications for the treatment of herbage for nutritional studies
Authors: West Janet , Mangan J. L.
Published: March 2009

Photosynthetic electron transport, osmotic volume changes and protein loss on osmotic shock were measured in isolated pea chloroplasts after treatment with a range of aldehyde concentrations at various temperatures and times. ADP+Pi-stimulated oxygen production was the most sensitive to inhibition by the aldehyde treatment. With suitable conditions, osmotic volume changes could be prevented and protein losses on osmotic shock reduced to about 1% of the control value, whilst NH3-uncoupled electron transport retained about 40% of its activity. Results showed that basal, ADP + Pi-stimulated and NH3-stimulated O2 production could be used together to indicate the extent of chloroplast fixation thus providing a way of assessing fixation in preparations where osmotic changes are difficult to measure.

Glutaraldehyde (M.W. 100) was found to be 60–80 times as effective as formaldehyde (M.W. 30), on a molar basis, in preventing osmotic volume changes and protein loss on osmotic shock.

The application of this work for the production of large amounts of glutaraldehyde fixed chloroplasts and of fixed herbage for use as a tool in nutritional studies in ruminant animals is discussed.
Comparisons of anhydrous ammonia with solid ammonium nitrate for spring barley and winter wheat 1967–70
Authors: Rodger J. B. A. , Gill W. D. , Shukla G. K.
Published: March 2009

Fourteen trials on spring barley and eleven on winter wheat, grown in the east of Scotland, compared the effects on yield of liquified anhydrous ammonia and solid ammonium nitrate at various levels of application.

For grain yield, the optimum N level in these trials was about 100–113 kg N/ha. The object of including in the trials N input levels higher than optimum was attained. Yield response to the two forms of N was similar for both wheat and barley at the different N input levels.

Winter injection of anhydrous ammonia was less efficient than spring application. Injection of anhydrous ammonia into young wheat resulted in frequent reduction of plant population and, on occasion, loss of yield.

At equivalent rates, anhydrous ammonia caused less lodging than ammonium nitrate; it also appeared to be less readily leached from the soil. Ammonium nitrate gave more rapid early growth and this led to a greater proneness to leaf disease.

Considering the complexity of storage and injection equipment required to handle anhydrous ammonia, it is questionable if these agronomic advantages justify its use on cereals where rates of use do not also confer the benefits of cheaper unit cost of nitrogen.
The effect of time of sowing and harvesting on growth, yield and nitrogen fertilizer requirement of sugar beet
Authors: Draycott A. P. , Webb D. J. , Wright E. M.
Published: March 2009

Four field experiments (1968–71) investigated the effect of changing the length of the growing period on the nitrogen fertilizer requirement of sugar beet. The crop was sown on three occasions (March–May), harvested on three occasions (September–December) and given four amounts of fertilizer (0–225 kg N/ha). Plant samples were analysed at several stages of growth (1969–71) in an attempt to predict the amount of nitrogen fertilizer needed for maximum sugar yield and also at the end of the season to determine the nitrogen uptake. Increasing the length of the growing period increased sugar yield greatly but the amount of nitrogen fertilizer needed for maximum sugar yield was unchanged. The crop given the largest dressing of nitrogen and with the longest growing period contained most total nitrogen, but in every experiment, giving more than 75 kg N/ha neither increased nor decreased the sugar yield significantly. As a result of the small variations in nitrogen requirement, the plant analyses during the growing season were of little value in predicting the needs of the crop.
The definition of milk yield and milk fractions in lactating animals
Authors: Morag M. , Sagi R. , Eyal E. , Folman Y.
Published: March 2009

There is considerable confusion in some lactation studies as to the meaning of the term milk yield. Furthermore, the various fractions of milk yield are ill defined. This note proposes a standardization of terminology on this subject. The problem is general and applies to all mammals. We will discuss it, however, in terms of the dairy sheep, the animal with which we are most familiar.
Quantitative digestion of fresh herbage by sheep: II. The sites of digestion of some nitrogenous constituents
Authors: MacRae J. C. , Ulyatt M. J.
Published: March 2009

Sheep prepared either with a rumen cannula, or with a rumen cannula plus re-entrant cannulae in the duodenum and ileum were fed fresh ‘Ruanui’ perennial ryegrass (R), ‘Manawa’ short rotation ryegrass (M) and white clover (C) at dry-matter intakes ranging from 450 to 1000 g/24 h. Paper impregnated with chromic oxide was given once daily via the rumen fistula as a marker.

Amounts of non-ammonia-nitrogen (NAN) entering and leaving the small intestine and nitrogen (N) excreted in the faeces were regressed against the intake of N for each sheep and these equations (all significant P < 0·05) were used to calculate the extent of digestion in the stomach, the small intestine and the large intestine at two levels of OM intake (500 and 800 g daily). Amino acid analyses of feed and digesta samples are also presented together with calculations of the apparent absorptions of individual amino acids from the small intestine.

At an intake of 500 g OM amounts of NAN entering the small intestine were significantly greater (P < 0·05) in sheep given M than in sheep given R or C. At an intake of 800 g OM amounts in sheep given M were significantly greater (P < 0·01) than in sheep given R. NAN leaving the small intestine and N excreted in the faeces were similar for all three diets.

At an intake of 800 g OM apparent absorptions of NAN from the small intestine of sheep given M (0·47 × N intake + 2·8 g/24 h) and sheep given C (0·51 × N intake – 1·3 g/24 h) were significantly greater (P < 0·01 and P < 0·05 respectively) than of sheep given R (0·41 × N intake – 0·5 g/24 h). As intake of herbage was increased the partition of digestion altered.

Only small differences between herbages were found in the amino acid composition (g amino acid/100 g protein) of either duodenal or ileal digesta, but because of the large differences in the flows of NAN, the apparent absorptions of individual amino acids from the small intestine were much higher in sheep given M than in sheep given the other two species.

The results are discussed in the light of available information on sites of digestion of herbage diets in sheep.
Agronomic evaluation of Stylosanthes guyanensis and its use in the diet of laying hens
Authors: Onwudike O. C. , Adegbola A. A.
Published: March 2009

The responses of Stylosanthes guyanensis (Stylo) to frequency and height of cutting and the effects of feeding increasing amounts of stylo meal on egg production, yolk vitamin A, yolk colour and percentage hatchability were studied. In the agronomic study, the higher the cutting height, the higher the total yield of dry matter, yield of crude protein, yield of carotene, percentage of crude fibre and the lower the carotene and crude-protein content. A highly significant correlation between the carotene content and crude-protein content (r = +0·91) was obtained.

The addition of stylo meal as more than 10% of the feed significantly (P < 0·01) depressed egg production. On the other hand, yolk colour, yolk vitamin A status and percentage hatchability were significantly improved with the feeding of stylo meal.
Game domestication for animal production in Kenya: activity patterns of eland, oryx, buffalo and zebu cattle
Authors: Lewis J. G.
Published: March 2009

Studies of the day-time activity of night-enclosed eland, oryx, buffalo and cattle in a hot, semi-arid area in Kenya showed that, on average, eland spent 70% of the day feeding, oryx 60% and buffalo and cattle 52%.

The distribution of activity throughout the day of all species was similar and the mobile activities of feeding and walking tended to be concentrated in the early morning and late evening.

Correlation and multiple regression analyses were used to investigate changes in the activity of the animals in relation to changes in meterological and vegetative factors. The activity of both eland and buffalo was found to be particularly sensitive to the meterological factors.

The duration of feeding for cattle and buffalo was related to the state of the vegetation, but that of the oryx was not. Similar analyses were not possible for eland.

The activity of each species could be related to mouth size, feeding habits and the effectiveness of the animals' coat in dealing with conditions of high heat load.

It is concluded that a naturally short daily feeding time and an independence of activity from the environmental heat load on the animals are advantageous characteristics for a species under domestication in a hot semi-arid environment.
Water status and yield of sunflowers (Helianthus annuus) subjected to water stress during four stages of development
Authors: Sionit N.
Published: March 2009

The effects on seed yield of two levels of water stress at four stages of development were investigated in two varieties of sunflower, Krasnodarets and Record. The plants were grown from seed in large pots in an air-conditioned glasshouse at 26/20 °C and 70% relative humidity, with natural summer illumination. They were subjected to water stress before head formation, during head formation, during flowering, and during seed development.

The leaf water potential of plants subjected to a water stress of – 16 bars returned to normal after rewatering, but plants subjected to – 23 bars did not return to their prestress level and some leaves died. A water stress of – 16 bars caused no significant reduction in dry weight of the vegetative structures, but stress at all stages of growth reduced seed yield. A water stress of – 23 bars reduced both total dry weight and seed yield at all stages of growth, seed yield being reduced more by a stress of – 23 bars than of – 16 bars. Oil content was slightly reduced by water stress.

Water stress during anthesis reduced sunflower seed yield more than during later stages of development.
The assessment of genetic variation from normal, self and backcross families of a triple test cross of pure-breeding lines in wheat
Authors: Virk D. S. , Virk Parminder S.
Published: March 2009

Normal, self and backcross families in a triple test cross were used to investigate the inheritance of number of days from sowing to flowering and dry plant weight for a population of pure-breeding lines of bread wheat (Triticum aestivum L.). Several tests of non-allelic interaction, additive genetic and dominance variances were made that involved triple test cross and single tester analyses. Non-allelic interaction was found to be a component of the genetic variation for both traits. The additive and dominance variances were prevalent for both traits. Alternative estimates of additive genetic and dominance variance components did not differ significantly when tested by a weighted least-squares model fitting procedure. The results are discussed in relation to genetic improvement of bread wheat.
A comparison of vaginal, cervical and intrauterine insemination of sheep
Authors: Maxwell W. M. C. , Hewitt L. J.
Published: March 2009

Practical systems for the artificial insemination of sheep have been available for many years (reviewed by Maxwell, 1984). The traditional method is to separate from the flock ewes exhibiting a natural oestrus as identified by ‘teaser’ rams, and inseminate these ewes with freshly collected and diluted semen. The ewes are generally inseminated by suspension of the hindquarters over an elevated rail and deposition of the semen within the first fold of the cervix using a plastic pipette, speculum and headlamp (the cervical insemination method, Salamon, 1976).
Estimation of the carcass composition of different cattle breeds and crosses from conformation assessments adjusted for fatness
Authors: Kempster A. J.
Published: March 2009

Carcass data for 1053 steers from the Meat and Livestock Commission's beef breed evaluation programme were used to examine the prediction of carcass composition from conformation-related characteristics corrected to equal fatness. The data were from four trials and comprised both dairy-bred and suckler-bred cattle by a wide range of sire breeds.

When used with carcass weight (W) and a visual assessment of carcass subcutaneous fat percentage (SFe) (the most precise simple assessment of carcass lean percentage, residual S.d. = 2·28), m. longissimus area (MLA) at the 10th rib was the most effective conformation-related assessment (residual S.d. = 2·10). Precision was improved by the further addition of a visual conformation assessment (C15) on a 15-point scale (residual S.d. = 2·06). The use of equations combining W, SFe, MLA, C15 and other simple assessments of fatness improved the precision further (residual S.d. = 1·94).

The measurement combinations above also provided a significant prediction of the percentage of total carcass lean distributed in the higher-priced joints. Residual S.d.s were: W + SFe, (1·12); W + SFe + MLA (1·07); W + SFe + MLA + C15 (1·06).

When the equations were applied to the breed means, there was substantial bias (predicted – actual carcass lean percentage). Bias ranged from approximately + 1·5 (purebred Canadian Holsteins and Luings ) to – 1·6 (Limousin crosses). The accuracy of carcass lean prediction was not improved by the addition of bone measurements to the equations but there was some improvement in the prediction of lean to bone ratio: cattle with light, thin bones tended to have higher ratios.

Similar combinations of independent variables were found to provide the most precise prediction within breed.
Field studies on the magnesium, copper and zinc nutrition of maize
Authors: Alloway B. J.
Published: March 2009

Soils from 55 maize fields in southern and eastern England were tested for available zinc, copper, magnesium and potassium by routine extraction procedures. A high proportion (64%) of the samples contained less than the recommended 50 mg/kg available magnesium, and 24% were within the deficiency range (< 25 mg/kg) for this element. Fewer sites were deficient in copper (7%) and zinc (5%) and these were mainly sandy soils or loams developed on Clay-with-Flints over Chalk. Zinc deficiency in maize does not appear to be a serious potential problem in Britain even though it occurs frequently in other countries, including parts of France.

A field of maize with growth problems of varying severity was studied in detail and the available magnesium concentrations found to correlate most closely with the degree of stunting. Soils with healthy plants differed from those in stunted patches of the crop by having higher extractable magnesium, copper and potassium contents. In general the composition of the maize leaves tended to reflect the supply status of the soil, except in the case of chlorotic plants.

The influence of factors affecting the availability of the elements investigated and the significance of marginal deficiencies of magnesium and micronutrients in maize are discussed.
Rumen fermentation patterns in sheep receiving silages of different chemical composition supplemented with concentrates rich in starch or in digestible fibre
Authors: Martin P. A. , Chamberlain D. G. , Robertson S. , Hirst D.
Published: March 2009

In each of two experiments, eight silages supplemented with concentrates containing a high proportion of either starch or digestible fibre were given to rumen-cannulated sheep. The silages constituted c. 65% of the total dry matter and differed widely in chemical composition, reflecting differences in the extent of fermentation in the silo.

Rumen pH was lower (P < 0·01 and P < 0·001 for Expts 1 and 2 respectively) and the concentration of total volatile fatty acids (VFA) in the rumen was higher (P < 0·001 for Expt 2) for the starchy concentrate. Silages differed in their effects on ruminal proportions of acetate (P < 0·001 and P < 0·01 for Expts 1 and 2 respectively) and, inversely, of propionate (P < 0·001 for Expt 1). There was evidence of a strong relationship between the molar proportion of propionate in the rumen and the concentration of lactic acid in the silage. The results indicate that the production of propionate during the metabolism of silage lactic acid by the rumen microbial population was the predominant influence on rumen fermentation pattern.

It is suggested that this relationship is the basis of some of the differences in milk production reported for silages showing restricted as opposed to extensive fermentation.
The resistance of new varieties of maize to post-harvest infestation by Sitophilus zeamais Motsch and Sitophilus oryzae (L.)
Authors: Ivbiljaro M. F.
Published: March 2009

The indices of susceptibility of five new varieties of maize: TZE 3 (3·01), TZE 4 (6·69), TZSR (5·58) developed at the International Institute of Tropical Agriculture, Ibadan, and MSRB-W (9·53) and MSC-opaque (5·0) at the National Cereals Research Institute, Ibadan, showed that the yellow variety, TZE 3, is the most resistant to post-harvest infestation by Sitophilus zeamais Motsch and Sitophilus oryzae (L.), the latterbeing the more abundant species.

Emerging F1 generation adults of either species of Sitophilusdeveloped longer, and were more numerous in soaked maize seeds without testa than in unsoaked, intactmaize seeds. Seed germinability declined as the number of holes per maize seed caused by adult insect emergence increased.
Comparative performance of Mussoorie rockphosphate, single superphosphate and their combinations in potato
Authors: Sahota T. S. , Sharma R. C.
Published: March 2009

A field experiment on an acid soil of Shillong, in 1982 and 1983, investigated the comparative performance of Mussoorie rockphosphate (MRP), single superphosphate (SSP) and their combinations for potatoes. MRP, when applied alone, proved much inferior to SSP, on an equal P basis, in tuber characters, tuber yield and nutrients (N, P and K) uptake. Application of SSP together with MRP improved the efficiency of the latter. SSP and MRP combinations in 25:75, 50:50 and 75:25 proportions, on a P basis, were 79·3, 95·8 and 101·2% as effective as SSP in terms of tuber production. The response to P was optimum at 70 kg P/ha with SSP and was linear up to the highest rate (105 kg P/ha) with the combinations of SSP and MRP. Concentration of N in tubers declined with the increasing amounts of P, whereas P and K concentrations were little affected.
Effect of simulated wet spring conditions on the relative efficiency of three forms of nitrogen fertilizer on grassland
Authors: Watson Catherine J. , Adams S. N.
Published: March 2009

There is evidence from solution culture studies that ammonium nitrogen is taken up by grass preferentially to NO3-N at low temperatures (Clarkson & Warner, 1979). In addition NH4 ions are less subject to leaching losses or denitrification (Ryden, 1982). It has been speculated therefore that ammonium N could be the best form of nitrogen for early grass, especially in wet springs. Field experiments have studied the efficiency of different nitrogen forms at the first application over a number of years (McAllister et al. 1965; Van Burg, Dilz & Prins, 1982). The yield response has tended to be variable and may have depended on climatic and soil conditions. Investigations of climatic effects on fertilizer efficiency have often necessitated long-term field studies, but it is proposed that the importance of rainfall in particular could be investigated by means of a short-term irrigation experiment. This paper reports such an experiment using irrigation to simulate a wet spring while keeping other conditions the same for all treatments.
Effects of fertilizer nitrogen on soil nitrogen availability after a grazed grass ley and on the response of the following cereal crops to fertilizer nitrogen
Authors: Webb J. , Sylvester-Bradley R.
Published: March 2009

Nitrogen nutrition of two succeeding wheat crops was studied after ploughing of grassland in July 1987 on a clay soil at ADAS Drayton. The four plots of grassland had received 100, 250, 450 and 750 kg N/ha per year for 4 years from 1984 and were grazed by beef cattle at stocking densities which varied according to grass growth.

Determinations of soil mineral N taken to 60 cm every 3 weeks from July to the following May were particularly variable. However, in the first 2 years after ploughing the means of the series of mineral N measurements were directly proportional to the amounts of fertilizer N applied to the grass.

N offtake in winter wheat grain without fertilizer N was directly proportional to fertilizer N applied to grass but this had little effect on maximum grain yields. Large soil N supplies did not necessarily predispose the wheat crops to large grain N concentrations because fertilizer N caused grain N offtake to reach a similar maximum, irrespective of previous grass N.

Optimum amounts of fertilizer N for the wheat were 188, 147, 87 and nil kg/ha in 1988 and 152,130, 89 and 25 kg/ha in 1989 after 100, 250, 450 and 750 kg N/ha per year applied to the grass. Soil N supply as indicated by both the amount of fertilizer applied to grass and means of mineral N measurements accounted for almost all of this variation. Mean soil mineral N over winter was no better as an indicator of soil N supply than the amount of N applied to the grass. However, before adopting N applied to grass as a more general index of N supply, it would need to be adjusted for variation in N removed and lost during grass growth; these were controlled in this experiment.
Diallel analysis of competition between diploid and tetraploid genotypes of Secale cereale grown at two densities
Authors: Norrington-Davies J. , Hutto Janice M.
Published: March 2009

Two inbred diploid lines of Secale cereale L. and their derived tetraploids were grown together with a commercial diploid and tetraploid in all possible pair combinations in a pot experiment. Comparisons between lines and varieties were made in respect to dry weight measured at 30 weeks.

The competitive effects within mixtures were not compensatory, the commercial varieties tending to increase in dry weight more than the homozygous inbred lines decreased. This gave rise to mixture means which tended to exceed their mid-constituent values.

The analysis of reciprocal differences in dry weight showed that the effects of competition between any one genotype and its associate in mixtures were constant (alpha competition), the sign and magnitude of the alpha effect being related to the pure stand values of the genotype.

The mean effect of competition was to increase the difference in dry weight between genotypes by 2·108 g for each gram by which the genotypes differed when grown alone. In each case the values for genotypes with the higher dry weight increased in mixture whereas the values for those with lower dry weights decreased.

Not surprisingly, the commercial varieties were found to be better competitors than the inbred lines, but of more interest was the ineffectiveness of chromosome doubling on competitive ability. Under the conditions of density and fertility reported here, the tetraploid inbred lines could not be distinguished from their diploid progenitors either in their competitive ability or in their reaction to increased density when grown in mixtures. The same is true for the tetraploid and diploid commercial varieties.
Adjustment factors for weaning weights of Mashona cattle in Zimbabwe
Authors: Buvanendran V.
Published: March 2009

The effects of year of birth, age of dam, sex of calf, month of birth and weaning age on weaning weights of Mashona calves on six commercial farms in Zimbabwe were estimated by least squares procedures from data of 6365 calves born 1977–85. The least squares mean weight at 205 days among farms ranged from 123 to 159 kg while the linear regression coefficients of weight on age ranged from 0·31 to 0·46 kg. Adjustment for weaning age by the average daily gain from birth to weaning failed to remove the dependence of adjusted weight on age. Sex was the most important source of variation and the mean difference between male and female calves was 12·9 kg. Sex difference was markedly influenced by herd production rate, being greater in herds of above average production.

Weights of calves of 3-, 4- and > 11-year-old dams deviated from those of dams aged 5–10 years (mature) by 14·5, 8·5 and 2·9 kg, respectively. Herd mean influenced the difference between 3-year-old and mature dams, the difference increasing as herd mean declined. Herd-year specific factors seem more appropriate for sex and 3-year-old dams and an annual crop of > 50 calves would confer an advantage to herd-specific over general adjustment factors. On the basis of equality of variances within subclasses, multiplicative factors were superior to additive factors for sex of calf and month of birth; both types of adjustment were suitable for age of dam.