bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of microdigestion techniques under range and drylot conditions
Authors: Van Dyne G. M. , Weir W. C.
Published: March 2009

The nutritive evaluation of range forages often is limited by the size of the forage sample available, by the difficulty of determining both the quantity and quality of the forage eaten, and by the labour and other costs of making total faecal collections in digestion trials under range conditions. Microdigestion techniques utilizing either the nylon bag in the rumen (hereafter referred to as nylon bag in vivo) and artificial rumen techniques (hereafter referred to as in vitro) have been reviewed by Annison & Lewis (1959), Barnett & Reid (1961), and Johnson (1963). Forage evaluation could be greatly simplified if such microdigestion techniques could be utilized under range conditions. Following preliminary studies (Van Dyne, 1962), the research reported in this paper was undertaken to evaluate these techniques under both range drylot conditions in studying the intake and digestion of forages. Other aspects of these trials are reported elsewhere (Van Dyne & Weir, 1964; Van Dyne & Meyer, 1964; Van Dyne & Lofgreen, 1964; Van Dyne & Heady, 1965a, b).
Resistance to eyespot disease (Cercosporella herpotrichoides Fron) determined by a seedling test in some forms of Triticum, Aegilops, Secale and Hordeum
Authors: Macer R. C. F.
Published: March 2009

A screening technique is described for determining the resistance of seedling cereal plants to Cercosporella herpotrichoides by observing the rate of penetration of successive leaf-sheaths by the pathogen pathogen growing from an artificially colonized 'cylinder' of straw placed over the emerging coleoptile.
The effects of grinding, supplementation and incubation period on cellulose digestibility in vitro and its relationship with cellulose and organic matter digestibility in vivo
Authors: Wilkins R. J. , Minson D. J.
Published: March 2009

The in vitro cellulose digestibility of thirteen cuts of perennial ryegrass, cocksfoot and two varieties of Rhodes grass was determined under different conditions. Cellulose digestibility was increased by increasing the length of the incubation period (1,2 and 6 days), the fineness of grinding of the samples and by addition of a supplement. The effects of fineness of grinding and of supplement were greatest after incubation for 1 day and least after 6 days. Between-run variation in cellulose digestibility was reduced by the supplement and by increasing the length of the incubation period.

In a comparison of different methods of predicting in vivo organic matter digestibility the lowest residual standard deviation ( ± 2·29) was with in vitro organic matter digestibility (1 mm screen and incubated with supplement for 2 days). Other residual errors were: in vitro cellulose digestibility ± 2·40, pepsin-soluble organic matter ± 4·93, total available carbohydrate ± 6·39, cellulose ± 6·40 and nitrogen ± 6·46.
The effect of a nitrification inhibitor on the concentration of nitrate in plants
Authors: Nowakowski T. Z. , Gasser J. K. R.
Published: March 2009

Calcium nitrate, or ammonium sulphate without or with 1% of the nitrification inhibitor 2-chloro-6 (trichloromethyl) pyridine were applied in the spring to winter wheat growing on clay- and sandyloam soils; 50 or 100 lb N/acre was applied on the clay-loam and 75 or 150 lb N/acre on the sandyloam. On permanent grassland ammonium nitrate or ammonium sulphate without or with 1 or 2% of inhibitor were broadcast to supply 100 or 200 lb N/acre. Winter wheat was sampled 32 days, and grass 68 days after applying fertilizers. Ammonium sulphate increased nitrate in the wheat on the clayloam soil but significantly less with than without the inhibitor. On the sandy-loam, wheat given ammonium sulphate with and without the inhibitor contained similar amounts of nitrate-N. The double amount of ammonium sulphate without inhibitor increased the nitrate content of grass most, and the nitrate content decreased with increasing amount of inhibitor.
The lipolysis and hydrogenation of lipids in the digestive tract of the sheep
Authors: Bath I. H. , Hill K. J.
Published: March 2009

1. The flow of digesta in the duodenum and the changes in the lipid composition of ruminal and duodenal digesta of sheep accustomed to receiving hay and oats, hay and palm oil and hay and tallow have been studied.
Calorimetric studies on the utilization of dietary energy by the laying White Leghorn hen in relation to plane of nutrition and environmental temperature
Authors: Waring J. J. , Brown W. O.
Published: March 2009

1. Calorimetric experiments on the utilization of dietary energy by the laying White Leghorn hen are described.
Sodium and potassium in pig muscle
Authors: Lawrie R. A. , Pomeroy R. W.
Published: March 2009

1. The sodium and potassium content of longissimus dorsi (lumbar), psoas major, rectus femoris, triceps (lateral head) and extensor carpi radialis from 6 pigs each at pork, bacon and manufacturing weights were determined: these varied significantly and systematically between muscles and between groups.

2. Since the concentration of potassium may differ by at least 30% between muscles, it is concluded that assessment of total muscle mass may be inaccurate if based on the integration ofγ-ray emission from 40K.
Plasma lipids of newborn and adult ruminants and of lambs from birth to weaning
Authors: Leat W. M. F.
Published: March 2009

The plasma lipid concentrations of newborn lambs, kids and calves and of adult ruminants in 0various physiological states have been reported. In newborn ruminants plasma lipid concentrations were 20–40 % of those found in their dams at parturition.

The concentrations of blood lipids have also been estimated in five lambs from birth to weaning at 90 days post partum. The plasma free fatty acid concentrations rose to a maximum at about 45 days post partum and then declined. Possible reasons for this elevation in plasma free fatty acids have been discussed with reference to published data on age changes in lambs of plasma glucose and volatile fatty acid concentrations. The concentration of plasma esterified lipids, mainly phospholipids and cholesterol esters, were very low at birth and rose to reach maximum values at about 20 days post partum before declining to adult values at weaning. These changes have been discussed in relation to diet and rumen development.
High level cereal diets for the growing/finishing pig: II The effect of cereal preparation on the performance of pigs fed diets containing high levels of maize, sorghum and barley
Authors: Lawrence T. L. J.
Published: March 2009

(1) In a 3×2 factorial experiment sixty Large White type weaner pigs (30 hogs and 30 gilts) were individually and restrictedly fed to 200 lb live weight, six diets (as wet mashes) containing 70 % of either maize, sorghum or barley, each cereal having been processed by either crimping or grinding prior to inclusion in its respective diet. A further two groups of six litter-mate hog pigs per group were used to measured the digestibility of and the nitrogen retention from these six diets at approximately 50, 110 and 190 lb live weight.

2. Grinding gave significantly better digestibility than crimping, the ground diets having significantly higher digestible energy contents than the crimped. Between cereals the order of significant decreasing digestible energy content was from maize to sorghum to barley dietary treatments.

3. There were no significant differences between cereals in nitrogen retention. Between processing treatments grinding, in terms of g. retained per kg live weight per day, gave a significantly higher value than crimping, at 107 lb live weight.
Retention of calcium, phosphorus, magnesium, sodium and potassium by the developing sheep foetus
Authors: Field A. C. , Suttle N. F.
Published: March 2009

1. Data on the fresh weight, mineral and fat composition of foetuses from Border Leicester / Cheviot ewes were obtained for seven singletons, fourteen sets of twins and four sets of triplets. The age of the foetuses ranged from 80 to 144 days. The foetuses were dissolved individually in concentrated nitric acid and the mineral composition of the resultant solution determined.
The effect of cold exposure on wool growth in Scottish Blackface and Merino × Cheviot Sheep
Authors: Slee J. , Ryder M. L.
Published: March 2009

(1) Nine Scottish Blackface and four Merino × Cheviot ewes were shorn and given an acute cold exposure (at approximately −18 °C) in climate chambers. Individual exposures lasted up to 10 h. Because they were shorn, the sheep subsequently received 4 weeks of mild cold exposure, although kept indoors at an ambient temperature between + 8 °C and +15 °C. Skin and wool samples were taken before and after treatment. Twelve unshorn control ewes were also sampled.

(2) Wool production in the Blackface sheep was depressed following the treatment, and this was accounted for by a reduction in both the mean length and the mean diameter of the wool fibres.
The artificial rearing of calves and their growth on grass diets: II. The effect of length of period of feeding cold milk substitute to spring–born calves at pasture
Authors: Lonsdale C. R. , Tayler J. C.
Published: March 2009

An experiment was conducted with 32 spring-born Friesian heifer calves, purchased at an average age of 10 days and fed on cold reconstituted milk substitute at pasture.

The milk feeding treatments were 4, 4½, 6½ and 9½ weeks in length, during which time calves consumed an average of 17, 23, 43 and 70 kg dry matter/head of milk substitute respectively. The differences between treatment mean live-weight gains for 10½ weeks of the experiment were highly significant (P < O·OOl): the gains were 0·49, 0·43, 0·64 and 0·78 kg/head/day. There was no significant difference between mean rates of live-weight gain after the tenth week so that the overall treatment—mean live-weight gains for the first 23 weeks, which were 0·65, 0·61, 0·72 and 0·74 kg/head/day, strongly reflected the length of the milk-feeding period and demonstrated no significant compensatory growth by the calves.

Twenty of these animals were housed for the subsequent winter period and were returned to pasture for a second grazing season. These were artificially inseminated as their individual live weights reached approximately 320 kg. Animals weaned after only 4 weeks of milk feeding took an average of 9½ weeks longer to reach live weights of 320 kg than these receiving milk for 9½ weeks. There were no marked indications of compensatory growth during this extended period of observations.
The in vitro digestion of roughage dry matter
Authors: Walker D. M.
Published: March 2009

1. An in vitro apparatus is described for measuring the percentage dry-matter digestibility of roughages.

2. Samples of hay, dried herbage, oat hay and oat straw were tested in vitro and the values obtained compared with in vivo results obtained with sheep.
The minimum amount of white-fish meal required to supplement the proteins in some vegetable-protein concentrates
Authors: Evans R. E.
Published: March 2009

It was shown in previous work (Evans, 1958) that a cereal diet supplemented with 7% of white-fish meal supplied around 0·76% of lysine and 0·5% of methionine plus cystine. The addition of more pure l-lysine monochloride or dl -methionine to this animal-protein diet failed to bring about any significant improvement in the rate of growth, efficiency of food conversion or in the nitrogen retention of the pig, in the critical period between weaning and 80 lb. live weight. When the same cereal diet was supplemented by as much as 20% of ex. dec. ground-nut meal, however, the lysine content amounted to only 0·62% but the methionine plus cystine was 0·53%. On adding 0·2% l-lysine plus 0·2% dl-methionine to the 20% ground-nut diet the utilization of the nitrogen in the food was improved and the excretion of nitrogen in the urine was reduced. This finding was confirmed by means of a statistically designed growth trial, the daily rate of live-weight gain, improving from a mean value of 0·86 to 0·98 lb. following the addition of 0·2% of lysine and methionine, respectively, to the diet, the corresponding saving in meal consumption, between 35 and 80 lb. live weight, amounting to 16 lb. One group of ten pigs received a supplement of 0·2% of methionine only, and since it failed to show any improvement in performance over the control group it was concluded that 0·5% of methionine plus cystine must suffice to support satisfactory growth.
Lucerne investigations IV. Effect of germination and seed rates on establishment, mortality and yield of dry matter and protein per acre
Authors: Zaleski A.
Published: March 2009

The experiment with two trials was carried out to determine the effect of low and high germination and three seed rates of lucerne on the establishment, mortality, and yield of fodder on heavy soil at Cambridge during 1955–8.

Highly significant differences were obtained between seed rates and germinations in the number of plants established in the year of sowing. The highest number of plants with thin and short tap roots were in a dense crop at 15 lb./acre and 83% of them were unable to survive the first winter. The highest mortality occurred between sowing and the first harvest year, and the heaviest loss of plants was in the lucerne drilled at 15 lb./acre and lowest at 5 lb./acre. Interaction between germination and seed rates was significant at 1% level in the first and at 5% level in the second count only.

The highest differences in yield results were in the first harvest year, when a significantly lower yield was obtained at 5 lb./acre than at 10 or 15 lb./acre, but there was no significant difference in yield between 10 and 15 lb./acre. Lucerne with a high germination at all seed rates gave significantly higher yields than lucerne with a low germination in both trials.
The development of the digestive system of the young animal III. Carbohydrase enzyme development in the young lamb
Authors: Walker D. M.
Published: March 2009

1. Twelve lambs varying in age from 5 to 35 days in age were slaughtered and their carbohydrate-digesting enzymes studied for any change in activity with increase in age.

2. Results are given for the changes in weight of different parts of the digestive organs and their contents, and for the content of NaCl and of total acidity in the abomasum contents.

3. Pancreatic and small intestine amylase showed only a slight increase in activity up to 5 weeks of age.

4. Lactase and maltase activity in the small intestine were almost constant from 1 week to 5 weeks of age.

5. No sucrase activity was measurable in any of the lambs slaughtered in either the small intestine wall or its contents.

6. A comparison was made between the carbohydrase activity of the young pig and the lamb.

7. Calculations based on the enzyme activities of the tissues showed the theoretical amounts of different carbohydrates which can be digested by lambs and young pigs of varying age groups.

8. The results suggest that the young lamb is dependent on the early development of its rumen fauna and flora for the utilization of all other carbohydrates except lactose and glucose.
The development of the digestive system of the young animal IV. Proteolytic enzyme development in the young lamb
Authors: Walker D. M.
Published: March 2009

1. The digestive organs and contents of twelve lambs, varying in age from 1 to 5 weeks, have been examined for their proteolytic enzyme activity at pH 1·8, 3·5 and 8·5.

2. Enzyme activity at 1·8 was present only in the abomasum and its contents.

3. All tissues and contents examined were active on haemoglobin at pH 3·5.

4. Small intestine contents and pancreas alone were active on azocasein at pH 8·5.

5. The majority of tissues and contents increased their proteolytic activity with increase in age. The abomasum wall, however, increased in activity up to 21 days and thereafter decreased, both at pH 1·8 and 3·5.

6. Milk-clotting action was measured on abomasum wall and contents. There was an absence of milk clots in the abomasum after 21 days, by which time rumen function had commenced.
An evaluation of Merino wool quality:I. The incidence of coarse fibres in two Australian Merino flocks
Authors: Gallagher J. R. , Yeates N. T. M.
Published: March 2009

The fibre length and diameter distributions of the wool of two Merino flocks were evaluated at the neck, mid-side and breech positions, to determine the incidence of fibres which were off-type by reason of excessive length, diameter or possession of a medulla.

The ranges of fibre lengths for 10·5–11·0 months' growth were 1·0–17·5 cm. in flock 1 and 1·0–16·5 cm in flock 2. There was no evidence of a bi-modal length distribution in either flock.

Fibre diameters at 15–16 months were observed in the range 6–69 μ in flock 1 and 5–52 μ in flock 2. Medullated fibres ranged from 7 to 50 μ in flock 1 and 5–64 μt in flock 2. The incidence of medullation increased in an antero-posterior direction from 0·17 to 0·28% in flock 1 and 0·11 to 0·28% in flock 2.

Tests for homogeneity of variance were applied to the estimates of fleece characters in this study as well as estimates of other workers. From these comparisons it is suggested that sheep in the present study are representative of the Merino breed in staple length, fibre diameter and to a lesser extent crimp frequency. The considerable between-animal variation in the observed incidence of medullation should aid in selection against that character with a consequent improvement in wool quality.
Nutritional stress and pre-implantation embryonic mortality in Merino sheep, 1967
Authors: Edey T. N.
Published: March 2009

Three groups of mature Merino ewes, balanced for body weight and number of ovulations, and totalling 122 animals, received the following treatments subsequent to mating to fertile rams: 1. approximately half maintenance requirements from day 7 to 37; 2. approximately half maintenance requirements from day 7 to 37, plus 10 mg progesterone daily from day 20 to 37; 3. control.

The ewes, which were in fat condition, had a mean ovulation rate of 121·3 %; except during the submaintenance period, they gained weight throughout pregnancy.

The percentages of ova not represented by lambs at term were 34·7, 46·0 and 42·6 in groups 1 to 3 respectively, the differences being non-significant. Detailed examination of the cycle length data of ewes returning to service suggests that some embryos may have been killed by the submaintenance treatment. Progesterone treatment was not beneficial, nor did its sudden withdrawal on day 37 appear to be detrimental to foetal survival. In a sample of ewes slaughtered on day 37, adrenal gland weights were significantly lower in the two treated groups.

Significantly higher losses of ova occurred among twin than among single ovulators and there was some evidence that this was non-random. There was no significant relationship between prenatal mortality and body weight at mating.
The effect of mixing ejaculates from different bulls on motility characteristics and acid production of the spermatozoa in a constant environment
Authors: van Duijn C.
Published: March 2009

Motility characteristics of bull spermatozoa in mixed ejaculates of different bulls were compared with those of the unmixed samples after 40-to 50-fold dilution with clarified standard egg-yolk—citrate buffer (pH 6·80 ± 0·05 at 37° C., 6·75 ± 0·05 at 22–23° C).

Using the photo-electric equipment described by Rikmenspoel (1957b) and by Rikmenspoel & Van Herpen (1957) the mean velocity , the number of spermatozoa passing by a constant spot per time unit n, the total number of spermatozoa moving normally N, the velocity decrease with time ( — d/dt), the half-life period of the number of passages per time unit t½(n) and the half-life period of the total number of spermatozoa moving normally t½(N) were determined. For none of these characteristics was any statistical difference found between the actual results and the expected values based on calculation from the data obtained with the unmixed ejaculates.

Acid production was investigated by accurate determination of pH change on incubation of samples diluted ten times with standard egg-yolk—citrate buffer containing 736 mg. added fructose per 100 ml. Again there was no statistical difference between the values found with the mixed semen samples and the expected values.

It is concluded that differences observed by other authors must be due to the effect of environmental factors, i.e. to the semmal plasma, for which there is analogous evidence in human sperm physiology.
The post-natal growth of the visceral organs of the lamb Part II. The effect of diet on growth rate, with particular reference to the parts of the alimentary tract
Authors: Wardrop I. D.
Published: March 2009

1. A study was made of the effects of diet on the growth of the internal organs, and in particular the four stomachs of lambs.

2. A total of twenty-three lambs was reared from birth on various diets ranging from all milk to small amounts of milk and roughagead lib.The lambs were slaughtered at various ages and the fresh wet weights of the parts of the alimentary tract and the other internal organs were recorded.

3. The growth rates of the four stomachs were influenced by the plane of nutrition, however, the type rather than the plane of nutrition was more important in determining the weights of the stomachs relative to each other and to live weight.

4. Lambs fed solely milk from birth had the development of their fore-stomachs retarded at about the level found in the 3-week-old grazing lamb. The abomasums of these lambs were abnormally heavy.

5. The rumens and reticulums, which were retarded in their growth by milk feeding, reached normal proportions very quickly once roughage was fed.
Studies of the effects of manuring and season on the yield and chemical composition of the cattle cabbage
Authors: Jones D. J. C.
Published: March 2009

1. Ten manurial treatments were applied annually to cattle cabbage grown in a six-course rotation for 7 years. Samples were taken in the early winter each year, and from five harvests taken at fortnightly intervals in the last year.

2. The dry-matter yields each year closely followed the weather conditions during the growing season. There was no significant fall in the dry-matter yield during the last season. The treatments supplying phosphorus or phosphorus and potassium substantially increased yield, but the application of nitrogen did not.

3. The application of nitrogen, potassium or phosphorus increased the levels of these constituents in the crop in practically all cases. The application of phosphorus produced hearted plants which contained significantly less dry matter than the openleavod plants produced in its absence. The levels of ether extract, crude fibre, ash, silica and magnesium wore not significantly affected by the manorial treatments.

4. There was little variation in composition as the season advanced except for significant increases in the crude-fibre levels and decreases in the nitrogen-free extractives levels.

5. The distribution of the chemical components was investigated in the outer leaves, heart leaves and stem of the plant. This was compared with that in the marrow-stem kales.

6. The chemical composition of the cattle cabbage compares fairly closely with that found for the marrow-stem kales grown under similar conditions. It is, however, lower in dry matter, crude fibre, magnesium and chlorine. It may be considered as a replacement for marrow-stem kale as a source of crude protein and all the major minerals except chlorine and possibly magnesium.
Studies on the production of beef from zebu cattle in East Africa I. A description of the Muguga herd
Authors: Lampkin G. H. , Lampkin K.
Published: March 2009

1. The formation of a herd of Northern Frontier Zebus for genetical research has been described.

2. Details are given of the system of mating used and the type of management adopted.

Thanks are due to Dr J. W. B. King of the Animal Breeding Research Organization, Edinburgh, for his advice, to Mr M. A. Witcomb for taking the photographs, and to the Directors of the East African Veterinary Research Organization and the East African Agriculture and Forestry Research Organisation for their encouragement.
A comparison of the efficiency of food utilization for egg production of some inbred lines of Brown Leghorn fowls
Authors: Bolton W.
Published: March 2009

1. The efficiency of food conversion of Brown Leghorn fowls inbred for egg number, or egg size, or egg number and egg size have been compared.

2. Comparison between the lines was made for egg numbers, total egg weight and total egg energy. Egg energy was the best measure of production, total egg weight was the next best and egg number the poorest.

3. When allowance was made for differences in rates of egg production and egg size, there were no differences in the efficiency of conversion of food to eggs between the lines.

4. The standard errors of the means for the analytical data on the twelve replicate mixes of the diet were relatively small, but the range in values was appreciable. The importance of analysing diets in nutrition experiments is stressed, particularly for ‘iso-caloric’ diets.
The influence of aureomycin on chick-rearing results using East African feedingstuffs with special reference to importance of experimental design for accurate statistical analysis
Authors: Trail J. C. M. , Casley D. J. L.
Published: March 2009

Groups of Rhode Island Red chicks were fed a mash made up from East African feedingstuffs or that diet supplemented with a high level rate of aureomycin—97 g. aureomycin hydrochloride per ton of feedingstuff. The chicks were kept on wire for 8 weeks. The initial improved growth rate of the chicks fed the aureomycin supplemented feedingstuff was not maintained, nor was there any statistical indication that the addition of aureomycin improved the feed conversion rate.

Although the mortality rate appeared to be very much lower in the chicks fed the aureomycin supplement, the evidence was too limited to allow this to be attributed solely to the effects of the aureomycin.

The experiment illustrates the need for careful design in order that the effect of the factors to be tested may be separated from the effects of other factors contained in the experiment and not confounded with them. Moreover, advanced statistical analysis should be used as an invaluable aid to, but not a substitute for, visual or graphical examination of results, for such examination often yields valuable indications of possible lines of analysis and may avoid the drawing of unjustified conclusions.
Genetic relations between carcass fat and body weight in mice
Authors: Hull P.
Published: March 2009

Three different stocks of mice were selected for five generations for high body weight at 3, 4½, or 6 weeks of age. Changes in body weight at the three ages and in abdominal fat weight, an index of carcass composition, which occurred in the three lines were compared. It was found that the proportion of fat in the carcasses of the selected animals increased markedly in the lines selected for high 3-week weight, while in the other two lines the proportion remained the same as that in the control line.

The theoretical treatment of the genetic relationship between body weights at different ages and between body weight and abdominal fat was reasonably adequate in accounting for the correlated responses actually observed.
The effect of environmental temperature on the energy metabolism of cattle
Authors: Rogerson A.
Published: March 2009

1. A relatively inexpensive closed-circuit respiration chamber for cattle is described.

2. Experiments with two steers are reported in which heat production and energy retention data were measured at different levels of food intake and at different environmental temperatures.

3. The energy lost in faeces increased with improving plane of nutrition but was not significantly affected by the environmental temperature. Urine energy losses fell with increasing environmental temperature at low planes of nutrition. Methane losses increased with improving nutritional plane but were reduced by high environmental temperatures at high levels of food intake.

4. The heat production of fasting animals, or animals on low planes of nutrition was not influenced by the environmental temperature in the range 20–40° C. On higher planes of nutrition an increasing environmental temperature increased the animals' heat production.

5. The major factor determining energy retention in different environments is the heat production of the animal. Net energy values consequently vary with temperature.
Effect of age and carbon-dioxide concentration on assimilation by detached leaves of tea and sunflower
Authors: Barua D. N.
Published: March 2009

A simple method has been described for measuring photosynthesis of detached leaves.

The reduced rate of photosynthesis of the tea leaf, immediately after excision, is due to stomatal closure. In mature detached leaves, kept well supplied with water in diffuse light or darkness and in a humid atmosphere, normal stomatal opening and maximum photosynthetic rates were obtained between 12 and 30 hr. from excision. Stomata on sunflower leaves do not close on excision.

Variation in the initial concentration of CO2between 1·0 and 4·0% vol. with a final concentration not below 0·5% did not affect the rate of photosynthesis of sunflower leaves at 25° C. and under 32 klux light intensity. Under the same conditions of light and temperature, there was no change in the photosynthetic rates of tea leaves in 1 and 2% initial and 0·2% final CO2concentrations. There were indications that CO2concentrations below 1·0% might be rate-limiting for certain tea leaves, assimilating under low light (4 klux).

The development of photosynthetic capacity in the young leaves of tea and sunflower is a gradual process. In sunflower, the photosynthetic capacity develops fully before, and in tea after the leaf reaches half its final size.
The measurement of yield, voluntary intake and animal production of tropical pasture mixtures
Authors: Olubajo F. O. , Oyenuga V. A.
Published: March 2009

The consumption of three different tropical pastures by the conventional clipping method and by the nitrogen–chromic oxide technique were assessed and compared over a 2-year period. The clipping method was found to give consistently higher estimates of consumption of herbage dry matter by grazing steers than the chromic oxide method by approximately 16, 14 and 25% respectively for treatments E (Gynodon + Centrosema), F (Mixture E + Stylosanthes) and G (Digitaria + two legumes), when data for the 2 years were pooled for each treatment.

The mean live-weight gain over the 2-year period was 0·19 kg per head per day. This figure is essentially in agreement with that obtained for the same group of animals in the previous 2 years. As would be expected the lowest gain was recorded during the dry season when there was little or nothing to graze. It was similarly observed that during a severe attack of trypanosomiasis the animals sustained some losses even though there was abundant pasture to graze.
Application of split-root technique in orthoposphate absorption experiments
Authors: Kalra Y. P.
Published: March 2009

The absorption and translocation of phosphate by roots of intact seedlings of rape, oats, flax and buckwheat were studied. Two hydroponic experiments were conducted in the greenhouse. A split-root technique was used in which a single root of the culture plants was grown in one solution and the rest of the roots in another solution in a twocompartmented glass jar.

The presence of other nutrients had a favourable effect on root growth and was essential for efficient phosphate absorption. There was a positive relation between the extent of root growth and phosphorus uptake. On the basis of unit weights of a single root, rape was not any better than oats and buckwheat. A single root of rape, in the presence of other nutrients, absorbed two-thirds of the phosphorus absorbed by all the other roots, whereas single roots of buckwheat, oats, and flax were much less efficient than the rest of the roots. In the absence of other nutrients, single roots of buckwheat, rape and oats absorbed 4·61, 0·18 and 3·49%, respectively, of the phosphorus supplied. However, in the presence of other nutrients, the corresponding values were 21·68, 43·86, and 7·62%, respectively. Both in the presence and absence of other nutrients the single root of flax did not absorb phosphorus from solutions high in phosphate. The results indicate that the age of the plant has an important bearing on the uptake and translocation of phosphorus.
Multiple sire mating in swine; evidence of natural selection for mating efficiency
Authors: Sumption Lavon J.
Published: March 2009

Evidence of natural selection for certain aspects of mating efficiency in swine are advanced based on preliminary studies with thirty-one sires, fiftyeight dams and their progeny. Selective fertilization was conclusively demonstrated. Variations in male and female mating behaviour were sufficiently large to indicate considerable non-randomness of mating frequency under the conditions of multiple sire mating (i.e. group exposure of dams to selected sires). The combined effects of the separate phenomena of selective fertilization and mating behaviour are discussed in relation to their evolutionary significance in animal breeding.
The absorption of subcutaneously implanted thyroxine in the sheep
Authors: Lewis D.
Published: March 2009

1. Pellets of L-thyroxine (30 mg.) were implanted subcutaneously in sheep. The loss in weight of the implants and the plasma P.b.i. level were determined at intervals.

2. The P.b.i. concentration increased within a few days from a normal value of around 5 μg./100 ml. to one of 15–20 μg./100 ml. After 10–20 days the concentration slowly returned to normal, and at 70 days subsequent to implantation was only slightly above the normal level.
The effects of time of ploughing and time of drilling on the development and yield of the winter wheat crop following a clover ley
Authors: Hanley F. , Jarvis R. H. , Whitear J. D.
Published: March 2009

1. Two experiments designed to investigate the effects of different times of ploughing a clover ley on the growth and yield of the subsequent winter wheat crop are described and the results discussed.

2. Although the different times of ploughing led to considerable differences in the growth of the wheat, their effect on yield was not consistent. This in agreement with the results of an earlier series of experiments. The effects of time of ploughing are attributed mainly to the resulting differences in the physical condition of the seed-beds.
Studies on the habits of Zebu cattle VI. The results on different pastures
Authors: Harker K. W. , Rollinson D. H. L. , Taylor J. I. , Gourlay R. N. , Nunn W. R.
Published: March 2009

The data collected during 26 days of cattle watching have been examined. Differences in the distribution of the habits, and of the length of time spent on each habit, larger than those recorded by other workers, are given. Possible explanations for these differences are discussed; part of the variations may have been caused by individual behaviour, and part by changes in climatic conditions. It is concluded that the major cause of variation is the difference between the herbage quantity and quality on the different pastures.
Growth and performance of cotton in a desert environment: I. Morphological development of the crop
Authors: Hearn A. B.
Published: March 2009

Variety, sowing date, irrigation water and plant spacing were the variables in five experiments over three seasons in southern Arabia. The results are used to develop the idea that morphological change and increase in dry weight—two aspects of the growth of cotton which are often studied separately—must be linked to explain or predict crop performance.

A straight line related the number of flower buds counted at any time to the number of mainstem nodes on a plant. The mainstem was therefore a simple parameter for the effect of age, temperature and water on the development of plant structure. The relationship was explained by a model in which fruiting branches compete with one another. The structure of the crop plants, as measured by the types and number of nodes, developed along a course in time determined by variety and spacing at a rate dependent on temperature. The rate decreased with age, but was independent of the quantity of water available, until a critical amount had been used, when development stopped abruptly.

Accumulated day degrees accounted for the differences between dates of sowing in the subsequent production of nodes. This relationship was consistent with work on temperature elsewhere. Date of sowing effected the position of the first fruiting branch in the variety Bar XL 1 but not in Wild's Early. The position of the first fruiting branch and spacing affected the number of vegetative branches. Wider spaced plants produced flower buds faster only because they had more fruiting branches, a result in turn of more vegetative branches. The ratio between the mean rates of production of nodes on vegetative branches, and on fruiting branches were varietal constants and agreed with results elsewhere in contrasting conditions.
Rapid changes in nitrite after gamma irradiation of fresh soils
Authors: Cawse P. A. , White T.
Published: March 2009

Increases in nitrite in ten gamma-irradiated soils have been investigated under aerobic conditions up to 7 days after treatment over the range 0·25–2·5 Mrad. The formation of nitrite showed significant correlations with the percentage of soil inorganic carbon and incubation time, and over 100 ppm nitrite-N accumulated within 3 days in Broadmoor series, which contained the most inorganic carbon. Only the very acid series failed to produce nitrite, but formation and persistence was poor in all soils below pH 7.

Leaching with ammonium or nitrate ions after irradiation suggested that microbial reduction of nitrate was the mechanism responsible for nitrite accumulation, rather than inhibition of nitrite oxidation.
Complete diets given ad libitum to dairy cows: the effect of straw content and of cubing the diet
Authors: Owen J. B. , Miller E. L. , Bridge P. S.
Published: March 2009

Twelve Friesian cows were given six complete diets ad libitum in an experiment designed as a double 6 × 6 Latin Square balanoed for residual effects. The main energy components of the diets were rolled barley and 20, 35 or 50% chopped barley straw. The diets were given either as a loose mix or extruded through a fin. die. Dry-matter intake, milk yield and solids not fat % declined while butter fat % increased progressively with increased levels of straw in the complete diets which were fed in the loose form. In comparison with the loose diet containing 20% straw, the corresponding cubed diet was associated with a depression in dry matter intake and a decreased butterfat %. In contrast, the oubed diets containing 35 and 50% straw supported higher dry-matter intakes, higher solids oorrected milk yield but lower butter fat % than the corresponding loose diets. The effect of cubing the 35 and 50% straw diets was to make the voluntary dry-matter intakes and lactational performances comparable to those obtained with the loose mixes containing 20 and 35% straw respectively. In general the voluntary intake data agrees with a previously proposed model. However, the depressed intake obtained with the 20% straw diet in the cubed form would not have been predicted by the model. It is suggested that complete diets could be used in large units to combine the low labour costs of self feeding of dry feed with a high degree of control over nutrient intake and laotational performance.
Growth rates and crop morphology in vernalized and non-vernalized swards of perennial ryegrass in spring
Authors: Davies Alison
Published: March 2009

Relative growth rates in swards of vernalized plants of perennial ryegrass were one and a half times as great as those found in swards of comparable non-vernalized material. This difference was associated with changes in the distribution of the products of photosynthesis and differences in the scale of losses of dead matter. Changes in sward geometry appeared to be of less importance.
A note on observations on the effect of photostimulation and hormone treatment on the oestrous activity and lambing performance of North Country Cheviot ewes
Authors: Robinson J. J. , Gill J. C.
Published: March 2009

Twelve non-pregnant and 20 pregnant North Country Cheviot ewes due to lamb in April 1969 were subjected to an 18 h daylength during the previous December. Thereafter daylength was reduced by 25 min per week. Eight ewes mated naturally in late May and early June and 22 of the remainder mated within 6 days after treatment with progesterone and gonadotrophin. Five of the photostimulated and 14 of the photostimulated plus hormone-treated ewes subsequently lambed in November 1969. The lambs were weaned at 28 days and 16 of the ewes were returned to fertile rams immediately after weaning. All 16 ewes were re-mated to naturally occurring oestrus during January-February 1970 and 13 proved pregnant.
Evaluation of tests for predicting the availability of soil manganese to plants
Authors: Browman M. G. , Chesters G. , Pionke H. B.
Published: March 2009

Eight soil Mn tests, namely, CH3COONH4-, Mg(NO3)2-, H3PO4-, hydroquinone-, 3m-NH4H2PO4-,1·5m-NH4H2PO4- and EDTA-extractable Mn and total Mn were evaluated for their ability to predict Mn uptake by maize (Zea mays L.) on 63 soils of diverse origin. Regression equations were derived by comparing Mn uptake with each test in combination with pH. The best prediction of Mn uptake was provided by a combination of CH3COONH4-extractable Mn and pH; 52·9 % of the variability in Mn uptake was accounted for by these two variables. EDTA and H3PO4-extractable Mn were superior to the other soil Mn tests in predicting Mn uptake.

The effect of soil properties on the extractability of soil Mn by each extractant was analysed statistically. Only with hydroquinone-extractable Mn did the soil variables investigated account for a major portion of the variability in the Mn test. The soil variables most often correlated significantly with the Mn test were pH and total Mn. Organic carbon and clay contents were significant only in determining EDTA- and Mg(NO3)2-extractable Mn, respectively.
Calcium metabolism of cows at parturition and during milk production
Authors: Sansom B. F.
Published: March 2009

Calcium metabolism in dairy cows has been studied at three periods, namely 2 weeks before and 2 weeks after parturition, and also at peak lactation. Of the four parameters studied—percentage absorption from the diet, endogenous excretion, exchangeable pool size and bone accretion rate—only the last showed significant changes, falling at parturition and rising to pre-calving levels subsequently. There was no increase in the percentage absorption of calcium from the diet after calving but total calcium absorption rose because of increased dietary intake.
Seasonal production of Andropogen Gayanus: II. Seasonal changes in digestibility and feed intake
Authors: Haggar R. J. , Ahmed M. B.
Published: March 2009

Twenty-seven sheep feeding trials were carried out on freshly cut Andropogon gayanus, fed daily during three wet seasons, 1966–8.

In each year, dry-matter voluntary intake and digestibility were highest during the first part of the growing season and declined with advancing maturity of the herbage. However, at the time of ear emergence in early October, there were small increases in voluntary intake of dry-matter and crude protein digestibility, although further decreases followed after mid-October.

Determinations of in vitro digestibility indicated that elongating stems during early October were at least as digestible as leaves.

Seasonal changes in crude protein digestibility were much greater than changes in dry-matter digestibility; seasonal changes in feed intake were intermediate. Voluntary feed intake was related to dry-matter digestibility.

Voluntary feed intake and digestible crude protein were both closely related to the crude protein content of the forage. It was concluded that crude protein is a useful criterion for predicting nutritive value.
The effect of date of sowing on the growth and yield of spring cereals
Authors: Jessop R. S. , Ivins J. D.
Published: March 2009

Experiments to study the effect of date of sowing at two centres in each of 3 years, 1967–9, are described and the results discussed. The earliest sowing date (early March) gave the highest yield of spring barley at both centres and of spring wheat at Sutton Bonington, but at Boxworth in 1967 and 1969 later sowing (early or late April) gave higher yields of grain, which were attributable mainly to increased grain numbers per ear. It is argued that in 1968 poor weather conditions in July and August resulted in very low 1000 grain weights, and although grain numbers were again higher from late sowing at Boxworth this treatment gave the lowest yields because of poorly filled grain. The date of sowing also affected yields of total dry matter, ratios of grain to straw, leaf-area indices, numbers of grains per ear and 1000 grain weights.
Screening potato clones for resistance to common scab (Streptomyces scabies) in the field
Authors: Langton F. A.
Published: March 2009

Potato varieties were grown in the field in soil uniformly infected with Streptomyces scabies. In 1969 tubers were severely and evenly infected but in 1971 infection was slight and not uniform. Agreement of varietal ranking with agricultural experience was good in 1969 but poor in 1971.

In 1971, plots protected from rainfall after planting were dry enough at the start of tubering for severe infection; covering the plots for a further 6 weeks followed by irrigation to field capacity resulted in good yields of evenly and severely scabbed tubers. Irrigation during this period suppressed scabbing. The results were easily interpreted in relation to fluctuations in soil-water content measured by a neutron moisture-meter.

The efficiency of using only one site and the need to reduce variability in scab screening tests are discussed.
Effects of nitrogen fertilizer, plant population and irrigation on sugar beet: I. Yields
Authors: Draycott A. P. , Webb D. J.
Published: March 2009

Five experiments (1965–9) on calcareous sandy loam tested all combinations of four amounts of nitrogen (0–1·8 cwt/acre N) and four plant populations (8000–54 000 plants/ acre) given to sugar beet grown with and without irrigation. On average, nitrogen and plant population influenced yields greatly but irrigation relatively little. In all years between 0·6 and 1·2 cwt/acre N and between 17000 and 32000 plants/acre gave largest sugar yield. Giving more nitrogen or increasing the plant population neither increased nor decreased sugar yield much in any year. Irrigation was beneficial in only two out of five years.

Sugar yield was linearly related to root dry-matter yield. Although total dry matter was greatest when the largest plant population was given the largest dressing of nitrogen and irrigation, the proportion of dry matter in the roots was decreased by all three factors.
A study of the theoretical expectation ofF1hybridity resulting from bulk interpopulation hybridization in herbage grasses
Authors: Foster C. A.
Published: March 2009

A study of the theoretical expectation ofF1hybridity resulting from bulk interpopulation hybridization in herbage grasses has been made. It is concluded that the main factor affecting the percentage interpopulationalF1hybrid content of the seed product of a two-population mixed sward is degree of coincidence of population flowering patterns. The effects of differences in population parameters are examined for a range of population types. Other factors such as differences in total gamete frequencies, preferential fertilization and differential pre- and post-harvest seed losses are also considered.