bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of time of sowing on flowering and fertile tiller production in S. 48 timothy
Authors: Langer R. H. M. , Ryle G. J. A. 
Published: March 2009

1. In a field experiment all plants of S. 48 timothy produced ears after being sown on or before 24 April; more than 90% of the plants still flowered if sown up to 19 May but fertility declined after later sowings, until only vegetative growth resulted in plants sown on or after 30 June.2. In a pot experiment, during which the performance of individual tillers was recorded, all tillers arising after 23 July were found to remain vegetative. Ear-bearing capacity declined towards this date but was still high in tillers appearing as late as 2 July in plants sown in the middle of May.3. Tillers on the main stem were more fertile and produced heavier ears than other tillers of the same age and order of succession on the plant.4. Many plants sown late in the field produced ears which formed vegetative proliferations after the end of the summer.5. The results are discussed in relation to the response of timothy to the changing environment, notably the length of day. It is suggested that timothy does not react to favourable photoperiods immediately upon germination and that failure to flower in plants sown after the middle of May does not necessarily imply any inadequacy of the environment to cause floral initiation, since it was possible for tillers appearing up to 2 July to produce ears, with few exceptions. Factors inherent in the organization of the plant are considered to be responsible for a decline of ear-boaring capacity from tiller to tiller, which occurred irrespective of changing environmental conditions.
Studies on the cutting management of grass-clover swards. I. The effect of varying the closeness of cutting on the yields from an established grass-clover sward
Authors: Reid D. 
Published: March 2009

1. A 3-year experiment is described in which perennial rye-grass/white clover swards were cut to within either 1 in. of 2–2½ in. of ground level when the herbage had reached either the ‘grazing’ or the ‘silage’ stage of growth. Superimposed on the cutting treatments were several fertilizer treatments which involved application of varying amounts of nitrogen at different dates over the season.2. Throughout the experiment cutting to within 1 in. of ground level gave greater dry-matter and crude-protein yields of mixed herbage and of clover than cutting to within 2–2½ in. of ground level, the increase in dry-matter yield ranging from 39 to 49%.3. The response of clover to these ‘height of cutting’ treatments developed more slowly than the response of the sward as a whole, and was modified in the later stages by the particular fertilizer nitrogen treatment applied.4. It is suggested that the greater herbage yields obtained from close- than from lax-cut swards resulted from the differential effects of the two cutting treatments on stem and leaf formation in the grasses, but the need for further investigation is stressed.5. Discrepancies between the effects of the ‘height of cutting’ treatments in this experiment and those reported by other workers are indicated, and it is shown that these discrepancies probably result from the varying cutting frequencies adopted.6. Cutting the sward at varying stages of growth and increasing the rate of fertilizer nitrogen application had very similar effects on mixed herbage and clover yields in this experiment to those reported previously by other workers.7. Where the total amount of fertilizer nitrogen applied over the season was small (4 cwt. ‘Nitro-Chalk’/acre) delaying the first dressing until after the first or second cut reduced the dry-matter and crude-protein yields of mixed herbage, and had little effect on those of clover. A similar delay where greater total amounts of fertilizer nitrogen were used (8–12 cwt. ‘Nitro-Chalk’/acre) reduced the dry-matter yields of mixed herbage, and slightly increased the dry-matter and crude-protein yields of clover. Under these heavy nitrogen treatments the crude-protein yields of mixed herbage decreased only where the delay involved a reduction in the total amount of fertilizer nitrogen applied over the season.8. Although delaying the first dressing of the season reduced mixed herbage yields at all fertilizer nitrogen levels, it resulted in a more uniform distribution of production over the season. The practical significance of this is discussed.
Metabolism of nitrogen during long-term incubation of soil treated with fresh and rotted organic materials
Authors: Cornfield A. H. 
Published: March 2009

The metabolism of nitrogen during incubation, at 28° C. for 184 days, of a soil treated with 1% by weight of five different bulky organic manures and 0·5% calcium carbonate was studied.1. Ammonia and nitrite could not be detected at any sampling date with any treatment, hence nitrate levels in treated soils compared with that in the control soil indicated the extent of mineralization or fixation of nitrogen.2. A good straw compost (carbon/nitrogen ratio, C/N, 20·6) was the only material which showed mineralization of nitrogen over practically the whole of the incubation period.3. Rotted farmyard manure (C/N 15–6) caused a small, whilst fresh grass (C/N 22·6), caused a fair amount of nitrogen fixation in the early stages, but there was a small overall mineralization of nitrogen by the final sampling.4. A poor straw compost (C/N 42·5) and straw (C/N 147·0) both caused considerable fixation of nitrogen in the early stages. With continuing incubation the bulk of the nitrogen fixed by the poor compost, but only a small portion of that fixed by the straw, was released.
The comparative fertility of bovine semen of four ages diluted with skim-milk and skim-milk + glycerol
Authors: O'Connor L. K. , Smith G. F. 
Published: March 2009

A split-sample experiment involving 14,319 first inseminations was carried out at sixteen artificial insemination centres to compare the fertility of semen diluted with skim-milk and skim-milk containing 10% glycerol when used on the first, second, third and fourth days after the day of collections.The addition of glycerol to the heat-treated skimmilk diluent significantly reduced the decline in fertility with increasing age. However, there were indications that glycerolization also reduced initial fertility.
The influence of heavily fertilized grass on mineral metabolism of dairy cows
Authors: Mudd A. J. 
Published: March 2009

SUMMARYGroups of lactating dairy cows were fed on grass which had received various amounts of nitrogen and potash fertilizers. In the early part of the season not only was the herbage concentration of calcium and phosphorus lower in grass which had received potash fertilizer but in addition the ‘availability’ of the calcium to cows was depressed. Grass which had received large amounts of nitrogen fertilizer had a comparatively low dry-matter content in the autumn. Cows fed such grass were in negative balance for calcium at this time. As expected high dietary potassium gave rise to high excretion of potassium in the urine which in turn was correlated with high excretion of magnesium. These various factors are likely to affect the incidence of metabolic disease.
The uptake of initially available soil potassium by ryegrass
Authors: Addiscott T. M. 
Published: March 2009

SUMMARYThe potassium potential which limits uptake of K by ryegrass, ‘the uptake potential’, was derived from the uptakes of K and from the quantity/potential relationships of a number of soils by a method which avoids exhausting the soil by cropping. This potential was – 5600 cal/equiv in Rothamsted soils, but the method was unsuitable for Woburn soils. In Rothamsted soils uptake of K was more closely related to quantity than to potential of K, but in Woburn soils it was equally well related to both. From 28 days until 82 days, when the initially available K had been used in most soils, diffusion in the soil seemed to control rate of uptake of K. On longer cropping, much initially nonavailable K was released, the grass still grew and the mean K potential had fallen to only –5189 cal/equiv in Rothamsted and –5336 cal/equiv, in Woburn soils.
Comparisons of liquid and solid fertilizers and anhydrous ammonia for sugar beet
Authors: Draycott A. P. , Holliday R. 
Published: March 2009

SUMMARYSix field experiments (1963–8) in eastern England compared solid fertilizer with liquid fertilizer or anhydrous ammonia for sugar beet. Two glasshouse experiments investigated the interaction between depth of placement of fertilizer and soil moisture.Yields of sugar were the same from broadcast solid and sprayed liquid in all the experiments, but nitrogen uptake by the crop was less from liquid than from solid. Three experiments tested placement of liquid 4 in to the side and either 2 or 6 in below the seed. Plants with deep-placed fertilizer consistently out-yielded those with shallowplaced fertilizer, but yields were never significantly different from broadcast solid fertilizer. Dry-matter yields of sugar beet grown in containers indoors showed that the crop responded to deep placement when the surface soil was watered infrequently.With anhydrous ammonia injected during seed-bed preparation, sugar yield and nitrogen uptake were the same as with solid fertilizer in the seed bed, and were greater than with anhydrous ammonia injected in the ploughed land during early spring. A side-band injection of anhydrous ammonia before singling gave a crop containing as much nitrogen at harvest as, but less sugar than, nitrogen applied in the seed bed.
β-Globulin polymorphism and economic factors in dairy cattle
Authors: Ashton G. C. 
Published: March 2009

1. The serum β-globulin phenotype of 141 bulls located at Cattle Breeding Centres in England and Wales was determined by starch-gel electrophoresis.2. The distribution of the contemporary comparison values of these bulls with respect to β-globulin type was investigated. The great majority of the bulls were βAA, βAD, or βDDwith very few βAEand βDEand no βEEtypes.3. The contemporary comparison values for 130 bulls of the three types βAA, βADand βDDeach fell into a normal distribution. The mean and its standard error and the standard deviation of the mean and its standard error were calculated for each of the three curves. The mean contemporary comparison value for the βAAbulls was + 12·2 ± 5·4 gal., for the βADbulls + 26·8 ± 5·4 gal., and for the βDD bulls + 38·2 ± 5·5 gal. The βAAand βDDmeans were significantly different (P< 0·01).4. The pooled contemporary comparison values of the βAA, βADand βDDbulls did not give a normal distribution curve, neither did the contemporary comparison values for a sample of 1028 bulls quoted by the Milk Marketing Board. However, when the contemporary comparison values of the βAA, βADand βDDgroups were superimposed around the same mean, the ensuing distribution was normal.5. It is concluded that the β-globulin locus is concerned in the genetic control of milk yield. The estimated mean genetic value of βDover βAis approximately + 50 gal. This is about one-sixth of the total genetic variation in milk yield in the major milk breeds.6. The distribution of butterfat percentages with respect to β-globulin phenotype in four Ayrshire and one Friesian herds was investigated. No difference between the mean first lactation butterfat percentage of the βAA, βAD, and βDDcows in each herd was found. There was an indication (not significant) that the mean butterfat percentage of the βAEand βDEcows in three of the four Ayrshire herds studied was higher than the mean of the other groups.
The value of calcium nitrate and urea for sugar beet, and the effect of late nitrogenous top dressings
Authors: Adams S. N. 
Published: March 2009

1. Twenty-eight experiments on sugar beet in 1956–8 compared ammonium sulphate, calcium nitrate and urea applied to the seedbed before sowing. The three fertilizers were compared at rates which supplied nil, 0·6 and 1·2 cwt. N/acre. Treatments in which 0·6 cwt. N/acre was held back until the end of June were also included.2. Average responses in sugar yield were low, 0·6 cwt. N/acre provided virtually all the nitrogen required for maximum sugar production. The heavier nitrogen dressing, on the other hand, substantially increased the yield of tops.3. Calcium nitrate and urea were as effective as ammonium sulphate at raising sugar yield. There was no damage to germination with any fertilizer, and when urea containing 4·5% biuret was used for topdressing in 1956, no damage was seen. Calcium nitrate and, to a lesser extent, urea produced more tops than ammonium sulphate.4. Putting all the nitrogen into the seedbed was as effective as a split dressing in raising sugar yield. Leaching of nitrogen in a wet summer is therefore not important to sugar beet. Late nitrogen, on the other hand, never harmed sugar production if some had been given to the seedbed.
Measurements of the ‘motility’ of bull sperm cells under various conditions
Authors: Rikmenspoel R. 
Published: March 2009

In this paper the results are described of experiments on bull sperm cells with the photo-electric device for measuring the ‘motility’, as developed by Rikmenspoel, van Herpen & van Dam (1956).It was found that the velocity distribution of sperm samples differs only slightly from a Gaussian one. The form of the distribution curve, which is a bit skew, is rather constant between ejaculates. This means that generally the ‘motility’ of a sperm sample can be characterized by the mean velocity of the sperms, the standard deviation of the velocity distribution and the number of cells moving normally. The mean ratio of velocity and frequency of rotation (the ‘speed’ of the screwing movement of the head of the sperm cell) was found to be a less important motility characteristic for most experiments.The scattering of the above-mentioned properties in various ejaculates were measured, while the sperm samples were all kept in the same conditions. It was found that the mean velocity has a rather constant value.A linear relationship between the mean velocity of the sperms of a sample and the viscosity of the diluent is found. This holds also for the dependence of the ‘speed’ of the head movement and the viscosity.The mean velocity of sperm cells was found to increase approximately in a straight-line relationship with the temperature in the range 33–41° C. There were indications that the mean velocity may reach a maximum in the region of 42–45° C.If sperm samples are stored at 4° C, the mean velocity and the number of cells moving normally is found to decrease exponentially. The decrease of the number of cells moving normally is three to four times faster than that of the mean velocity. Some evidence was obtained that the characteristic time for the decrease of the number of cells moving normally is bull-specific.
Experiments on rumen retention time, fermentation rate and dry-matter digestibility in zebu and european-type cattle on a grass hay ration
Authors: Phillips G. D. , Hungate R. E. , MacGregor A. , Hungate D. P. 
Published: March 2009

1. Experiments are described in which retention time of digesta in the reticulo-rumen, fermentation rates of rumen contents, and dry-matter digestibilities were studied simultaneously in four grade European and three zebu steers.2. Fermentation rates and rumen retentions were significantly negatively correlated.3. Correlations between digestibility and the other two factors were not significant at a high level.4. The multiple regressions calculated for retention time and fermentation rate were significant at the 5% level and that for digestibility approached this level.5. While only fermentation rates show significant differences for the two types of cattle, the results suggest that grades and zebus differ also in the rate of passage of digesta through the rumen.6. The loss in weight of substrate per unit of fermentation products was measured inin vitroexperiments.7. Using certain assumptions, estimates are made of the extent to which the measured fermentation rates could account for the loss in weight of dry matter during digestion, and are compared with the loss actually found.
Ammonia toxicity in the ruminant
Authors: Lewis D. 
Published: March 2009

1. The normal level of blood ammonia in the sheep seems to be somewhat higher than in nonruminants.2. The toxicity of ammonium acetate, ammonium chloride or urea placed in the rumen follows different metabolic pathways. In the case of the chloride there is an uncomplicated metabolic acidosis which is not, however, adequate to account for the toxic symptoms. When the acetate is administered there is also a respiratory alkalosis and in the presence of urea the changes in the acid-base status, though interesting, do not account for the toxicity.3. The toxicity is almost certainly due finally to a direct effect of the circulating ammonium ion level though in the case of urea, there is an earlier effect that may be of a pharmacological type and is less severe.4. The organisms within the rumen rapidly reach a maximum level of adaptation (7 days) to handle large quantities of ammonia by a synthetic pathway.5. The intravenous administration of L-arginine did not markedly ameliorate the ammonia toxicity.
The feeding of calcium lactate to laying hens
Authors: Kent Susan E. , Reid T. F. , Worden Alastair N. 
Published: March 2009

1. Three completed series of laying trials involving the incorporation of calcium lactate in the diet are reported.2. The addition of 1 or 2% calcium lactate to a layers mash results in a significant increase in egg production and/or the efficiency of the ration in terms of numbers of eggs per unit weight of food consumed. This effect has been obtained in birds at the onset of lay and also in birds that have been in lay for some 5 months.3. The incorporation of 0·5% calcium lactate appears to be inadequate.4. There is no evidence to date that the effect is attributable to dietary calcium, but the mechanism of action is unexplained.5. Egg-weight, but not egg-quality, as judged by routine candling, is slightly lowered by feeding calcium lactate.
The digestibility of mash and pellets by chicks
Authors: Bolton W. 
Published: March 2009

1. The digestibilities of the protein, oil and carbohydrate by chick in mash and pellets made from this mash have been determined at weekly intervals from 0 to 9 weeks.2. There was no difference in the chemical composition of the food due to pelleting, not were there any differences in the digestibilities due either to pelleting or the age of the chick.
Cotton crop environment, growth and yield in the Sudan Gezira: I. The Gezira observation plots: experimental design, cultural methods and yield analysis
Authors: Jackson J. E. 
Published: March 2009

SUMMARYAnalysis of 21 years' cotton yield data from factorial experiments at three sites in the Sudan Gezira established that yields were significantly increased by nitrogenous fertilizer, that close spacing outyielded wide spacing and that variety X1730A (L type) outyielded variety MSDS (a Sakel type). The effect of nitrogen varied depending on variety and spacing and there were also marked variations from year to year in the effects of nitrogen, spacing, variety and some of the interactions. Year-to-year variations in the overall level of yield were very pronounced and accounted for more than half of the total variance at each site. Causes of year to year variation and the mechanism of the treatmenteffects will be discussed in subsequent papers.
The digestibility of fats differing in glyceride structure and their effects on growth performance and carcass composition of bacon pigs
Authors: Davis R. H. , Lewis D. 
Published: March 2009

SUMMARYThe digestibility of fats differing in glyceride structure has been investigated, the fats used being natural lard, interesterified lard and beef tallow. Natural lard was found to be better digested than interesterified lard which in turn was better digested than beef tallow, the differences being the result of differences in the digestibility of the saturated fatty acids. The digestibility of palmitic acid was found to be dependent upon its positioning within the glyceride molecule, absorption being greatest when it was esterified in the β-position. The positional distribution of stearic acid was thought not to be the factor limiting the extent of its absorption in the given circumstances. The fats did not differ in their effects upon growth performance or carcass composition and differences in the digestibility of the fats were not reflected in the quality of the carcass backfat. It was demonstrated that increasing the nutrient density of diets through the addition of fat, together with careful regulation of nutrient intake, resulted in improved growth performance and carcass composition.
Grain quality in hybrids of Avena sativa L. and A. byzantina C. Koch
Authors: Jenkins G. 
Published: March 2009

SUMMARYResults of grain analyses for the content of nitrogen, oil and husk are presented from trials in the F1 and F2 generations of four subject varieties, Condor (Avena sativa), Sierra, Avon and Anita (A. byzantina), nine tester varieties, mainly of north-west European origin and the 36 crosses between them.Yield of grain crude protein per unit area was positively correlated with grain yield, but nitrogen content of the grain, expressed as a percentage of dry matter, was inversely related to grain yield in both trials. Although the highest values for grain nitrogen content were invariably associated with low grain yields, the highest yielders had average or slightly better than average values for nitrogen content.Analysis of straw samples from the F2 trial revealed considerable differences between varieties and crosses in the proportion of the total shoot nitrogen (grain + straw) ultimately found in the grain. The proportion of total shoot nitrogen translocated to the grain was positively correlated with the ratio of grain yield to straw yield. High grain yielders took up more nitrogen per unit area from the soil and translocated relatively more nitrogen to the grain from the vegetative tissues than did varieties with low grain yields.Yields of grain oil were highly positively correlated with yields of grain per unit area but there was no significant regression of oil content on grain yield in either trial. In the F2 trial, oil yield per unit area was positively correlated with oil content of the grain. The variety Avon and its crosses had consistently high oil content.There was no correlation between yielding ability and husk content of the grain, and some of the highest grain yields were associated with low mean husk contents. High husk content of the grain tended to be associated with stiffer straw.The results are discussed in relation to improving grain quality in the breeding of new varieties of oats.
Utilization of surplus protein by sheep
Authors: Dror Y. , Bondi A. 
Published: March 2009

SUMMARYThe utilization of different levels of protein, supplied mainly as soybean meal, was examined by a feeding experiment with sheep. Measurements of the concentrations of N-containing rumen metabolites and of blood urea showed that protein degradation in the rumen and removal of urea by the kidneys were limited when highly increased amounts of protein were ingested.
Accumulation of nitrate in fresh soils after gamma irradiation
Authors: Cawse P. A. , White T. 
Published: March 2009

SUMMARYIncreases in nitrate have been found in eight out of ten soils irradiated over the range 0·25–2·5 Mrad, with maximum accumulation between 0·25–0·75 Mrad. Oxidation of ammonium added to normal soils was poor at low pH, and showed a highly significant correlation with nitrate produced after 0·25 Mrad. It is suggested that radiation-released ammonium is less limiting to nitrate formation than the original population or activity of nitrifying organisms, which are favoured by alkaline conditions.