bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of fertilizers on herbage production Part I. The effect of nitrogen, phosphate and potash on yield
Authors: Reith J. W. S. , Inkson R. H. E. , Stewart A. B. , Holmes W. , Maclusky D. S. , Reid D. , Heddle R. G. , Clouston D. , Copeman G. J. F. 
Published: March 2009

The paper reports the results for six factorial experiments carried out over a period of 3 years, and designed to measure the effects of nitrogen, phosphate and potash on the yield of dry matter and to determine the effect of nitrogen on the phosphate and potash requirements of grass being cut five times per annum for conservation.Heavy dressings of nitrogen reduced the percentage of dry matter in the fresh herbage, but produced a very large increase in the yield of dry matter. There were quite large variations in the response to this plant food, but 348 lb. N per acre per annum practically doubled the yield and generally the response curves were substantially linear.The response to nitrogen depended on an adequate supply of potash and at five of the centres there were very large interactions between these two nutrients. The need for potash was greatest at the highest nitrogen rate and was much greater in the second and third than in the first year of the experiments.At the highest nitrogen rate some of the responses to potash were very large. The yields of dry matter showed no large or consistent differences between applying 336 lb. K2O in one dressing during the winter months or applying this amount in five equal dressings, one for each cut. The results demonstrated the ability of the soils to supply potash and showed that the regular cutting and removal of herbage, especially if heavy dressings of nitrogen were applied, exhausted the potash reserves in the soil.Phosphate had practically no effect on the yield of dry matter either in the presence or absence of nitrogen.With adequate potash the production of dry matter per lb. of fertilizer nitrogen was practically independent of rate and the overall mean results are between 14·0 and 15·7 lb. In the absence of fertilizer potash there was a very large effect of rate: 15·0 lb. dry matter per acre was produced per lb. N with the 87 lb. N per annum treatment, 13·7 lb. with 174 lb. N and 10·0 lb. with the 348 lb. N treatment.Approximately 70–75% of the annual production was obtained before the end of July. Thus 1 lb. of fertilizer nitrogen produced considerably more dry matter per acre during May, June and July than later in the season.
A quantitative study of the inheritance of resistance to bacterial blight in Upland cotton
Authors: Innes N. L. , Brown S. J. 
Published: March 2009

SUMMARYPopulations derived from a diallel set of crosses involving five inbred Upland varieties were tested for bacterial blight resistance at Wad Medani in the Sudan and at Namulonge in Uganda. Four of the varieties carried a knownBgene for resistance; noBgene was present in the fifth, which was used as a susceptible parent. The importance of genotype/environment interaction was emphasized and it was found that theBgenes did not maintain the same dominance relationships at the two sites.The Reba gene,B9L, segregated as a gene or ‘effective factor’ of large effect but Mendelian segregation was not discernible in hybrid populations not involving Reba. Most of the genetic variance was accounted for by additivity and dominance. Although statistical analysis failed to reveal epistasis there was a strong interaction in theB2×B6cross.At Namulonge, where it was possible to test for leaf and boll resistance, the proportion of dominant and recessive alleles was the same for both phases of the disease.
The relationship between productivity and some components of canopy structure in ryegrass (Lolium spp.)
Authors: Rhodes Ian 
Published: March 2009

SummaryProductivity and percentage conversion of light energy were measured in (a)clonallypropagated swards of populations of genotypes selected from the variety S. 321 forcontrasting combinations of leaf rigidity and tiller angle, and (b) families from assortativecrosses between genotypes of this variety of differing canopy structure. A further experiment was carried out to examine the canopy structure and pattern of light interception of populations, families and genotypes of contrasting productivity.Under infrequent cutting (28–34 days) the tiller population selected for erect tillers and rigid leaves was more productive than those selected for prostrate tillers and rigid leaves, and prostrate tillers and lax leaves. Under frequent cutting (14–17 days), however, the populations with prostrate tillers were most productive.Considerable differences existed in the productivity of the S. 321 families, and their relative performance differed under the two cutting frequencies. Under infrequent cutting the highest yielding family was 17% more productive than the base population, whilst under frequent cutting the yield of the most productive family was 19% greater than that of the base population.The heritability of sward yield was 0·64 under infrequent cutting and 0·86 under frequent cutting.The most productive genotypes, populations and families under infrequent cutting had the highest leaf-area index (LAI) at complete light interception and the lowest extinction coefficients for visible radiation (Kvis). By contrast, under frequent cutting the most productive types had high extinction coefficients and large LAI in the basal layers of the canopy.The physiological basis of differences in productivity is discussed in relation to canopy characters whioh may be used as selection criteria for increasing the efficiency of light utilization in herbage grasses.
The influence of feathering and environmental temperature on the heat production and efficiency of utilization of metabolizable energy by the mature cockerel
Authors: O'Neill S. J. B. , Balnave D. , Jackson N. 
Published: March 2009

SummaryThe effect of temperature on the heat production, of temperature-acclimatized feathered and defeathered cockerels was examined at 15, 22, 25, 29, 34 and 38 °C. The maintenance ME requirements and the net availability of ME (NAME) were determined for each temperature.The fasting heat production of defeathered cockerels measured at 22, 29, 34 and 38 °C, decreased continually with increasing temperature. The feathered cockerels also showed a general decrease in fasting heat production with increasing temperature between 15 and 34 °C, but there were relative increases in fasting heat production between 22 and 29 °C.The ME requirement for maintenance and the NAME were determined from measurements of heat production at different levels of ME intake. In general, the maintenance ME requirement decreased with increasing temperature for both feathered and defeathered cockerels. The NAME for the defeathered birds varied between 75 and 77% at 29, 34 and 38 °C. There was evidence for the feathered birds of an increasing NAME with increasing temperature, one feathered bird having a NAME of 56% at 15°C, increasing to 81% at 34 °C.The importance of feathering and environmental temperature on the heat production and the possible effect of feather cover and activity on the NAME are discussed.
A physiological analysis of the growth of oilseed rape
Authors: Allen E. J. , Morgan D. G. , Ridgman W. J. 
Published: March 2009

SummaryFor seed crops other than cereals there have been comparatively few comprehensive field studies which have analysed the physiological basis of the effects of genotype and agronomic treatments on growth, development and yield. Milbourn & Hardwick (1968), working on vining peas (Pisum sativum L.), have recently shown that pod growth rate and the yield of seeds are not simple functions of leaf area index and that sourc es of materials other than the leaves are important in affecting the yields of pods and seeds. Furthermore, Flinn & Pato (1970) have shown that the pods themselves can contribute to assimilation in the field pea (Pisum arvense L.). Field experiments carried out at Cambridge in 1968 and 1969 have produced evidence on the relative importance of leaves and other photosynthetic tissues in determining the yields of pods and seeds in another seed crop, namely oilseed rape. The experiment in 1969 is described and discussed below.
Studies on the adaptability of three breeds of sheep to a tropical environment modified by altitude VII. Sexual activity in relation to age of ram
Authors: Symington R. B. 
Published: March 2009

The effect of age on attainment of puberty and on seminal characteristics in yearling and mature rams was studied in German Merino, Persian Blackhead and indigenous Native rams living on Rhodesian highveld.1. Puberty occurred at age and live weight proportional to mature live weight. Well-grown Native lambs ejaculated first at 169 days of age and 46 lb. live weight; Merino lambs when 250 days old and 79 lb. live weight and Persians were intermediate. Onset of sexual maturity was related more closely to live weight than to age, since runts ejaculated first at live weights close to those of well-grown lambs.
Studies of the effects of soil aggregate size on the emergence and growth of beet (Beta vulgaris L.) I. Seedling emergence
Authors: Hammerton J. L. 
Published: March 2009

A fine soil separate gave the highest and most rapid seedling emergence. This was considered to be due to its better moisture supply characteristics and the lower mechanical impedance compared with coarser seed-beds. There was no evidence that natural seed clusters are any less responsive to soil aggregate size than processed beet seed clusters.Consolidation slightly hastened emergence, though the mechanism of this is not clear. Sowing at ¾ in. was superior to deeper sowing (1½ in.), both in speed of emergence and in ultimate emergence. This was partly an effect of decreased mechanical impedance, and partly due to the shorter period over which the seedlings were susceptible to pathogens. Heavy dressings of soluble fertilizers were found to delay emergence, though without effect on the ultimate emergence.
Studies on the Northern Rhodesia Hyparrhenia veld III. The effect on the growth and grazing-behaviour of indigenous cattle of restricting their daily grazing time by night kraaling
Authors: Smith C. A. 
Published: March 2009

1. The effects of restricting the daily grazing hours of indigenous cattle have been studied on grazing behaviour and cattle weights. The cattle grazed on natural veld.2. Three cattle-management treatments, i.e. free range, moderate kraaling (11 hr. grazing day) and severe kraaling (7 hr. grazing day), were compared during seasonal periods of low cattle-weight gains, large cattle-weight gains and large cattle-weight losses.
Protein, lysine and feed intake level effects on pig growth: I. Main effects
Authors: Blair R. , Dent J.B. , English P.R. , Raeburn J.R. 
Published: March 2009

SUMMARYA total of 512 pigs were given from 50 lb live weight one of 16 diets, i.e. with 4 lysine levels at each of 12, 14, 16 and 18% protein, at one of 4 levels of intake. They were killed at 100, 150, 200 or 250 lb live weight.Live-weight gain was not improved significantly by increasing the protein level above 16, 14, 12and 12%, respectively, for the 50–100, 100–150, 150–200and200–2501bstages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the protein to 18%. Gain in lean meat and in the efficiency of conversion of feed to lean meat were improved by increasing the above protein levels slightly.Live-weight gain was not improved significantly by increasing the lysine level above 1·04, 0·74, 0·70 and 0·59%, respectively, for the 50–100, 100–150, 150–200 and 200–250 lb stages. However, conversion of feed to live-weight gain was improved significantly during the 50–100 lb stage by increasing the lysine level to 1·22%. Raising the lysine level at each level of protein had no significant effect on the rate and efficiency of lean meat gain.Live-weight gain was significantly improved by increasing the level of feed intake almost to ad libitum levels for the 50–100, 100–150 and 150–200 lb stages. There was a suggestion of a similar effect in the 200–250 lb pigs although it was not statistically significant. Conversion of feed to live-weight gain was improved in the 50–100 lb pigs only by increasing the level of feed intake: in the older pigs increasing the level of feed intake caused a worsening in feed conversion ratio. Increasing the level of feed intake gave a significant improvement in rate of lean meat gain but a significant worsening in the efficiency of conversion of feed to lean meat during all stages up to 200 lb.Interaction effects of these factors and sex, on growth performance, are described.
The tillering pattern in barley varieties: II. The effect of temperature, light intensity and daylength on the frequency of occurrence of the coleoptile node and second tillers in barley
Authors: Cannell R. Q. 
Published: March 2009

SUMMARYControlled-environment experiments showed that development of the coleoptile node tiller (T1) was suppressed much more than that of the tiller appearing in the axil of the first true leaf (T2) by high temperature (24/15 °C; 19/10 °C; 10/6 °C), by reduced photoperiod (16 h; 12·5 h) or by low light intensity (1100 ft-c; 1000 ft-c), but minimally in the newest variety, Deba Abed. Unlike previous field experiments, the T1 tiller appeared on more Spratt Archer than Maris Badger plants. Maris Badger plants produced more T1 tillers in a high-low temperature regime (19/10 °C; 10/6 °C) than in continuous low temperature (10/6 °C). In a field experiment T1 tiller number (and yield), but not the number of other major shoots, were severely reduced by late sowing of Spratt Archer, progressively reduced in Maris Badger, but minimally in Deba Abed. This seemed to be associated with higher temperatures at later sowings.
Calorimetric studies on the effect of dietary energy source and environmental temperature on the metabolic efficiency of energy utilization by mature Light Sussex cockerels
Authors: Shannon D. W. F. , Brown W. O. 
Published: March 2009

SUMMARYExperiments to determine the net availabilities of the metabolizable energy (NAME) of a cereal-based diet and a maize-oil diet for maintenance and lipogenesis and the effect of environmental temperature on the NAME of the cereal-based diet are described. Four 1- to 2-year-old Light Sussex cockerels were used.The relationship between ME intake and energy retention was linear for each diet. The NAME'S of the cereal-based diet given at 22° and 28 °C (70.6 ± 1.83 % and 73.6 ± 3.54%, respectively) were significantly (P < 0.05) lower than the NAME of the maize-oil diet (84.1 ± 1.85%). It is concluded that the beneficial effect of maize oil on the efficiency of energy utilization is due to a reduced heat increment rather than a reduction in the basal component of the heat production. The higher efficiency from the maize-oil diet led to an increase in the energy retained as fat.The mean fasting heat production at 28 °C was 15 % lower than at 22 °C (43.2 ± 1.45 and 51.2 ± 1.09 kcal/kg/day, respectively). The NAME of the cereal-based diet was not significantly different when the birds were kept at 22° or 28 °C. The lower metabolic rate at 28 °C was reflected in a lower maintenance requirement and in an increase in the deposition of body fat.
In vitro maturation and attempted fertilization of cattle follicular oocytes
Authors: Sreenan J. 
Published: March 2009

SUMMARYMaturation studies were carried out on 241 cattle oocytes. Media used were bovine follicular fluid and growth medium. Both media supported a resumption of meiosis in ca. 80 % of cases, but growth medium proved superior in terms of final maturation.Fertilization attempts were carried out on 564 oocytes following culture (27–32 h) in growth medium. In vitro fertilization attempts (107 oocytes) and in vivo fertilization attempts (82 oocytes) in the rabbit yielded negative results. Following in vivo fertilization attempts in the ewe, ova containing pronuclei as well as apparently normal cleaved ova were recovered.
Sweating rate and the electrolyte content of skin secretions of Bos taurus and Bos indicus cross-bred cows
Authors: Johnson K. G. 
Published: March 2009

SUMMARYSweating rate and the electrolyte content of secretions from the skin of cattle have been measured on five Bos taurus and five B. indicus cross-bred cows by absorbing secretions into filter papers under polythene disks applied to shaved skin areas on the shoulder, sacral and lumbar regions for 5 min. The increase in weight of the filter paper was taken as a measure of sweating rate and the distilled water eluate from the filter paper was analysed for sodium and potassium. Animals were exposed for 4 h to air temperatures of 20–45 °C at 30% r.h., and for 5–7 h to air temperatures of 40 and 45 °C at 40% r.h. Estimated sweating rates were low by comparison with previously reported values, probably due to rising levels of humidity under the polythene disks during exposure to the skin. B. indicus cross-bred cows had higher sweating rates than B. taurus cows at high air temperatures but the difference between the groups was not significant statistically. Sweating rates were generally highest on the shoulder and lowest on the lumbar region.The amounts of sodium and potassium recovered from filter papers were small and very variable at low air temperatures but increased significantly with air temperature (P < 0·01). No significant differences in the amounts of electrolyte recovered from filter papers were recorded between the species groups or between different sites of collection. The secretions from cattle skin at high ambient temperatures contained at least four to five times as much potassium as sodium. Total sodium and potassium loss through the skin of these experimental animals at the highest ambient temperatures was estimated to be no more than 1–3 % of the sodium and potassium intake in the feed. Absorbing sweat on to filter paper as a method of measuring sweating rate and sweat composition is rather less satisfactory for use with cattle than with man.
Evapotranspiration from barley grown at different plant densities
Authors: Kirby E. J. M. 
Published: March 2009

SUMMARYEvapotranspiration from spring barley plots grown at a range of densities was estimated using the neutron probe technique. Early in the season rainfall led to percolation and kept the soil at field capacity, but from the beginning of June significant differences were found in the cumulative evapotranspiration. As the crop canopy was complete by this time in all densities, it seems probable that evapotranspiration at this time was dependent on rooting density. Although the total water use at the end of the season was similar at all densities, the more rapid use earlier in the season at higher densities may have led to a reduction in growth at the grain filling stage.
The influence of live weight and body condition on the subsequent milk production of Blackface ewes following a period of undernourishment in early lactation
Authors: Peart J. N. 
Published: March 2009

SUMMARYIn each of two years, 36 Blackface ewes were brought to a high state of body condition at mating and in early gostation. At approximately 16 weeks prepartum the ewes were divided into two similar groups and fed to maintain the live weight and body condition of one group (fat), and to decrease that of the other group (lean). At 8 weeks prepartum mean differences of 14kg live weight and two scores of body condition had been created between the groups. During the last 6 weeks of pregnancy food was rationed to all ewes per unit of live weight to provide the theoretical requirements of Blackface ewes in late pregnancy. Both groups of ewes made similar live-weight gains in late pregnancy and blood plasma F.F.A. values confirmed that the ewes had been similarly nourished regardless of live weight or body condition. During early lactation food was restricted to fat and lean groups of ewes for either a 2- or 4- week period followed by ad lib. feeding for the remainder of lactation. A lamb-suckling technique was used to measure milk production during a 10-week lactation. During the first and second weeks of lactation the mean milk production of groups of both fat and lean ewes was approximately 2·1 and 1·3 kg/day for twin- and single-suckled ewes respectively. Ad lib. feeding following restricted feeding during the first 2 weeks of lactation resulted in increased milk production of fat and of lean ewes to mean maximum values of approximately 2·7 and 1·7 kg/day for twin- and single-suckled ewes respectively. In contrast, groups of ewes which had restricted feeding for the first 4 weeks of lactation showed almost no increase in milk production when fed ad lib. During the extended period of restricted feeding the milk production of twin-suckled ewes which were fat at parturition was significantly greater than that of twin-suckled lean ewes but there was no difference with singlesuckled ewes. All groups of ewes lost similar amounts of live weight and body condition during their respective periods of restricted feeding. In the respective 6-week periods following ad lib. feeding the live-weight gain of the lean ewes was significantly greater than that of the fat ewes (339 v. 222 and 356 v. 250 g/day for twin- and single-suckled ewes respectively), but they did not attain parity of live weight by the end of lactation. When fed ad lib. the mean intake of all groups of ewes attained similar maximum values of approximately 2·2 kg D.O.M./day. The results indicate that the stage of lactation is an overriding factor governing the response to increased nutrition and that body condition of ewes at parturition acts as a buffer between nutrient intake and nutrient requirements for lactation. It is suggested that when body reserves of ewes are severely depleted, factors other than nutrient intake may become limiting to milk production.
The effect of nitrogen fertilizers on the ensiling characteristics of perennial ryegrass and cocksfoot
Authors: Jones D. I. H. 
Published: March 2009

SUMMARYThe effect of three levels of N fertilizer on the ensiling characteristics of S. 24 perennial ryegrass and S. 37 cocksfoot have been examined during first growth in two growing seasons. The effects of sucrose supplementation, inoculation with Lactobacillus plantarum and wilting were also examined in certain cuts. All silages were made in the laboratory using a small scale vacuum silage technique.The perennial ryegrass herbage was higher in water soluble carbohydrates than the cocksfoot, N fertilizers decreased soluble carbohydrates and dry-matter content in both species. Buffering capacity was not consistently different between grasses or between N levels.Herbage was cut at two stages of maturity in the first year. In the first cut (8 days before ear emergence), perennial ryegrass silages were well preserved irrespective of the amount of N applied to the grass. Cocksfoot silages were well preserved only when the lowest level of N fertilizer had been applied (50 kg/ha). Supplementation of cocksfoot with sucrose prior to ensiling markedly improved silage quality, but inoculation had no effect. In the second cut (26 days after ear emergence) the grasses were higher in drymatter content and showed a lower buffering capacity, but neither ryegrass nor cocksfoot silages were well preserved unless supplemented with sucrose prior to ensiling.In the second year of the experiment only one cut was taken (9 days after ear emergence). As in the previous year, silages made from herbage at a late stage of growth were poorly preserved. Wilting prior to ensiling resulted in well-preserved silages.It is concluded that the need for additives and wilting to ensure satisfactory preservation varies in relation to the variety of grass used and its stage of growth.