The relationship between the digestibility of a sward and the herbage consumption of grazing calves

1968 ◽  
Vol 70 (1) ◽  
pp. 47-51 ◽  
Author(s):  
J. Hodgson
Keyword(s):  
Food Intake ◽  
Linear Relationship ◽  
Full Range ◽  
Chromic Oxide ◽  
Regression Equations ◽  
Faecal Output ◽  
Herbage Intake ◽  
The Relationship ◽  
Very High

SUMMARYNitro-chalk was applied to S.23 ryegrass swards, at approximately monthly intervals, at two contrasting levels in 1961 and three levels in 1962. Steer calves, 3–6 months old, grazed in rotation round a series of four paddocks on each treatment. Paddocks were trimmed and fertilizer applied after each grazing. The herbage intakes of the calves were determined on three occasions in 1961 and four occasions in 1962. Faecal output was estimated by chromic oxide dilution. In vitro digestibility determinations were carried out on samples of herbage clipped from the swards.There was a close linear relationship between the digestibility of the herbage and the amount eaten, over the full range of digestibility encountered (68–82%). Regression equations calculated within seasons and fertilizer levels, and within years, did not differ significantly. The regressions of faecal output on herbage digestibility were not significantly different from zero.The observed relationship between herbage digestibility and herbage intake may reflect (a) the greater sensitivity of young ruminants than adult stock to changes in the digestibility of the diet, and (b) the reduced importance of the chemostatic control of food intake, except at very high levels of digestibility, in young rapidly growing animals.

The effect of pre-ovulatory nutrition on the subsequent development of superovulated sheep ova in an in vitro culture system.

1994 ◽  
Vol 1994 ◽  
pp. 82-82
Author(s):  
J. Creed ◽  
T.G. McEvoy ◽  
J.J. Robinson ◽  
R.P. Aitken ◽  
R.M. Palmer ◽  
...  
Keyword(s):  
Food Intake ◽  
Oocyte Maturation ◽  
Culture System ◽  
Subsequent Development ◽  
Plasma Progesterone ◽  
Wide Range ◽  
In Vitro Culture System ◽  
High Level ◽  
The Relationship

Superovulatory treatments for ewes are normally preceded by a period of priming. In a recent study involving two contrasting levels of feeding (0.6 versus 2.4 x maintenance), McEvoy et al (1993) observed that the higher level of feeding suppressed pre-ovulatory plasma progesterone concentrations and the subsequent early development and viability of fertilized ova. This finding suggests that there is a need to reconsider the recommendation, based on data for spontaneously-ovulating ewes, that ‘superovulated embryo donor ewes’ should be maintained on a high level of feeding during the period of oocyte maturation. It also raises questions regarding the form of the relationship between food intake and plasma progesterone concentrations over the wide range of feeding levels that occur in practice. The aims of the present study were therefore two-fold; firstly, to investigate the relationship between level of feeding and plasma progesterone for feed intakes that ranged from 0.6 x maintenance (M) to 2.4 M and secondly to assess the effect of pre-ovulatory feeding levels on the number, quality and viability of ova produced following superovulation.

The herbage intake of cattle grazing lucerne and cocksfoot pastures

1963 ◽  
Vol 60 (3) ◽  
pp. 359-369 ◽  
Author(s):  
F. E. Alder ◽  
D. J. Minson
Keyword(s):  
Organic Matter ◽  
Sampling Methods ◽  
Live Weight ◽  
Ground Level ◽  
Cattle Grazing ◽  
Chromic Oxide ◽  
Grazing Experiment ◽  
Herbage Intake ◽  
The Mean

1. From 1955 to 1957 a cattle grazing experiment was carried out on lucerne and cocksfoot pastures. Hereford-cross steers were used. Results obtained on the assessment of herbage intake either by the use of chromic oxide and faecal index methods or by herbage sampling are presented here.2. Except in 1955, when techniques were being developed, the digestibility of the herbage on offer to the bullocks was estimated by cold storing herbage, cut with an Allen Autoscythe and later feeding it to sheep in indoor digestion trials. The in vitro digestibility of herbage samples cut in 1955 and 1956 was also determined.3. In 1956 the mean intake of organic matter (lb.) per 100 lb. live weight by faecal methods was 2·38, 2·07, 2·20 and 2·29 on pastures of lucerne, cocksfoot, lucerne/cocksfoot (broadcast) and lucerne/cocksfoot (alternate 1 ft. drills), respectively, and 1·99, 1·76, 2·02 and 1·97, respectively, in 1957.4. In 1956 the mean intake of organic matter (lb.) per 100 lb. live weight by herbage sampling methods was 2·14, 1·70, 2·11 and 1·99 on the same pastures of lucerne, cocksfoot, lucerne/cocksfoot (broadcast) and lucerne/cocksfoot (drills), respectively, and 2·49, 1·32, 2·35 and 2·03, respectively, in 1957. The modified Tarpen trimmer, cutting to within 1 in. of the ground was used for sampling in 1956 and the Allen Autoscythe cutting to within 2 or 3 in. of ground level in 1957.5. Detailed botanical separation of herbage samples showed that the bullocks were selecting the more digestible parts of the plants; the top 4 in. of lucerne and the ends of leaves and stems of cocksfoot. This and other factors which could affect the estimates of digestibility of herbage eaten by the cattle are discussed together with possible sources of error in the herbage sampling methods.

Mutation to auxotrophy and prototrophy as related to symbiotic effectiveness in Rhizobium leguminosarum and R. trifolii

1969 ◽  
Vol 15 (6) ◽  
pp. 611-622 ◽  
Author(s):  
E. A. Schwinghamer
Keyword(s):  
Rhizobium Leguminosarum ◽  
Auxotrophic Mutant ◽  
Metabolic Inhibitors ◽  
Nutritional Requirement ◽  
Metabolic Defects ◽  
Resistant Mutants ◽  
The Relationship ◽  
Derivatives Of ◽  
Very High

Auxotrophs were isolated from four effective strains of Rhizobium leguminosarum and R. trifolii for a study of the relationship between metabolic defects and loss of ability for symbiosis. Most auxotrophs were isolated indirectly by prior isolation of mutants for resistance to metabolic inhibitors, especially D-alanine and D-histidine. The likelihood of some nutritional requirement was greatly increased among such resistant mutants, and was very high for derivatives of the R. trifolii strains. The complexity of growth factor requirement varied greatly between auxotrophs, and few had simple requirements. The most common requirement was for vitamins, notably thiamine. Partial or full restoration of effectiveness in symbiosis often accompanied reversion to prototrophy in some ineffective auxotrophs. The frequency of some degree of restoration among prototrophs varied from 0% to 100%, depending on the auxotrophic mutant involved. In one ineffective auxotroph of R. trifolii strain T1 the level of reversion (partial to complete) in vitro varied considerably and generally paralleled the degree of restoration of effectiveness. Biochemical deficiency appeared to be meaningfully related to impaired symbiosis in some auxotrophs but the relationship was probably incidental in most others. These auxotroph–prototroph studies are considered from the standpoint of relationship to several areas of research on Rhizobium.

Theory of Scarcity-Variability, Conflict, and Cooperation

2016 ◽  
Author(s):  
Shlomi Dinar ◽  
Ariel Dinar
Keyword(s):  
Environmental Change ◽  
Linear Relationship ◽  
Water Scarcity ◽  
Water Abundance ◽  
Conflict And Cooperation ◽  
International Water ◽  
Mitigation Costs ◽  
The Relationship ◽  
Very High ◽  
Large Corpus

This chapter explores the linkages between water scarcity and variability and conflict and cooperation. It focuses on the scarcity-cooperation contention and then hypothesizes that, rather than a linear relationship, an inverted U-shaped constitutes the relationship between scarcity and cooperation and between water variability and cooperation. The chapter surveys a large corpus of literature (both theoretical and empirical) from various disciplines to build a theory to explain the relationship between level of water scarcity and level of cooperation over international water. While the premise that scarcity motivates cooperation (or coordination across parties) is not novel, it has been fairly rare compared to the literature that touts the relationship between scarcity, environmental change, and conflict. The model suggests that cooperation is more likely when scarcity and variability are moderate (and by extension require smaller mitigation costs). The theory also suggests that while scarcity and variability may indeed lead to cooperation, very high levels of scarcity and very low levels of scarcity (water abundance) actually reduce the incidence of cooperation.

A study of food intake and production in grazing ewes Part I. The measurement of food intake

1963 ◽  
Vol 61 (2) ◽  
pp. 267-274 ◽  
Author(s):  
J. B. Owen ◽  
Jean W. Ingleton
Keyword(s):  
Food Intake ◽  
Sheep Grazing ◽  
Reasonable Estimate ◽  
Output Data ◽  
Faecal Output ◽  
Grazing Animal ◽  
Or Groups ◽  
Milled Sample ◽  
The Relationship

The problems involved in estimating the food intake of the grazing animal are considered and an account is given of studies made on eighteen Clun ewes and six Hampshire × Clun wethers. Results are given from sixty-eight observations on the relationship between food intake and a fraction dissolved in the faeces when a milled sample is left to stand in 0·2N-HCl for 18 hr. Using, in addition, data from grazing ewes subjected to total faeces collection during winter and spring 1959–60 it is concluded that 4 consecutive days of collection give a reasonable estimate of faecal output, and that where similar groups of sheep are grazing on the same pasture at the same time it is unnecessary to convert faeces output data to intake figures in order to compare intake-production relationships between individuals within a group. Where, however, comparisons are to be made between individuals or groups of sheep grazing different pastures at different times then it becomes necessary to allow for differences in food-faeces ratios; for this purpose the dissolved fraction discussed here is likely to prove a useful faecal indicator eliminating many disadvantages of earlier methods and some of the seasonal bias inherent in other indicators at present in use.

Conclusions and recommendations from the Helene Harris Memorial Trust Fourth Biennial International Forum on Ovarian Cancer 11–14 May 1993, Toronto, Canada

1994 ◽  
Vol 4 (2) ◽  
pp. 135-143 ◽  
Author(s):  
T. Blackett ◽  
F. Sharp
Keyword(s):  
Ovarian Cancer ◽  
Tumor Suppressor Genes ◽  
Malignant Tumors ◽  
Full Range ◽  
Brca1 Gene ◽  
Future Research ◽  
Relationship Of ◽  
The Relationship

The Helene Harris Memorial Trust organizes biennial international meetings of leading clinicians and scientists to discuss progress in the understanding and treatment of ovarian cancer. The conclusions of this meeting, together with recommendations for future research are published as a guide to others working in this field.The 107 conclusions and recommendations presented cover the full range of current topics in ovarian cancer research including the biology of early and borderline tumors, the relationship of benign to malignant tumors,in vitromodels, the role of cytokines, genetic epidemiology, oncogenes and tumor suppressor genes, allele loss, localization of the BRCA1 gene, DNA ploidy in prognosis, the therapeutic use of interferon, platinum and taxoid drugs, screening with panels of tumor antigensm immunotherapy and potenial for gene therapy.

Studies on the nutritive value of the diet selected by grazing sheep V. Further studies of the relationship between digestibility estimated in vitro from oesophageal fistula samples and from faecal and dietary composition

1969 ◽  
Vol 11 (3) ◽  
pp. 379-387 ◽  
Author(s):  
J. P. Langlands
Keyword(s):  
Nitrogen Content ◽  
Nutritive Value ◽  
Live Weight ◽  
Faecal Output ◽  
Faecal Nitrogen ◽  
Grazing Sheep ◽  
Predicted Values ◽  
Stocking Rates ◽  
The Relationship

SUMMARYDigestibility was estimated in vitro from a total of 167 oesophageal fistula samples collected over a period of 16 to 24 months from adult sheep grazing eight Phalaris tuberosa-Trifolium repens pastures stocked continuously at rates of from 2·5 to 37·1 sheep per ha. Corresponding estimates of the nitrogen content of the faeces and of the fistula samples, the live weight and faecal output of the sheep, and of the herbage availability of the pasture were obtained.The observations were stratified on the bases of stocking rate, digestibility, month of the year, herbage availability or organicmatter intake. Relationships between digestibility estimated by the fistula technique and faecal nitrogen content (model B) and between digestibility and faecal nitrogen content, nitrogen content of the dietary dry and organic matter, and faecal output per unit live weight (model A) were calculated for each stratum.There were significant differences between relationships derived for the various stocking rates, levels of digestibility, times of year, levels of intake and levels of herbage availability; predicted values of digestibility for given values of the independent variables differed by as much as 20 units of digestibility. Model A was substantially more precise than model B.Differences between estimates of digestibility, derived by the fistula technique and by a general faecal nitrogen—digestibility relationship, established by Lambourne and Reardon (1963a) were calculated. The differences were related to digestibility and to herbage availability.The implications of these results are discussed and it is concluded that faecal nitrogen content is not a satisfactory index of the digestibility of the diet selected by grazing sheep.

scholarly journals Effect of average diurnal barn airspace temperatures on prediction of their development during the day

2011 ◽  
Vol 59 (6) ◽  
pp. 161-166
Author(s):  
Gustav Chládek ◽  
Oto Hanuš ◽  
Daniel Falta
Keyword(s):  
Statistical Analysis ◽  
Polynomial Regression ◽  
Regression Equations ◽  
Degree Polynomial ◽  
Reliable Prediction ◽  
The Third ◽  
University Training ◽  
Diurnal Temperatures ◽  
The Relationship ◽  
Very High

A year-round (i.e. 365 days) experiment was performed at the Mendel University Training Farm in Žabčice, Czech Republic (GPS 49°0’51.967”N and 16°36’14.614”E, the altitude 179 m) with the aim to quantify the effect of the variation of average diurnal barn airspace temperatures on prediction of their changes during the day. Barn airspace temperatures were monitored daily in one-hour intervals and the recorded values were used for calculations of average diurnal temperatures. These were classified into 7 categories (i.e. below 0 °C; 0.1 to 5 °C; 5.1 to 10 °C; 10.1 to 15 °C; 15.1 to 20 °C; 20.1 to 25 °C and above 25 °C). Regarding this classification system, all differences between temperatures measured at identical hours but within various limits were statistically highly significant. The statistical analysis involved also the calculation of the third degree polynomial regression equations, which enabled to characterise the relationship between the temperature and the hour of measurement within the aforementioned categories of diurnal temperatures. Individual equations were markedly different and ranged from y = − 0.0019x3 + 0.0596x2 − 0.3797x − 1.2169 (for temperatures below 0 °C) to y = − 0.0108x3 + 0.3297x2 − 1.9367x + 24.3931 (for temperatures above 25 °C). Correlation coefficients (r) and coefficients of determination (R2) of these regression equations were generally very high and ranged from 0.872 to 0.976 and from 0.760 to 0.953, respectively. Regarding high values of both coefficients it can be concluded that the calculated equations enable a good and reliable prediction of the diurnal development of barn airspace temperatures.

The nutrition of grazing ewes during pregnancy and lactation: a comparison of alkane-based and chromium/in vitro-based estimates of herbage intake

2000 ◽  
Vol 51 (6) ◽  
pp. 765 ◽  
Author(s):  
H. Dove ◽  
M. Freer ◽  
J. Z. Foot
Keyword(s):  
Late Pregnancy ◽  
In Vitro Digestibility ◽  
Faecal Output ◽  
Stage Of Lactation ◽  
Herbage Intake ◽  
Faecal Samples ◽  
Pregnancy And Lactation ◽  
The Difference

The n-alkane and chromium/in vitro procedures for estimating herbage intake were compared in grazing ewes during late pregnancy, early lactation, and mid-lactation. To ensure differences in herbage intake, the ewes were grazed in 4 plots of phalaris-dominant pasture at 2 levels of stocking: 17.1 ewes/ha and 30.8 ewes/ha. To investigate whether either procedure for estimating herbage intake was influenced by supplement consumption, half of the ewes at each stocking level received 500 g/day air-dry of a pelletted supplement (1 : 1 milled oat grain : sunflower meal). Supplement intakes were estimated using tritiated gypsum as a marker. During intake measurement periods, ewes were dosed twice daily with both alkane capsules and capsules containing chromium sesquioxide. For the last 6 days of the 12-day dosing period, rectal faecal samples were taken twice daily, immediately before the dosing. Over these same periods, wether sheep fitted with faecal collection harnesses were similarly dosed and sampled, and their total faecal output collected to establish the faecal recovery of chromium and the alkanes. Herbage intakes were estimated using the C27/C28, C29/C28, C31/C32, and C33/C32 alkane pairs. Estimates of intake based on the shorter alkane pairs were lower than those estimated with the C33/C32 alkane pair, by amounts which differed between the periods. Evidence is presented that estimates based on the last pair of alkanes (C33/C32) are the most accurate and are also more accurate than those based on the chromium/in vitro procedure. The relationship between these 2 methods for estimating intake was different in mid-pregnancy compared with either stage of lactation. The consumption of supplement did not interfere with any of the methods for estimating herbage intake. Estimates of faecal output based on the use of chromium, C28 alkane, or C32 as an external marker were statistically identical, indicating that the difference between the 2 methods for estimating herbage intake was not related to a failure to accommodate the incomplete recovery of any of the markers used or to the failure of rectal grab samples to be representative of total faeces. Our results indicate that herbage collected by oesophageally fistulated (OF) sheep was representative of that grazed by the ewes and could thus be used to provide the herbage alkane data needed to estimate herbage intake by the alkane method. However, the in vitro digestibility values obtained from the OF samples did not represent the digestibilities actually occurring in vivo. This was the main cause of the observed difference between the 2 methods for estimating intake. Possible reasons for the differences between the in vitro and in vivo estimates of digestibility are discussed.

scholarly journals A Linear Relationship between Fitness and the Logarithm of the Critical Bottleneck Size in Vesicular Stomatitis Virus Populations

2008 ◽  
Vol 82 (24) ◽  
pp. 12589-12590 ◽  
Author(s):  
Isabel S. Novella ◽  
Ranendra N. Dutta ◽  
Claus O. Wilke
Keyword(s):  
Linear Relationship ◽  
Population Size ◽  
Vesicular Stomatitis Virus ◽  
Linear Correlation ◽  
Large Population ◽  
High Fitness ◽  
Size Population ◽  
Vesicular Stomatitis ◽  
The Relationship ◽  
Very High

ABSTRACT We explored the relationship between fitness change and population size during transmission in vesicular stomatitis populations of very high fitness. The results show a linear correlation between the logarithm of the critical bottleneck size (population size at which there are no significant fitness changes after 20 passages) and the initial fitness of the population. In addition, limits to fitness increases during large-population passages of very-high-fitness strains were abolished by increasing the population size during transmission, indicating that beneficial variation is still available in these populations.

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