bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in rheological properties and endosperm peroxidase activity associated with breeding for an osmoregulation gene in bread wheat
Authors: Morgan J. M.
Published: September 2002

Backcross lines which had been bred for an osmoregulation gene to improve the
drought tolerance of 3 commercial bread wheat cultivars were tested for
standard grain, dough, and baking characteristics. Three field sites were used
to provide a range of protein contents of 10–14%. It was found
that backcross lines with high osmoregulation had alterations in dough
strength which could only be understood in terms of genetic linkage. Evidence
of a linkage effect was found by comparing lines with recurrent parents in a
season of low water stress, i.e. where yields and hence protein contents of
each group were the same. On average, lines which had been bred for high
osmoregulation had significantly shorter development times and significantly
lower maximum resistances to extension than recurrent parents. Other
parameters were not significantly different.
A probable explanation of the dough strength effect lay in a difference in
peroxidase activity due to linkage between the endosperm peroxidase,
Per-A4, locus, and the osmoregulation, or, locus. There
was an expectation, from published work, that dough strength could be affected
by peroxidase. The hypothesis was confirmed by measurements of peroxidase
activity. On average, lines with high osmoregulation (lower dough strength)
had lower peroxidase activities than recurrent parents (higher dough
strength). This effect, however, depended on protein content and genotype.
Significance for plant breeding is discussed.
Wheat spike temperatures in relation to varying environmental conditions
Authors: Panozzo J. F. , Eagles H. A. , Cawood R. J. , Wootton M.
Published: September 2002

Most field studies investigating the effect of temperature on growth processes
use temperatures recorded within a Stevenson screen. These are likely to
deviate from temperatures within the plant. This investigation reports a
comparative study of methodologies and applications for measuring temperatures
in the field during grain development by comparing Stevenson screen, ambient
(air temperatures within the crop canopy), and wheat spike temperatures.
Miniature sensors were inserted into wheat spikelets located midway on the
spike of a primary tiller at anthesis. Located also within the crop canopy,
and at the same height as the spike sensors, were sensors to measure ambient
temperatures. Stevenson screen temperatures were also recorded at the site.
Temperatures were recorded automatically every 12 min during grain filling
from anthesis to maturity. Plants were grown in dryland and irrigated
conditions within the same location, with the aim of determining differences
in plant temperatures between stressed and non-stressed plants.
Stevenson screen temperatures did not relate closely to ambient or spike
temperatures. Plants growing in adequate soil moisture conditions had spike
temperatures lower than ambient temperatures, but in some dryland trials,
where soil moisture was limiting, spike temperatures equalled ambient
temperatures, indicating that the plants were under moisture stress.
Temperature differences of up to 5˚C were observed between the spikes of
irrigated and non-irrigated crops on a hot day. Neither ambient nor screen
temperatures gave an accurate measurement of spike temperature on hot days.
Spike temperature differences between 2 cultivars, awned and awnless, were
investigated. Trends were not consistent over both years; however, in 3 of the
4 environments, the maximum spike temperatures were higher for the awned
cultivar (Hartog) than the awnless cultivar (Halberd). On very hot days, when
ambient temperatures exceeded 40˚C, spikes of Hartog were cooler than
those of Halberd.
Pollen grain expression of a gene controlling differences in osmoregulation in wheat leaves: a simple breeding method
Authors: Morgan J. M.
Published: September 2002

The possibility that a gene conditioning differences in osmoregulation in
wheat leaves (or) is also expressed in pollen grains was
investigated in order to differentiate heterozygous and homozygous lines for
use in backcross breeding. The difference in osmoregulation in leaves was
expressed as a difference in solute accumulation which was calculated from
responses of osmotic potential and relative water content to reductions in
water potential caused by droughting plants in pots. A corresponding allelic
difference was found in pollen grains. It was demonstrated by a difference in
relative size, and solute accumulation, after stressing using polyethelene
glycol solution. The response occurred only after addition of a small quantity
of potassium chloride, and the maximum response occurred at concentrations of
approximately ≥0.2 mM (at least to 10 mM). This suggests that
or may condition high affinity potassium transport.
Single-gene control was confirmed using pollen responses, and pollen grain
expression was further demonstrated by the use of pollen responses, to
identify alleles and thus manipulate leaf responses in a backcross breeding
study. Because the differences in pollen grain size may be readily observed
without measurement using a microscope with relatively low magnification, and
because the pollen grains are easily sampled at flowering, the pollen response
is suitable as a routine test in plant breeding involving pedigree or
backcross methods.
Germination and seedling growth at low temperature: comparisons of Lotus species and effects of selection and seed source in L. pedunculatus Cav.
Authors: Kelman W. M. , Forrester R. I.
Published: September 2002

The association of seed size, type of life cycle (annual/perennial), and
ploidy (diploid/tetraploid) with low temperature (5˚C), germination
rate, and seedling growth was examined under controlled conditions in 9
Lotus species. Seeds harvested at 2 localities from 2
populations of L. pedunculatus, one selected for early
flowering and the other unselected for flowering time, were included in the
study to examine the influence of selection history and seed provenance on
cold temperature germination rate and seedling growth. Seed size and ploidy
level were not significant factors influencing germination rate of the
Lotus species, but both seed size and life cycle had
significant associations (P< 0.01) with seedling dry
weight. Seed of the selected, early flowering population of
L. pedunculatus germinated significantly faster than
that of the unselected population (P< 0.01), and this
difference was more pronounced in seed from the site where early flowering
would confer advantages of better seed production and the potential for better
persistence through seedling recruitment. Anarrow-sense heritability estimate
for the germination rate of L. pedunculatus was high at
the 2 localities (0.84 ± 0.17 and 0.65 ± 0.16) and it was thus
promising as a selection criterion for improved establishment. If
interspecific hybridisation can be achieved between the annual and perennial
species, a longer term prospect exists to utilise the high capacity of annual
species to germinate and grow at low soil temperatures.
Rate and duration of grain filling and grain nitrogen accumulation of wheat cultivars grown in different environments
Authors: Panozzo J. F. , Eagles H. A.
Published: September 2002

In Australia, the period during grain filling for wheat
(Triticum aestivum L.) is often associated with
increasing ambient temperatures and diminishing soil moisture conditions. This
can affect grain size and grain protein concentration. In this study, grain
filling and nitrogen accumulation were investigated by sampling every 7 days
during grain filling for 4 cultivars: Rosella, Hartog, Halberd, and Eradu. The
plants were grown in trials with and without irrigation in 1991 and 1992,
which were seasons with divergent temperatures and rainfall during this
period. A4-term logistic function, using both days after anthesis (DAA) and
growing degree days (GDD), was fitted to data to estimate maximum rate and
duration of grain filling. The logistic model proved to be, in most cases, an
accurate method to determine the rate and duration of grain filling and
nitrogen accumulation. Probably because of differences in availability of soil
moisture, the use of GDD did not improve on the estimates obtained from using
DAAas the independent variable.
In 1991, a relatively dry year, non-irrigated plants showed signs of wilting.
In that year, grain nitrogen contents on a per grain basis were similar in
both the irrigated and non-irrigated (dryland) environments, but grain weights
were much higher from the irrigated environment. The maximum rate and duration
of grain filling were lower in the dryland environment. In contrast, whereas
the duration of nitrogen accumulation was similarly shorter in the dryland
environment, the maximum rate of accumulation was substantially higher. In
1992, a cooler and wetter year, differences between irrigated and
non-irrigated environments were smaller, but the trends for rate and duration
were similar. We concluded that, under stress conditions, higher rates of
accumulation of grain nitrogen and lower rates of accumulation of
carbohydrate, rather than differences in duration of accumulation, were
primarily responsible for increased grain nitrogen concentrations.
In general, cultivars used in this study were ranked similarly for rate and
duration of grain filling across environments, with the exception of Hartog,
which had a significantly lower maximum rate in the dryland treatment in 1991.
This suggests that Hartog may be more sensitive to drier conditions than the
other cultivars. In almost all environments, Eradu had a higher maximum rate
of accumulation of grain nitrogen than other cultivars; however, the duration
was reduced, so that in the mature grain, grain nitrogen concentration was not
significantly different.
Cereal structure and composition
Authors: Evers A. D. , O'Brien L. , Blakeney A. B.
Published: September 2002

Cereals are cultivated grasses that are grown throughout the world. As well as
providing food for man, they, or fractions derived from processing them, make
an important contribution to the diets of farm stock. Cereal grains have a
long storage life under favourable conditions because they are harvested at a
relatively low moisture content and comprise stable components. The principal
energy sources within the grains are protected from infestation by outer
coverings that are difficult to penetrate and in some cases unpalatable
components in the coverings discourage predation by wild populations. The
largest morphological component of all grains is the starchy endosperm, and
approximately 80% of this is starch, occurring as microscopical
granules with forms characteristic of the species. Also characteristic of the
species are the storage proteins, which make the next largest contribution to
endosperm dry weight. Proteins are important both as nutrients and by virtue
of the fact that the class includes enzymes which, although making a small
contribution to grain weight, can have a marked effect on grain quality and
hence price. Other chemical components present as minor contributors, but with
potential for exerting significant nutritional influence, are phytates and
tannins, and current knowledge of these is briefly discussed. The walls of
endosperm cells comprise a complex mixture of polysaccharides including
cellulose, arabinoxylans, and β-glucans, as well as proteins and
esterified phenolic acids. Attention is drawn to the difficulty in defining
‘fibre’ as it is method- or function-dependent and includes
contributions from the endosperm cell wall components as well as the lignified
walls of cells in the outer protective pericarp and the contents and cuticle
of the testa.
Chemical and physical characteristics of grains related to variability in energy and amino acid availabilityin ruminants: a review
Authors: van Barneveld Samantha L.
Published: September 2002

This paper reviews the carbohydrate, protein, lipid, anti-nutritional, and
physical characteristics ofgrains that determine the variability in their
nutritional quality for ruminant animals. The amount, rate, and extent of
starch fermentation in the rumen have been the subject of many studies, with
large variation found between and within grain species. Electron microscopy
scanning techniques have shown that the protein matrix limits the microbial
colonisation of starch granules in some grain species, whereas in others it
may be the structural carbohydrates that affect colonisation. The composition
of the different fibre fractions of grains and their interaction with non-fibre
carbohydrates requires investigation, since it has been shown that
non-starchpolysaccharides, including neutral detergent fibre and acid
detergent fibre, may not be specific enough to predict animal response to
grain. Fermentation patterns of the non-starch polysaccharide components of
legumes are also poorly understood and hence require further investigation.
Different varieties of grain and different seasonal conditions show variation
in the protein fractions of the kernel. Since these fractions display
different solubility and degradation rates in the rumen, rumen solubility
values cannot be generalised for grains. The variability in solubility caused
by rumen flow rate and pH is a further complication. Finally, the lipid
content of grains varies greatly, with high-oil grains potentially contributing
to the energy level of the diet, but possibly negatively affecting rumen
fermentation. Due to the degree of variability of characteristics discussed in
this review, it is clear that the nutritional quality of grains cannot be
assessed in a single rapid assay.
Chemical and physical characteristics of grains related to variability in energy and amino acid availability in pigs: a review
Authors: van Barneveld Robert J.
Published: September 2002

To optimise pig production, there is a need to define the variation in the
available energy and amino acid content of feed grains and to understand those
factors that influence nutritive value. Differences of up to3.7 MJ/kg dry
matter (DM) in digestible energy (DE) content were observed following a review
of data for more than 70 cultivars of wheat. Similarly, analysis of data for
more than 125 cultivars of barley revealed a range in DE estimates from 11.7
to 16.0 MJ/kg DM. Differences of this magnitude are economically
significant to pig producers. Cultivar has a minimal effect on the
availability of energy and amino acids in cereals, although this variation is
larger in legumes, particularly lupins. The cultural conditions and agronomic
practices (e.g. fertiliser rate) have a greater influence on amino acid and
energy availability than the growing region or the growing year. Many factors
are shown to influence the availability of energy and amino acids in feed
grains, including protein source and type, starch characteristics, fat source
and type, non-starch polysaccharide components, and anti-nutritional factors.
Although all of these factors can influence the nutritive value of a feed
grain for pigs in some way, the availability of energy and amino acids will
ultimately depend on the particular combination of these components in a grain
and how they behave in the presence of nutrients from other feed ingredients.
For this reason, an understanding of the factors that influence the nutritive
value of feed grains is more likely to eventuate when multiple regressions of
grain components are made against the availability of energy and amino acids.
Chemical and physical characteristics of grains related to variability in energy and amino acid availability in poultry
Authors: Choct M. , Hughes R. J.
Published: September 2002

Grains such as wheat and barley, combined with legumes and oilseed meals,
provide not only the bulk of essential nutrients for commercial poultry production and
reproduction, but are also the prime source of anti-nutritive components,
which are likely to have significant bearing on how effectively all dietary
components are utilised by poultry. Sources of variation in the physical and
chemical characteristics of grains used in poultry diets include variety,
seasonal effects, and growth sites, crop treatment and grain fumigants, and
post-harvest storage conditions and period of storage. The available energy
and protein contents of grains fed to poultry, which best represent nutritive
value, are extremely wide and in consequence there is an urgent need to
develop rapid and objective tests for the assessment of nutritive value prior
to including grains in poultry diets. Variation in the available energy and
protein content of grains can be attributed to a wide range of anti-nutritive
factors such as non-starch polysaccharides (NSP), enzyme activity, tannins,
alkyl resorcinols, protease inhibitors, α-amylase inhibitors,
phytohaemagglutinins, alkaloids, saponins, and lathyrogens. The relative
importance of such factors will also differ according to the type of grain in
question. However, NSP seem to be the predominant factor in Australia over the
past few years given the volume of published literature on this topic. This
argument is strongly supported by the fact that NSP-degrading enzymes are
routinely used in monogastric diets with great success throughout the world.
Numerous attempts over a long period have failed to provide unequivocal
evidence that nutritive value in grains for poultry can be predicted with
sufficient accuracy and precision by simple, low-cost physico-chemical
measurements used singly or in combination. Nevertheless, it is highly
desirable to continue to explore these simple measurements in the expectation
that useful statistical relationships with more complex measurements will
emerge, or that simple measurements can be used to fine-tune prediction
equations based on more powerful techniques such as near infrared
spectrophotometry.
Finally, the nutritive value of grains for poultry will be determined not only
by the chemical and physical properties of grains but also by the way that
these interact with the processes of ingestion, digestion, absorption, and
metabolism in birds. For this reason it is imperative that plant and animal
scientists join forces to improve the nutritive value of plant material as
feed for animals for the benefit of grain growers and producers of livestock.
Genotype and environment effects on feed grain quality
Authors: O'Brien L.
Published: September 2002

The extent of genotype and location effects on chemical composition and
nutritive value of grains fed to animals was surveyed. The review covered the
winter cereals (wheat, barley, oats, and triticale), the summer cereals
(sorghum and maize), and the pulses (field pea, lupins, faba beans, and
chickpea) when fed to cattle, sheep, poultry, pigs, rats, and mice.
The bulk of the literature does not meet the statistical criteria required to
differentiate genotype and environment effects. When the criteria were
satisfied, significant genotype differences were shown to exist for chemical
composition in wheat, barley, triticale, and sorghum, for nutritive value as
determined by methods in vitro in wheat, barley, oats,
triticale, and sorghum, and in vivo for wheat, barley,
triticale, sorghum, and maize. Valid comparisons across grain species are few,
but in vitro gas production ranks wheat > oats >
barley. Significant location, year, genotype × location, genotype
× year, and genotype × location × year effects were reported
for nutritive value for some grains.
Wheat feeding trials with poultry indicate that environment can affect
apparent metabolisable energy (AME) as much as, if not more than, genotype. A
greater range in nutritive value appears to exist in barley than in wheat. The
information is unclear in the case of triticale, where despite some reports
claiming that grain of this species has high lysine content, the difference
does not appear to translate to improved performance in animals. Insufficient
studies exist for oats despite it being one of the most widely used on-farm
feed grains. No examples could be found of studies with rye.
The most thoroughly researched grain has been sorghum, which is principally
grown in developed countries for feeding to livestock. Here, some definitive
studies have been conducted to define the extent of genotype, location, and
genotype × environment interaction effects. Scope exists to enhance the
nutritive value of sorghum by breeding through modification of endosperm
composition, tannin content, and improved protein digestibility. Variation in
endosperm composition in maize due to simply inherited mutations provides the
opportunity to improve its nutritive value.
This review indicates that before any plant breeding is undertaken for feed
grain quality, a better understanding of what determines nutritive value and
the relative importance of genotype and environment in modulating these
factors is required.
Processing cereal grains for animal feeding
Authors: Rowe J. B. , Choct M. , Pethick D. W.
Published: September 2002

This review concentrates on factors influencing the nutritive value of cereal
grains for animals and strategies, in particular processing and storage, which
may be used to optimise fermentation and digestion. The main focus is on the
utilisation of starch in cereal grains by ruminants. Extensive comparisons
have been made between grains and between animals to understand the reasons
for differences in pattern of fermentation and/or intestinal digestion in
response to a range of processing techniques. In addition, differences between
the animal species have been reviewed to understand further the factors
critical for maximising post-ruminal starch digestion.
Increasing the utilisation of grain when fed whole to ruminants
Authors: Kaiser A. G.
Published: September 2002

Feeding grain whole to cattle generally results in a lower digestibility than
that obtained with processed grain. If this problem could be overcome, feeding
with whole grain would reduce processing costs, and the slower rate of starch
digestion in the rumen could improve fibre digestion with potential beneficial
effects on intake and animal production.
Two strategies are available to increase the digestibility of whole grain. The
first, longer term strategy relies on the selection or breeding of feed grains
that are efficiently digested by cattle when fed whole. The review considers
the chemical and physical properties of grains likely to increase the degree
of grain damage during mastication, and increase the digestibility of the seed
coat fraction. Research is required to determine the feasibility of selecting
feed grains with these characteristics.
The second strategy is to treat whole grain with chemicals or enzymes to
increase digestibility of the seed coat and consequently whole grain digestion
within the rumen. Considerable research has been conducted on the sodium
hydroxide (NaOH) treatment of grain, and there is sufficient evidence from
cattle experiments to indicate that digestibility, liveweight gain, and milk
production on NaOH-treated whole grain can be similar to that on rolled grain,
provided sufficient NaOH is applied. However, a number of practical and
commercial considerations have limited the more widespread adoption of this
technology on farms. Although ammonia treatment offers a more practical
alternative to NaOH, digestibility and animal production responses have been
highly variable, and research is required to identify effective ammoniation
procedures.
The increased availability of enzymes for livestock feeding has potentially
provided another grain treatment option. The application of fibrolytic enzymes
to whole grain prior to high-moisture storage or feeding, and their subsequent
effect on grain digestibility, require research. The impact of grain
characteristics, both physical and chemical, on the response to alkali or
enzyme treatment also requires research.
Associative effects between forages and grains: consequences for feed utilisation
Authors: Dixon R. M. , Stockdale C. R.
Published: September 2002

Intake of metabolisable energy (ME) when forages and grains are fed together
to ruminants may, due to digestive and metabolic interactions, be lower or
higher than expected from feeding these components separately. These
interactions, or associative effects, are due primarily to changes in the
intake and/or the digestibility of the fibrous components of forage.
Effects on voluntary forage intake (substitution effects) are usually much
larger than on the digestibility of fibrous components, although the changes
in forage intake may be a consequence of changes in the rate of digestion of
the fibrous components. Positive associative effects, where grains increase
voluntary intake and/or digestion of forage, are usually due to the
provision of a limiting nutrient (eg. nitrogen, phosphorus) in the grain which
is deficient in the forage. Negative associative effects, where grains
decrease voluntary intake and/or digestion of forage, occur frequently and
can cause low efficiency of utilisation of grain.
Rate of substitution of grain for forage is related to forage intake, forage
digestibility, the proportion of grain in the diet, and the maturity of the
animal. Substitution rates are usually high in ruminants consuming high
intakes of forage of high digestibility, probably due to the metabolic
mechanisms which control voluntary intake reducing forage intake. Substitution
rates are often low when animals are consuming forage of low to medium
digestibility. Since voluntary intake of such forages is most likely
determined by the capacity of the rumen to accommodate and pass to the lower
gastrointestinal tract undigested forage residues, and of the rate of forage
fibre digestion in the rumen, substitution is likely to be determined by
changes in these processes. Reduced rate of fibre digestion in the rumen is
often due to low rumen pH and/or an insufficiency of essential substrates
for rumen microorganisms. Use of grains for lactating dairy cows involves an
additional constraint since dietary grain may severely reduce milk fat
content. Negative associative effects can be alleviated by ensuring supply of
essential microbial substrates, feeding management, and modification of grain
to minimise their adverse effects on fibre digestion, while ensuring
satisfactory digestion of the grain and efficient microbial protein
production.
Methods for the analysis of premium livestock grains
Authors: Petterson D. S. , Choct M. , Rayner C. J. , Harris D. J. , Blakeney A. B.
Published: September 2002

The literature contains a wide range of reported values for the content of
most chemical constituents of feed grains and meals. It is not possible to
assess accurately how much of this variation is due to genotypic and
environmental factors and how much to differences in methodologies between
laboratories. We have reviewed the literature for the preparation and analysis
of feed grains (cereals, legumes, and oilseeds) and made recommendations for
procedures considered to give the most accurate and reliable results.
Recommendations are also made for a quality assurance scheme, an
inter-laboratory evaluation program, and the use of reference materials.
Australia-wide adoption of these practices should ensure that any future
variations observed can be ascribed to genotype and/or environment. This
review is part of a national premium feed grains quality project which, in
turn, is part of a program to provide more accurate and reliable information
about the true value of our feed grains to the domestic and international
feeds industries.
Potential methodologies and strategies for the rapid assessment of feed-grain quality
Authors: Wrigley C. W.
Published: September 2002

The efficient use of grains for animal feed requires the use of analytical
methods that can provide rapid indications of the suitability of the grain for
animal nutrition. Ideally, these methods need to be applied at the site of
grain receival within the tight time and cost confines of grain delivery. In
addition, methods are needed in plant breeding to efficiently screen for
target aspects of feed-grain quality to facilitate the development of
genotypes with improved nutritional quality. This review describes a range of
techniques that can fulfil these analytical requirements. These include visual
examination of grain samples for species identification and for recognition of
defects and contaminants. This long-standing approach is rapid, but it is
subjective and dependent on the expertise of the operator. The newer
technology of image analysis offers the prospect of providing similar
information automatically and quantitatively, without the risk of operator
bias. Near-infrared (NIR) analysis is already in general use for grain
analysis at many receival depots in wheat-growing countries, mainly for the
determination of moisture and protein content. There are promising indications
that NIR can be extended to the determination of many other aspects of grain
composition, both the positive aspects that contribute to feed quality, as
well as components such as beta-glucan content that have negative
contributions for non-ruminants. Furthermore, NIR is being developed to
provide a direct indication of metabolisable energy for a range of grain
types. Whereas NIR is primarily suited to the determination of quantitatively
major components of the grain, without the requirement of significant sample
preparation, immunological analyses are appropriate for the determination of
specific and minor components, such as mycotoxins, lectins, alkaloids, and
pesticide residues. These and other methods, suited for on-site analysis,
need to be combined with effective sampling to ensure that the results of
testing are representative of the whole of the grain consignment, and also
integrated into a systematic strategy to ensure cost-effective testing.
Physical and chemical contaminants in grains used in livestock feeds
Authors: van Barneveld Robert J.
Published: September 2002

This review focuses on 3 main sources of contamination of Australian grains
used in livestock feeds, namely chemical residues, moulds and mycotoxins, and
weed seeds, including natural toxins such as pyrrolizidine alkaloids. By
evaluating the risk to livestock from chemical contaminants (pre-emergent
herbicides, selective herbicides, fungicides, insecticides used during growth
phases and at pre-harvest, and post harvest insecticides) and the influence of
chemical contaminants on livestock production efficiency and grain nutritional
quality, the relative priorities for residue management strategies can be
established. The chemicals with the highest priority for inclusion in a
residue management strategy include bifenthrin (synthetic pyrethroid),
chlorpyrifos-methyl (organophosphate), deltamethrin (synthetic pyrethroid),
endosulfan (organochlorine), and fenitrothion (organophosphate). It also
appears that the Australian maximum residue limit standards do not meet the
needs of the livestock industries for effective management of residues in
animal feeds, and consequently, a revised approach is required. The amount of
research and literature available on the effects of mould and mycotoxin
contamination of grain on livestock production, and techniques available for
the measurement of moulds and mycotoxins, far exceeds the potential risk these
contaminants pose to the livestock industries in Australia. In addition, the
effects of moulds and mycotoxins are rarely widespread, with many accounts in
the literature referring to a small number of animals on individual
enterprises. The actual economic impact of moulds and mycotoxin contamination
is also difficult to assess due to a lack of systematic surveys and varying
livestock production responses to the presence of these compounds. Finally,
weed seeds and the toxic components of weed seeds are still prevalent
contaminants of Australian grains used in livestock feeds, and are responsible
for significant livestock losses, but there is a lack of screening methods for
qualitative or quantitative identification of these contaminants and a lack of
uniform standards for use of contaminated grain.
Comparison of methods used to predict the in vivo digestibility of feeds in ruminants
Authors: Kitessa S. , Irish G. G. , Flinn P. C.
Published: September 2002

Digestibility is a very useful index of the energy content of ruminant feeds,
but cheaper and quicker laboratory methods are required as an alternative to
the ultimate measure of in vivo digestibility using
animals. These methods involve either prediction of digestibility from
chemical composition or in vitro and
in situ simulation of the digestion process. This review
presents a range of chemical and in vitro techniques for
predicting digestibility, together with an assessment of their advantages and
limitations, particularly the degree to which they account for the sources of
variation in in vivo digestibility in ruminants.
In situ digestion of feed samples in the actual rumen
environment is probably the most accurate of the non
in vivo procedures, but is not suitable for routine
application. Thein vitro gas production technique offers
no advantages in prediction of total tract digestibility, but is useful for
screening cereal grains for rate of starch hydrolysis in the rumen. The
preferred procedure for routine laboratory prediction of digestibility is the
pepsin-cellulase technique, provided amylase is included or high temperature
digestion is used for samples high in starch content. Prediction of
digestibility from chemical composition is not recommended. The optical
technique of near infrared reflectance spectroscopy can be calibrated against
any of the methods outlined in this review, and is unsurpassed in terms of
speed and repeatability. Direct NIR prediction of
in vivo digestibility is also possible, but is limited
by the lack of adequate numbers of feed samples with known
in vivo values. Future work should be aimed at filling
this gap and also improving the accuracy of laboratory methods for predicting
the digestibility of low quality feeds.
An assessment by in vivo methods of grain quality for ruminants
Authors: Hogan J. P. , Flinn P. C.
Published: September 2002

For the purpose of this review, grain quality refers to the efficiency with
which a grain supports growth in cattle fed diets which contain grain as a
major component. Grains are fed as concentrated sources of energy. Their
quality depends on the energy content of the grain, the amount eaten, and the
efficiency, both of extraction of nutrients from the diet and of conversion of
nutrients to weight gain. This paper briefly describes the fermentative and
digestive processes involved in releasing energy from grain and in ensuring an
adequate supply of other essential nutrients to the animal. Methods are then
described for measuring net energy storage, nutrient release in various
sections of the tract, and storage of energy and protein both directly and
indirectly in studies of growth. It is recommended that
in vivo assessment of the energy content of grains for
ruminants be conducted in stages. Digestibility in the whole tract should be
used to rank a range of grains, then comparisons made between grains using
growth studies. Discrepancies arising from these assessments should then be
investigated using more detailed measurements, particularly starch digestion
in the stomach and intestines.
A review of methods for assessing the protein value of grain fed to ruminants
Authors: Ashes John R. , White Colin L.
Published: September 2002

The protein value of feed grains for ruminant rations is currently described
in modern feeding systems in terms of total protein, potentially degradable
protein, and potentially undegradable protein. Progress is being made towards
full standardisation of methods to measure these components, although it is a
goal yet to be achieved. Whereas in the future it is desirable that protein
value be defined in terms of individual amino acid availability at the
intestine, in the immediate term it can best be described by the rate and
extent of degradability of protein in the rumen and the availability in the
intestine of the rumen undegraded protein. Refining the methodology for
measuring these characteristics is important, but it is equally important that
the existing methods be validated using in vivo
experimentation.
In vitro techniques for the assessment of the nutritive value of feed grains for pigs: a review
Authors: Moughan Paul J.
Published: September 2002

The philosophy inherent in developing in vitro
digestibility assays for dietary energy and protein is reviewed and an
historical account is given of the development of such assays for the pig.
General principles to be considered in the development of
in vitro digestibility assays are discussed, as are
limitations of the in vitro approach. The importance of
choosing the most appropriate in vivo measures of
digestibility for the evaluation of in vitro assays is stressed. For protein
sources that do not contain anti-nutritional factors or plant fibre,
‘true’ ileal digestibility should be the
in vivo baseline, while plant proteins should be tested
against ‘real’ ileal digestibility. There is a dearth of
adequately conducted validation studies for in vitro
digestibility assays. It appears that the 3-step (pepsin, pancreatin,
Viscozyme) closed in vitro system to allow prediction of
organic matter and gross energy digestibility in the pig has particular
promise for practical feed evaluation. Similarly based protein digestibility
assays may require further development before they can be applied with
confidence.
In vivo and in vitro techniques for the assessment of the energy content of feed grains for poultry: a review
Authors: Farrell D. J.
Published: September 2002

The focus of this paper is on the energy evaluation of foodstuffs,
particularly of food grains for poultry. Apparent metabolisable energy (AME)
is currently the preferred feeding system for poultry but net energy systems
are future possibilities and one is currently being used in some poultry
growth models. These systems take into account the efficiency with which AME
is being utilised by the bird. Aspects such as AME adjusted to zero nitrogen
retention and true metabolisable energy (TME) are discussed. Shortcomings of
the AME system are also discussed and recent net energy systems are described
briefly. The in vitro prediction of AME or TME has not
shown great promise although the European Tables of Energy Values for
Foodstuffs contain detailed analysis of chemical composition and
AMEn data allowing improved accuracy of prediction. It
is suggested that data generated on Australian grains should be tested using
these tables, and if successful, these tables may be useful to industry.
Near infrared reflectance analysis (NIRA) is likely to be the preferred
in vitro method for predicting a range of
characteristics of food grains including AME. A new method of grain evaluation
developed in Canada is described and this approach, with modification, may be
worth pursuing in Australia. For the in vivo method of
measuring AME of grains, the classical total collection method with broiler
chickens is recommended with minor changes. The use of acid-insoluble ash for
estimating dry matter digestibility for subsequent determination of AME may
have merit. A rapid assay appropriate to laying hens is proposed because of
the known increase in AME of grains as birds age. It has been established that
AME values generated using adult cockerels also apply reasonably well to hens.
Amino acid availability in poultry—in vitro and in vivo measurements
Authors: Ravindran V. , Bryden Wayne L.
Published: September 2002

Methodology to evaluate the protein quality or amino acid availability in feed
ingredients for poultry using in vitro (enzymic,
chemical, or microbiological assays), indirect
in vivo (plasma amino acid assays), or direct
in vivo (growth or digestibility assays) measurements
has been reviewed. The specific applications and limitations of these methods
are examined. In vitro assays are useful in providing
information on heat damage in selected protein sources under defined
conditions, and on relative ranking of different samples, but they cannot form
the basis of practical feed formulations. While growth assays remain the only
direct means of confirming nutritional relevance of values obtained by other
procedures, in vivo digestibility assays appear to be
most useful, at present, to estimate amino acid availability. Amino acid
digestibility assays in poultry should be based on the analysis of digesta
from the terminal ileum rather than excreta, because of the variable and
modifying effects of hindgut microflora. Techniques used to estimate
endogenous amino acid losses in poultry are discussed. The needs for
correction of endogenous losses in amino acid digestibility calculations and
the relative merits of apparent and true digestible amino acid systems are
still being debated. It is, however, clear that both digestible amino systems
are superior to the total amino acid system currently employed to formulate
practical diets. Digestible amino acid values are likely to form the basis of
poultry feed formulations in the future. In particular, there is an urgent
need for more precise information on the variation in digestible amino acid
contents of locally grown ingredients and on the factors causing this
variation (e.g. variety, location, season, agronomic practices, processing,
etc.).
Relationship of rainfall, cultural practices, soil and plant nutrients, and seedling survival with root disease and parasitic nematode numbers in annual Medicago spp. Pastures
Authors: You M. P. , Riley I. T. , Sivasithamparam K. , Barbetti M. J.
Published: September 2002

Surveys were conducted for annual Medicago spp. (medic)
pastures in the grain belt of south-west Western Australia during spring 1996
and winter–spring 1997 to determine the relationship of rainfall,
cultural practices, soil and plant nutrients, and seedling survival with
severity of root disease and numbers of parasitic nematodes. Medic pasture was
sampled on 116 farms. Most pastures consisted of a single medic variety, viz.
Serena, Santiago, Cyprus, or Caliph, whereas about 33% of sites had
mixed varieties. Regression analyses showed that high rainfall and application
of phosphorus fertilisers were correlated with increased severity of rot in
medic tap roots. Crop history and medic variety were not related to the level
of root rot. Numbers of Pratylenchusin medic roots were
not correlated with the level of tap or lateral root rot, medic variety,
rainfall, or with the application of insecticide, fertilisers, or herbicides.
Soil with relatively high levels of P,
NO3-, or Fe was associated
with an increased level of tap root rot. Soils with high pH were associated
with reduced tap root rot. Soils with relatively high K were related to severe
lateral root rot, whereas relatively high levels of P in soil were associated
with reduced lateral root rot. Plants with high levels of tap root rot showed
low levels of Mg, whilst low levels of Ca and
NO3– in tissues were related
to high levels of lateral root rot. High levels of tap root rot were
associated with relatively high levels of total N, K, and S, Cu, Zn, Mn, and
NO3- in plant tissues.
Plants with relatively high levels of lateral root rot had relatively high
levels of Cu in shoots. Of the 116 annual Medicago
pastures sampled, only 1% had adequate Mg content and only 19%
had adequate Ca content. However, 83% had higher than adequate levels
of Cu, 70% had higher than adequate levels of Mn, and all samples
showed more than adequate levels of chloride. Experimental sites of
M. polymorpha cv. Serena at 6 farms showed that the
percentage survival rate of seedlings was negatively correlated with the
severity of tap and lateral root rot in the previous year. These results
indicate that in the farms surveyed there is a serious threat to annual medic
pastures from root rot fungi. The severity of the disease was partly
determined by soil conditions and cultural practices.
Adaptation of Lupinus angustifolius L. and L. pilosus Murr. to calcareous soils
Authors: Brand J. D. , Tang C. , Rathjen A. J.
Published: September 2002

Current varieties of narrow-leafed lupin
(Lupin angustifolius L.) are poorly adapted to alkaline
and calcareous soils found commonly throughout the south-estern Australian
cropping zone. Apot experiment compared the growth of
Lupinus angustifolius cv. Gungurru with
L. pilosus P20954 in a range of soils collected
throughout South Australia. The soils displayed a range of texture (clay,
3–82%), pH (1:5 soil:H2O,
7·0–9·6), and calcium carbonate content
(CaCO3, 0–47%). Potting mix (pH
5·8) was used as the control. The plants were grown for 7 weeks with
weekly measurements of chlorosis score and leaf number. At harvest, dry
weights were recorded and the youngest fully expanded leaves were analysed for
nutrient concentrations.
The line P20954 grew much better in all the soils than Gungurru in terms of
plant dry weight relative to the control soil, this being particularly evident
in the calcareous soils. Chlorosis score correlated highly with shoot dry
weight for Gungurru, but not for P20954. The main soil factor contributing to
the chlorosis score of Gungurru was CaCO3 content,
whereas none of the soil factors significantly affected P20954, although in
Weeks 2 and 3 chlorosis score correlated with CaCO3
content. The dry weight of Gungurru was affected by a combination of factors
including clay content, pH, and CaCO3 content, whereas
the dry weight of P20954 was affected by most of the soil factors measured.
The dry weight of P20954 was positively correlated with aluminium and
magnesium concentrations. Concentrations of all nutrients were above critical
levels for both genotypes grown in all soils. The results indicate that
L. pilosus has the potential to be grown in areas where
current varieties of L. angustifolius are poorly
adapted.
Optimum plant density of desi chickpea (Cicer arietinum L.) increases with increasing yield potential in south-western Australia
Authors: Jettner R . J. , Loss S. P. , Siddique K. H. M. , French R. J.
Published: September 2002

The response of chickpea (cv. Tyson) seed yield to sowing rate (30–180
kg/ha) was examined in 18 field experiments across 3 years in
south-western Australia. The economic optimum plant density was estimated at
each site by fitting an asymptotic model to the data and calculating the point
where the cost of extra seed equalled the return from additional seed yield,
allowing a 10% opportunity cost for the extra investment.
When averaged across all sites and seasons, plant densities varied from 14
plants/m2 when sown at 30 kg/ha to 84
plants/m2 when sown at 180 kg/ha. Therefore,
only about 54% of seeds sown established into viable plants, even
though the germination test of the seed was about 80%. The poor
establishment rate is thought to be mainly due to physical damage to the seed
during transport and sowing, as well as unfavourable seed-bed moisture and
temperature conditions. At most experimental sites the seed yield of desi
chickpea responded positively to an increase in sowing rate up to about 120
kg/ha. Increased yields at high sowing rate can be directly attributed to
large plant populations. Although in many cases the number of pods per plant,
seed size, and harvest index were reduced at high plant populations, increased
plant density compensated for these effects and seed yield tended to increase.
There was a good relationship between economic optimum plant density and yield
potential derived in this study (r2 = 0.497,
P< 0.001) and this improves the ability of desi
chickpea producers to select the most profitable sowing rate, depending upon
their yield potential. These results suggest that the optimum plant density is
50 plants/m2 for most chickpea crops in
south-western Australia yielding about 1.0 t/ha, whereas in high-yielding
situations (>1.5 t/ha), plant densities >70
plants/m2 produce the most profit. Although not
observed in these experiments, high plant densities can exacerbate fungal
diseases, and hence, reduced plant densities are desirable in disease-prone
situations. Differences in sowing rate responses may be expected between Tyson
and new large-seeded cultivars such as Heera and Sona, which have longer
branches and more open canopy, or kabuli types, and this deserves further
investigation.