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.
In vitro techniques for the assessment of the nutritive value of feed grains for pigs: a review