10 de septiembre de 2014Feed additive producers are researching ways to help poultry producers deal with the challenges of using high-fiber raw materials
The
use of alternative raw materials, to reduce reliance on imported
materials and improve sustainability, has been much discussed. Food security is
high on the agenda for government and retailers, so research into homegrown
crops and co-products is important. There are economic, logistical and
agronomic reasons why these resources are not used to their full potential.
However, this article will look at performance limitations and how various
technologies can improve them.
Challenging materials
There
are several challenges to formulating with alternative raw materials. They may
be higher in fiber or include anti-nutritional factors (ANF). In particular, there are higher levels of insoluble fiber in crops like sunflower and oilseed
rape (canola). Arabinoxylans form complexes with protein, reducing nutrient
availability. Digestibility is therefore lower and results in more undigested material
in the digestive tract. This in turn can encourage the proliferation of pathogens,
which has a negative effect on poultry health and performance.
Consistency
can be a particular issue when using co-products; nutrient profile and
digestibility may vary between sources — and even batches. In a recent
experiment, four batches of Dried Distillers Grains with Solubles (DDGS) were
each fed at two different levels to laying hens. There were significant
differences in digestible energy and protein digestibility between the batches
that were not correlated to differences in proximate nutrient composition. This
unpredictability will have a corresponding effect on the productivity of the
birds.
Processing for
improvements
There
are various options to process or treat raw materials prior to feeding in order to
improve their nutritional value. Pulses may benefit from de-hulling to reduce
both the fiber and ANF levels. Heat treatment has been used to improve
digestibility of a variety of cereals and pulses. Micronization, in particular,
has a positive effect on insoluble fiber meaning that nutrients have a longer
time to be digested and absorbed.
The
use of enzyme pre-treatment for co-products like DDGS and rapeseed meal has
been investigated. The use of proteases is particularly interesting to make
protein more digestible before it is fed. Phytases are already used in ethanol
plants, resulting in lower levels of phytate in DDGS. However, cost and
logistics currently preclude these kinds of processing despite the significant
opportunities.
Enzyme
technology
Enzyme
technologies can help to improve feed formulation precision, diet efficiency
and ultimately performance by reducing raw material variability. They also have
the potential to complement endogenous enzyme production, sparing energy. When
formulating with alternative raw materials there is more potential for enzymes
to have a positive effect than with standard diets.
Luis
Romero, Danisco Animal Nutrition stated, “In general, you see bigger energy and
protein digestibility improvements with alternatives.”
This
is particularly true for the disruption of protein-fiber interactions, which
are important in DDGS, rapeseed and sunflower.
A
recent broiler digestibility study looked at the effects of adding high-fiber
ingredients to both corn and wheat based diets. Corn DDGS and rapeseed meal had
the effect of reducing the availability of protein in particular. Greater effects of enzymes were found
in the higher fiber diets, increasing the combined energy contribution of
protein, starch and fat (see Figure 1).
“The
additive protein digestibility effect of protease on top of xylanase and
amylase was also demonstrated,” Luis reiterated.
The
lower digestibility of alternatives means there is the potential for more
undigested material in the poultry digestive tract. This creates an environment
that is favorable for pathogen growth, making birds more susceptible to
enteric disease. Xylanase is able to create the prebiotic compounds
arabino-xylo-oligosaccharides from cereals. They encourage the growth of
beneficial bacteria and the production of short-chain fatty acids.
Performance
benefits
A
number of investigations have been carried out to demonstrate the efficacy of
enzymes in diets containing alternative raw materials. These recent examples were
presented at the XIVth European Poultry Conference 2014 and are summarized
below.
In
two trials, broilers were fed diets made up of corn, corn DDGS, soybean and
rapeseed meal – supplemented with either xylanase or xylanse and beta-gluconase.
The enzyme combination significantly improved FCR and ileal digestibility
energy, compared to the control. Both treatments significantly improved starch
digestibility and tended to improve ileal fat digestibility (see Figure 2).
Another
study fed broilers diets containing three different levels of rapeseed and
sunflower meal; with or without an enzyme combination, i.e. xylanse and
beta-gluconase. Birds fed diets with high (H) levels had lower weight gain and
poorer FCR, compared to those fed the medium (M) or low (L) treatments. Enzyme
supplementation was shown to significantly improve FCR for the three diet
types, with the highest response being seen in the H treatment (see Table 1).
Novel
strategies
The
combination of different groups of feed additives with potentially
complementary modes of action, e.g. probiotics and enzymes, has also been
investigated. These can help improve digestibility, support a healthy gut
microbiota and improve bird liveability. In trials with non-challenged broilers
fed a corn-soy diet containing some fibrous cereal byproducts, significant
incremental increases in nitrogen corrected apparent metabolizable energy (AMEn) with additions of a three-strain
Bacillus probiotic and xylanase,
amylase and protease enzymes. Luis commented, “This combined mode of action
further improves the digestibility of alternative raw materials.”
Older
birds deal better with solubilized fiber due to gut maturity. This is why the
use of some alternatives is limited or precluded in younger poultry. By having
a maturation effect on the intestine, the combination of enzymes and DFMs could
allow some increase in levels. Laying hens, breeders and turkeys have longer
lifecycles, and so have a larger fermentative capacity and are able to better digest
fiber. Therefore, there is even greater potential for enzymes to improve
performance in diets containing alternative raw materials.
Future
possibilities
With
advancements in enzyme technology it is possible to significantly improve
poultry performance when fed rations containing alternatives. By improving the
digestion and absorption of nutrients, nutritionists are able to make greater use
of ingredients like DDGS, rapeseed and sunflower. This offers flexibility when
formulating different types of diet, dependent on both the cost and
sustainability of the raw materials.
Research
has shown that enzyme combinations are particularly effective, when feeding alternatives.
Whilst carbohydrases help to improve fiber digestion, proteases are interesting
to get more value from lower quality protein sources. Enzyme producers are
looking at the possibility of creating raw material specific matrixes for their
products. This would enable formulators to better predict the nutrient value of
alternative raw materials, particularly when there is variability. Creating
confidence in consistent poultry performance when fed rations containing these
products. Then potentially alternative feed ingredients can be included at
higher levels, benefiting both efficiency and environmental impact.