 
Who saw this article? New!
Author: Dr Gary Partridge
Summary
Enzymes which target the fibre components in feeds are now routinely added to
broiler, layer and swine diets containing wheat or barley. However, the acceptance
of enzymes for diets based on maize has been much slower, particularly in swine.
This is due to the perception that fibre in such diets is present at relatively
low levels and therefore has no, or little, negative effects on the animal. However,
new research conducted by Finnfeeds has suggested that there is a role for such
enzymes, particularly when grain by-products such as wheat bran/pollard ('wheaten
bran'), or rice bran are also present in the ration. This article describes some
of this work, and its implications for more cost-effective feeding of growing/finishing
pigs particularly when the by-product price is attractive relative to corn and
soybean meal.
Why the need for enzymes?
In maize-based rations containing some grain by-products such as rice bran or
wheat bran/pollard the amounts of fibre (non starch polysaccharides, NSP's) are
quite considerable. This fact is not fully appreciated by some nutritionists,
because when assayed as crude fibre, these NSP's are vastly underestimated.
As a general rule, the total fibre (defined as non-starch polysaccharides + lignin)
in such ingredients is more than 3 times the amounts indicated by a crude fibre
measurement.
For example, maize contains 2.5% crude fibre, but actually contains 10% total
fibre. Similarly wheat by-products contain 8-11% crude fibre, but in reality contain
30-40% total fibre. Table 1 illustrates this point with several commonly used
ingredients.
Table 1. Fibre composition of several ingredients
(various sources)
|
%, as is |
Maize |
Rice bran |
Wheat bran |
Wheat pollard |
| Crude fibre |
2.5 |
9 |
11 |
8 |
|
Total fibre*
- Beta glucans
- Arabinoxylans
- Cellulose
- Lignin
|
10 |
20 |
40 |
29 |
|
- |
- |
1.8 |
1.9 |
|
4.4 |
10 |
20 |
14 |
|
2.0 |
6 |
11 |
8 |
|
0.5 |
4.5 |
5.8 |
3.5 |
Not only are there large amounts of total fibre, but its location in the cell
walls creates a protective 'box' effect whereby potentially useful nutrients (e.g.
starch, amino acids, minerals) are unavailable for digestion in the small intestine.
This fibre also acts like a 'sponge' in the gut, sucking up water-soluble nutrients
and interfering with their effective digestion and absorption. The overall effect
is that the bacteria in the hindgut get the benefit of many of these nutrients
rather than the host animal, and growth and feed conversion suffers (Dierick and
Decuypere 1994; Hazzledine and Partridge 1996).
By adding appropriate enzymes to the feed, which the animal cannot secrete itself,
we aim to reverse some of the negative effects of fibre on digestibility (Table
2). These extra nutrients released can be used by the pig for better lean gain
and feed conversion and, importantly, to make savings in costs of production by
using cheaper diets to maintain the same pig performance.
Table 2. Effect of a specific in-feed xylanase
on digestibility (%) of nutrients in a maize/wheat by-product diet compared to
a maize-based control (Hazzledine and Partridge 1996)
|
|
Maize Control |
Maize + 25% wheat by-products |
Maize + 25% wheat by-products + xylanase** |
| Dry
matter |
|
72.6c |
80.2b |
|
Protein |
82.6a |
71.1b |
79.2aa |
|
Energy |
86.9a |
73.3c |
80.2b |
Trial results
Over the past 3 years a number of trials have been run in research institutes
and commercial farms to test this concept using a xylanase (Porzyme 9300) specifically
selected to target the insoluble fibres present in grain and grain by-products.
Some recent examples are shown in Tables
3 and 4. In each of these
trials, and others, the approach has involved comparison of a standard formulation
with a cheaper, downspecified formulation (lower energy) containing higher levels
of these fibrous ingredients. In each case performance of the specific xylanase-supplemented
diet at least matched the 'standard' control and offered savings in costs of production.
Table 3. Effect of Porzyme 9300 in a high
wheat pollard diet
| |
Control(10% wheat by-product)
|
Downspecified diet(20% wheat by-product)
|
Downspecified diet (20% wheat by-product)+
Porzyme
|
| Initial weight, kg |
39.4 |
39.4 |
39.4 |
| Final weight, kg |
81.2 |
78.9 |
81.2 |
| Daily gain, g |
696 |
659 |
696 |
| Feed Intake, g/d |
2020 |
2020 |
1920 |
| Feed:gain |
2.89ab |
3.07b |
2.76a |
| Net profit per pig ($US)relative to control* |
- |
+3.53 |
+5.95 |
Table 4. Performance effects of Porzyme
9300 in an energy reduced diet (20% maize substituted by 20% wheat by-product)
|
Maize-soy control |
Maize/soy/wheat by-product (20%) |
Maize/soy/wheat by-product (20%) + Porzyme |
|
Initial weight, kg |
28.2 |
28.1 |
28.6 |
|
Final weight, kg |
61.2 |
59.1 |
61.4 |
|
Daily gain, g |
944 |
886 |
938 |
|
Feed Intake, g/d |
1812a |
1651b |
1705ab |
|
Feed:gain |
1.92 |
1.88 |
1.82 |
Re-formulation of the diet to reduce energy and, in some trials, amino acid
specification when using a specific xylanase enzyme, together with increased
by-product inclusion level (+10% normally), is the principal approach in many
markets for grower/finisher pigs. However, we also have a large number of trials
where the product has been used 'on top' of an existing diet based on maize,
soya and grain by-products to reap benefits in improved pig performance.
A recent summary of 15 such trials by Finnfeeds (Tan 1999) showed an average
improvement in weight gain and feed:gain of 7.4% and 6.1% respectively. The
only proviso with this approach is that diet specifications in relation to animal
nutrient requirement are sufficiently well understood to allow the pig to respond
to the extra energy and amino acids made available. In other terms an unimproved,
low lean deposition, high appetite pig already at or close to its lean deposition
maximum, fed a high nutrient dense diet, has little opportunity to use the extra
nutrients liberated for productive purposes!
Conclusions
It is now well recognised that ingredients such as maize, soybean and, particularly,
grain byproducts contain relatively high levels of dietary fibre and that this
fibre has negative impacts on feed digestibility and pig performance. The use
of a well-researched xylanase based enzyme product (Porzyme 9300), which targets
the relevant fibre, has the effect of overcoming some of these negative effects,
leading to improved nutrient availability. This allows for the option of using
the enzyme to improve pig growth and feed:gain or, alternatively, to use it
in diets with lowered levels of energy and protein/amino acids, with higher
by-product levels, to maintain performance with lower net feed costs.
by Dr Gary Partridge, Technical
Services Manager, Finnfeeds, PO Box 777, Marlborough, Wiltshire, SN8 1XN, UK
References
· Dierick N.A. & Decuypere (1994) 'Enzymes and growth in pigs' In
Principles of pig science , Nottingham University Press, pp 169-195
· Hazzledine M. & Partridge G.G. (1996) 'Enzymes in animal feeds
- application technology and effectiveness' In Proc. 12th Carolina Swine Nutrition
Conference, Raleigh, N. Carolina, USA pp 12-33
· Partridge G.G., Alcantara P.F. & Creswell D. (1998) 'Effect of
xylanase addition to corn/soybean meal/wheat pollard diets for grower/finisher
pigs'
· Proc. 8th World Congress Anim. Prod. pp 626-627
· Tan M.Y. (1999) 'Enzymes can be used effectively in swine diets' Asian
Pork June/July pp36-37
Author: Dr Gary Partridge
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