Facts about fats a review of the feeding value of fats and oils in feeds for swine and poultry

65 Pages·2010·1.217 MB·English

by  Aar, Piet ˜van derœ, Doppenberg, Jannes

Facts about fats
A review of the feeding value of fats and
oils in feeds for swine and poultry
J. Doppenberg
P.J. van der Aar
Wageningen Academic
P u b l i s h e r s
Schothorst Feed Research
Facts about fats
A review of the feeding value of fats
and oils in feeds for swine and poultry
J. Doppenberg, Ph.D.
Dr. ir. P.J. van der Aar
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e-ISBN: 978-90-8686-861-2
DOI: 10.3920/978-90-8686-861-2 The content of this publication and any
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First published, 2010
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Table of contents
Introduction 5
1. Chemical composition and characteristics of fats and oils 7
1.1 Chemical composition 7
1.2 M elting point in relationship with chain length and saturation 10
1.3 Omega-3, omega-6 fatty acids and LC-PUFA 13
1.4 Omega-6 to omega-3 fatty acids ratio 14
2. The role of fats in the animal body 17
2.1 Fatty acid composition and synthesis of sow milk and
body fat 18
2.2 Effects from different dietary energy and fat sources on
animal products and sow milk fat composition 20
2.3 Fat digestion 25
2.4 Medium chain fatty acids 27
3. Application of fats and oils in compound feed production 29
3.1 Processing/production from fats and oils 29
3.2 Fat quality assessment characteristics 30
3.3 Effects on pellet quality and practical feed formulation 31
4. Factors affecting fat digestibility and energy content 33
4.1 The fatty acid and glycerol content and the chain length
of fatty acids 33
4.2 The ratio between unsaturated and saturated fatty acids
(U:S ratio) in the added fat or oil 35
4.3 The proportion of free fatty acids in relation to the total
crude fat content of the feed 39
4.4 The position of the (saturated) fatty acids on the
triglyceride molecule 41
4.5 Feed composition 45
4.6 Animal effects 47
5. Energy value of animal fat and vegetable oils 49
5.1 DE, ME and NE energy systems 49
5.2 ME and NE value of fats and oils 51
5.3 Calculated NE and AME value of animal fats, plant oils
and fatty acids mixtures 53
5.4 Economical aspects of energy system used in feed
formulation and the value of different animal fats, plant
oils and fatty acids mixtures 57
5.5 Summary 59
6. References 61
Facts about fats 3

Introduction
Since the BSE crisis the use of animal fat in animal feeds has been
prohibited in certain countries in the EU but not all. In all countries
however the production of animal by-products has changed considerably.
Only parts of animals fit for human consumption are used for production
of animal fat and the production is separated per animal species so
that distinguished products like tallow, lard and poultry fat are on the
market. Recently some countries have relaxed the usage of animal fats
in animal feeds. It is to be expected that in the near future animal
proteins will be allowed to be used as feedstuffs for animal feeds again.
Considering these developments it is prudent to review the feeding value
of animal fat in comparison to plant oils and fatty acid mixtures in
animal feeds with special consideration for swine and poultry feeds.
Facts about fats 5

1. Chemical composition and characteristics of fats
and oils
This chapter will describe the chemical composition of fats and oils
in relation to the characteristics and functionality in nutrition. The
chemical composition, the melting point in relationship to chain length
and degree of saturation of the fatty acids will be discussed. Also
biochemical role of omega-3 and omega-6 fatty acids and LC-PUFA’s
will be discussed.
1.1 Chemical composition
Chemically fats are triglycerides in which glycerol is esterified with three
fatty acids. All fats consist of fatty acids (chains of carbon and hydrogen
atoms, with a carboxylic acid group at one end) bonded to a backbone
structure of glycerol (a ‘backbone’ of carbon, hydrogen, and oxygen).
Chemically, this is a triester of glycerol, an ester being the molecule
formed from the reaction of the carboxylic acid and an organic alcohol
(Figure 1).
Figure 1. A triglyceride molecule.
Therefore chemically the differences between different fats and oils are
due to the fatty acid composition. Fats may be either solid or liquid at
normal room temperature. When liquid at normal room temperature
they are classified as an oil. As outlined in Table 1 fats in contrast to
oils typically have a higher content of long chain fatty acids and/or are
more saturated.
Facts about fats 7
Chemical composition and characteristics of fats and oils
Table 1. Fatty acid composition of common fats and oils.
Coconut oil Butter fat Linseed oil Palm oil Rapeseed oil Soybean oil Sunflower oil Fish oil Tallow Lard Poultry fat
C4-10 15 9
C12:0 47 3
C14:0 16 10 1 1 1 1 8 3 2 1
C16:0 9 26 7 40 4 8 6 16 26 24 19
C16:1 1 2 1 1 2 1 1 11 4 3 5
C18:0 2 12 5 5 2 4 3 3 21 15 7
C18:1 6 25 18 46 53 28 26 14 38 39 33
C18:2 2 2 18 7 22 55 55 2 3 11 22
C18:3 1 55 1 11 6 1 1 1 1 2
C20:4 1
C20:5 9
C22:6 6
The tallow specification are from Smilde, lard and poultry fat are from Sonac, Burgum.
The chain length of a fat is given by the number after the capital C.
This is an even number since fats are bio-synthesized from acetyl CoA.
The amount of unsaturated bonds is given as the last number: i.e.
0=saturated, 1= monounsaturated etc.
It can be concluded that:
Vegetable fats (with the exception of palm and coconut oil) are in general
softer and contain less (long chain) saturated fatty acids than animal
fats. The tropical oils (coconut and palm kernel oil) are rich in the
medium chain fatty acids (MCFA) C8:0-C14:0. Vegetable oils in general
are rich in mono- and poly unsaturated fatty acids (MUFA and PUFA).
Milk or butter fat is characterised by a relative high content of medium
chain fatty acids for a fat of animal origin. Fish oil in general has a high
content of palmitic acid (C16:0) but is rather unsaturated, due to a high
content of long chain poly unsaturated fatty acids (LC-PUFA). Fish oils
vary considerable in fatty acid composition per specie.
Butter fat is comparable in fatty acid composition to tallow except that
it contains about 25% medium chain fatty acids. These are synthesized
from the volatile (short chain) fatty acids produced in the rumen.
8 Facts about fats
Chemical composition and characteristics of fats and oils
Because of hydrogenation of (poly) unsaturated fats in the rumen, the
content of stearic acid (C18:0) is higher in tallow and that of linoleic
(C18:2) and linolenic acid (C18:3) lower in lard (Woods and Fearon,
2009). Note that grass is rich in both linoleic (C18:2) and linolenic acid
(C18:3) which is in grazing ruminants the source of PUFA’s.
About half of the fat from butter fat and up to 85% of the (body) fat
from pigs is directly derived from feedstuffs, the rest is produced via
biosynthesis from acetyl CoA. In ruminants acetyl CoA is metabolised
from acetic acid derived from fibre digestion, in non ruminants from
glucose derived from starch digestion. Resultantly the fatty acid pattern
of fat rich feedstuffs and the fat content of the feed has a strong influence
on the fatty acid pattern of animal products in non ruminants (bacon
quality).
Palm oil is rich in palmitic acid (C16:0). Vegetable oils extracted from
soybeans, sunflower seeds, rapeseed, maize(germs), cotton seed and
safflower are lower in palmitic acid(C16:0) but higher in oleic acid
(C18:1, rapeseed and olive oil) or linoleic acid (C18:2, soybean- and
sunflower oil).
The most concentrated sources of linoleic acid (C18:3) is linseed oil,
next to rapeseed- and soybean oil. The long chain polyunsaturated
fatty acids (LC-PUFA) like arachidonic (C20:4), EPA (C20:5) and DHA
(C22:6) are found in fish oils from deep see fish, specifically salmon.
The source of these omega-3 fatty acids is plankton. It is rich in linoleic
acid (C18:3) which is elongated and desaturated by these types of fish
(see chapter 1.4). In pond raised fish and fish from tropical waters the
levels of LC-PUFA are clearly lower and influenced by the type of fat fed
to these fish via the feed.
Industrial processing like hydrogenation or hardening of oils will
lead to a different fatty acid composition and physical characteristics
(spreadability margarines). The content of (poly) unsaturated fatty acids
will be reduced and trans fatty acids can be formed. Trans fatty acids
are considered to be ‘bad fats’ since they have very negative health
effects. Several dietary guidelines restrict the consumption of trans fatty
acids. Positive exceptions are the CLA’s (conjugated linoleic acid) found
in dairy milk fat(products). One conjugate t c reduces fat synthesis
10, 12
and the other c , t is considered to be anti carcinogenic.
9 11
Facts about fats 9