Page 2 - National Poultry Newspaper

Figure 1: Oxidation pathway (simplified).
Table 1: Summarised changes (%) due to oxidised fats/oils, calculated from 23 recordings from eight studies; ADG, average daily gain; ADFI, average daily feed intake; FCR, feed conversion ratio.
Figure 2: Oxygen absorption over time for an untreated tallow sample and a sam- ple from the same source with a liquid antioxidant.
Figure 3: Oxygen absorption over time for an untreated poultry oil sample and a sample from the same source treated with a liquid antioxidant.
Figure 4: Oxygen absorption over time for an untreated fish oil sample and a sam- ple from the same source treated with a liquid antioxidant.
Figure 5: Oxygen absorption over time for an untreated meat meal sample and a sample from the same source treated with a liquid antioxidant.
The chemical pathways aren’t very helpful when trying to relate (per-)oxi- dation to the practicalities of formulating and feed- ing diets containing fats and oils.
TBARS measures sec- ondary oxidation com- pounds (such as malon- dialdehyde) resulting from the decomposition of per- oxides.
Actions needed to help prevent the negative im- pacts of feeding oxidised feed ingredients include:
To help ensure this, and to protect oxidative stabil- ity during storage, treat fats/oils with a suitable antioxidant at a level ap- propriate to the conditions and duration of storage.
Oxidative status of fats and oils is important to pigs
THE oxidation process is complex and generally not well understood and often overlooked in the routine activities of for- mulating diets and feed- ing pigs.
1), but the chemistry is oxidised fats/oils (Hung
ity, increased number of conditions with antioxi-
The steps and stages of oxidation are well de- scribed (such as in Figure
Confusion continues when the word ‘peroxida- tion’ is sometimes used in place of oxidation – per- oxidation being the oxida- tion of fats and oils, that is, lipids.
measurements recorded in the studies, Hung et. al. identified that the TBARS content of the diet was the best oxidative meas- ure that correlated with growth rate.
Boyd et. al. (2019) con- sidered younger pigs as particularly susceptible to the negative impacts of peroxide stress including oxidative-induced disrup- tion to the intestinal wall. Actions
These ratings assume high-quality feed ingre- dients of low oxidative status on arrival at the feed mill.
complicated and includes terms like ‘free radicals’ and ‘reactive oxygen spe- cies’ that add to the mys- tery of oxidation.
et. al., 2017)
Based on the oxidation
pigs requiring medical treatment and the number of culled pigs.
dant dose rates adjusted accordingly (Table 2).
% Recordings with negative responses
Ave. % response
Range of % responses
ADG
78
-9
-35 to +5
ADFI
74
-6
-23 to +10
FCR
61
-3
-16 to +6
Fortunately, we can test fats and oils for oxida- tion indicators to create indicative standards, such as peroxide value, thio- barbituric acid reactive substances – but which measurement(s) relates to pig growth performance?
Feeding oxidised fats/ oils may reduce the anti- oxidant status of the pig and contribute to oxida- tive stress (Shurson et. al., 2018).
2. Manage these pur- chased ingredients appro- priately, including
Examples of preserving the oxidative stability of fats and oils with properly formulated antioxidants are shown in figures 2 (tallow), 3 (poultry oil), 4 (fish oil) and 5 (meat meal).
Additional tests can be used to help predict the oxidative stability of fats and oils and protein meals containing residual fat/oil, including an oxygen bomb test and oxygen stability index test.
This was recently con- firmed by Chang et. al. (2019) in an experiment with 2200 weaned pigs (averaging 5.95kg) housed in 100 pens and fed diets for 43 days with varying ratios of non-oxidised corn oil and oxidised corn oil to create five levels of diet peroxidation: no peroxidation, low, medi- um-low, medium-high and high.
•where tanks are out- side, locate them in the coolest location,
The oxygen bomb test was used in these exam- ples as an accelerated stress test.
Oxidation is a normal process occurring both in the body and in fats, oils, protein meals and other ingredients fed to pigs.
3. Have a suitable an- tioxidant included at an appropriate level by the producer of the fats/oils or add the antioxidant to the fats/oils on arrival at the feed mill (large or small); and
Comparing tallow, poul- try oil and fish oil, the oxygen absorption val- ues for the control sam- ples after 24 hours were 201mg, 315mg and 450mg respectively, indicating the increasing sensitivity of these lipid sources to oxidation.
Oxidative ‘stress’ can arise when an imbalance between free radicals (re- active oxygen atoms) and antioxidants (antioxidants pair up with free radicals making them less reac- tive) occurs.
The results showed:
4. Advice from a con- sulting pig veterinarian (Dr Peter McKenzie 2019, pers. comm.) is not to use peroxidised fats/oils and suggests the use of antiox- idant-treated canola oil in lactating sow and weaner diets to help achieve more consistent and stable re- productive performance and progeny growth rate. Dr McKenzie advises this is an important compo- nent of a broader ‘health by management’ program because peroxide-induced poor growth rate often re- sults in the use of antibiot- ics (which do not address oxidative damage). Insure against oxida- tion/peroxidation with an antioxidant
The body has its own antioxidant system and in- creased awareness of non- infectious diseases related to oxidative stress has led to people consciously con- suming foods and supple- ments that contain anti- oxidants.
• The number of pigs re- moved for medical treat- ment, total number medi- cally treated, pigs culled for low-end weight and mortality, all increased with increasing peroxida- tion;
The inclusion of 250g of a liquid antioxidant ensured stability of meat meal, which typically contains 10-12 percent fat (Figure 5).
Summary
Similarly, antioxidants can be added to pig di- ets including into fats and oils, protein meals and vitamin/mineral premixes to insure against oxidative degradation.
• There was a linear decrease in the total pen gain with increasing per- oxidation (weight of vi- able pigs that remained in the pens at the end of the trial minus the weight of pigs placed at the start of the trial); and
• Knowledge of the oxi- dative status of fats and oils is useful;
Apart from ever-present oxygen, factors that can promote oxidation include temperature increases and the presence of metal ions (such as copper, iron and manganese).
Including a liquid anti- oxidant into fats and oils is inexpensive insurance against the invisible but potentially damaging ef- fects of oxidation.
• Storage conditions and storage duration are rel- evant to the ongoing qual- ity of fats and oils; and
There was a linear (straight line) decrease in growth rate as the TBARS content of the diet in- creased.
1. Know the oxidative status of fats and oils at the time of purchase;
While this is best done at the time of production of the fats/oils, it can be done on arrival at the feed mill.
• There was a linear in- crease in FCR with in- creasing peroxidation;
The inclusion of 500g/ tonne of a liquid antioxi- dant prevented the loss of oxidative stability in all three of these fat/oil sources.
• There was a linear de- crease in the number of full value pigs with in- creasing peroxidation;
Oxidised/oxidising fats and oils have negative im- pacts on young pigs;
• tanks used to store fats/ oils should be properly cleaned at least four times per year,
• endeavour to turnover inventory regularly;
The presence of water in fats and oils leads to another process called hydrolysis, resulting in increased production of free fatty acids, which in- creases the susceptibility to oxidation.
The negative impact of oxidised oil in this experi- ment was primarily meas- ured as increased mortal-
Relative risk ratings can be ascribed to varying
Rick Carter
Kemin Industries Tech- nical Services Manager
• There was a linear de- crease in the total antioxi- dant capacity of the pigs with increasing peroxida- tion.
Antioxidants slow the progress of oxidation and are sacrificed in the pro- cess.
• Insurance against oxi- dative degradation of fats and oils by including a suitable liquid antioxidant at an appropriate level is recommended.
Risk factor
Feed ingredients
Finished feed
1. Quicker inventory turnover
a) cool, dry conditions
L
L
b) warm, hot conditions
M
M-L1
c) mainly saturated fat
L
L
d) higher unsaturated fat level
M
M-L1
e) ‘typical’ fat content
L
L
f) high fat content
M
M-L1
2. Slower inventory turnover
a) cool, dry conditions
M
M-L1
b) warm, hot conditions
H
H-M1
c) mainly saturated fat
M
M-L1
d) higher unsaturated fat level
H
H-M1
e) ‘typical’ fat content
M
M-L1
f) high fat content
H
H-M1
Page 2 – Australian Pork Newspaper, May 2020
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So while the initial oxidative status of feed ingredients is important, also of critical importance are the climatic conditions during storage (season), storage location (indoors/ outdoors), storage condi- tions (tank hygiene) and the duration of storage of the feed ingredients used in diets as well as the final feed containing the oxidisable ingredients. Pig’s response to oxi- dised fats and oils
Table 1 summarises the changes in growth rate, feed intake and feed conversion ratio in pigs when fed oxidised fats/ oils compared with non-
Table 2: Oxidation relative risk rating for feed ingredients and finished feed (H=high risk, M=medium risk, L=low risk). 1, lower risk rating when fat/oil/protein meal has been protected with an antioxidant.
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