NUTRITION ▶▶▶
Classically, the reactive Lysine assay is a very demanding wet chemistry meth- od. Today how- ever, Near-infra- red Spectroscopy (NIR) techniques are available that can deter- mine the amount of reac- tive Lysine and thus estimate the degree of heat damage.
• Mycotoxins Mycotoxins are one of the biggest concerns leading to low di- etary inclusion rates of DDGS. Nutritionists try to minimise to- tal mycotoxin content because mycotoxins can have signifi- cant adverse health and performance effects. Clearly, the fungal contamination of grain used for the DDGS product, the drying equipment and storage could lead to a greater preva- lence and concentrations of mycotoxins. During the fermen- tation process the corn starch is converted into alcohol and the remaining corn components of corn are accumulated. Thus, DDGS typically contains three times more nutrients like amino acids than corn, but this also applies to mycotoxins. Fungi toxins cannot be destroyed by heat during the drying process. If the source of the corn is contaminated with fungi toxins, DDGS will have three times more mycotoxin content as well.
• Oil oxidation DDGS are traditionally rich in fat and thus very attractive eco- nomically when working with layers. Nutritionally the high fat content is also interesting due to high concentrations of polyunsaturated fatty acids which are important for yolk for- mation, particularly linoleic acid that positively influences egg weight at production onset. Unfortunately, polyunsatu- rated fatty acids are highly susceptible to oxidation and dry- ing processes accelerate this process. Feeding diets with oxi- dized lipids negatively affects the liver status and, as a result, egg quality and egg production. NIR provides a fast and relia- ble way to assess fat quality and determine the fatty acid con- tent of DDGS, alongside other analytical methods, such as the TBARS (Thiobarbituric acid reactive substances) test that can give a good estimation of lipid peroxidation.
32 ▶ ALL ABOUT FEED | Volume 28, No. 6, 2020
• Yolk pigments DDGS can provide a good source of pigment for the yolk. Pig- ments like xanthophylls or carotenoids are liposoluble nutri- ents that cannot be synthesized by birds. Therefore they must be offered in the diet. DDGS inclusion levels have been shown to result in better distribution of colour particles during feed mixing in comparison with smaller dose products. DDGS pro- vides a good yellow pigmentation base and thus reduces diet cost while meeting consumers’ desired egg yolk colour quali- ty standards. However, lighter coloured DDGS is more likely to contain larger amounts of xanthophylls than darker coloured DDGS due to its liposoluble nature. Overheating of DDGS may cause oxidation of carotenoids resulting in lower concentra- tions. Complementing the yolk pigmentation using natural or synthetic products over a homogenized base of yellow from DDGS is therefore recommended.
• Sulphur content Sulphuric acid is commonly added during the dry grind etha- nol production process to keep pH at the desired level to en- sure optimal yeast propagation and fermentation for efficient starch to ethanol conversion, as well as for cleaning purposes. However, sulphur is one of the core chemical elements need- ed for biochemical functioning and is a key macronutrient for all living organisms. Despite its importance, sulphur levels greater than 0.6% in poultry can produce wet litter problems, while 1.2% sulphur results in depressed growth. However, it is very unlikely that DDGS will contain very high levels of sul- phur. However, the general concern about sulphur levels in feeds and how using DDGS influences them, is reasonable. It is therefore important to consider the sulphur additivity of other feed ingredients, too.
PHOTO: EVONIK
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