PARTNER FEATURE ▶▶▶
Need for natural alternatives to AGPs
Necrotic enteritis in broilers is just one of many diseases held at bay by in- feed antibiotic growth promoters. However, the ban on in-feed AGPs creates a need for natural alternatives. One of the latest substances added to the toolbox are wood lignans in the polyphenol category offering interesting properties for controlling NE.
BY NINA NEUFELD T
Virginiamycin --- agromed® ROI ---
Feed intake d 1-42, g 4,348d End weight d 42, g 2,626c FCR d 1-42 Carcass, % Breast, % Thigh, %
1.71d 67.8d 31.7c 31.9
a,b,c,d significant differences p < 0.005 32 ▶ POULTRY WORLD | No. 7, 2020
he sub-therapeutic use of antibiotics as growth pro- moters (AGPs) has been practiced for decades to im- prove performance and reduce the infectious pres- sure of certain diseases. Due to the existing problem
of growing resistance which greatly impairs the effectiveness of therapeutic antibiotics in humans and animals, many countries have banned the use of antibiotic performance en- hancers. There is a worldwide trend to look for alternatives and several substances, like phytogenics, essential oils, en- zymes, organic acids, as well as pre and probiotics, have been proposed for this purpose. Restrictions on the use of AGPs have led to an increased inci- dence of necrotic enteritis (NE) in broilers which is associated
Table 1 – Trial design with four experimental groups. NC
PC
negative control positive control 16.5 ppm ---
Table 2 – Performance data. NC
PC
4,328c 2,627c 1.68c 68.6c 31.1d 31.9
NC+wood lignans PC+wood lignans --- 400 ppm
16.5ppm 400 ppm
with considerable economic losses. The causative agent of NE is the gram-positive bacterium Clostridium perfringens. How- ever, C. perfringens also occurs physiologically in healthy ani- mals. Possible factors are stress and imbalances in the feed which favour the growth of Clostridia perfringens. The most important predisposing factor is coccidiosis triggered by the protozoa Eimeria. These parasites multiply in the intestinal mucosa, damaging it and stimulating mucogenesis. For Clostridia perfringens, the presence of 13 different amino acids is necessary as a nutritional source (auxotrophy), while an oversupply of protein contributes to excessive bacterial re- production. Due to the resulting overpopulation, particularly virulent strains of Clostridia perfringens dominate the popula- tion, leading to a progressive destruction of the intestinal mucosa that was previously damaged due to coccidiosis (Figure 1).
NC + wood lignans PC + wood lignans 4,511b 3,132a 1.46a 68.9b 33.5a 32.0
4,621a 3,076b 1.52b 69.6a 32.5b 31.7
New class of active substances Wood lignans as a new class of active substances for feed purposes have shown remarkably positive effects on the per- formance of broilers in various experiments (product agromed ROI, Agromed Austria GmbH). Wood lignans are bio- active substances with strong antioxidative, anti-inflammato- ry and antimicrobial properties. In scientific studies the sup- plementation of lignans modulated inflammatory events in the small intestine of animals with endotoxin (LPS)-induced inflammation (Figure 2). Subclinical NE under practical conditions shows minimal clini- cal signs but has an estimated prevalence of 20%, with a strong impact on performance reflected in reduced weight gain and increased feed conversion. These effects on perfor- mance can be related to intestinal inflammation which induc- es a loss of energy and protein that cannot be used for growth. Current results from a feeding trial with broilers correlate to this connection. The trial compared the effects of a specific
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