Graduate Thesis Or Dissertation

Use of herbal feed additives in poultry feeding

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  • The use of an antibiotic as a growth promoter (AGP) began in the 1940’s with the discovery of growth responses from Streptomyces aureofaciens in the monogastric diet. However, resistance and residue problems have increased the negative consumer perception of growth promoting antibiotic use in animal diets. Although no direct link between antibiotic resistance in animals and succeeding antibiotic resistance in humans, there has been increased interest and push to find alternatives to AGPs. Many different types of alternatives such as pre/probiotics, phytogenic compounds (e.g. herbs, and essential oils), enzymes and organic acids are being studied as AGP alternatives. Herbs are one of the four subgroups of the phytogenic classification. Plant based products contain plant secondary metabolites or phytochemicals which are effective as feed additives. Previous studies have found positive results with inclusion of phytogenic feed additives in poultry diets. Two experiments were carried out to test the effectiveness of herbal supplements (Superliv® Concentrate Premix (broiler) and AV/HLP/16 (layer)) on production performance, hindgut bacterial proportions of microbes, liver and muscle tissue lipid composition, and nutrient efficiency in broilers and on production performance, egg quality, egg and liver fatty acid composition, lipid stability, and hen serum lipids in laying hens. In experiment one, effect of the herbal blend (Superliv® Concentrate Premix) and different levels of nutrient density in the diet of meat-type chickens was investigated. A total of 120, one day-old Cobb broiler chicks were fed diets varying in metabolizable energy (ME) (Control, 2.5% reduced ME, 5% reduced ME) with and without Superliv® Concentrate Premix herbal blend. Body weight was the lowest for birds receiving the 5.0% Low Energy diet at the prestarter, grower and finisher phase (p≤0.05). Feeding 2.5% Low Energy diet had no effect on final body weight (p>0.05). No effect of energy level of the diet on total feed conversion ratio (FCR) was observed (p>0.05). Gizzard weight was lowest in Control birds (p≤0.05). The Control diet broilers had significantly higher liver total lipid levels than the 2.5% and the 5.0% reduced energy diets (p≤0.05). The apparent total tract retention of fat was increased in birds fed 2.5% and 5.0% Low Energy diets (p≤0.05). Fecal dry matter (%) was lowest for birds fed 5.0% Low Energy (p≤0.05). Energy level in the diet did not impact total relative proportions of the Lactobacillus, Bifidobacterium and Salmonella in the cecum (p>0.05). With respect to herbal supplementation in the diet, there was an increase in relative fat pad weight in birds receiving the supplement (p≤0.05). Total lipids was higher in the thigh muscle of birds fed the herbal supplement (p≤0.05). A significant increase in the relative proportion of Lactobacillus was observed in birds fed a diet containing the herbal supplement (p≤0.05). Fecal dry matter (%) was reduced in the birds receiving the supplement (p≤0.05). No effect of herb was found on the production performance indicators (FCR, body weight) or the apparent total tract retention of energy or fat (p>0.05). In experiment two, the inclusion of an herbal blend formulated for layers (AV/HLP/16) at different levels in the diet was investigated. A total of 96 brown layers (age 27 weeks) were kept in individual cages and fed a commercially formulated diet with either 0% (Control), 0.1% (Diet 1), 0.15% (Diet 2) or 0.2% (Diet 3) AV/HLP/16 supplement for four months. Egg mass and egg production were highest in hens receiving Diet 3 (p≤0.05). Feed consumption did not differ significantly among the treatments (p>0.05). FCR was lowest for Diet 3 but there was only a trend for significance (p>0.05). Shell, yolk and albumen weight (%) did not differ between diets (p>0.05). Haugh unit and yolk index values were highest in birds fed Diet 3 (p≤0.05). Lipid oxidation products in the liver were highest for Diet 1 and Diet 3 but there was only a trend for significance (p>0.05). Egg lipid oxidation products were highest in Diet 2 (p≤0.05). Total lipids (%) in the liver was lowest in Diet 2 and Diet 3 (p≤0.05). There was no difference in yolk total lipids (%) (p>0.05). There were differences in individual yolk fatty acids. There was a significant decrease in stearic acid and arachidonic acid in egg yolks from Diet 3 (p≤0.05). Linoleic acid was reduced in supplemented diets (p≤0.05). Egg lipid content decreased as the hen aged (p≤0.05). No effect of diet on egg cholesterol or hen serum triglycerides was observed (p>0.05). Overall, Superliv® Concentrate Premix herbal supplementation in the 2.5% Low Energy broiler diet maintained production performance while enhancing the beneficial bacteria in the hindgut when compared to the Control diet. In the layer, AV/HLP/16 herbal supplementation at 0.2% increased egg weight and improved production performance.
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