The in ovo approach to optimizing poultry gut health and performance: an inquiry

Abstract

Several proposed alternatives to antibiotic growth promoters (AGP) in poultry have been reported ineffective due to limitations of delivery routes. Hence, an urgent need for new approaches to maintain poultry gut health exists. This thesis thus evaluated the in ovo approach to optimizing broiler chicken’s gut health and growth performance in five experiments involving three bioactive substances (probiotics, essential oil, and folic acid).

Experiment 1 revealed that the in ovo delivery of probiotics product (Bacillus subtilis fermentation extract) enhanced gut morphology without compromising hatch and gut homeostasis. Experiment 2 showed that all probiotics (independent of delivery routes and dose) were mostly comparable to the in-feed antibiotics treatment in their ability to ensure gut microbiota homeostasis, enhanced gut morphology, and feed conversion efficiency. Experiment 3 indicated that the in ovo delivery of an essential oil blend reduced hatchability and chick length in broiler chickens. However, successive delivery of this essential oil blend via in ovo and in-water routes improved broiler chicken’s antioxidant status and blood biochemical profile with no adverse effect on growth performance. In ovo, delivery of folic acid (0.15 mg /egg) is observed to increase hatchling weight and enhance broiler chicken gut morphology and feed conversion ratio in a similar capacity as the in-feed antibiotic treatment in experiment 4. However, hatchability was reduced by the in ovo delivery of folic acid. Finally, experiment 5 was conducted to validate the gut-optimizing potential of these in ovo-delivered bioactive substances under a heat stress challenge. Results showed that independent of heat stress, the successive delivery of essential oil via in ovo and in-water routes improved broiler chicken gut morphology and intestinal barrier integrity. Under heat stress conditions, the in ovo + in-water EO routes induced a numerical increase in feed conversion efficiency (+30%) and as much as a 3.5-fold significant upregulation of amino acid transporter gene, suggesting that the delivery of this bioactive substance offer potential gut thermo-protective functions under heat stress condition. Summarily, results from this thesis reveal that the in ovo delivery of probiotics, essential oil, and folic acid shows promising benefits as alternatives to AGP in the post-AGP era.