Abstract
The recent trend toward reduction of antibiotic growth promoters (AGP) in North American poultry diets has put tremendous pressure on the industry to look for viable alternatives. In this context, phytogenic feed additives (PFA) are researched to improve gut health and thereby performance. An experiment was conducted with the objective to evaluate the effects of PFA as an alternative to AGP on small intestinal histomorphology, cecal microbiota composition, nutrient digestibility, and growth performance in broiler chickens. A total of 432-day-old Vencobb 400 broiler chicks were randomly assigned to one of three dietary groups, each consisting of 12 replicate pens (n = 12 chicks/pen). The chicks were fed a corn–soybean meal-based control (CON), CON + 500 mg/kg of AGP (bacitracin methylene disalicylate containing 450 mg active BMD/g), or CON + 150 mg/kg of proprietary blend of PFA (Digestarom® Poultry) until 39 days of age when samples were collected. Birds fed either AGP or PFA had increased villus height in all three segments of the small intestine in comparison to the birds fed CON (P ≤ 0.05). Furthermore, the PFA-fed birds had significantly increased villus height and lower crypt depth compared to AGP fed birds (P ≤ 0.05). Birds fed either additive also had increased total tract digestibility of dry matter, crude protein, and ether extract (P ≤ 0.05). The strong effect of the PFA on villus height in the jejunum may suggest augmented nutrient absorption in PFA-fed birds. Although both additives reduced total cecal counts of anaerobic bacteria and Clostridium spp., PFA alone reduced the total coliform count while increasing the Lactobacillus spp. count (P ≤ 0.05). These results suggest the establishment of beneficial microbial colonies in PFA-fed birds. Overall, both PFA and AGP increased body weight gain while lowering the feed conversion ratio (P ≤ 0.05). Hence data from this experiment demonstrate the efficacy of PFA as a substitute to AGP in poultry diets.
Highlights
Sustaining a healthy gut environment is a prerequisite to efficient broiler performance
Supplementation of Phytogenic feed additives (PFA) significantly lowered the overall feed conversion rate (FCR) by 3.6% (7 points) and 7.0% (14 points) in comparison to the Antibiotic growth promoters (AGP) and CON groups, respectively. This was in agreement with earlier reports [5], which indicated improvement in final BW and FCR with PFA supplementation without any effect on the feed intake (FI)
The growth promoting effects of the PFA and the AGP in this experiment may be correlated with the significant increase in apparent total tract digestibility of nutrients
Summary
Sustaining a healthy gut environment is a prerequisite to efficient broiler performance. Antibiotic growth promoters (AGP) have been used since the mid-1940s to maintain a healthy gut environment and in turn improve the performance [1]. Phytogenic feed additives (PFA) have been gaining considerable interest lately due to their ability to improve performance by sustaining a healthy gut environment. According to European Union legislation (EC 1831/2003) [4], PFA are categorized as sensory and flavoring compounds, which consist mainly of plant extracts (essential oils, oleoresins, and flavonoids) and their active principles [5]. The essential oils present in PFA, which contain most of the active substances of the plant, have been suggested to increase the growth performance [6, 7], nutrient digestibility [8], and gut health [6, 9] in poultry species. It is these properties of PFA that project them as suitable alternatives to AGP
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