A team of Chinese researchers examined effects of oil use on bird development, intestinal health and production in an attempt to better understand the intestinal reaction of broilers.
The oregano essential oil (OEO) also was examined as a possible replacement for antibiotic growth promoters (AGP), they said.
“Inclusion of OEO at 300 and 600 mg/kg in feed increased the ADG [average daily gain] of broilers which may be related to the increased VCR [villus height to crypt depth ratio] and decreased CD [crypt depth] in the jejunum of broilers,” said researchers. “Furthermore, dietary OEO at 600 mg/kg could improve dressing percentage, eviscerated rate, and leg muscle percentage and induce a decrease in abdominal fat percentage of broilers.”
Why oregano oil
As restrictions are placed on the use of antibiotics with animal production, different treatments have been researched in poultry to boost growth, said researchers. These treatments include phytogenic feed additives and essential oils.
Oregano essential oil has been classed as GRAS or generally recognized as safe in the US and is considered beneficial for intestinal microflora, they said. However, results of tests with poultry have been inconsistent.
Additionally, the effect of oil supplementation on abdominal fat is not clear, they said. Nor is there a great understanding of what oil use does to intestinal morphology and health.
“It seems that the response of broiler chickens to the dietary inclusion of OEO is not clear,” said the scientists. “Therefore, this study was conducted to evaluate the effects of OEO supplementation to basal diet on growth performance, carcass traits and jejunal morphology of broilers, and accordingly estimate the potential of OEO as an alternative for AGPs.”
In the experiment, 448 birds were started on one of four experimental diets with seven repetitions, said researchers. The trial ran for 42 days.
The diets included a control diet of corn and soybeans (CON), the diet with 8 mg/kg aviamycin (AVI), the control diet with 300 mg/kg oregano essential oil (OEO300) and the corn-soybean diet with 600 mg/kg (OEO600), they said. The oil additive was Orsential Dry produced by Kemin Industries.
Birds were weighed by pen and feed intake was recorded on days 1, 21 and 42 to calculate ADG, average daily feed intake (ADFI) and the feed conversion ratio (FCR), they said.
Two birds per pen were harvested at the end of the trial to assess abdominal fat along with breast and leg muscle characteristics, said researchers. Dressing percentage was calculated and intestinal segments were collected.
Both groups getting the oregano oil demonstrated improved final body weight compared to the control group, said researchers.
“OEO supplementation exhibited a significantly positive effect on the growth performance, carcass traits and intestinal health of broilers, indicating that OEO may be a promising alternative to antibiotic growth promoters,” they said.
By day 21, birds getting the OEO600 diet saw improved ADG and had a lowered feed conversion ratio compared to the control group, they said. Broilers getting the OEO600 diet also had better ADG and ADFI than the AVI group for the entire experimental period.
Both groups getting supplemental oil also showed boosted ADG and ADFI when compared with the control group, said researchers.
Carcass traits were similar for groups getting either of the oil treatments and AVI, they said. The treated birds had better dressing percentage and eviscerated rate when compared to the control group.
Broilers getting the OEO600 diet had highest breast muscle percentage and the least abdominal fat percentage, they said.
No treatment altered the villus height in the jejunum, they said. But the oil supplements decreased the crypt depth and boosted the villus height to crypt depth ratio compared to the control birds.
Source: Animal Feed Science and Technology
Title: Effects of dietary supplementation with oregano essential oil on growth performance, carcass traits and jejunal morphology in broiler chickens
DOI: published online before print: doi:10.1016/j.anifeedsci.2016.02.010
Authors: Q.Y. Peng, J.D. Li, Z. Li, Z.Y. Duan, Y.P. Wu