Traditional herb provides broilers non-medicated performance boost: study

The use of Allium hookeri (AH) root could boost the weight gain of broilers and support antioxidant production without the use of antibiotics, say researchers.

An international team of scientists from the US, South Korea and China examined the use of AH root in the diets of juvenile broilers to determine if the feed additive could influence bird performance or antioxidant activity.

 “In the present study, two forms of AH (fresh and fermented) at different concentrations (1% or 5%) were used to evaluate the antioxidant effect of AH as a feed additive in broiler chickens."​

 The team found that although the feed additive provided an initial boost to weight gain, it did not last through the entire feeding study. However, there were lasting influences on antioxidant and RNA expression levels.

“Antioxidant potential was mostly increased in all the treated groups when compared to the control, but 1% root supplementation performed was the best based on RNA expression levels, which was consistent with the tested antioxidants and MDA in the serum​, the researchers said. “Future research is needed to determine an optimal dose of AH and the precise mechanisms of action to promote efficient antioxidant activity, maintained growth promotion, to further establish its use as an alternative to antibiotics in the agriculture animal industry.”​

 The group published its work in the journal Research in Veterinary Science​​​.

 Why Allium hookeri root?​

Antibiotics have been commonly used in animal agriculture since about the 1940s, including as antibiotic growth promoters (AGPs), the researchers said. However, increasingly restrictions are being placed on those practices and alternatives are needed to promote growth and reduce economic damages from infectious diseases.

 There has been a growing interest in the use of dietary feed additives that have been linked to improved production – like probiotics, prebiotics, essential oils, phytochemicals, organic acids, hyper-immune immunoglobulin (Ig) Y and enzymes, they said. However, there also is a lack of understanding of the efficacy of multiple medicinal plants on production animals.

 “The traditional medicinal plant Allium hookeri (AH) has been used to treat cough, the common cold, burns, and wounds in eastern India and southern China,”​ they said. “Other members of this family include green onion, garlic, and onion, which contain abundant organo-sulfur compounds that have been reported to have antioxidant, anti-cancer, anti-coagulation, anti-cholesterol, and antibacterial activities.”​

Oxidative stress stems from high levels of reactive oxygen species (ROS) and is linked to several metabolic disorders noted in poultry experiencing stressful conditions, said the researchers. Stressors like heat stress and disease challenge are viewed as a major detractor on chicken performance.

 A dietary supplement for young broiler chickens that would be able to mitigate oxidative stress would be of interest to the industry, they said.

Methods and materials​

In the feeding trial, 125 broilers were given one of five diets for a period of 21 days, the researchers said.

The diets included a control or basal diet with 24% crude protein, they said. The remaining diets included supplemental AH that was either powdered or fermented and powdered at 1% or 5%.

On days 14 and 21 body weights were taken and at the end of the feed trial blood and jejunum samples were collected for analysis, they said.  

“Individual body weight was measured to assess growth performance, and expression of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), aflatoxin B1 aldehyde reductase (AFAR), and heme oxygenase (HMOX1) were determined by quantitative real-time polymerase chain reaction (qRT-PCR),” ​they said. “In addition, levels of malondialdehyde (MDA), CAT and SOD in serum were measured.”​

Results​

Overall mortality among the groups was the same as were feed intake and feed conversion ratios, the researchers said.

On day 14, birds getting 1% powdered AH had statistically higher body weights than those on the control diet, however, that was not noted on day 21, they said. AFAR concentrations also were higher for birds on the 1% powdered AH diet, but not for those getting the fermented AH additive.

“These results indicated that an optimum level of dietary AH supplementation to young broiler chickens influences growth and improves antioxidant activities,”​ they said.

HMOX1 expression levels were higher for birds getting either the 1% fermented AH or 5% fermented AH supplement, they said. CAT levels were upregulated in birds getting the 1% AH or 5% fermented AH additive.

“CAT and SOD enzyme activities were increased in birds fed diets supplemented with AH root and fermented root, as compared to the non-supplemented group, and serum MDA concentration were significantly decreased when compared with the basal diet group,”​ they said.

Source: Research in Veterinary Science​

Authors: Y Lee, S-H Lee, S-J Lee, U Gadde, S Taek Oh, H Han, H Lillehoj