Poultry Health Research Round-up08 February 2015
Recent research with broiler chickens has revealed that coccidiosis can be controlled by probiotics and genetic selection, while dietary organic acids help tackle other enteric diseases. A prebiotic/probiotic product has been found to be effective against a form of lameness.
Preventing Leg Problems in Broilers
Bacteria entering the bloodstream from the digestive tract can infect the cartilage of the upper and lower leg bones and cause lameness in broilers, according to R. Wideman of the University of Arkansas and others there and with Cobb-Vantress and Quality Technology International. Affecting the tibia and femur, this condition is known as bacterial chondronecrosis with osteomyelitis (BCO).
They found that adding a prebiotic and probiotic product to the feed was as effective at preventing BCO as an antibiotic, which led the researchers to conclude that probiotics potentially can provide effective alternatives to antibiotics for reducing BCO lameness attributable to bacteria in the bloodstream.
In their study, published in Poultry Science, broilers were fed a standard feed, with or without BacPack 2X in the first of two experiments. This product includes the prebiotic, IMW50 (a mannan oligosaccharide beta-glucan yeast cell wall product) plus the probiotic, Calsporin (Bacillus subtilis C-3102).
BacPack 2X in the feed throughout rearing from day-old to 56 days of age reduced the cumulative incidence of BCO on wire flooring to 24 per cent, compared to 41 per cent in the unsupplemented controls.
In a second experiment, the birds were reared to 62 days of age, either untreated or with therapeutic levels of the potent fluoroquinolone antimicrobial, enrofloxacin, in the water from days 35 to 54.
Cumulative lameness incidence for whole period was 26 per cent for the treated group receiving the antimicrobial and 39 per cent for the control group.
The researchers concluded that prophylactically adding BacPack 2X to the feed reduced the incidence of BCO lameness by a proportion similar to that achieved with enrofloxacin.
Effects of Probiotics and Salinomycin Compared for Coccidiosis Control
The annual financial loss to the poultry industry as a result of coccidiosis has been estimated at about US$3 billion, according to Wael Abdelrahman of Biomin and others with the organisation and Southern Poultry Research in the US.
From the results of a paper published in Poultry Science, they concluded that supplementation of the diet with probiotics could be considered as a potential strategy to control coccidiosis in broiler chickens.
They found that the dietary treatments containing the probiotics and salinomycin (66mg per kg) resulted in similar mortality, litter and lesion scores at 21 and 42 days of age as well as oocyst shedding on day 21.
Bodyweights of the probiotic group at the end of the experiment on day 42 were significantly lower than the salinomycin group but the feed conversion ratio (FCR) was similar for both groups.
In the experiment, 360 Cobb male broiler chickens had been randomly allocated to four groups:
- untreated, unchallenged negative control group
- untreated, challenged positive control group
- negative control supplemented with salinomycin, challenged group and
- negative control supplemented with probiotics, challenged.
On day 15, all birds (except group 1) had been challenged with approximately 75,000, 25,000 and 75,000 of Eimeria acervulina, E. maxima and E. tenella oocytes, respectively, that were mixed into the feed.
Genetic Selection for Coccidiosis Resistance
The USDA Agricultural Research Service has developed a novel selection method for chickens based on high and low pro-inflammatory mediators. In a recent paper in Poultry Science, Christi Swaggerty explained that the resultant high line of chickens is more resistant to Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) than the low line.
Working with Cobb-Vantress on the latest study, the researchers aimed to find out if the high line birds were also more resistant to the protozoan parasite causing coccidiosis, Eimeria tenella.
They carried out three separate experiments, which revealed that the high line birds were indeed more resistant to the caecal pathology associated with costly coccidial infections.
Necrotic Enteritis and E. coli Reduced by Dietary Organic Acids
The addition of organic acids to a broiler diet was more effective than an antibiotic in reducing the intestinal counts of Escherichia coli and Clostridium perfringens, the cause of necrotic enteritis.
This was the main conclusion of an experiment reported by M.A. Mohamed of the National Research Centre in Dokki and others and published in the International Journal of Poultry Science.
Mohamed and co-authors found that the organic acids stimulated some histological changes in the villi in the intestine and immune-related organs.
Growth and feed efficiency are closely related to the quantitative microbial load of the gut, the morphological structure of the intestinal wall and the activity of the immune system, they said.
The organic acid product they used (Galliacid) improved the performance and intestinal health and morphology of broiler chicks and so offers potential as an alternative to antibiotic growth promoters in broiler diets or as a tool of controlling intestinal pathogenic bacteria, Mohamed and co-authors concluded.
In their experiment, they used 150 Cobb broiler chicks for three dietary treatments: a basal corn-soybean meal diet served as a control treatment with no supplements or supplemented with either 0.025 per cent bacitracin methylene disalicylate (BMD, antibiotic) or 0.06 per cent Galliacid from 10 to 36 days of age.
Birds fed antibiotic or organic acids gained significantly more bodyweight than those fed the control diet. No significant differences were detected among treatments on feed intake while FCR values were significantly different; the addition of organic acids or antibiotic improved FCR by about nine and four per cent, respectively.
1. Abdelrahman A., M. Mohnl, K. Teichmann, B. Doupovec, G. Schatzmayr, B. Lumpkins and G. Mathis. 2014. Comparative evaluation of probiotic and salinomycin effects on performance and coccidiosis control in broiler chickens. Poultry Science. 93:3002-3008.
2. Mohamed M.A., E.F. El-Daly, N.A. Abd El-Azeem, A.W. Youssef and H.M.A. Hassan. 2014. Growth performance and histological changes in ileum and immune related organs of broilers fed organic acids or antibiotic growth promoter. International Journal of Poultry Science. 13:602-610.
3. Swaggerty C.L., I.Y. Pevzner and M.H. Kogut. 2015. Selection for pro-inflammatory mediators produces chickens more resistant to Eimeria tenella. Poultry Science. 94:37-42.
4. Wideman R.F. Jr, A. Al-Rubaye, Y.M. Kwon, J. Blankenship, H. Lester, K.N. Mitchell, I.Y. Pevzner, T. Lohrmann and J. Schleifer. 2015. Prophylactic administration of a combined prebiotic and probiotic, or therapeutic administration of enrofloxacin, to reduce the incidence of bacterial chondronecrosis with osteomyelitis in broilers. Poultry Science. 94:25-36.