Incidence of Tendon Rupture in Broilers16 May 2014
More tendon ruptures were observed in broilers reared during cooler months in this US trial, which the researchers attributed to the use of a growth promoter resulting in heavier bodyweights.
Authors of this paper in International Journal of Poultry Science explain that they carried out the study in response to reports indicating higher-than-expected leg condemnations in a commercial processing plant in Mississippi.
Other studies have found lameness problems, such as rupture of the gastrocnemius tendon, in broilers as a possible side-effect of using the 3-nitro-4-hydroxyphenylarsonic acid (3-nitro) as a growth promoter in broilers, especially when combined there are other stressors such as high temperatures.
In the paper, A.O. Sokale of Mississippi State University and co-authors there, Sanderson Farms and Zoetis Global Poultry describe their study examining the effect of feeding 3-nitro in broiler diets during low (May) and high (July) temperature months on the incidence of gastrocnemius tendon rupture (GTR).
All observations were made at a single processing plant during the months of May and July 2010.
The average live bodyweight of birds processed in May and July were 3.8 and 3.6kg, respectively.
The birds processed in May were fed 3-nitro in starter and grower diets (22g per ton), whereas birds processed in July were fed 3-nitro in the grower (34g per ton) and finisher (22g per ton) diets.
Affected gastrocnemius tendons were classified as fibrosed and trimmables tendons, with trimmables subdivided into acute or chronic tendons.
Data analysis by Poisson regression showed higher incidence of both acute and fibrosed tendons in May than July.
GTR can be caused by pathogenic and non-pathogenic factors, according to Sokale and co-authors. However, they concluded from this field study that a higher incidence of GTR observed in birds reared during cooler months may be associated with a heavier bodyweights and the introduction of 3-nitro early (starter diet) in the grow-out period.
Sokale A.O., E.D. Peebles, P.A. Stayer, T.S. Cummings and R.W. Wills. 2013. Evaluating the incidence of gastrocnemius tendon rupture in broiler chickens. International Journal of Poultry Science. 12: 685-688.
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