Over the past 50 years genetic selection and refinement in nutrition have facilitated a tremendous increase in the bodyweight gain of broilers. These genetic and nutritional advances have opened the door for the large-scale, high-performing broiler production that we know today and enables us to produce large amounts of broiler meat while minimising the costs. Unfortunately, selection for increased weight gain and breast yield in broilers has increased the incidence of breast muscle myopathies such as Wooden Breast, White Striping and Stringy-Spongy or Spaghetti Breast. Such myopathies cause changes in chicken meat that affect colour and tenderness. Wooden or woody breast (WB) is characterised by palecoloured, very tough and chewy meat. It is caused by myofiber fibrosis and necrosis. White striping (WS) is recognised by white striations parallel to the muscle fibres. These white striations consist of fatty acid tissue and collagen which accumu-lates in the muscle tissue when the muscle grows so fast that there is insufficient oxygen supply to the muscle to support this fast growth. This increase in fat content leads to a reduction in meat quality. Although breast muscle my opathies do not cause a food safety issue, the meat from broilers affected with WB/WS negatively affects its sensory qualities and results in large economic losses for broiler producers. Therefore it is important to find strategies that can reduce the incidence of such myopathies and minimise the economic impact. The supplementation of certain feed additives, such as organic selenium and 25-hydroxyvitamin D3, betaine and guanidine acetic acid may contribute to a reduction in the incidence of breast muscle myopathies. Orffa Additives, as an engineer of feed solutions, performed a trial together with the University of Lavras (UFLA) in Brazil, to study the efficacy of different feed additives in reducing the incidence and severity of wooden breast and white striping.
Answer to the problem
A trial with 900 day-old Cobb-500 chicks was performed to evaluate the effects of multiple combinations of four feed additives on the incidence and severity of WB and WS: L-sele-nomethionine (Excential Selenium 4000), 25-OH-vitamin D3 (Excential First25), betaine hydrochloride (Excential Beta-Key) and guanidine acetic acid (GAA). The chicks were divided over 9 treatments, in a factorial scheme (2×2 x 2 + 1) with two L-selenomethionine levels (selenium supplementation at 0.175 and 0.350 ppm) x two 25-OH-vitD3 levels (1,000 and 3,000 IU/kg) x betaine/guanidine acetic acid (1,200/0 and 600/600 ppm), and a control treatment with 0.350 ppm of inorganic se-lenium (sodium selenite) and 3,000 IU/kg of vitamin D3, with-out betaine/GAA. After 42 days, the birds were slaughtered and 20 birds per treatment were selected for WB and WS scoring.