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Food, fibre and pharmaceuticals from animals

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The impact of two different hormonal growth promotants (HGPs) on the eating quality of feedlot finished steer carcasses.

David Packer , Geert Geesink , Rod Polkinghorne , John Thompson , Alex Ball


The Meat Standards Australia (MSA) beef grading model applies a variable adjustment for different cuts for Hormonal Growth Promotant (HGP) treated carcasses but does not differentiate between different HGP types. Using 300 non implanted Bos indicus/Bos taurus composite steers an experiment was conducted to compare the effects on eating quality in the mm. longissimus dorsi (LD) and gluteus medius (GM) muscles of an oestradiol only (OES) and a combination trenbolone acetate with oestradiol (TBA+OES) implant with non-implanted animals (CON) fed a concentrate ration for 73 days prior to slaughter. Sensory and objective LD and GM samples were aged for either 5 or 35 days before freezing at -20°C. Carcass weights from each group were significantly different (P<0.05). Corrected for carcase weight, both HGP treatments had a significant effect on hump height, ossification score, marble score, P8 fat depth and eye muscle area. The TBA+OES treatment resulted in significantly tougher meat than the OES and CON treatments as assessed by shear force (P<0.05), although this difference was reduced with aging. Sensory scores (tenderness, juiciness, like flavour, overall liking and a composite MQ4 score) confirmed a negative HGP treatment effect, whereby TBA+OES was significantly lower than the CON and OES groups after 5 days of aging, and these differences were reduced through aging. TBA+OES had a greater impact on sensory scores in the LD when compared to the GM. Both HGP treatments increased calpastatin activity, and the TBA+OES group was significantly different to the CON and OES groups (P<0.05). It was concluded that OES and TBA+OES implants have different impacts on meat eating quality measurements, which could have important implications for the Australian and international beef industry.

AN17121  Accepted 19 September 2017

© CSIRO 2017