O’Neill, H. Adri (Hester Adriana)Webb, E.C. (Edward Cottington)Frylinck, L.Strydom, P.E. (Phillip Evert)2011-04-082011-04-082010O’Neill, HA, Webb, EC, Frylinck, L & Strydom, P 2010, 'The conversion of dopamine to epinephrine and nor-epinephrine is breed dependent', South African Journal of Animal Science, vol. 40, no. 5, suppl. 1, pp. 502-504. [http://www.sasas.co.za/]0375-1589http://hdl.handle.net/2263/16237In previous reports, Nguni type cattle have shown to have a lower glycolytic potential with less glycogen measured in muscles 1 h post-mortem. With the release of catecholamines in the immediate pre-slaughter period, there is potential for depletion of muscle glycogen, because of the fact that epinephrine activates muscle adenylate cyclase and thereby stimulates glycogen breakdown. Epinephrine and nor-epinephrine are secreted as a result of any “fight or flight” situation. Tyrosine is a conditionally non-essential large neutral amino acid and the precursor of the neurotransmitters dopamine, nor-epinephrine and epinephrine. Ante-mortem stress experienced by an animal may be influenced by amino acids that provide substrates for neurotransmitter synthesis. The Nguni type cattle showed 55.8% and 55.1% greater urinary nor-epinephrine values than for the Brahman- and Simmental type cattle respectively. The Nguni type cattle showed 35.6% and 43.8% greater urinary epinephrine values than the Brahman- and Simmental type cattle respectively. The higher urinary nor-epinephrine and epinephrine levels measured in Nguni type cattle could either be explained by a greater neuronal out flux immediately prior to slaughter or a slower re-uptake.en© South African Society for Animal ScienceMeat tendernessUrinary catecholaminesEpinephrineDopamineBeef cattle breedsGlycogenArticle