SciELO - Scientific Electronic Library Online

 
vol.40 issue5Growth performance of feedlot weaners cattle fed diet containing different levels of cold press soya bean oilcake author indexsubject indexarticles search
Home Pagealphabetic serial listing  

South African Journal of Animal Science

Print version ISSN 0375-1589

Abstract

O'NEILL, H.A.; WEBB, E.C.; FRYLINCK, L.  and  STRYDOM, P.. The conversion of dopamine to epinephrine and nor-epinephrine is breed dependent. S. Afr. j. anim. sci. [online]. 2010, vol.40, n.5, pp. 502-504. ISSN 0375-1589.

In 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.

Keywords : Meat tenderness; urinary catecholamines; beef breeds; dopamine.

        · text in English     · pdf in English