Dietary influences on lutein pigments and carcass fat quality in wethers of different maturity types

Abstract

The aim of this research was to study the effect of high-maize diets and pelleting on the accumulation of lutein pigments and appearance of the subcutaneous fat in Dorper and SA Mutton Merino wethers. High and medium energy maize diets were fed to Dorper and SA Mutton Merino wethers from an initial live weight of ca. 21 kg to a target weight of 43 kg. Fat colour and firmness were evaluated subjectively on a 5-point scale. Samples of the subcutaneous fat and feed were collected for fatty acid and lutein analyses. Loin samples (L1-L6) were oven-roasted and fat characteristics evaluated by a trained sensory panel. The concentrations of lutein pigments and total long-chain fatty acids were influenced mainly by the fattening period (p<0.05) and pelleting of the diets (p<0.05). Lutein concentrations increased during longer fattening periods and resulted in lower colour scores for subcutaneous fat. Neither breed nor the maize content of the diet significantly affected the concentration of lutein in the subcutaneous fat. Lutein concentrations resulted in lower subjective colour scores (p<0.05) and improved the aroma of lamb during carving (p<0.05). The present results suggest that the 'unacceptable' lutein pigments contribute to the typical aroma of lamb.Die doel van die studie was om die invloed van hoe mielie-diete en verpilling van hoe mielie-diete op die aansameling van luteinpigmente en voorkoms van die subkutanevet van Dorper en SA Vleismerino hamels te bestudeer. Hoe en medium energie mielie-diete is aan Dorper en SA Vleismerino hamels vanaf ca. 21 kg tot teikenmassas van 37 en 43 kg gevoer. Onderhuidse vetmonsters en voermonsters is versamel vir vetsuur- en luteinontledings. Subkutanevet-eienskappe is subjektief geevalueer op 'n 5-punt skaal. Monsters van die linker lende (L 1-L6) is geoondbraai en vet-eienskappe is sintuiglik geevalueer deur 'n opgeleide proepaneel. Die konsentrasies van lutein pigmente en totale langketting-vetsure is beinvloed deur die tydperk van vetmesting (p<0.05) en die verpilling van die dieet (p<0.05). Luteinkonsentrasies het verhoog tydens langer vetmestingsperiodes terwyl die kleur van die subkutane vet verswak het. Die ras en vlak van mieliemeel-insluiting in die dieet het geen betekenisvolle invloed gehad op die konsentrasies van lutein in die subkutane vet nie. Die konsentrasie van luteinpigmente het die subjektiewe kleurtellings verlaag (p<0.05) en aroma tydens voorsny verbeter (p<0.05). Die huidige resultate dui daarop dat 'n klein hoeveelheid van die 'onaanvaarbare' luteinpigmente bydra tot die tipiese aroma van lamsvleis.