Changes in composition and quality characteristics of ovine meat and fat from castrates and rams aged to 2 years

A comprehensive set of quality parameters has been recorded for meat and fat from groups of castrate and ram lambs raised on pasture and slaughtered in groups of six at 91-day intervals from 122 to 668 days of age. These include mechanical evaluation of meat tenderness, sensory evaluations of meat flavour and fat odour, and measurements of fat colour, fatty acid composition, vitamins C and E, free glucose and iron in the meat, and of the concentrations of the flavour compounds indoles, phenols, and branched chain fatty acids in the fat. There was significant variation in many parameters between slaughter days, including markedly lower meat tenderness in one slaughter group, probably in response to unfavourable pasture conditions. Older ram lambs tended to be less tender than castrates of the same age. However, no longer-term age-related trends were observed in tenderness or flavour quality. Concentrations of free glucose in rigor muscle and vitamin C showed a declining trend with age. Concentrations of the branched chain fatty acids 4-methyloctanoic and 4-methylnonanoic acids in fat increased with age. Sex category effects were observed for the branched chain fatty acids and for indole and skatole. Higher concentrations were observed in ram lambs. The data indicate there is only a limited decline in lamb meat quality characteristics up to nearly 2 years of age, but that pasture feeding conditions may affect quality significantly.