Effect of linseed supplementation level and feeding duration on performance, carcass and meat quality of cull ewes

The effects of linseed supplementation level (LSL: 5%, 10% or 15%) and feeding duration (FD: 30, 50 or 70 days) were analysed on productive, carcass and meat quality parameters using 72 cull ewes (n = 8 for each group), to improve their commercial value and meat quality. Both LSL and FD influenced productive parameters, carcass and meat quality. Feeding duration affected final body condition score (P<0.001), which increased up to 50 days of supplementation, keeping constant afterwards. Carcass yield (P < 0.001) and shoulder weight (P = 0.005) raised up to 70 d of fattening. Both LSL and FD increased subcutaneous fat thickness. Tissue composition was mainly affected by FD (P < 0.001), thus the percentage of muscle decreased and the percentage of fat increased along FD whereas increasing LSL at 15% produced the lowest muscle percentage. Colour was modified by FD, the longer the intake, the paler and lower redness (P < 0.001) and yellowness (P < 0.05) presented the meat. Texture and proximate composition were unaffected by both factors. Fatty acid composition was mainly modified by LSL, increasing polyunsaturated fatty acids (PUFA, P < 0.05), n-3 PUFA (P < 0.001), PUFA/SFA ratio (P < 0.05), and reducing n-6/n-3 (P < 0.001) with increasing linseed levels. Longer supplementation intakes decreased n-6 percentages (P < 0.05). LSL and FD had a small effect on sensory attributes, although lower LSL and FD had the lowest fat intensity and longer periods of fattening increase undesirable odours or flavours such as rancidity and old (P < 0.05). Therefore, linseed diet supplementation could be considered in cull ewes as a good practice, being 10% of LSL and between 30 or 50 days of FD the best option to improve fatty acid profile, productive, carcass characteristics and meat quality, and subsequently the commercial value of these animals.