Does forage type (grazing vs. hay) fed to ewes before and after lambing affect suckling lambs performance, meat quality and consumer purchase intention?

The aim of the study was evaluate the use of forage diets (grazing pasture vs. hay) around ewe parturition on the performance and meat quality of suckling lambs (10–12kg body-weight). Forty-eight multiparous single bearing ewes from the Churra Tensina breed were used. The experimental treatments were conducted during the last 5 weeks of pregnancy (pre-partum period) and the 5 weeks of lactation (post-partum period) in a 2×2 factorial design. Ewes were fed ad libitum on mountain pastures or pasture hay. Hay was made in late spring from the same pasture paddocks to those grazed in autumn. Results showed that ewes body-weight (BW) and body condition score (BCS) were not affected by forage type feed around ewe parturition. The week post-partum had a more determinant effect on milk production and composition than forage type pre- and post-partum. The energy-corrected milk yield peaked on first week of lactation (1.39l/day, P<0.05), and decreased significantly from week 3 post-partum onwards (1.29l/day vs. 1.02l/day, P<0.05). Forage type supplied to ewes during the pre-partum period did not affect any of the studied variables on lambs. During post-partum period forage type had effect on lamb ADG, which was higher in grazing system than in hay feed (259g/day vs. 220g/day). Consequently, age at slaughter was greater in lambs raised by ewes receiving hay post-partum compared to grazing ewes (36 days vs. 32 days, P<0.05). Caudal fat colour was affected only by post-partum forage type, showing grazing group greater redness, yellowness and absolute value of the integral of the translated spectrum (SUM) than that forage type (P<0.05). Carcasses from lambs raised by post-partum grazing ewes led to a muscle with lower lightness and yellowness and greater redness than hay forage type (P<0.05). Lambs whose dams grazed presented a higher visual appraisal score at cutting time, however these differences disappeared as time advanced. Grazing forage had a positive effect on consumer purchasing decision (P<0.10). In conclusion, forage type in pre-partum period did not affect the studied parameters whereas ewes grazing on mountain pastures after autumn-lambing improved lamb performance without any detrimental effect on carcass and instrumental meat quality.