Effects of feeding strategies during lactation and the inclusion of quebracho in the fattening on performance and carcass traits in light lambs.

The interest for grazing systems and the use of condensed tannins (CTs) as sources of natural antioxidants in animal diets has been increasing in recent years. The objective was to study the animal performance and carcass quality of the lambs according to the feeding strategy during lactation (indoors, grazing alfalfa, grazing sainfoin) and the inclusion of quebracho as a source of CTs (50 g kg-1 ) in the fattening concentrate.The feeding strategy during lactation only had effects on carcass quality. Indoor lambs had a greater dressing percentage and deposition of kidney fat than sainfoin and alfalfa lambs. The kidney fat of sainfoin- and alfalfa-fed lambs had a greater yellowness, chroma and carotenoid content than the fat of indoor-fed lambs (P < 0.05), whereas the subcutaneous fat colour was not affected by the feeding during lactation. The use of fat colour to trace the feeding strategy was assessed and found insufficiently accurate to implement its use. The inclusion of 50 g kg-1 quebracho in the concentrate fed during the fattening period increased lamb weight gains and feed intake but had little effect on the carcass characteristics.The feeding strategies during lactation had an effect on the carcass characteristics, highlighting the importance of the dam's diet during this period. The inclusion of quebracho in the lamb's concentrate had minor effects.

The authors wish to thank the staff of the CITA de Aragon for their help in data collection and lab assistance. This study was supported by the Ministry of Economy and Competitiveness of Spain and the European Union Regional Development Funds (INIA RTA2012-080-00 and INIA RZP2013-00001-00) and the Research Group Funds of the Aragon Government (A49 & A11). M. Blanco is supported by INIA-EFS and S. Lobón by a doctoral grant from the Aragón Governmen

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