Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:, 2004), improve carcass characteristics (Swingle et al., 1979; Matulis et al., 1987; Cranwell et al., 1996a; Stelzleni et al., 2007) and meat quality (Cranwell et al.
Category: