Effects of sheep alpha(s1)-casein CC, CD and DD genotypes on milk composition and cheesemaking properties

The effects of sheep alpha(s1)-casein CC, CD and DD genotypes on milk compo sition and cheese yield were studied. Processed bulk milk was collected fro m three groups of 15 ewes, carrying alpha(s1)-casein CC, CD and DD genotype s. CC milk was higher in casein content than CD or DD milk (+3.5 and +8.8% respectively), and had a higher protein:fat ratio and a smaller casein mice lle diameter. In addition, DD milk had a significantly lower alpha(s1)-case in content. The main differences were in curd formation: CC milk had better renneting properties. Cheesemaking trials, carried out in a pilot plant, s howed that CC milk had better cheesemaking characteristics than DD milk, wh ile CD milk was intermediate. Both 1 d old and fully ripened cheeses had di fferent fat:dry matter ratios and alpha(s1)-I-casein electrophoretic mobili ties: these were lower for DD cheese. As a consequence: these genotypes cou ld be considered as markers of milk and/or cheese quality.