Scottish Milk Testing Scheme

Summary A survey of the results of tests for chemical composition of the bulk milk of some 160 producers delivered to eight creameries in different parts of the Scottish Milk Marketing Board's area during a period of twelve months has yielded some interesting results. The conclusions drawn, however, are purely tentative and provide only pointers o differences in the composition of the supplies. The causes of the differences have not been investigated but they are probably related primarily to differences in feeding and herd management. The first portion of the survey shows that in about eighty per cent of individual supplies the maximum variation in the fat content of four consecutive weekly samples was 0·60 per cent with an average of 0·30 per cent and that it would therefore appear reasonable to allow a tolerance of ±0·10 per cent from the average fat content of the four weekly samples when determining the monthly true mean fat content of a bulk supply of milk as delivered to a creamery. Similarly since 82·5 percent of individual supplies showed a maximum difference in any one month of 0·30 per cent in the solids‐not‐fat content a tolerance of ±0·05 per cent when four consecutive weekly samples are examined might reasonably be allowed. The second portion of the survey shows that the average composition of bulk supplies as delivered to creameries varies widely in different areas. In the South Western area the fat content of the milk reached a higher level during the late summer and was maintained at this higher level for a longer period than in the East Central area. Although the trends of the fat and solids‐not‐fat contents were somewhat similar in the South West during the months of August to January this similarity was not continued during the remainder of the year, nor did it appear to be evident in the East Central area at any time of the year. The marked rise in the total solids content of the milk from the South Western area during the months of September to November contrasts markedly with the consistency of the total solids content of milk produced in the East Central area during September to February. The results of the tests also show that on the whole producers in both areas should find no serious difficulty in complying with the Scottish Milk Marketing Board's standards of 3·5 per cent of fat during the months of August to January (inclusive) and 3·4 per cent during the remainder of the year. Finally consideration might be given to basing any system of payment by quality on the total solids content of the milk rather than on the fat or solids‐not‐fat content alone.