H.—29,

Clinica mastitis is, however, not marked in the herd. The leucocyte assessment also is deteriorating from' A to C.

It is of interest to note the continuous history of infected quarters which, in the case of staphylococci infections, tend to change to streptococci : — 1938. 1939. Six streptococci quarters . . . . . . Four streptococci quarters. One dry quarter. One normal quarter. Six staphylococci quarters .. .. .. Three staphylococci quarters. Three streptococci quarters. A tentative figure has been obtained by Mr. James to correlate the leucocyte assessment of gravity cream with the Breed count in milk. His average figures, which will be improved upon during the next year, are as follows : — Assessment Leucocytes per Cubic Centimetres Figure. Whole Milk (averaged). 0 .. .. .. .. .. .. .. .. 90,000 1 .. .. .. .. .. .. .. .. 170,000 2 .. .. .. .. .. .. .. .. 370,000 3 .. .. .. .. .. .. .. .. 1,450,000 4 .. .. .. .. .. .. .. .. 3,500,000 5 .. .. .. .. .. .. .. .. 8,870,000 6 .. .. .. .. .. .. .. .. 19,730,000 Sterility.—Work in connection with the sterility problem in dairy herds has been undertaken by Messrs. T. A. Blake and A. L. Thompson, stationed in Hamilton. Mr. Blake, as in past years, has taken particular interest in semen examination of bulls. During the year 103 samples of semen were taken and reported upon, 95 being from bulls, the remainder from horses and rams. Of the bulls, 27 were good, 27 fair, 26 poor, 8 bad, and 7 completely sterile. The percentage of successful first services of fifty of these bulls is given :—

An experience is recorded by Mr. Blake where a bull known to be good after being placed in a herd already returning in a serious manner, failed on each of eight cows. A record has also been made of one good bull over a period of seven years. This is worth placing on permanent record.

This bull in 1937 went to a herd troubled with temporary sterility and appeared to give less satisfaction than usual, but in his second round the cows held to him, and last year on his first service in this same herd he put up an exceptional performance.

4 11. 29.

25

Percentage, A Group Percentage, B Group Percentage, C Group Season. Quarters: 0, 1, 2 Quarters: 3 and 4 Quarters: 5 and 6 Leucocyte Counts. Leucocyte Counts. Leucocyte Counts. 1938 43-4 34-2 22-4 1939 37-0 31-0 32-0

Fertility judged on Morphology Number Qf B „ Percentage of First and Motility. Service buccessiul. Good .. ,. .. .. 18 63 Fair .. .. .. .. 9 49 Poor 12 37 Bad .. .. .. 5 31 Sterile .. .. .. .. 6 0

Examined. Class. Number of Cows. Per cent. October, 1932 .. .. .. Good 91 21 October, 1933 .. .. .. Good 82 29 October, 1934 .. .. .. Good 78 28 September, 1935 . . . . . . Good 88 46 September, 1936 .. . . .. Good 74 42 1937 (not examined) .. .. .. 42* 52 October, 1938 .. .. .. Good 91 61 * 82 per cent, including second service.