Report / Committee on Cattle Diseases.

  • Great Britain. Committee on Cattle Diseases.
Date:
1934
Catalogue details

Licence: Public Domain Mark

Credit: Report / Committee on Cattle Diseases. Source: Wellcome Collection.

    14/166 (page 12)
    to maintain an average economic yield in his milking herd. In part, however, they are indirect losses attributable to disease. An interesting example of the importance of the latter was given to us by one experienced witness, who had made an analysis of the milk yields of the cows in a large herd, dividing them up into groups according as they were or were not infected with mastitis or contagious abortion (not in an active form). The average yields in the different groups (corrected to allow for the various extraneous factors which normally affect productivity*) were as follows :— TABLE 2. Average milk yield in healthy and infected cows. | Nai. of Corrected yield of milk in pounds per annum. —— Disease ition. isease conditio Ria Group (1) .... Mastitis free, abortus free Vals oe 9,718 + 243 Group (2) .... Mastitis infected, abortus free...| 56 8,116 + 274 Group (3) .... Mastitis free, abortus infected...| 12 7,702 + 630 Group (4) Pe —, infected, abortus in- ecte ae ciate Bie 19 7,416 + 350 It may therefore be safely inferred that many of the animals sold out of herds nominally on account of their low milk yield, are in fact the victims of disease. 17. The next group in table 1 refers explicitly to disease; to tuberculosis, Johne’s disease, udder disease (principally mastitis), and to miscellaneous diseases. Almost last in the list comes old age. The small number of disposals recorded under this head is not due to a commendable preference on the part of farmers making returns to giving a definite rather than an indefinite reason for each disposal ; but simply to the fact that very few cows survive so long that their death can be attributed to old age. Such evidence as we have suggests that the rate at which cattle are disposed of is practically constant at all ages up to perhaps eleven or twelve years, and is so high that only few cows reach these latter. Disposals on account of reaction to the tuberculin test are practically confined to tested herds. Though an unimportant cause in the aggregate, it is in these herds a serious drain, being responsible for as much as one sixth of the total losses. Animals sold on account of reaction to the tuberculin test are frequently again bought into dairy herds. Though the statistical inquiries which we have been discussing in the preceding paragraphs do not enable us to assess the absolute importance of each disease, they show how serious a part disease * The most important of these factors are age and date of last calving.