Abstract
As the first step of the investigation on the mechanism of exhibition of dairy performance, the structural changes of mammary tissues of three lactating goats with different performance were studied onfive stages. Results obtained here are briefly summarized as follows.
(1) As there was no significant difference in the tendency of decrease of daily production after the maximum period between these three goats, the peak production and duration of lactation, especially the former had a great influence upon the total production.
(2) In the mammary tissue such characters as number of alveolus per lobulus, sectional area of alveolus and number of glandular cells per section of alveolus decreased with the abvance of lactation. Whereas number of alveolus per sight field and height of glandular cells increased, the coefficients of sectional area of alveolus decreased a little. Particularly, the tendency of decrease of sectional area of alveolus was similar to that of milk production.
(3) Such characters as the sectional area of alveolus, number of glandular cells per section of alveolus and number of alveolus per lobulus may be important qualities of mammary tissue which related to milk production. And further, it seems to be necessary for exhibiting high production that these characters are as large as possible, and decrease very slowly after the maximum period. Accordingly, it may be important in the selection of dairy animals to judge precisely on several stages of the lactation the mammary gland quantity and quality as the response of the gland to the stimulators.
