The goat mammary gland parenchyma: breed and milking frequency influence.

Abstract

Tissular percentages (secretory, connective, ductal and vascular tissues), number and size of the alveoli were studied in udders of three dairy goat breeds under two milking frequencies (once vs. twice daily milking).The objectives of this study were to elucidate the influence of the breed and milking frequency on the proportion of the tissue components in the mammary gland in dairy goats;and to correlate the productive parameters (milk yield, milk composition, milk fractions and udder morphology) with the tissue parameters.Three goats of each studied breed (Majorera, Palmera and Tinerfeña), were milked during 6 weeks (mid lactation). The right half udder was milked twice daily and the left half udder was milked once daily. Moreover, during the experimental period,the productive parameters were recorded.Two samples from each gland were taken for the histological study and were analyzed using morphometric software. Macro and microscopic observations revealed a healthy mammary parenchyma, not damaged by the milking frequency. The statistical analysis revealed that tissue parameters were not influenced by the milking frequency, and the breed determined different percentages of tissue components. Correlations between udder morphological parameters and milk yield parameters determined the importance of globosity and udder cisternal compartment in milk yield of these breeds. Furthermore, it was determined that the percentage of secretory tissue in the mammary parenchyma had no correlation with the milk yield parameters in different high-production dairy breeds. In conclusion, the histological parameters were only influenced by the breed, and there were not correlations with the milk yield parameters.