Effect of Prepartum Milk Removal on Quantitative Morphology of Bovine Lactogenesis

Abstract

The effect of prepartum milking on bovine mammary histology and milk composition was studied in 5 Holstein cows. One udder half was milked twice daily starting 10 days before the estimated calving date. One udder half was not milked until 2 days postpartum when all quarters were milked and 2 tissue samples per quarter were taken for morphological analyses. Lactose, casein and fat concentrations differed from prepartum-milked to postpartum-milked quarters (.82, -1.44 and 3.29%). Quarters milked prepartum were more developed: mature epithelium 24.8%, immature epithelium -8.9%, total epithelium 15.6%, stroma -24.8% and alveolar lumen 8.5%. Most alveolar cells in prepartum-milked halves had prominent rounded basal nuclei, hypertrophied secretory vesicles and a mixed array of lipid droplets. Cells within alveoli were morphologically similar. Secretory epithelial cells from postpartum-milked glands had irregular randomly located nuclei, indistinct Golgi, variable lipid content and less cytoplasm. These differences demonstrate the importance of prepartum-product removal on secretory cell development and subsequent milk production.