The efficiency with which feed is used by meat and milk animals has increased enormously as a result of nutritional research, but in the future water may become a more limiting resource than feed.
This photomicrograph of lactating mammary tissue from a rat shows the presence (in brown) of aquaporins: membrane proteins that transport water. By understanding more about these important molecules we will be able to increase the efficiency with which water is used by dairy cows.
We have demonstrated developmentally-regulated expression of AQP1, AQP3 and AQP5 during the lactation cycle of rats. AQP1 and 3 expression increased from pregnancy into lactation, whereas AQP5 expression decreased.
Paradoxically, it was AQP5 that showed most evidence of localisation to the apical membrane of the secretory cell, the site of water movement into milk.
We are investigating the hypothesis that AQP5 is synthesised during pregnancy as a stable protein that functions to regulate water secretion during lactation