A polymer of acrylic acid has been used continuously on a number of dairy farms throughout the UK for the past five years. The polymer is fed as a gel and absorbs 100 times its own weight of water. Commercial farmers report that the polymer allows them to reduce concentrate allowances whilst maintaining milk yields. The results of an experiment with grazing cows in late lactation were reported to this meeting in 1988. It was found that the polymer did not affect milk yield but caused a significant increase in the rate at which cows laid down body reserves.

There is a lack of experimental evidence to support the commercial findings for cows in early lactation and little information on the mode of action. The main experiment reported here was conducted to investigate the effects of feeding a polymer gel to dairy cows in early lactation and in vitro studies were performed to investigate the mode of action.