Response of teat enzymes of sheep and cattle to stimulation by stilboestrol and oestrogenic subterranean clover

Abstract

The activities of glucose-6-phosphate dehydrogenase (G-6-PDH), malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICDH) were investigated as indicators of oestrogenic response in sheep and cattle. The activities of the enzymes were higher in teat tissue from wethers and steers injected with stilboestrol dipropionate than in control groups not receiving oestrogen. There was a positive linear relationship between teat enzyme activity and log(dose + 1) in wethers injected with stilboestrol dipropionate over the dose range 0–40 µg/day.

G-6-PDH and MDH were used to detect oestrogenic responses in sheep and cattle to feed containing a high proportion of subterranean clover (Trifolium subterraneurn L.) cv. Dwalganup. The differences in mean enzyme activities between treatment and control groups were highly significant. The results indicate that in the short term, teat enzymes of cattle respond to oestrogenic feeds in a manner similar to those of sheep.