Thank you Dr Rosol,
Would you mind giving me your further thoughts after reading my responses to your suggestions, below?
A general note is that the present more severe level of green juice production may be co-related with the last month of green autumn pastures after a very dry summer here. I am not sure if there is any connection there or not.
The green liquid is really a liquid, it doesn't look like recently swallowed food that has not even made it down into the rumen yet. The liquid seems to me to more likely be gastric juices from the rumen or further. Plus Twitchy brings up these juices most at the around the same time that her mother Rosie is chewing her cud, again suggesting something from the rumen.
2) Rumen diverticulum
Isn't this just the name of the compartment wall[s] within the rumen?
3) Plant toxicity: rhododendron family including evergreen rhododendrons and deciduous azaleas, mountain laurel and Japanese pieris. Goats eat these even if not hungry because they taste good!
I am in SE Australia, my goats don't have access to any of these plants. They are fed branches of tagasaste ['tree lucerne', Chamaecytisus palmensis] every second evening. Other branch fodder is fruit tree prunings - peach, apple, pear, almond, olive, [not walnut or pecan]. Unless tagasaste is causing the problem, the other branches are so varied, and mostly so palatable, that I feel they would be unlikely to be related to such a consistent and long lasting problem.
4) Rumen acidosis (stop feeding alfalfa if you do feed it, keep baking soda available for your goat to consume. Epsom salt can also help).
I don't feed grain to them, but maybe, just maybe, the tree lucerne has similar enough characteristics to alfalfa to be contributing to a disturbance in the rumen. If you think this is possible, can you expand on this point, please? I can stop feeding tagasaste, and you say to make sodium bicarbonate and epsom salts available?
5) Rumen or abomasal foreign body/obstruction
6) Growth within the abomasum
7) Vascular ring anomaly (congenital remnant on the heart which causes stricture of the esophagus)
I don't have any comment on these last three suggestions.
Do my notes above help shed any more light? I look forward to hearing from you, and thanks again.