According to previous findings the circadian manner of pH of ruminal fluid as a consequence of animal-related or environmental-related (such as diet) modifiers clearly could be understood and all know that reporting pH as a single value itself is not useful tool for evaluations (of diet, health or …) or decision makings (even for models).

On the other hand some markers could be used for predicting ruminal pH such as DMI, total or individual VFA, the acetate:propionate ratio, microbial N flow from the rumen, milk and component yields, milk fat percentage, or even the fat:protein. Although these markers are considered as good assistants for predicting pH (qualitatively and not quantitatively), to my knowledge, nobody does not claim that ruminal pH is precisely predictable by such above mentioned tools.

So let me conclude that: as ruminal pH value is floating on the sea of large number of effectors, its predictions as one reliable value or designing one simple and easy formula for it, would be very difficult and high input. Please pay attention that the measurement of runimal pH as itself is the most easy and cheap way for predicting some parameters such as microbial N flow, milk and component yields, or milk fat percentage!

Please take a look at these two papers;

“Prediction of Ruminal pH from Pasture-Based Diets” J. Dairy Sci. 85:1255–1266

“Simultaneous Estimation of the pH of Rumen and Reticulum Fluids of Cows Using a Radio-Transmission pH-Measurement System” J. vet. Med. Sci. 74(4): 531–535

Ruminal Ph sensors/boluses