The quality of TMR may vary between days (in relation to inputs and mixing), within days (due to sorting by cows or environmental exposure) and along the feedbunk (due to improper mixing or uneven feed distribution and usage). Recent research at UBC has shown that this variability can have profound effects on dairy cattle feeding behavior.

Many producers have abandoned feeding multiple totally mixed rations (TMRs) to milking cows after they leave the fresh group (or after calving), despite great differences in nutrient requirements and animal physiology between cows in early and late lactation.