Will not be that much blood, once the heart stops beating the blood flow is near nothing.
Also, about blood and the battlefield and effects on morale, the British used red as the main color for the reason of this issue. Which is why the French used Blue, uniform colors matter. That is why Dark Blue and Black work best to check morale. Bad examples of using the wrong color uniform are Austria's white and the Russia green of the Napoleonic warfare.
I study warfare from over 2000 years ago to modern warfare and the effect on troop loses and blood on the battlefield. Battle of Cannae is a prime example of a battlefield covered in blood, the limited battles in siege warfare in a breech the bodies and blood are a huge factor in the outcome.
Morale is fleeting on a battlefield; the route of the oxen and cattle stampede play a larger role than written about at Isandlwana. The effect on footing at the battle due to blood on the field is amplified with those using handheld thrusting weapons and those running to change positions on the battlefield.
Time consumed in killing the cattle, oxen etc. while still fighting an enemy shooting slowed the Zulu warriors down somewhat. The main effect of this stampede is to divide the British and drive many down from the saddle.
The accounts of eyewitness' need to be looked at in detail, just a question here, but were saviors on the other side of that split of the British on the saddle by that stampede?
Just a few comments and thoughts on this issue.