About 8% of cattle had high pH following being mixed with unfamiliar animals even though they came from the same farm. In contrast the cattle that stayed in their familiar mob and were yarded and transported together had a much more acceptable hit rate. Only 3.6% had high pH.
The recommendation from Galwey is to only mix mobs if farmers are prepared to wait at least seven days to slaughter.
“This had the biggest effect of all onfarm management.”
Of interest was that inclement weather events when cattle were in the yards also affected pH. Storms or very hot weather in the yards were linked to high pH.
“Don’t send in your cattle if this happens as why waste all that time and effort to grow them with a stress event like this?”
Galwey describes pH as being like a bucket. Stress such as running, fighting and-or mixing unfamiliar cattle punctures holes in the “bucket” so the glycogen in the bucket is used up. What’s left in the bucket determines pH, she said – see Figure 1.
“Low glycogen means low lactic acid and low lactic [acid] means high pH.”
The study found a seasonal difference in pH, with 8% of cattle killed in March having pH of more than 5.8. The reasons are not clear but Galwey suspects that lower feed quality and digestibility may be an issue. High quality ad-lib feed two weeks prior to slaughter is the ultimate feed regime, she said, because it builds glycogen reserves.
“It helps fill the bucket.”
Minimising the chance of a tough steak is all about handling and reducing change. ANZCO has compiled the findings into a best practice sheet for managing cattle pre-slaughter.
