Rob says the quality team were aware of seasonal and feed changes impacting the flavours that come through in milk but had never experienced this specific flavour. After testing samples of milk direct from the farm, Riverina Fresh felt its scope narrow.
“What confused us initially is that the milk coming in on one tanker will be from four or five different farms. It looked like we had only a few farms’ milk with this unusual flavour, but when you mixed it with milk from our other farmers, it was mitigated so there was a minor or limited impact” Rob says.
“We collected separate milk samples daily from all our individual farms for lab and sensory testing. It was through these we started to isolate the unusual flavour in some of the milk.” The other confusing aspect was that the flavour appeared across a few individual farms but not on all days – so individual farms had typical milk some days and milk with a flavour note on others, but not consistently.
Rob says there were two key questions to answer: what is causing it? And how to mitigate it? “We had all this milk coming in from farm that we needed to utilise, but we needed to ensure it was completely fit for purpose and to our usual standard.” he says.
Riverina Fresh spoke with individual farmers about what changes were taking place on farm and specifically whether there had been changes to the cows’ diets and discovered that, due to early spring like weather, most of their farms had quickly transitioned the majority of their diets to predominately fresh feed. In isolation, this was not unusual at the beginning of spring. However, this early spring was taking place in typically winter months and after two or three consecutive years of drought, where a lot of the feed for cows had been supplemented by brought-in fodder because farmers haven’t been able to grow enough fresh grass and crops on their own properties” Rob says.
“This year we’ve had what farmers are referring to as an ‘early spring’ in the Riverina. It has been relatively warm with good rainfall, so grass and crops have jumped out of the ground. Cows diets have moved very quickly from predominately stored feed and grain to fresh new seasons silage and grasses. These range from silage like rye grass, shaftel, clover, oats, barley and canola supplemented with hay.
While Riverina Fresh believed the fast transition to new seasons feed and cows taking a few days to become used to change in diet was a likely underlying cause it didn’t explain the variability they were seeing across individual farms.
“The strange taste in a small amount of milk still wasn’t fully explaining it, because most of the farms have the similar feed and are doing the same things, but we were only getting the unusual flavour from some of them and only some of the time,” Rob says.
“It turned out there were one or two feeds that were common across the affected batches as well as the timing of consuming the feed. We were literally able to line up the days the cows grazed on particular feeds on days immediately after rainfall (when the feed was particularly fresh) with the days we were getting a milk impact. To make it more complicated, the flavour impact was more pronounced when the cows grazed the grass right down to the stems.”
This explained why milk from the same farm was different on different days.