Transportation is a tiny portion of any agricultural emissions, it's really producing it in the first place that matters. If global consumption levels don't reduce, then this is just an accounting shell game with emissions happening elsewhere
Transport is a small contributor to emissions. For most food products, it accounts for less than 10%, and it’s much smaller for the largest GHG emitters. In beef from beef herds, it’s 0.5%.
Not just transport, but all processes in the supply chain after the food left the farm – processing, transport, retail and packaging – mostly account for a small share of emissions.
This data shows that this is the case when we look at individual food products. But studies also shows that this holds true for actual diets; here we show the results of a study which looked at the footprint of diets across the EU. Food transport was responsible for only 6% of emissions, whilst dairy, meat and eggs accounted for 83%.
https://ourworldindata.org/food-choice-vs-eating-local
New Zealand needs larger reduction in cattle sizes than just a 10x in many areas for other environmental impacts. For instance, the dairy production in Canterbury is so high that there needs to be a 12x reduction in size to keep water at safe drinking levels because of its nitrate pollution
The large footprint for milk in Canterbury indicates just how far the capacity of the environment has been overshot. To maintain that level of production and have healthy water would require either 12 times more rainfall in the region or a 12-fold reduction in cows.