Herd average masks wide divide

The UK 'average' herd has 224 cows yielding 8,520 litres (Kingshay Costings).

It is highly likely that that herd has animals yielding 5,500 litres through to 11,000 litres on a 305-day yield.

It is worth taking time to consider the consequence of this wide variation in yield in terms of income, nutrition, management, health and carbon footprint.

The charts below show the 305-day yield from four farms. Heifers are shown in pink and other lactations in blue.

It is notable that there are heifers not performing, making the spread of yield even wider. The herds wide wide variations in heifer yield tend to have wide variation in cow yield.

The lactation curves below show the variation in milk yield for a 6,500 litre cow versus one giving 10,500 litres.

Feeding to yield across a wide variance within the herd is possible with the technology we have today, but managing body condition score can be tricky.

It's much easier to feed a herd of cows with a narrow spread in yield than it is one which is flat and wide. Ironically it often ends with the cows becoming either flat or wide!

Breeding for yield alone isn't neccesarily the right thing to do. Lifetime yield, lifetime health, milk composition etc. are all important, but how much of the vriance is breeding and how much is feeding and environment.

Productivity variance is an important metric. Understanding the width of spread highlights the need for change, and can highlight the measures needed to enact that change.