Heavy yearlings but moderate weight hinds – the conundrum

by Dr Alastair Nicol, Lincoln University

(for Canterbury Imported Deer Stud website)


A good case can be made for having heavy yearling deer destined for the early season venison market. Heavier carcass weights mean not only higher returns to the producer but greater yields of saleable venison for the processor.

If heavy yearlings mean the hinds are a lot heavier, then there is a downside with higher hind maintenance requirements and lower stocking rates.

How ‘tight’ is the relationship between 12 month liveweight and mature liveweight? Are there deer which have a yearling weight that is high relative to their mature liveweight?

We can use breeding values to investigate this. I have extracted from the DeerSelect website sire stags in the ‘European’ category in 2008 which have accuracies of their 12 month and mature liveweight BV of >0.8, meaning there are a good number of records on which the BVs are based. There are 65 of them. By graphing each individual stag’s BV for 12 month weight against their BV for mature weight we can identify the overall relationship between 12 month and mature BV and spot individual stags that stand out as having relatively high (or low) BVs for 12 month weight compared to their BVs for mature weight.



Figure 1: The relationship between the BV 12 month weight and BV mature weight for 65 stags (European listing from DeerSelect, 2008). Stags A and B have a high BV 12 months compared to their BV mature weight. Stags C and D are examples of the opposite.

The graph shows that there is quite a strong relationship between the two BVs. As BV for mature weight increases by 1 kg, BV for 12 month weight increases by about 0.9 kg. This is of course not unexpected and is simply an illustration of the classic rules of growth and development.

However, some stags do stand out. For example, the two stags above the line A and B (with solid rings around them) are stags which have a high 12 month weight relative to their mature weight. Stag A would genetically increase 12 month weight (albeit from a lower base) by 10 kg for every 1 kg increase in mature weight and Stag B has a 12 month weight BV 1.6 x his mature weight BV. On the other hand stags C and D would increase mature weight more than they would increase 12 month liveweight.

Another way of looking at this is in Figure 2 which shows the same data but illustrates that for a similar increase in BV for 12 month weight, stags vary widely in their BV for mature weight. For example, a +20 kg BV for 12 month weight is associated with only a +12 kg BV for mature weight in Stag B but a +20 kg BV for mature weight in Stag. Similarly the range in BVs for mature weight associated with a BV for 12 month weight of +10 kg is from +1 kg (Stag A) to +12 kg (Stag F).

Figure 1: The relationship between the BV 12 month weight and BV mature weight for 65 stags (European listing from DeerSelect, 2008). Stags A and F (and B and E) have similar BV 12 months but markedly different BVs for mature weight.

So although there is a powerful positive relationship between BVs for 12 month and mature liveweight, it is possible by the kind of scrutiny shown here to pin-point stags which will increase 12 month weight more than mature weight.

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