Measuring our cows’ performance

We have just weighed the spring drop calves and they are looking very good at this stage. Our spring calvers really have had a dream run. They ran on the agistment place at Greenwich Park until July and came from there as fat as fools. We had no paddock feed here so we supplemented them with silage through to calving. With a lower stocking rate (the autumn calving cows are still away) they have had really good feed since calving. Calf growth has been outstanding – averaged 1.45 kg /day which is the best we have had. We are hoping to average better than last year’s effort by getting an average weaning weight over 300 kg at weaning in February. (Last year’s average was 298 kg.)

We always try to join the majority of our heifers and then assess them on the growth of their calves. All our data goes in the Cattlelink software and the analysis is dead simple. Below is a table of the lifetime performance of the spring calving females and a photo of top performing heifer HR1 G215 with her newborn calf.

Because this is a lifetime performance and this year was exceedingly good (so far), it is fair to only judge within the heifer group (n=7) which has run under the same conditions. So from this we can easily see which heifers performed really well and which ones we might sell. Our lower ranking heifers are not duds and we have been able to sell these to commercial clients at a good price.

We are only really interested in keeping the heifers that we believe will perform better than their mothers. Because we might retain 4 heifers we then have to consider which cows they will replace. This becomes more complex because some older cows will have to be culled for reasons other than progeny performance – most commonly for feet or fertility – and this does reduce our selection intensity somewhat.

Also we have to consider the spring and autumn groups when deciding what cows to cull. As it happens the autumn calving cow group has a larger “tail” in progeny performance and the poorer performers from that group will be culled when their calves are weaned shortly.

In a previous post (https://cadfor.com.au/2013/10/10/what-is-the-value-of-breedplan/) we said “We base our selection within our herd on our own measurements rather than EBVs.” To explain this further, our selections depend on ranking the merit of cows’ performance within our herd. Currently we have 39 females with estimates of their progeny’s Daily Weight Gain (DWG). I ranked these cows 1 to 39 in order of their progeny performance. Also I ranked them 1 to 39 in order of their 200 Wt EBVs from Breedplan September 2013 analysis. Simply put there is no useful correlation between the two estimates of cow production. Expressed graphically as a scatter graph with DWG ranking (x axis) against 200 wt EBV ranking (y axis) the relationship is shown below.

We feel that growth to weaning is the most important trait for us and our commercial clients, hence we focus on it. Unfortunately we find that the 200 day EBV is the least useful of the Breedplan EBV estimates. We take very little notice of this EBV when assessing cattle, either in our herd or in others.