Splitsal

A common situation in extensive herds is that the sale of stock from one age cohort can be spread over two separate time periods up to one year apart, with the first draft of steers or heifers going when they reach the target weight and the second a year or season later, e.g. some of the bullocks may go at three and a half years, and the balance at four and a half.

Producers will usually have some idea, based on experience, of what proportion they expect to get off at the earlier weight and the average turnoff weights at each age.

But what happens when growth is improved such as by pasture development, a reduced stocking rate, supplementation or genetic improvement? The Splitsal program can be used to consider the approximate change in the proportion turned off from a mob of cattle under such circumstances.

The Splitsal program can be used to:

• predict the effect of increased growth on proportions turned off at each age in a split turnoff and
• estimate average turnoff weights at each age for both growth patterns.

There are no direct links between the Splitsal program and any other Breedcow and Dynama program although sale weights can be manually transferred to Breedcow+ and Dynama+.

Using the Splitsal program

The program is located with the [Breedcow and Dynama Software], within the Tools tab, which can be accessed after registering or logging in to use the free software.

A new scenario can be created by clicking the Save button beside a blank yellow name bar and can be named by typing in the yellow bar. This scenario or previously created scenarios can be edited by clicking the Open button.

To open an example scenario click the Copy button beside the example scenario and it will be copied into your scenario list where it can be opened as your own scenario.

Example one

Copy the User manual example scenario from the examples list and open the scenario, this will illustrate how the program may be used in the following example.

Splitsal assumptions

The Splitsal program is based on the assumption that the distribution of weights in the turnoff group is a normal distribution. A normal distribution is defined by the mean (average) and standard deviation (SD). In a normal distribution, 95 percent of the observations (weights) lie within 1.96 standard deviations of the mean. The Splitsal program displays this range and users can look at these ranges to judge if the standard deviation should be increased or decreased to make the range fit their situation.

Please note that in a normal distribution, the distribution each side of the mean is the same. The curve of distributions is bell-shaped with each side a mirror image of the other. If a group of turnoff cattle does NOT fit this distribution, then SPLITSAL will NOT give reasonable estimates of turnoff proportions and weights.

Once the lead or the tail off the mob has been removed, the distribution, if originally “normal” can no longer be “normal”. Thus the Splitsal program applies only to a mob which has not previously had a cut taken out of it (other than perhaps a random cut).

The Splitsal program might also be used to estimate proportions of heifers reaching puberty at a particular age under different growth rate regimes, where the cut-off weight is used to represent expected weight at puberty.