What is the target joining weight for your heifers?
Fertility of the first oestrus is low, thus it is desirable that heifers have already cycled a couple of times before they are joined.
Target joining weight, also referred to as critical joining weight, is the weight in which a large enough percentage of heifers are expected to be already cycling to ensure acceptable pregnancy rates (>85%) by the end of the joining season.
It is also important to highlight that the target weight is not to be used as an average for the heifer herd, but must be reached by every heifer destined for breeding by the onset of the joining season.
They are usually between 60-65% of the mature cow weight of the herd (weight of five year old cows at weaning). It will differ from breed to breed and even within a breed depending on cow type. Compared to early mature types, late maturing type cows have higher mature cow weights and are leaner.
Mature cow weights have increased for most breeds over the last 10-20 years, meaning that old 'rules of thumb' for target joining weights for British and European breeds may no longer be applicable.
Results from the Beef CRC Maternal Productivity Project showed that although joining weight was the most important factor influencing heifer fertility, fat was also influential.
Fat cover may be influenced by nutrition and genetics, with later maturing types tending to lay down fat at a heavier weight.