Fertility and Efficiency

At Cashmore we have always been interested in improving fertility of our self replacing maternal sheep flock.  Approximately 70 % of a ewe’s annual energy requirement goes into maintenance, with the first lamb adding 10% and the second a further 5 %.  So as we drive reproduction rates higher the proportion of output of lamb relative to the weight of the ewe and hence the energy required to maintain her changes.  This increases efficiency with more lamb product per hectare and higher profitability resulting.

Sheep farmers have 3 mechanisms to “set” desired reproduction rates.

The first is time of lambing with ovulation rates increasing with decreasing day length from the summer to winter solstice period. This is in the order of 100% across 150 days.

The second is weight/condition of the ewe with approx 3% extra fetus pregnancy scanned per 1 kg increase of weight of a XB ewe.

The third is better DNA.

Cattle are not affected by time of calving and show very small reproduction change to weight, ie they are hotwired to have just one ovulation.

To increase beef production efficiency one strategy is to retain the previous year calf drop and run into a second spring, which in effect decreases the % of maintenance energy across the herd with more young growing animals available to consume pasture..

The second is better ovulation/reproduction DNA.

Current research indicated that cows with twins produce 60% more calf weight at weaning than those rearing singletons.  It seems reasonable to expect a self replacing herd pregnancy scanning 150% and weaning 140% calves will produce 20% more beef than a standard system.