Guidelines to determining the best calf weaning age
As a principle, the sooner calves are weaned the greater will be the potential turnoff of young cattle. Earlier weaning age is the single most important way to increase weaner throughput.
The keys to maximising the benefits of weaning age to throughput and productivity are to:
• Identify the time when the efficiency of pasture use will be greater for the calf alone than for the cow and calf together. This is normally around six months into lactation when the higher quality pasture required to maintain cows and produce a relatively small amount of milk is better consumed directly by the weaned calf.
• Implement a weaning strategy that ensures no check occurs in calf growth.
These management practices need to be in place when weaning as early as possible and without compromising the overall calf growth rate.
In southern Australia, current industry practice is to wean calves between six and nine months of age.
Weaning age and projected liveweight gains post-weaning depend on pasture availability and quality. Ideally, weaning needs to take place when pasture height and availability are best for maximum intake by the weaned calf and the pasture has a nutritional quality of more than 11.5 megajoules per kilogram of dry matter (MJ ME/kg DM) and at least 15% crude protein. When weaning in summer, use the best available dry pasture for the weaners.
In general, use the combination of age and weight of calves, and condition score of cows, as the basis for a decision to wean calves as early as possible. This is particularly important when there is a limited quantity of high quality pasture available. Determine your weaning strategy based on the following guidelines:
• Minimum age – 100 days from when the last calf was born, and weight of the lightest calves in the group is at least 100kg. Weaning calves too early can result in calf deaths, reduced ability to thrive and reduced throughput of saleable animals;
• Maximum age – 6 months old depending on the season and quality of pasture available;
• When cow condition score reaches 2.5. If weaning is too late, the loss in cow condition score can be so great that fertility is reduced at the subsequent joining.
If female calves destined to become replacement heifers are over-fed and become over-fat or are weaned too late, ‘fatty udder’ syndrome can occur, resulting in reduced milking ability when they rear their own calves. If heifers deposit fat instead of building muscle or frame size the genetic parameters need to be altered in the breeding objective for the herd.
Early weaning is a useful management strategy in drought. It is also a tactic of disease control that requires the separation of cows and calves, eg in a Bovine Johne’s Disease management program. Early weaning may also be the best management option when the liveweight and condition score of the cow and calf could benefit from weaning, for example with first calf heifers, older age or broken mouth cows.
To make an earlier weaning strategy worthwhile in normal seasons, the additional pasture (resulting from reduced consumption by lactating cows) needs to be utilised by increasing the number of calves reared or by other avenues (such as purchased growing stock) to achieve an increased throughput of saleable product.
Early weaning as a management option
Early weaning is a management strategy that can be implemented to improve throughput of sale.
Many experiments have shown that beef calves can be weaned successfully at 100 days of age and from weights as low as 100kg provided they are offered high quality feed. The feed offered to early weaned calves must be of high nutritional quality and contain more than 11.5 MJ ME/kg DM and at least 15% crude protein.
Several experiments have also shown higher performance and better meat quality from early-weaned calves when compared with conventionally weaned animals. Earlier weaning of calves provides substantial benefits to the cows through reduced weight loss during lactation with higher body condition scores and significantly shorter calving intervals.
What to measure and when
• Age and weight of calves at 100 days from when the last calf was born;
• Any harmful effect on cow health and udder damage to high milk yield cows;
• Quality and quantity of pasture available for weaned calves (at least 11.5 MJ/kg DM and 15% crude protein) – assess weekly immediately before the proposed weaning time, and then following weaning.
Note: The predicted effect on enterprise profitability from earlier weaning and better utilisation of available pasture by animals destined for sale can be determined in relation to variation in weaning age.