Successful calf growth starts on day one. Well-grown heifers have greater reproductive and milking performance as adults and last longer in the herd.
DairyNZ has set heifer growth targets of 30% of mature live weight at six-months of age, 60% at mating (15-months old), and 90% at calving1.
As bodyweight is the main determining factor of when a heifer reaches puberty the six-month and 15-month targets are crucial for a successful first mating and future in the herd. So how can you ensure that your replacements are meeting these targets?
Successful calf growth starts on day one. Alongside good calf rearing and colostrum management, you can give your calves an additional boost from day one with Horizon’s InjectaMax or InjectaMin multi-mineral injection. Both contain zinc, manganese, copper and selenium, while InjectaMax has the additional benefit of B12. Boosting these minerals on day one helps enhance the immune system and lowers the incidence of illnesses such as scours and navel ill. An additional dose may be given prior to weaning to aid in overcoming the change in diet and the stress related to this period.
InjectaMin and InjectaMax may be given up to every three months in cattle, however, as they both contain selenium and copper care should be taken in areas where copper and selenium levels are already sufficient and concurrent use with other copper and selenium products should be on veterinary advice only.
Alongside good nutrition and optimal mineral levels an effective drench programme is paramount to raising healthy calves. When considering calf drenches there are three factors that need to be considered:
- Calf weight: Calves under 100kg are susceptible to Abamectin toxicity so drench combinations including this should not be used in this weight group.
- Age: Cattle under 12-months of age require Levamisole to target Cooperia worms, so all calf drenches need to contain this drench component.
- Oral drench is best.
For a first drench in calves under 100kg, consider Active + Merge, a 1mL/10kg oral drench of Oxfendazole and Levamisole, which is both a safe and effective choice for this weight range. Once calves are greater than 100kg in weight, a triple combination oral drench such as Active+ Treble is recommended.
For young calves, a 28-day drench interval is recommended to reduce larval contamination on pasture. However, it is important that this interval is not shortened as it allows time in the worm life cycle for a population of “undrenched and susceptible worms” to be present for refugia. Taking a 10-day post drench faecal egg count (FEC) will aid in monitoring the effectiveness of the drench you are using. FECs can also be a useful guide when making drenching decisions. As a calf’s immune system develops over time, they can tolerate a worm burden more effectively and do not require such frequent drenching. Using targeted selected treatments (TSTs) by drenching only individual calves that fall below a set target growth rate has been shown to be a successful tool in reducing drench use.
To promote the sustainability of our drenches it is important to consider the other components of a parasite management plan as well. Where possible the use of crops, low stocking rates and maintaining young cattle on high grazing residuals will help to reduce parasite burden. Co-grazing with adult cattle and sheep can also be useful to reduce infective larvae on pasture.
Talk to your local Farm Source team about the right drench for your animals.
1 DairyNZ Liveweight targets, February 2024.