Get Your Calves off to the Best Start with AHV
Think of calf rearing as the golden ticket to a brighter future for your herd. The care and nurturing your calves receive during this crucial period aren’t just initial steps; they’re the foundation of a thriving, healthy, and profitable future herd.
There are countless factors which can affect the success of the calf rearing period and the performance and longevity of the future adult cow. Good calf health is determined by a delicate balance between the calf’s immune system and the bacteria in its environment.
If a calf is faced with stress or health challenges, it will divert its energy to the immune system rather than growth.
Extending beyond the immediate risks, health challenges in calf rearing can have long term effects on animal health and performance including lower milk yields and later finishing times. This is why it is essential calves are supported from day one, right through to post-weaning.

Figure 1: The immunity gap is the lag period between passive immunity and active immunity. The extent of this dip is influenced by colostrum quality and environmental factors.
The Immunity Gap
In the first few weeks of life, calves depend on passive immunity from colostrum for protection while their own active immune system begins to develop. At 2 to 3 weeks old, the immunity provided by colostrum will have decreased before the calf has fully developed its own active immune system as is shown in Figure 1. This transition period is known as ‘The Immunity Gap’. The AHV Calf Programme helps to support calves through this high risk period by bridging the immunity gap.
AHV Calf Start forms the first part of the proactive AHV Calf Rearing Programme. It supports the calf’s immune system and encourages optimal development of the digestive tract, helping the calf to absorb nutrients and limit digestive upsets. Calf Start is a powder that is dissolved in the calf’s milk at a rate of 25 grams per calf, twice per day for the first two weeks of life.
Addressing Respiratory Challenges
Respiratory challenges in calves result in significant economic losses on farm due to poor performance and reduced growth rates. Studies have revealed that calf weight gain could be reduced by half for 30 days or more when suffering from a respiratory challenge[1]. In addition, there are increased costs associated with the intervention surrounding respiratory challenges, coupled with the future impact this damage has on the animal.
Studies have shown respiratory challenges in young, pre-weaned calves can reduce first lactation yield by 4% and second lactation yield by 8%. Animals which experience respiratory challenge relapses have even further reduced first and second lactation yields, by 5% and 10% respectively[2].
AHV Respi continues the proactive approach of the AHV Calf Rearing Programme, working to minimize the impact of respiratory challenges. Respi helps to clear bad bacteria from lung tissue while the calf’s respiratory system is healthy and minimally stressed. By reducing the pathogen load, calves are better prepared to handle future stressors, such as dehorning and weaning. Respi is administered by adding 10 to 15 grams per calf (dependant on bodyweight) to milk during weeks 3 and 4 of life.
Managing Weaning
Weaning can be a high stress period for calves and can increase their vulnerability to health challenges. It can also hinder calf growth and development due to reduced feed intake. The ‘post-weaning growth dip’ occurs when feed intakes are so reduced that growth rates slow down, or calves even lose weight.
In order to minimise the impact of the post-weaning growth dip, whilst achieving growth targets, the rearing period can be extended. However, the financial impact of this is costly, due to the resulting increased time, labour and feed requirements.
When dairy heifer growth targets are missed, they are unlikely to be on track for breeding at 15 months of age and calving at 24 months of age[1]. Therefore, it is essential that heifers are supported around weaning to reduce the impact of the post-weaning growth dip and ensure growth rates are maintained.
AHV Booster Powder forms the third stage of the AHV Calf Rearing Programme. It closes the energy gap around weaning by stimulating feed intakes and encouraging good rumen function. This makes more energy available to the calf, which supports both growth rates and the immune system. It should be applied one week prior to weaning and for one week post-weaning as a top dressing on hard feed at a rate of 50 grams per calf, twice daily.
Take control of your calf rearing this year with a proactive approach, adopting the AHV Calf Rearing Programme to bridge the immunity gap and reduce the impact of the post-weaning dip.
Sources
[1] Brooks KR, Raper KC, Ward CE, Holland BP, Krehbiel CR, (2011) Economic effects of bovine respiratory disease on feedlot cattle during backgrounding and finishing phases. The Professional Animal Scientist, Volume 27, Issue 3.
[2] Morrison, S., Scoley, G. and Barley, J., (2013). The impact of calf health on future performance. Veterinary Ireland Journal, 3(5), pp.264-268.452
[3] Bach A., (2011) Associations between several aspects of heifer development and dairy cow survivability to second lactation. J Dairy Sci; 94:1052-1057
Get in touch!
Would you like to be visited by an advisor to discuss the health challenges on your farm together? Our AHV Specialist will be happy to visit you to jointly assess the health of your cows and come up with appropriate cow-specific advice.
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