How to prepare weaned calves for winter housing

Sebastian Batchelor BVSc MRCVS clinical director, Caledonia Farm Vets (Image: Caledonia Farm Vets)

1. Seasonal overview: preparing weaned calves for housing

As autumn arrives across Scotland, beef producers face one of the most critical health management windows of the year, transitioning weaned calves from pasture to the winter shed. Bovine respiratory disease (BRD) remains the single most costly health challenge in youngstock, driving up vet bills, reducing liveweight gains and impacting long-term herd productivity.

Housing brings together a cluster of risk factors, including weaning, transport, commingling, ration changes and reduced ventilation, creating ideal conditions for respiratory bugs to proliferate and spread. A proactive, practical vaccination strategy, combined with smart stress management, is the most effective way to safeguard calf health and protect farm margins this season.

2. Vaccination timing guide: when to administer

Timing is everything when it comes to vaccination. Calves need time to build strong immunity before they face peak pathogen challenge inside the shed.

3. Targeted vaccine selection: using diagnostic evidence

Rather than using blanket, ‘off-the-shelf’ treatments, working with your vet to identify the specific pathogens present on your farm ensures your vaccine investment pays off.

Nasal swab PCR: Taking deep nasal swabs from sick or sentinel calves provides fast, evidence-based identification of circulating viruses (BRSV, PI3, IBR and bovine coronavirus) and bacterial pathogens (Mannheimia haemolytica, Histophilus somni, Pasteurella multocida and Mycoplasma bovis). Matching vaccine to bug: If bacterial pathogens such as Mannheimia, Mycoplasma or Histophilus are identified, injectable vaccines with bacterial toxoid protection are required. If viral risks dominate early in the housing period, a live intranasal vaccine provides rapid front-line defence. Just be mindful that some intranasal vaccines will only provide protection for 12 weeks, leaving a susceptibility gap. In these scenarios, a booster before vaccine immunity wanes should be considered, especially on holdings that experience pneumonia at grass in early spring.

4. Stress mitigation and the role of mBAS (FerAppease)

High stress causes elevated cortisol levels, which directly suppress the calf’s immune system and can reduce vaccine efficacy. Managing stress at weaning and housing is essential to ensure vaccines work effectively.

Maternal Bovine Appeasing Pheromone (mBAS/FerAppease)

FerAppease contains mBAS, a synthetic analogue of the natural appeasing pheromone secreted by cows to calm nursing calves. Applied topically to the muzzle and poll at weaning or housing, mBAS acts on the brain’s threat-processing centre to blunt fear and reduce cortisol and adrenaline release.

Clinical benefits: Lower cortisol levels, reduced vocalisation and a quicker return to feed during the critical post-housing transition.

Vaccine synergy: Preserving immune function during housing stress allows calves to mount a stronger, more reliable response to respiratory vaccines.

Key management considerations

Stagger stressors: Avoid weaning, castrating, housing and ration changes on the same day.

Housing environment: Ensure pens are well ventilated, cleanly bedded with dry straw, adequately stocked (2.0–2.5 m² per 200kg calf) and supplied with fresh water.

5. Ration transition and the gut-lung axis

Nutritional disruption at housing directly influences respiratory vulnerability through the ‘gut-lung axis’. A sudden shift from pasture to rich indoor silages or high-concentrate feeds can lead to subacute rumen acidosis (SARA).

Gradual feed changes: Introduce housing concentrates over 10–14 days while cattle are still on pasture, or offer clean, long fibre (hay/straw) alongside indoor rations.

Endotoxin risk: Rumen acidosis damages the gut lining, releasing inflammatory endotoxins into circulation that can impair pulmonary immunity.

Trace minerals: Ensure adequate vitamin E, selenium, copper and cobalt levels to support immune defence and tissue repair.