Many farmers will have cows that suffered from heat stress in the recent heatwave, with symptoms ranging from mild dehydration to heatstroke.
However, for fall calves, the full effect may not be fully achieved until calving, and farmers are warned.
In a press release, Nia Williams, technical livestock manager at Nettex, advised farmers that “cows calving this fall are at greater risk of producing calves with compromised immunity.”
Williams advised farmers that calves may face a greater risk of skin disease in the early stages of life.
Heat stress can disrupt a cow’s normal feed intake levels, increase a cow’s susceptibility to infections such as pneumonia, and affect mammary gland development.
All of these can critically affect a cow’s ability to produce colostrum.
Commenting on the effects, Williams noted that:
“Calfs born to heat-stressed cows are often lighter at birth, and can show reduced growth rates before and after weaning.”
She advised farmers that colostrum should be fed quickly after birth, and that farmers should monitor the effect of transferring negative antibodies through a blood test during a period ranging between one and seven days after birth.
teaching
Tejasek advised that all calves receive 3 liters of colostrum within two hours of birth, from the cow’s first milking.
The sooner the calf receives colostrum, the more antibodies (immunoglobulin) will be absorbed and the stronger the calf’s immune system will be.
In some cases, colostrum may leak from the cow in the period leading up to calving. If colostrum loss occurs more than a few hours before delivery, the quality will be compromised.
Testing this colostrum using a refractometer is a simple and quick way to ensure your calves receive the best care. High-quality colostrum is at least 22% on the Brix refractometer, according to Animal Health Ireland.
However, farmers do not need to discard colostrum below the 22% level, as it is still an exceptional feed for second and third calves as it still shows high levels of immunoglobulin uptake.
Calves
According to Williams, calves suffering from heat stress may exhibit symptoms including poor suckling, low energy and open-mouthed breathing.
Nutritional support may be needed to improve the speed of healing.
Electrolytes are commonly used on the farm and are easy to use, cost effective and show rapid improvements in calf health especially when calves are groomed.
If symptoms do not reduce or go away, veterinary assistance may be needed.
Cow health
Those born in the fall will be especially at risk of heat stress. Water consumption and appetite decrease dramatically in the period leading up to birth, leading to dehydration and, in many cases, mineral deficiency.
Calcium deficiency or milk fever is the most common but other subclinical deficiencies can develop such as zinc, selenium, copper.
“During calving, cows can lose approximately 60 liters of water through blood and uterine fluids, along with significant losses of electrolytes,” Williams said.
It advises farmers to support cows immediately after their birth with nutritional support. Feeding dense mineral, electrolyte and vitamin products in solid or liquid form is increasingly common.
Postpartum dosing is also increasingly popular as are mineral injections (where deficiency is identified) as an insurance policy that mitigates the risk of developing clinical or subclinical deficiency postpartum.
Body condition score
As August and September calf farms begin planning for drying, their Body Condition Score (BCS) should be monitored. BCS should be given to cows entering the dry period Not less than 2.75.
Heat stress can cause a cow to lose condition, so farmers must act before low BCS begins to impact the calving and calving process through mineral deficiencies, compromised calf growth, and prolonged negative energy balance.
Teagasc data suggests that BCS can potentially decrease by 0.25 from prenatal to postnatal, so preventing and mitigating the effects of heat where possible is crucial.
A low BCS (less than 2.75) is easily identified by the cow having prominent hip bones, no padding of fatty tissue, visible ribs and a prominent spine with distinct rise and fall of bones (not smooth).
