Calf Nutrition in the Heat

Calf Nutrition in the Heat – How to Turn a Tough Start into a Long Productive Life 
We all know how crucial the early stage in a dairy calf’s life is for its future success as a dairy cow. In Cyprus, where I live, I experience on an annual basis, just how important that care is, when calves are born in the hottest month of the year in a hot climate.

Mastering that challenge is what you might call “calf rearing for the advanced”. I would like to share some calf nutrition and management practices that play a key role on dairy farms in Cyprus and other hot environments. 

Why are dairy calves born in August in Cyprus? 
August is the hottest month in Cyprus with temperatures averaging around 32°C. Adding the humidity coming from the sea, cows and people are continuously at risk to suffer from heat stress, much more than in other European countries. You could say it is a highly uncomfortable environment for a calf to be born into. Plus, with the mothers most likely experiencing some level of heat stress in the late stages of pregnancy, calves will already be disadvantaged in their start, before they were even born. 

Still, it is common practice for dairy herds in Cyprus to manage the calving cycle of their cows for a batched calving season in late August. The main reason being that is it is difficult to get cows into calf during the hot summer months.  
Heat stress reduces the duration and intensity of estrus, resulting in silent heat or weak estrus expression, making it difficult to detect cows on heat. On top of that it can depress follicular development leading to poor quality oocytes in cows, which altogether reduces the probability of successful inseminations.  

As a result, conception rates in dairy cows are generally low between July and September in Cyprus. Additionally, carry-over effects from the summer months can result in cystic ovaries in October, such that most dairy cows are generally not inseminated until November. 
 An unfair disadvantage 
 Several studies found calves born in the summer had significantly lower average daily gains than calves born at other times of the year, independent of housing types. Increasingly high summer temperatures and high humidity can cause heat stress in calves. This leads to reduced feed intake and increased maintenance energy needs coupled with lowered immunity, which are all factors contributing to poor growth and higher susceptibility to disease.  

The other disadvantage dairy calves in Cyprus are v...