May 2025
Hello and welcome to the May Newsletter – for once, we really can hardly complain about the glorious weather, what a wonderful year for lambing. For cattle owners, a reminder about the BVD Cymru change coming in on the 1st July 2025 – from that date, if you want to sell animals other than direct to slaughter, you must either be deemed ‘BVD negative’ – which means that you have had a totally negative BVD antibody blood test within the last year, OR that the animals being sold are BVD antigen free. These tests can be carried out at the pre-movement TB test that you would need to move them – as long as you factor in enough time for the results to come back.
Currently, you only receive our newsletter with a bill. If you would like to receive it every month without fail, please sign up on our website here: Newsletter
Also, we are moving towards email billing – please remind us to check your email details when you phone in for anything else. I hope you continue to enjoy the good weather.
Mary
Russell’s musings :
This month’s author is Russell Fuller who has picked out a few interesting titbits from his recent reading to share with us. They are a little different to the usual things you hear about, so if you have any questions it’s definitely best that you ask him.
Are wild cattle born that way?
We all know that cattle temperament varies but how much of that is genetic? Recent work has focused on beef cattle, as dairy cows are usually quiet (more later). Over 100 studies, looking at the behaviour of over 500,000 cattle have now been combined to estimate the genetic component of cattle temperament. Measures used included:
• Crush score – how the animal behaves in a crush – from calm to trying to jump out
• Flight speed – how fast the animal leaves the crush
• Pen score – how the animal behaves when kept on its own, able to see it’s herdmates
• Cow aggression at calving
Overall, it appears that genetics contribute around 25% of cow temperament, except cow aggression at calving, which is only 10%. This can be compared to 60% for body conformation, 40% for growth rate and 30% for milk yield.
However, it is worth noting that genetic effects are permanent and additive. If cattle have been bred to be quiet, those genetics stay, and they can be added to by using a quiet bull next time.
Finally, back to dairy cows. Cows were split into wild, intermediate, and calm. Surprisingly, wild cows and calm cows produce the same amount of milk, which is more than the intermediate cows…
Heat stress
Ever wondered what effects the recent weather has on our cows?
A temperature humidity index (THI) can be calculated and compared to tables which show how heat stressed cattle are. For example, 22o C at 50% relative humidity (this is the humidity seen last week) gives a THI of 68, which is fine for cows. 32o C at 70% relative humidity (seen in a warm shed in summer) gives a THI of 84, which puts cows under severe heat stress.
A dairy cow produces 1kW of heat – equivalent to 1 bar on an electric fire. To compensate for heat stress, she must reduce this heat output, so reduces her metabolic rate. Early lactation cows are the first to be affected but as heat stress increases, it is mid and late lactation cows that are affected the most.
Once cows become heat stressed, feed intakes, milk yield and milk protein fall, whilst butterfat remains unaffected. If the heat stress is prolonged, feed conversion also falls as milk yield falls faster than feed intakes. Overall, a 1 unit increase in THI causes feed intakes to fall by up to 4%, with a corresponding loss of 0.3 – 0.9kg milk per cow per day.
Do cows like hot sauce?
Not as strange a question as you may think, as numerous studies have been carried out to determine the effects of capsaicin (what makes chillies hot) on cattle, with quite surprising results.
Feeding chillies to cows gives a 3% increase in milk yield and 0.1% increase in butterfat, without any change in feed intakes, meaning milk production is more efficient. This is surprising, as humans eating chillies eat less and feel full sooner. Effects are larger in ‘challenged’ cows i.e. animals fighting infection or suffering from ketosis.
We think that these effects are controlled by insulin. When fed chilli, cows produce less insulin, and their body is less responsive to the insulin that is produces. This in turn allows the udder to take up more glucose for milk production, explaining the yield response. Challenged cows use glucose for their immune response. Feeding chilli controls the immune response, leaving glucose free for milk production.
However, before anyone tips hot sauce in the mixer wagon, a few words of caution. None of the trials were long term, so we have no idea what happens if chilli is fed for more than a few weeks. We are concerned that the increased butterfat is due to the cows losing weight faster, which will have all kinds of long term impacts. Finally, nobody knows how much chilli to feed either – trial doses were up to ½ a scotch bonnet chilli per cow per day.
Please make note of our new email address: info@swfv.uk
