Feeding for Fertility: How to Avoid Summer Slumps
Summer is an exciting time in the farming calendar. It's a season of abundant growth, vibrant pastures and thriving wildlife. However, behind the scenes, dairy farmers must also contend with a fresh set of seasonal challenges. As one of the major factors affecting the efficiency of your herd, maintaining fertility can be a significant concern during the summer months. The good news? With some thoughtful nutritional interventions, you can help your herds avoid these summer fertility slumps.
Summer Fertility Challenges
Maintaining fertility in dairy cows requires a complex balance of nutrition, health and environment management, and the summer months can easily tip that balance.
Warmer temperatures, even when not extreme, can affect a cow’s reproductive performance. Reduced dry matter intake from the effects of heat stress, shifts in hormonal patterns and lower conception rates are all common during this time.
Heat stress is one of the biggest culprits behind fertility dips in the summer months. Heat-stressed cows can have significantly reduced reproductive performance, with studies reporting conception rates of less than 10% during hot months of the year, compared to 40 to 50% in cool weather.
Even if your cows appear outwardly comfortable, staying alert through summer means you can catch the warning signs early and act before problems arise. The Megalac team has pulled together plenty of useful resources on heat stress over the years. These resources are a great place to start if you want to better understand how summer heat affects your cows and how to manage it:
Further Reading:
Nutrition: The First Line of Defence
One of the most effective ways to support fertility during the summer is by focusing on nutrition. As dry matter intake drops during warm spells, ensuring cows receive sufficient energy becomes even more important. This is where energy-dense fat supplements like Megalac can make a real difference.
There is a well-proven relationship between cow fertility and body condition score. Cows losing body condition (negative energy balance) take longer to return to cycling after calving, and it is well-established that the sooner a cow begins cycling after calving, the more likely she is to become pregnant at the subsequent service.
Similarly, negative energy balance has a major detrimental effect on conception rate. As a guideline, conception rate decreases by 10% for each 0.5 unit loss of body condition (5-point scale).
Megalac is a rumen-protected fat supplement that increases the energy supply within a cow's diet to support body condition and help maintain energy balance during the warm summer months. Unlike cereals and other starchy sources of energy, rumen-protected fats are not fermented in the rumen, meaning they do not add to the acid load or increase the risk of rumen acidosis. This makes Megalac a practical and effective option for helping to maintain fertility and support herd performance during the summer.
Fat: The ‘Cool Nutrient’
While fat supplements can help cows maintain energy balance and body condition, they also have an additional benefit during the summer months. Unlike fermentable carbohydrates, which increase heat production during digestion and elevate the risk of acidosis, rumen-protected fats are not fermentable and are very efficiently converted to energy used by the animal. This means they deliver high levels of energy with minimal additional metabolic heat load, making them an ideal nutrient source during periods of warm weather.
By reducing the internal heat generated during digestion, rumen-protected fats help cows stay cooler and more comfortable, allowing them to prioritise vital processes like reproduction. When combined with good summer management practices, feeding rumen-protected fats can help maintain both fertility and productivity.
Watch the video below to learn more:
https://www.youtube.com/watch?v=GMKnenpSuTU
How Fats Support Reproduction
Fats do more than simply provide energy. They also supply key building blocks for hormones, including progesterone, which is often called the 'hormone of pregnancy'. Progesterone is vital for supporting embryo development in early pregnancy, but many cows do not produce enough, leading to pregnancy failure. In fact, studies show that up to 55% of embryos can be lost during early gestation, with low progesterone being a major cause of these losses. By increasing dietary fat levels, research has shown that progesterone levels in the blood can be boosted, helping to support pregnancy and improve the chances of cows holding to calf.
Fats also play a direct role in egg development. Studies have shown that higher fat diets containing Megalac lead to stronger, more viable eggs, which are more likely to develop successfully after fertilisation. In particular, oleic acid (C18:1) plays a key role in supporting egg quality. Research has shown that while some saturated fats may harm egg development, oleic acid helps to improve it. With its high proportion of C18:1 fatty acids in rumen-protected form, Megalac delivers this important fatty acid directly to the small intestine, helping cows produce better quality eggs and improving overall fertility outcomes.
Read more on this relationship between fat and fertility here.
Conclusion
The effects of heat stress, reduced feed intake and hormonal disruption can all make it harder for cows to maintain fertility during the summer months. That’s why a proactive approach to nutrition is so important to keep your cows healthy and productive.
By incorporating rumen-protected fats like Megalac into summer rations, you can help maintain your cow’s energy balance, support hormone production and improve egg quality. With the right feeding strategy in place, it is possible to protect fertility and keep herds performing at their best, even when the temperature rises.