More and more, we’re beginning to understand and appreciate the importance of cow cooling. It’s easy to see the effects of heat stress in your lactating herd; there will be a milkfat depression, milk yield will drop, cows will stand more often and for longer periods of time, and subsequently, lameness rates will increase.

While some of the symptoms remain the same (standing, panting and bunching), for dry cows, the real dangers of heat stress are not immediately visible. 

We all want to set dry cows up for a smooth transition into the lactation pens. As heat stress is known to reduce feed intake, it should come as no surprise that cooled cows consume more feed at calving than uncooled cows. Heat stress will also inhibit mammary growth, and cows that are cooled during the dry period will produce significantly more milk beginning at day 70 and continue to do so throughout their lactation.

More than all of that, cooling your dry cows means cooling calves in utero, protecting your investment in the next generation. When a dry cow’s body is compensating for the negative effects of heat stress, she’s required to put out increased maintenance energy to increase her respiratory rate and combat any issues brought on by impaired rumen imbalance and lower immunity. This takes away from her ability to supply blood and nutrients in utero to the calf, negatively affecting growth.

Prolonged heat stress will compromise the secretion of somatotropin in calves, a growth hormone (GH) from the anterior pituitary. We all have seen a result of this with “dopey” calves at birth, resulting in slower growth rates and decreased lactation performance in the calf. 

One study showed that calves born from cooled dry cows are approximately 13 pounds heavier compared to calves from uncooled dry cows. This same study showed that weaning weights of calves from cooled dry cows are approximately 27.7 pounds higher than weaned calves from uncooled dry cows. 

A different study showed that heifer calves from uncooled dry cows have lower pre-pubertal growth rates and poorer reproductive performance. They take longer to reach sexual maturity, meaning they will enter the system later in life and produce less milk in their first lactation than heifers born from cooled dry cows. 

Operating without an effective cooling strategy for your dry cows is short-sighted and costly in both long-lasting and long-term ways. Investing in a cooling system for your maternity facilities is an investment in the next generation and the future of your herd.  

PHOTO: A cooling strategy for your dry cows is an investment in the next generation. Photo by Mike Dixon.

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Karen Lally is a marketing manager with Artex Barn Solutions. Email Karen Lally.