Taking a dip in the lake, spending more time outdoors with loved ones or enjoying an ice-cold beverage are all part of the joys of summer. But, what may be fun for us may not be so pleasant for our livestock. We have entered the time of year when dairy and beef cattle are feeling the consequences of high temperatures and humidity. The Temperature Humidity Index (THI) is a gauge used to assess the risk of heat stress in cattle, accounting for both ambient temperature and humidity. The effects of heat stress start in cattle with a THI around 72 and become more severe as it increases through the 80s and into the 90s. 

We are all aware of the production challenges that occur with livestock during times of heat stress. But, what are the factors that lead to this production loss?

Without question, reduced dry matter intake is a significant contributor, but research has determined that other metabolic effects occur, contributing to this loss of milk, weight gain and reproductive efficiency. One contributor that can seriously impact milk production in dairy cows is the increased incidence of subacute ruminal acidosis (SARA). Ruminal acidosis occurs in mostly high-grain diets, with inadequate fiber intake in the diet to induce rumination and the natural production of buffers such as sodium bicarbonate and sodium phosphate in the saliva to keep rumen pH at a safe level (greater than 5.5).

Much like our reduced desire to eat in hotter weather, a high THI can cause livestock to reduce their fiber intake, leading to reduced rumination. Cows will also try to cool themselves with an elevated rate of panting. As they pant, there is a greater loss of saliva, which contains the previously mentioned naturally produced buffers.

In dairy production, we often see a progressive loss of milk through summer heat periods. In an important research trial conducted in 2008, Dohme et. al concluded that “cows become more prone to acidosis over time even though they decrease intake of the challenge grain to avoid acidosis. The severity of each subsequent bout of acidosis increases, especially for cows fed diets low in physically effective fiber and at high acidosis risk. Therefore, a bout of acidosis that occurs due to improper feed delivery or poor diet formulation can have long-term consequences on cow health and productivity.” This helps to explain why, in late summer, when another severe heat episode occurs, the entire herd tends to “crash” and not recover until several weeks after the weather moderates.

A management tool called a “buffered block” is available for dairy and beef herds that have experienced episodes of production losses due to heat stress. A buffered block contains multiple buffer sources and alkalizing agents, which can reduce the severity of SARA. CRYSTALYX^® Buffer-Lyx^® block for dairy is the patented way to reduce the severity of SARA. A similar option for beef cattle is our CRYSTALYX Meta-bolyx^® block. Both take advantage of cattle’s natural desire to lick, thereby helping to replace some of the buffer lost when cows drool. These blocks also encourage natural buffer production. A dairy cow is estimated to produce up to 7 pounds of buffer daily through the rumination process, so this proven technology will help maintain rumen pH in a desirable range.

In a tough dairy market, economics should always be taken into consideration, so how can Buffer-Lyx be a good investment? Consider the multiple ways it can pay off: 

• Offsets loss of milk production during heat stress. Milk loss of 10–20 percent in some cows is not uncommon, so a small improvement can yield impressive results. Research and field trials have documented milk production responses of 4–9 pounds more milk, depending on the severity of SARA.
  
  
• Possible improvement in solids, especially fat. Sugar from molasses can help supply energy for fiber-digesting rumen microbes.
  
  
• Reduced waste of free-choice bicarb. Buffer-Lyx provides a palatable, predictable delivery system for buffers, which can be used in addition to buffers in the TMR. Replacing free-choice bicarb saves labor and waste. Expected intake is 0.25–0.75 pounds daily.
  
  
• Provides a supplemental buffer source for lower intake cattle that may not get what they need from the TMR and may be more prone to the effects of SARA. 

Click here for additional information about SARA, Buffer-Lyx studies or Meta-bolyx.

References

Repeated Ruminal Acidosis Challenges in Lactating Dairy Cows

at High and Low Risk for Developing Acidosis: Ruminal pH

Dohme, T. J. DeVries, and K. A. Beauchemin, J. Dairy Sci. 91:3554–3567