Shrink happens

When humans are stressed, our bodies react with physical, mental and emotional responses. The same goes for beef calves that experience stressors such as hauling, handling or food and water deprivation. In cattle, these factors can lead to “shrink,” or weight loss that occurs from the time an animal leaves one location and is weighed at another.

The amount of shrink a calf experiences increases along with the number and duration of the stressors (see chart at right).

Managing shrink has implications on your calves’ health and profit potential, as demonstrated by a recent study by the University of Florida Institute of Food and Agricultural Sciences Extension. Shrink was measured in stocker calves after weaning in two separate years. The amount of shrink in one day amounted to 3.5 percent and 3.9 percent respectively, similar to the amount of shrink after eight hours of standing in a dry lot. In both years, calves did not regain their off-pasture weaning weight until day 14, even though they were offered high-quality hay and a pelleted supplement. The shrink was associated not only with a dietary change but also with handling, change in environment and tissue loss from stress.

In the second year of the study, the calves were also backgrounded for 50 days and transported 1,000 miles over 24 hours. These calves were unable to regain the lost body weight within 14 days, despite adequate access to hay, supplement and water. The amount of shrink increased because feed and water removal was coupled with the stress of transit.

How does shrink affect price? The appearance of calves at market can most certainly affect the bid. University of Arkansas data indicates that buyers adjust the price per pound based on an estimate of shrink to follow the purchase. Shrunk cattle received $3 to $8 greater sale prices compared to average fill calves. In contrast, calves that were full or very full were discounted $3 to $24 from the base selling price received by average fill calves.

Many different factors can affect shrink, but these have the most impact:

• Transportation time: Studies show calves will shrink about 1 percent per hour for the first three to four hours, then 0.25 percent per hour for the next eight to 10 hours (e.g. 8 percent shrink in 16 hours).
• Amount of fill: Diets low in dry matter and high in moisture result in a greater shrinkage, such as stockers on wheat pasture, whereas drier diets lead to slower weight loss and less shrink.
• Body condition/weight: Typically, fatter cattle will not shrink as much as cattle with less body fat. Fat contains less water than lean muscle tissue, so lower amounts of metabolic- tissue water is lost to shrink.
• Season: Higher temperatures induce a greater stress response in cattle and thus a greater shrink response. In hot weather, cattle lose more water through heavy breathing and greater maintenance energy expenditure than during cool temperatures.
• Handling: Cattle shrink less when they are handled in a quiet manner using good Beef Quality Assurance practices.

Yes, shrink happens, but anything producers can do to minimize animal stress—and the resulting weight loss—protects the value of the calf when it is sold.