3 June 2014

3 minute read

Earlier research on this issue has produced mixed results, making science-based recommendations for appropriate bedding substrates to use within calf housing impossible, writes University of Tennessee dairy expert Peter Krawczel.

To address this uncertainty and evaluate a new practice being adopted in New Zealand (and one that is commonly used for calves in Tennessee), a group of researchers from the AgResearch organization in New Zealand published the results of their evaluation of the use of river stones as a bedding material on the behavior, cleanliness, weight gain and skin temperature of preweaned Friesian-cross calves in the journal Applied Animal Behaviour Science.

The calves were all born in the spring (August to October in the southern hemisphere), removed from their dam within 24 hours of birth and assigned to one of two treatments. In this study, the control treatment was 8 inches of sawdust, and the experimental treatment was bedding with approximately 8 inches of river stones (stones were roughly an inch long with smooth, rounded edges). The calves were housed in group pens and fed roughly 0.8 gallons of milk once daily (at 7 a.m.) from a 10-teat feeder.

They also had unlimited access to a grain supplement throughout the study. The response to treatment was evaluated both during the week of enrollment and five weeks later to assess both an initial response as well as one following acclimation to the bedding surface.

The behavior of the calves was determined using continuous video data for either a 10- or 24-hour period. The amount of weight gained was calculated from an initial weight collected during week one and a second during week six. Skin temperature was recorded by dataloggers attached to the calves on the rump, leg and chest.

During the study, temperatures were around 50 F with relative humidity averaging 69 percent. Overall, there was no difference in the dry matter content or the surface temperature between the sawdust or river stone bedding.

There were minimal differences between the behaviors of the two groups of calves; during the final week, calves on the river stone bedding spent 4.5 percent less time lying down. Otherwise, the behavior of the calves did not differ between the two bedding surfaces. Weight gain was unaffected by treatment with no differences observed either in weight at weeks one or six or in the total amount of weight gained during that time.

Additionally, the calves were very clean on both bedding surfaces with no calf scoring greater than 1 at any point in the study. The calves’ overall health was excellent for both surfaces, and there were no reports of disease, lameness, injury or leg lesion during the six-week study. The skin temperature recorded from the calves’ chests was 3-4 F cooler than those with sawdust bedding.

Overall, these data indicate that either river stone or sawdust can be used for bedding of calves during the preweaning phase. The calves in the study behaved quite similarly, their growth rates were not different, and their hygiene and health were similar. The only aspect that differed could be a positive or negative factor depending on the time of year. The lowered skin temperature of the calves’ chests may indicate a lowered body temperature.

For calves born in the late summer, this drop in temperature may be beneficial and help reduce some heat stress.

However, for calves born in the late fall or winter, supplemental bedding with straw may be needed (or another type of insulation material) to ensure that those calves do not experience cold stress.

Sutherland, M.A., M. Stewart, and K. Schutz. 2013. Effects of two substrate types on the behaviour, cleanliness and thermoregulation of dairy calves. Applied Animal Behaviour Science. 147:19-27.