More on heat stress - Part III

More on heat stress - Part III
By Roy Williams, 2010 DCHA Leadership Classmember

The usual advice for heat stress is pretty basic: provide shade, lots of drinking water, maybe some water spray, maybe feed in the evening and not in the morning. These management guidelines have been published many times in many different extension service and USDA publications.
A review of 40 online publications by extension services and the USDA found these six that went beyond the usual advice, and tackled some of the more complex components of heat stress.

http://www.uaex.edu/Other_Areas/publications/PDF/FSA-3040.pdf - Several suggestions for design/modification of confinement facilities that apply to both cows and heifers.

http://ag.arizona.edu/extension/dairy/conference/proceedings/2006/baumgard.pdf - This 10-page paper from a dairy conference goes into some detail about the relationship between heat stress and the components of the feed ration. If you formulate your feed rations for your heifers, this will probably be worth your time to read.

http://www.ansci.umn.edu/dairy/dairyupdates/du125.htm - This is another good, in-depth discussion of feeding strategies to reduce heat stress. This article discusses both feed ration issues and the timing of feeding.

http://animalsciences.missouri.edu/research/bec/Brody%20Lecture%20-%20Lucy.pdf - This article discusses the impact of heat stress on breeding, and offers some strategies for improving breeding success during periods of heat stress.

http://www.ars.usda.gov/Main/docs.htm?docid=15625 - This web page has photographs of cattle in various stages of heat stress. These may be useful in training your workers to recognize animals that are severely heat stressed.

http://www.dpi.nsw.gov.au/agriculture/livestock/dairy-cattle/feed/research/heat - For producers that raise heifers in a grazing system, this article discusses strategies for dealing with heat stress in grazing systems.

One factor that is not covered in these references is that of the importance of reflective roofs on shade structures. Reflective roofs have been shown to be highly cost effective for enclosed structures (like your home or a climate-modified, enclosed cross-ventilated barn). In some cases, the attic temperature of a house can be lowered by as much as 50 degrees with the application of a reflective coating to the outer surface of the roof. Galvanized metal sheets typically used on barn and shade structure roofs deteriorate rapidly, loosing most of their reflectance in a few years. While there are many paints on the market that are "reflective," these also lose their reflectance after a few years. Thick, rubberized paints containing tiny glass beads as the reflective element are expected to have 10 year life expectancies (or longer), and are being applied with good results to both commercial and residential structures in many geographical areas. However, some well-done studies have shown that in the typical freestall barn a highly reflective paint or coating will have no measurable effect on the animals under that roof. If this is true for sunshades that are relatively low (below 12 feet high) is unknown.

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