2000 Calf Crop May Be Extended

The extended hot weather and the reduced amount of available forage sets the stage for an extended calving season for 2000. One of the major reasons for this is the increase in body temperature frequently observed when the air temperature exceeds 85 degrees Fahrenheit. This is largely due to the level of endophyte in many of our Fescue pastures. The reduction in the diameter of the arteries reduces the rate of flow of blood throughout the entire circulatory system of the beef cow, which has a negative effect on body heat dissipation.

Checking with the Atmospheric Science Department, University of Missouri, we find that the daily temperature for a number of the weather collection sites throughout Missouri verifies the high temperatures we have experienced since the first week of June 1999. This extended period of time adds up to nearly 100 consecutive days with very little relief from the heat.

The second reason we can expect an increase in the number of non-pregnant cows this fall is the reduction in the amount of forage available for grazing. Many of the grazing areas are eaten into the ground and are nearly bare of vegetation.

Basically we have two choices to assist with the drought we are experiencing in our pastures. One alternative is to early wean the calf crop and reduce the amount of nutritional requirement for the nursing cow or supplement the feed supply. It is not hard to calculate what effect the extended feeding period will have on the available forage supply many producers have on hand. Starting the feeding process in August or September will definitely require more available nutritional inputs to reach May 2000. This certainly adds to the cost of maintaining the cow herd throughout the winter.

Whenever we have a combination of high temperatures and lack of available forages we can expect a reduction in reproduction. Ranking the four major functions of the beef cow -- growth, reproduction, maintenance, and production -- reproduction is usually the first one to exhibit a reduction in the normal functioning of the entire beef cow system. Maintaining normal body temperature and having access to required nutrition are very important physiological functions of the beef cow throughout the breeding season.

Dale's Country Trails - September 2, 1999
http://outreach.missouri.edu/agconnection/DCT/CT090299.html -- Revised: April 20, 2004
watsond@missouri.edu