Cow-Calf Corner: Beef and cattle trade a mixed bag; Heat stress can reduce pregnancy rates

June 13, 2015

Beef and cattle trade a mixed bag
by Derrell S. Peel, Oklahoma State University Extension livestock marketing specialist
The latest beef and cattle trade data shows a mixed bag of global market impacts. Total beef exports were down 5.3 percent in April compared to last year. This follows year over year increases in January and March and leaves the year to date total through April 0.4 percent below the same period in 2015. Exports to two major U.S. beef markets, Japan and Hong Kong, were both down compared to last year after increasing earlier in the year. April exports to Japan dropped 10.9 percent year over year and exports to Hong Kong decreased by 36.9 percent compared to last year. This leaves year to date beef exports to Japan up a scant 0.6 percent while exports to Hong Kong are down 2.3 percent for the first four months of the year.
Beef exports to South Korea were down fractionally in April but are still up 12.2 percent for the year to date compared to last year. South Korea was the only major beef export market to show year over year increases in 2015.
Exports to Canada continued year over year decreases in April, down 6.8 percent compared to one year earlier and down 8.2 percent for the year to date compared to last year.
In better news, beef exports to Mexico have improved the last two months after being down in January and February. April beef exports to Mexico were up 32.9 percent year over year with the year to date total now down 0.9 percent from last year.
Beef imports are also a mixed bag, though generally positive with total April beef imports down 21.2 percent from one year ago. Year to date beef imports are down 12.8 percent from 2015. Decreased beef imports are led by sharp reductions in imports from Australia and New Zealand. Imports of Australian beef were down 41.9 percent in April compared to last year and year to date imports are down 21.7 percent. Beef imports from New Zealand were down 29.6 percent in April and are down 21.7 percent so far this year.
In contrast, beef imports from Mexico continue to grow and were up 7.5 percent year over year in April and are up 11 percent in the first four months of 2016. Imports of Canadian beef were up 13.1 percent in April and are up 8.0 percent for the year to date.
Total cattle imports from Canada were down 13.7 percent in April compared to one year ago. This total includes a 25.5 percent year over year increase in slaughter cattle imports and a 38.7 decrease in feeder cattle imports in April compared to last year. Cattle imports from Mexico were up 22.7 percent in April compared to last year but are still down 1.5 percent for the year to date.
The U.S. beef and cattle trade situation is expected to continue slowly improving, but it takes time. Lower prices and increased supplies in the U.S. will likely continue to generally support increased U.S. beef exports and diminish beef imports. The U.S. dollar, which briefly weakened in the past few weeks, has strengthened again and will continue to hinder beef and cattle exports and support beef imports. Conditions in other countries matter as well and, in particular, herd rebuilding in Canada and Mexico, as well as Australia will impact flows of cattle and beef.
 
Heat stress can reduce pregnancy rates
by Glenn Selk, Oklahoma State University Emeritus Extension animal scientist
The effects of heat stress on reproductive performance of beef cows has been discussed by many animal scientists in a variety of ways. After reviewing the scientific literature available up to 1979, one scientist wrote that the most serious seasonal variation in reproductive performance was associated with high ambient temperatures and humidity. He further pointed out that pregnancy rates and subsequent calving rates were reduced in cows bred in July through September.
Typical Oklahoma summer weather can fit the description of potential heat stress, where many days in a row can exceed 95 degrees and night time lows are often close to 80 degrees. Many hours of the day can be quite hot and cause the slightest rise in body temperature of cattle. Research conducted several years ago at OSU illustrated the possible impact of heat stress of beef cows on their reproductive capability. These cows were exposed to bulls as one group (while in a thermoneutral environment) and one week later exposed to the environmental treatments listed below in Table 1.
Table 1. Effects of Imposed Heat Stress on Reproduction in Beef Cows   (Biggers, 1986;OSU) 

They found that heat stress of beef cows from day 8 through day 16 affected the weights of the conceptus (embryo, fluids, and membranes) and the increased body temperature may have formed an unfavorable environment for embryo survival. As noted in table 1, the percentage of pregnancies maintained throughout the week of severe heat stress was considerably reduced.
Florida scientists studying dairy cows reported that for high conception rates the temperature at insemination and the day after insemination was critical to success. They stated that the optimal temperature range was between 50 degrees F. and 73 degrees F. Marked declines in conception occurred when temperatures did not fall in this range.
Beef producers conducting Artificial Insemination or Embryo Transfer may want to take heed of this information. Make certain that cows are allowed access to shade and adequate air movement, at breeding, and immediately following breeding. Of course, adequate cool water is important anytime during the summer months. Avoid forcing  recently inseminated cows to stand in treeless, drylot situations where relief from the Oklahoma heat is impossible.
“Cow/calf Corner” is a weekly newsletter edited by Dr. Glenn Selk, Extension cattle specialist emeritus at Oklahoma State University with contributions from additional OSU Extension specialists.