The CATTLE
Red Brangus cattle have a proven ability to thrive in a variety of climates. They are particularly well adapted to the subtropical regions of the world. Red Brangus are solid red and naturally heat tolerant. But is that important?
The evidence is that a strictly regulated body temperature promotes the greatest productivity in beef cattle. Even small upward shifts in body temperature are deleterious to metabolic processes.
High temperatures raise the concern of heat stress on cattle. Heat stress is hard on livestock, especially in combination with high humidity. Hot weather and high humidity can reduce breeding efficiency, milk production, feed intake, weight gains, and sometimes cause death.
In the initial or early stages, when cattle start to suffer from heat, the early signs are not always apparent. Feed and roughage intake may drop a little but the animal may be fairly uncomfortable way before that. As cattle heat up and feed intake drops, cattle begin using additional energy in order to help keep themselves cool, therefore, heat stress reduces production and efficiency. Once this performance level drops it becomes very difficult to get it back. This is especially true in growing and feedlot cattle. Some of this loss is carried all the way through to the packinghouse. In many cases, with growing and feed yard cattle, the losses can equal ten percent or more. In breeding cattle, we see a similar response in terms of nutrient or feed intake and energy metabolism in an effort to stay cool. Often, this results in reduced breeding activity reduced cycling and lower conception rates.
Heat stress in cattle results in millions of dollars in lost revenue each year due to production losses, and in extreme cases, death. Death losses are more likely to result from animals vulnerable to heat stress. A study was conducted to determine risk factors for heat stress in feedlot heifers. Over two consecutive summers, a total of 256 feedlot heifers (32/breed/year) of four breeds were observed. As a measure of stress, respiration rates and panting scores were taken twice daily (morning and afternoon) on a random sample of 10 heifers/breed. Weights, condition scores, and temperament scores were taken on 28 day intervals during the experiment. Health history from birth to slaughter was available for every animal used in the study. It was found that at temperatures above 25.8C (78.5F), dark-hided animals were 25% more stressed than light-colored. The most striking outcome of this study found that black cattle were 5.7 times more likely to die from heat stress than other colors of cattle.
High risk cattle may include the following:
a. Newly arrived cattle that have experienced a fair amount of weaning,
processing or transportation stress.
b. Finished or nearly finished cattle, especially heifers.
c. Cattle that are or have been grazing infested fescue pastures.
d. Cattle that have been sick in the past and may have some preexisting lung
damage.
e. Black or very dark-hided cattle.
f. Heavy bred cows that will calve sometime during the summer months.
g. Older cows.
h. Cattle which may be somewhat thin due to inadequate nutrition.
NE-USDA- MARC Results of a study of relative heat tolerance among cattle of different genetics indicated dark-hided cattle were more stressed than light-hided cattle. Heat stress more than doubled drinking behavior, increased standing, and decreased eating, lying, and agonistic behaviors. Impact: It was found that dark-hided cattle with higher condition scores were more adversely affected by heat stress.
NY, HI and AZ compared the evaporation rates of black and white heat-stressed dairy cows under simulated direct solar radiation in a hot-dry environment. Black hair coats absorb more solar radiation and are warmer and have higher sweating rates than white hair coats. Impact: Solar radiation imposes a severe thermal load on cows where the impact of black hair coats and high sweating rates must be included in management strategies.
The research is settled. Dark-hided cattle are more adversely affected by extremes of heat and humidity. In the Gulf Coast region of the United States, Central and South America, red-hided cattle are better able to withstand the heat and humidity, resulting in greater production, efficiency and increased reproductive efficiency and conception rates. Additionally, unlike the bos Taurus (English) breeds, the bos indicus (Brahman-influenced) breeds have the ability to sweat and posses a natural resistance to parasites.
