One of the features of feeding cattle in the Plains states is changing weather conditions, and the cold weather descending on the region this week emphasizes the importance of cold-weather care.
The South Dakota State Extension service said such environmental conditions mean cattle are susceptible to cold stress for significant periods of the year. Understanding the effects of cold weather on the well-being and performance of cattle is important for efficiency and profitability.
ESTIMATING “EFFECTIVE AIR TEMPERATURE”
The effective air temperature an animal experiences is a function of the actual air temperature and wind, SDSU said. This relationship is commonly referred to as wind chill.
As wind speed increases, a greater amount of heat from the animal is lost to the environment, the Extension article said. Because wind exerts such a large influence on an animal’s thermal environment, management adaptations and animal behavior responses tend to address the effects of wind as a way to mitigate the effect of cold stress.
It’s often said that cattle can withstand a lot of cold unless they are wet. The SDSU article said wet conditions from rain or melting snow can slash the animal’s Lower Critical Temperature regardless of hair cover because of reduced thermal insulation and from the heat lost from the body as the water evaporates.
“As a rule-of-thumb, for every one degree that the effective ambient temperature is below the Lower Critical Temperature, the energy requirements increase by 1%,” SDSU said.
The energy required to drive the increased metabolism must come from feed or body reserves, the SDSU Extension service said. As ambient temperatures decrease, a point of maximum heat production (summit metabolism) is reached where continued cold exposure could lead to hypothermia and death.
INCREASING FEED ENERGY
The increase in maintenance energy requirements can be estimated by using the difference between the Effective Air Temperature and from the estimated LCT, the article said. The effect of a temperature change depends on the insulation value of the hair and the size of the animal. Larger cattle and those with greater insulation from a hair coat are less sensitive to degree of cold stress.
The amount of heat lost by the animal is proportionate to its surface area, SDSU said, but this relationship is not linear; i.e. a 1500-pound cow will not have a surface area that is 50% larger than that of a 1000-pound animal.
The SDSU Extension service used an example of a 1000-pound cow with a heavy winter coat experiencing a temperature of 10 degrees Fahrenheit with a wind speed of five mph. The LCT is 32 degrees so the effect LCT is 31, so the energy required for maintenance would increase by 21.7%.
CATTLE, BEEF RECAP
The USDA reported formula and contract base prices for live FOB steers and heifers this week ranged from $156.04 to $157.32 per cwt, compared with last week’s range of $155.00 to $158.55. FOB dressed steers, and heifers went for $243.82 to $249.01 per cwt, versus $243.78 to $250.21.
The USDA choice cutout Tuesday was up $1.22 per cwt at $265.05 while select was down $4.67 at $233.90. The choice/select spread widened to $31.15 from $25.26 with 81 loads of fabricated product and 26 loads of trimmings and grinds sold into the spot market.
The USDA said basis bids for corn from feeders in the Southern Plains were steady at $1.90 to $2.10 a bushel over the Mar futures and for southwest Kansas were unchanged at $1.00 over Mar, which settled at $6.52, up $0.04 3/4.
No cattle contracts were tendered for delivery Tuesday.
The CME Feeder Cattle Index for the seven days ended Monday was $178.01 per cwt down $0.73. This compares with Tuesday’s Jan contract settlement of $183.62, up $1.52.