David G. Boom

Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science

First Advisor

C. A. Dinkel


Animal productivity is a function of energy intake and heat production. The body core temperature must remain relatively constant and this is accomplished by regulating the balance between heat gain and heat loss. If, due to climatic stress, more energy is needed to maintain homeothermy, less energy is available for production. The range of ambient temperatures in which the animal can maintain homeothermy without increasing its rate of heat production is the zone of thermal neutrality. The lower border of the zone of thermal neutrality is the lower critical temperature. Temperatures below this zone cause the animal to immediately increase its rate of heat production. Upper and lower critical temperatures are a function of the degree of acclimation of an animal to its environment. Animals acclimated to a cold environment can tolerate low temperatures which would stress a non-acclimated animal. However, acclimation to cold increases the resting metabolism rate resulting in a higher maintenance energy requirement. Animal productivity can often be affected by climatic conditions. Hidiroglou and Lessard and Anderson et al. suggested beef cattle maintenance energy requirements were affected by climatic conditions. Ambient temperature was found to influence productivity by Webster et al. Young and Ames et al. Productivity has also been shown to be affected by windspeed and relative humidity. Extremes in climate such as blizzards obviously affect productivity in a cow-calf operation. However, seasonal variation in climate can also affect productivity. Climatic conditions in South Dakota can be quite variable and the effects of climate on cow-calf production are not fully understood. By understanding the relative effects of climate on productivity, it may be possible to implement changes in management to lessen the detrimental effects of climate. The objectives of this study were to determine the effects of ambient temperature, windspeed, precipitation and relative humidity on total digestible nutrient (TDN) intake of the cow during gestation, TDN intake of the cow during lactation, TDN intake of the calf as creep feed and cow efficiency.

Library of Congress Subject Headings

Cattle -- Feeding and feeds -- Environmental aspects



Number of Pages



South Dakota State University


No Copyright - United State