LeRoy Hahn

The effects of modified summer environment on swine behaviour

Abstract Daily observations were made at two-hour intervals over a 50-day period on growing pigs subjected to the following heat relief measures: shade only (controls), wallow in the sun, wallow in the shade, wallow combined with increased air motion, and access to an air-conditioned house. The pigs were maintained in dry lot concrete pens under California summer conditions with an average mean temperature of 75 °F. (average range of 58·5 to 94·4 °F.). Where shade was the only relief measure provided, it was used about 80 per cent, of the time from 7 a.m. until 3 p.m. Addition of a wallow reduced the time spent in the shade. Use of portable houses (3-sided, wooden floor, metal roof) was relatively low as compared to fabric shades and other shade on the concrete floor. Use of heat relief measures increased rapidly when the temperature went above 70 °F. The air-conditioned house was used about 60 per cent, of the time during the hours of observation. An increased weight gain in all treated lots over the control lot was not correlated with any behaviour pattern. The importance of suitable shade on summer days with temperature over 70 °F. is indicated. The use of other relief measures such as wallows also is of importance.

Evaluation of climatological records for rational planning of livestock shelters

Abstract Recent research investigations into the effects of climatic environment on livestock have provided functional relationships between weather events and production. Decisions involving shelters to overcome adverse environments for production must be based on economic returns to alternative investments. However, economic analyses require an integration of the effects of the weather factors over a specific period of time, usually several weeks or months in duration. Probability techniques applied to the weather events affecting production provide a basis for the required integration and thereby aid in establishing the economic benefits involved in environmental modification. Several years of summer weather data are analyzed in terms of probability distribution functions for selected stations in the United States. The weather events utilized are the Temperature-Humidity Index and dry-bulb temperature, since livestock production has been shown to be a function of these statistics. Specific examples are provided of the application of such distribution functions to decisions concerning livestock shelters.

Continuous versus periodic observations in behaviour studies with swine raised in confinement

Abstract A group of 9 hogs in confinement was observed continuously for different activity patterns for 12-hour periods on 5 different days during the summer. Data were analysed for different observation intervals up to 120 minutes and compared with the activity pattern recorded continuously. Depending upon the activity pattern or patterns of interest, observation intervals up to 60 minutes proved adequate. Activities consuming relatively small periods of time required a shorter observation interval. Significant differences among individual animal activity patterns were noted over the five 12-hour periods, emphasizing the shortcomings of observing only one animal per group.