Abstract
A mathematical model of the thermodynamic interaction between a steer and its environment is described. The model was used to assess the value of shelter in terms of animal performance by reference to meteorological data for six locations in Scotland. The computer model estimated the value of shelter for a 100 kg steer from November 1st to May 1st, in three different types of shelter (roof only, walls only, and roof and walls) and with no shelter (outside). The estimated energy intake was calculated from the Agricultural Research Council's recommendations to give a daily live-weight gain of 0·75 kg. The simulation was run using meteorological data from six Scottish meteorological stations over the five winters (1975–1979). For certain meteorological stations, the simulation was repeated for the 100 kg steer with a projected daily live-weight gain of 0·9 kg. This illustrated the effect of plane of nutrition on the value of shelter. The model estimated an average loss of performance ranging from 24 to 73 kg for an outwintered steer on a projected gain of 0·75 kg/d in comparison with the performance of a housed steer, in these locations. Increasing the plane of nutrition to give a projected gain of 0·9 kg/d reduced considerably the estimated average loss of performance (range 4·6 to 16·0 kg) for the outwintered steer. The model was programmed to simulate the conditions that prevailed (both feed intake and climate) during an experiment carried out at the North of Scotland College of Agriculture (1977–1978) to compare the performance of Friesian steers outwintered or kept outdoors. The computer model predictions were correlated with the experimental results. The computer model predicted that there would be no loss of productivity due to climate; the experimental trial found no statistically significant difference between the performance of the indoor and outdoor steers. In cold conditions it would be desirable to “tailor” feed rations to the climatic environment. The model was adapted to produce estimates of the level of nutrition that would be required for a housed 100 kg steer with a gain of 0·75 kg or 1·00 kg/d gain such that no loss of performance would be caused by cold stress. The model was also used to estimate lower critical temperatures for steers in an environment of different windspeeds, planes of nutrition, and feed qualities.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
