Energetic aspects of feed conversion in growing pigs
1980
Wenk, C. | Pfirter, H.P. | Bickel, H. (Swiss Federal Inst. of Technology, Zuerich (Switzerland). Inst. of Animal Production)
Feed conversion ratio (FCR), which defines the feed requirement in kg per kg body weight gain, is an important measure for judging the economic and breeding performance of a fattening pig. It is dependent on many different factors which include (1) the level of feeding, which affects the maintenance requirements, (2) the energy value of the ration and (3) the energy concentration of the body weight gains (c(, g)). The influence of these factors on FCR and, in general, on growth performance, is discussed using results from growth and balance experiments. Some inter-relationships between the factors are described and integrated into a model which predicts FCR. An increase in the level of feeding can reduce FCR. Experimental results indicate that the ad libitum fed pig has a lower maintenance requirement than the restrictively fed animal due to a reduction in its physical activity. As the level of feeding increases, there is usually a rise in c(, g) and an accompanying decline in FCR. However, FCR is only a useful indicator for judging the energetic efficiency of growth when c(, g) is known. A small FCR is only found when body weight gains are high and c(, g) low.
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