Modeling the pigs body mass growth and the stressing factors impact on the daily feed intake

Abstract

NOVáK, L., ZEMAN, L., NOVáK, P., MAREŠ, P.: Modeling the pigs body mass growth and the stressing factors impact on the daily feed intake. Acta univ. agric. et silvic. Mendel. Brun., 2005, LIII, No. 5, pp. 105-116 Modeling the body mass growth in fattened pigs by means of the exponential growth function enables to simulate the growth curve from three constants of the gender's, or the hybrid's combination, represented by their body mass phenotype: body mass at birth (G0) genetic limit of body mass (GLi) and the maximum body mass increase reached in the inflexion of the growth curve (dG max). However the expression of animal´s genome to its body mass phenotype depends on the amount and quality of the feed mixture consumed and mainly on the fact how much of the net energy gained remains left for production (NEp), after the mandatory needs of the body maintenance functions are saturated. Only this amount of net energy for production may be deposited into the proteins and fats of the body mass increase (dG/ dt). The net energy for production (NEp) is restricted; if a greater amount of net energy gained (NE) is spend, for compensation of the stressors impact (NE stx). The sum of particular stressor's action is expressed by stressor's index (STX) and indicates the proportional increase of net energy (NE) spend for the maintenance requirement of the animal (NEm). This contribution extends, the classic method of modeling the body mass growth, by the simultaneous modeling of the daily feed mixture intake (DFI) with the content of metabolizable energy (SMEF). The daily feed intake is calculated with respect to the impact of stressors on the net energy consumption. The setting of the model automatically increases the amount of the daily feed intake, so that the adequate amount of net energy for production will not be disturbed. The basic equation for the appropriate daily feed intake sounds as followDetails for calculation, of the net energy for production (NEp) from the input values of the body mass phenotype (G0, GLi, dG max), the content of the metabolizable energy in the feed (SMEF) and of the stressors index value (STX), are described. The validation of the method developed has been approved using the experimental data gained in the fattening of 33 pigs, both sexes, of PIC hybrid combination. Fenotyp hmotnosti prasat je projevem exprese genomu zvoleného plemene nebo hybridní kombinace. V předchozím sdělení (Novák, L. et al., 2004), bylo dokumentováno, že průběh růstu hmotnosti vykrmovaných prasat je charakterizován fenotypem hmotnosti vyjádřeným porodní hmotností, (G0, kg), gene-