肉豬生長模式之模擬與驗證

Abstract

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The purpose of this study was to integrate the current state of knowledge in a pig growth model to predict voluntary feed intake (VFI) and pig performance, and the aim was to explain the model and the method used to calculate the VFI of a growing pig and make it available as a decision support tool to end-users by online access. Chapter 1 describes simulation model and background of the use of growth models in pig science. In Chapter 2, NCHU (National Chung Hsing University) pig growth simulation model was developed and the main goal of this simulator is to predict voluntary feed intake based on the effects of temperature and stocking density. The model indicates the limiting factors relative to diet (protein, energy or ash), housing environmental conditions and stocking density. The concepts of compensatory protein growth, correction of lipid growth, the desired feed intake to meet energy, protein and ash requirements, and influences of stocking density, genotype and sex are also introduced in this model. This study draws a flow chart and steps to predict feed intake of a growing pig to make it clear how the model works. The model simulates the outcomes of feed intake, energy and protein requirements for maintenance, the energy cost for cold thermogenesis, and protein and lipid retention on a daily basis until slaughter weight. In Chapter 3, five parameters were used to describe the effects of pig genotype and sex based on the ratio of lipid mass to protein mass at maturity and the scaling of lipid mass to protein mass during potential growth (b). The simulation aimed to predict VFI, performance and body composition based on the inherent potential protein growth rate according to pig genotype and sex. All aspects of pig performance and body composition were affected to different degrees by both genotype and sex. In a simulation including both the growing stage and the finishing stage, type Lb1 (entire male with improved genotype) grew faster, had a lower feed conversion ratio, took less time reach to 120 kg and had a higher total protein mass and lower total lipid mass than the other types investigated. The relationship between different protein and energy intake levels on the performance and body composition of a growing pig are presented in Chapter 4. Fifty diets were used to describe the effects of protein and energy intake levels. The average daily feed intake increases with both protein and energy intake levels. The average daily gain increases with increasing energy intake and dietary ideal protein content. The feed conversion ratio, which is comprised of the feed used and the scaled feed intake, decreases with increasing protein and energy intake levels. Increasing the diet protein content improves daily protein retention and total protein mass. Increasing the diet energy content also improves daily lipid retention and total lipid mass. The ratio of LR to PR decreases with increasing protein contents and decreasing energy contents. The validation of this simulation is described in Chapter 5. The objective of the present study was to analyse the actual voluntary feed intake and performance of growing pigs to validate the NCHU simulation model. Nine diets were fed to 27 hybrid pigs to support the validation of this model. The diet that showed the highest level of agreement between the experimental and the simulated results for the average daily feed intake had CP 15 % and DE 12.77 MJ/kg. The results for the average daily feed intake suggest that the difference between the simulations and the experiment decreased in size from the beginning to the end of the validation. The model yielded better predictions of the average daily gain for the diet content level of CP 16% and DE 13.60 MJ/kg than for the other diets. The validations of the NCHU model for predicting the FCR and feed used indicated that the highest accuracy was obtained for the diet with CP 15% and DE 12.77 MJ/kg. The results of the comparison between the experimental and simulated results demonstrate that the NCHU simulation model could adequately simulate the average daily feed intake and performance of growing pigs.