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Title:The conceptual analysis of a dynamic mathematical model for the estimation of the amino acid requirements for pigs from weaning to maturity
Author(s):Cook, David Alan
Doctoral Committee Chair(s):Easter, Robert A.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Animal Culture and Nutrition
Abstract:A deterministic model for the prediction of amino acid requirements of growing pigs was developed. Comparisons between model outputs and literature values indicated that the model adequately predicts amino acid requirements. During the development of the model, limitations in the literature were identified. Therefore, the following experiments were conducted to provide needed components of the model.
Two experiments were conducted to characterize the potential gain in body nitrogen (GBN) of growing pigs. In experiment 1, pigs were grown from weaning to 150 kg to characterize protein and fat growth. In experiment 2, proximate analysis of the whole body of pigs raised to maturity provided estimates of the nitrogen content of the body at maturity (NBmx). The following equation was used to characterize GBN: GBN = KNmx* FFBW$\sp{\rm aN}$* ((NBmx - BN)/NBmx).
From data collected above, three relationships were used to describe DE intake. Two exponential equations, containing body weight (BW) or body protein (BP) as variables, were used. Use of BP in place of BW did not improve the statistical fit of the equation. Calculation of DE intake from estimated utilization of energy provided values that followed a similar pattern but were consistently lower than observed feed intakes.
An experiment was conducted to quantify the effect of energy density on DE intake and growth. Four DE levels (2.9, 3.2, 3.5 and 3.8 Mcal DE/kg) were fed. Increasing DE content resulted in a quadratic response (P $<$.01) for ADG and gain/feed and a cubic response (P $<$.05) for daily DE intake. A response surface regression (R$\sp2$ =.93) was used to describe the change in DE intake relative to DE concentration and BW.
In a final experiment, the effect of energy intake on protein and fat growth was investigated. Treatments consisted of four levels of feed intake: ad libitum (100%), 70%, 50% and 30%. Increasing ME intake resulted in a quadratic response (P $<$.05) for ADG and gain/feed. The response of GBN was dependent upon gender and BW. Gain in body fat responded linearly (P $<$.001). An equation to describe GBN relative to BW and ME intake was developed. The use of fat-free BW in place of BW did not improve the statistical fit.
Issue Date:1991
Rights Information:Copyright 1991 Cook, David Alan
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9210772
OCLC Identifier:(UMI)AAI9210772

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