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Modelling the effect of a nutrient imbalance on feeding behaviour and growth in growing pigs - Riet Desmet

Ingesting sufficient nutrients is essential for an optimal performance in growing-finishing pigs.These nutrients may affect behavioural feeding components, like feed intake, meal size and meal frequency. The aim of this study was to gain more insight in the effects of nutrients in the diet on behavioural feeding components and the underlying mechanisms.

In the pig industry, the major goal is to achieve optimal growth and productivity. Ingesting sufficient nutrients is essential for an optimal performance in growing-finishing pigs. Important nutrients are protein, energy and amino acids. These nutrients may affect behavioural feeding components, like feed intake, meal size and meal frequency. The aim of this study was to gain more insight in the effects of nutrients in the diet on behavioural feeding components and the underlying mechanisms. The effects of nutrient deficiency and excess were simulated in a computer simulation model. Two simulations were conducted: In simulation 1, different levels of protein, energy and lysine were simulated over a period of 120 days. Lower levels then the reference diet were used, as well as higher levels. In simulation 2, 4 diets were simulated over a 15 day period: 1. Reference diet (2 g tryptophan/kg), 2. Low tryptophan diet (0.5 g/kg), 3. Reference-low-reference and 4. Low-reference-low. In diet 3 and 4, tryptophan levels changed every 5 days.

In simulation 1, energy affected feed intake due to a changed meal frequency, which was influenced by a changed feeding drive and a changed meal size, which was influenced by a changed satiation level. Lysine and protein, on the other hand, affected feed intake due to a changed meal size, which was explained by a changed satiation level. For all three nutrients, body weight changed with a higher or lower level of the nutrient in the diet due to a different body composition. Energy mainly affected body lipid while protein and lysine mainly affected body protein. In simulation 2, low levels of tryptophan in the diet decreased feed intake via a lower meal frequency and meal size. After a period fed a low tryptophan diet, pigs did not compensate for this deficiency.

It is concluded that protein, energy and amino acids are important nutrients in a growing-finishing pigs diet. They affect feeding behaviour and growth differently. The model shows that changing protein levels changed satiation which affected meal size. While changing levels of energy changed both feeding drive and satiation, which had effects on meal frequency and meal size. Changes in body weight and growth can be explained by a different body composition.

Student: REJ Desmet

Supervisor: ing I Boumans, MSc

24 Ects