Description of a Model Integrating Protein and Energy Metabolism in Preruminant Calves

Abstract

This paper describes the development of a mechanistic model integrating protein and energy metabolism in preruminant calves of 80-240 kg live weight. The objectives of the model are to gain insight into the partitioning of nutrients in the body of growing calves and to provide a tool for the development of feeding strategies for calves in this weight range. The model simulates the partitioning of nutrients from ingestion through intermediary metabolism to growth, consisting of accretions of protein, fat, ash and water. The model contains 10 state variables, comprising fatty acids, glucose, acetyl-CoA and amino acids as metabolite pools, and fat, ash and protein in muscle, hide, bone and viscera as body constituent pools. Turnover of protein and fat is represented. The model also includes a routine to check possible dietary amino acid imbalance and can be used to predict amino acid requirements on a theoretical basis. The model is based on two experiments, specifically designed for this purpose. Simulations of protein and fat accretion rates over a wide range of nutrient input suggest that the model is sound. In can be used as a research tool and for the development of feeding strategies for preruminant calves.

Modelling growth ofColossoma macropomum(Cuvier): comparison of an empirical and an explanatory model

“…Kaushik & Médale 1994). Similar differences between species were reported in pigs (Bikker et al 1994; protein sparing only possible when dietary protein does not limit growth) and calves (Gerrits, Dijkstra & France 1997; even at very low protein rations protein sparing occurs when lipid is added to the diet).…”

Whey Protein Reduces Early Life Weight Gain in Mice Fed a High-Fat Diet

“…Mice and rats do however tend to eat in a meal-like pattern with three larger meals eaten during the dark phase [33], [34]. Catabolism of amino acids is an energy-consuming process [35], [36], hence an increased influx of amino acids into the urea cycle as a consequence of hepatic amino acid overload after whey intake could therefore explain the decreased feed efficiency at week 0–4 seen in the present study. After a couple of weeks, a physiological adaptation seems to occur and the amino acids of whey are apparently more successfully utilized for growth in consistency with the similar weight gain during the last period of the study and the similar final muscle mass to HF casein.…”

Interaction between protein and energy supply on protein utilization in growing cattle: A review

“…Moreover, the development of a functional rumen may also imply a higher demand for absorbed AA (Reynolds, 2002), and this may affect the efficiency of AA utilization. It was suggested, however, that the metabolism of absorbed AA should be similar in preruminants and ruminants animals at similar BW in terms of their response to protein and energy supply (Black and Griffiths, 1975;Gerrits et al, 1997). More experimental information about ruminant animals is needed to validate those conclusions.…”