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Theses

Besoins protéiques et énergétiques du veau de boucherie mâle de race Prim'Holstein

Abstract : Knowledge on protein and energy requirements of veal calves has been mainly established in the 1980’s. Since this decade, the veal calf industry has deeply evolved in connection with a greater BW at slaughter associated with greater duration of rearing and inclusion of increasing amounts of solid feed in veal calf rations. Additionally, nutritional requirements were determined from models which were physiologically and statistically inadequate. The objectives of the present thesis were 1/ to determine protein and energy requirements of veal calves and their equilibrium in the diet as the calf gets older and 2/ to evaluate growth response of the calf to the diet characteristics. The effect of introducing solid feed on these requirements has also been evaluated. Three trials have been conducted involving variation of protein content of the milk replacer, feed allowance of the milk replacer, or level of inclusion and composition of the solid feed. Responses of veal calves were evaluated from their protein and energy balance and the measurement of the components of heat production in respiration chambers. In total, 116 (48 + 48 + 20) nutritional balances were performed in male Prim’Holstein veal calves whose BW ranged from 60 to 265 kg. Our results indicate that the efficiency of utilizing digestible nitrogen decreased as the calf got older. Additionally, protein requirements of calves heavier than 200 kg were lower than estimates from nutritional recommendations. The metabolizability of the digestible energy decreased as the calf got older in connection with increasing glucose and urea excretion in the urine. The best suitable exponent for calculating metabolic body weight is 0.85, which differs from the traditionally used 0.75 exponent. Maintenance energy metabolism increases when feed intake increases (+0.29 kJ per additional kJ ME intake) and is greater (350 kJ/kg BW0.85/d for a mean feed intake) than the (constant) maintenance requirement calculated from nutritional recommendations (418 kJ/kg BW0.75/d). However, the estimated energy requirement for growth is lower according to a greater efficiency of utilizing ME for maintenance and growth (84%). Inclusion of solid feed has not affected maintenance energy requirement but has decreased efficiency of utilizing ME. Finally, our results allow establishing new protein and energy requirements determined from new approaches. They are also used for determining responses of body weight gain and its composition to protein and energy allowances.
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Submitted on : Saturday, June 6, 2020 - 10:32:44 PM
Last modification on : Tuesday, April 27, 2021 - 2:28:04 PM

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  • HAL Id : tel-02824388, version 1
  • PRODINRA : 29306

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Etienne Labussière. Besoins protéiques et énergétiques du veau de boucherie mâle de race Prim'Holstein. Sciences du Vivant [q-bio]. AGROCAMPUS OUEST, 2008. Français. ⟨tel-02824388⟩

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