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Accueil du site → Doctorat → Royaume-Uni → 1995 → Factors affecting feed intake, energy expenditure and work output of oxen and bulls used for draught purposes in semi-arid West Africa

University of Edinburgh (1995)

Factors affecting feed intake, energy expenditure and work output of oxen and bulls used for draught purposes in semi-arid West Africa

Fall, Abdou

Titre : Factors affecting feed intake, energy expenditure and work output of oxen and bulls used for draught purposes in semi-arid West Africa

Auteur : Fall, Abdou

Université de soutenance : University of Edinburgh

Grade : Doctor of Philosophy (PhD) 1995

Résumé
The objectives of this thesis were to i) determine the energy expenditure of draught oxen performing common farm operations, ii) establish the relationships between work on intake and digestibility of feeds by draught oxen, iii) investigate the effect of body condition before work and live weight losses during work on work output, and iv) investigate the implications of heat stress on draught oxen in semi-arid areas. The ultimate aim of this study was to generate information necessary for the design of feeding and working strategies for draught animals in semi-arid areas. To meet these objectives four experiments were conducted at the ICRISAT Sahelian centre, with the collaboration of the International Livestock Centre for Africa.In the first experiment the Oxylog, a portable breath by breath gas analyser, was used on 7 animals to determine their standing metabolic rate, their energy cost of walking on soils of different consistencies, and their efficiency of doing work, i.e. ploughing and carting. The average standing metabolic rate of animals was 487 ( 10.6) kJ/kg LW0.75. The consistency of the soil on which animals were working had a marked effect on their energy cost of walking which was 1.59 ( 0.069), 2.15 ( 0.084) and 1.0 ( 0.10) J/m/kg live weight on unploughed land, ploughed land and laterite tracks, respectively. The efficiency of ploughing sandy soils was 0.32 and was not significantly different from the efficiency of carting with different loads. The efficiency of doing work was not influenced by the type of work performed, the draught force exerted or the walking speed.In the second experiment intake of millet stover, water intake, live weight, plasma concentrations of T3, T4 and urea-nitrogen were measured on 18 animals that worked for 0, 2 or 4 h/day in sequence during three 3-week experimental periods. In addition to these variables, the digestibility and rate of passage of feeds through the digestive tract were measured during the third experiment on 12 animals working either 0, 2.5 or 5 h/day in sequence during three 2-week experimental periods. In the fourth experiment feed intake was measured on 18 animals of different body condition that worked 4 days a week for 7 weeks. The absence of effect of work on intake of millet stover was consistent during these experiments. The efficiency of utilisation of eaten roughages and the rate of passage of the digesta in the gastro-intestinal tract were not influenced by work either. This suggests that the nutrient supply from intake of roughages by working oxen and bulls is unlikely to be sufficient to compensate for the extra energy expended during work. Feed intake was however significantly affected by the quality of the millet stover fed and by the body condition of the animal.

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