Adaptation of whole animal energy metabolism to undernutrition in ewes: influence of time and posture

Abstract

The effects of undernutrition and of the duration of undernutrition on changes in whole animal energy metabolism and on spontaneous physical activity were studied in adult, non-lactating, non-pregnant ewes. Animals were first given food at 338 kj metabolizable energy (ME) per day per kg live weight-°' 75 (LW 0 ' 75 ), (M). Intake was then reduced by half (0-5M) during 7 weeks. Diet apparent digestibility decreased slightly with undernutrition. Rate of LW loss remained constant throughout the whole 0-5M period. Heat production (HP) declined by proportionately 0-18 within the 1st week at 0-5M and by another 0-05 in the following weeks. These latter changes were directly related to LW loss, since HP scaled to metabolic LW remained unchanged over the whole 0-5M period. Time spent standing decreased with undernutrition from proportionately 0-42 at M to 0-33 at 0-5M as a result of a reduction in the average duration of individual standing periods at all hours of the day except in a few hours preceeding feeding times. Energy cost of standing could not be dissociated from the energy cost of eating; these overall costs were not clearly modified by undernutrition but varied with time post prandially. Standing cost alone was estimated at 10 J/min per kg LW. Efficiency of ME utilization for maintenance (k m ) was calculated at 0-71, and ME requirements for maintenance (MEm) at 338 kj/day per kg LW 0 ' 75 . No adaptation was noted with the duration of undernutrition. Accounting for the behavioural adaptation tended to increase k m to 0-74 but MEm remained unchanged, suggesting that the behavioural changes observed with undernutrition were not sufficient to significantly modify whole animal energy metabolism.

Effect of energy restriction and re‐alimentation in Belgian Blue double‐muscled beef cows on digestibility and metabolites

“…The body N loss in restricted cows is in agreement with a previous experiment, where the live weight loss was not only exclusively due to a mobilization of adipose tissue, but also coincided with a N loss (Fiems et al., 2005). A body N loss during a restriction period has also been reported for beef cows (Ortigues et al., 1993; Grimaud and Doreau, 1995; Freetly and Nienaber, 1998) and for ewes (Ortigues and Vermorel, 1996). A higher N loss for restricted cows may be due to the physiological mechanism to keep plasma glucose at a constant level, necessitating the breakdown of muscle tissue.…”

Métabolisme énergétique des muscles squelettiques chez les animaux producteurs de viande

“…Cependant, à taille équivalente des animaux, l'activité métabolique musculaire est fortement influencée par le niveau moyen d'activité physique et de nombreux autres facteurs (statut hormonal, type de fibres, température ambiante). Par exemple, chez le mouton couché ou debout, l'activité métabolique du quartier arrière est respectivement de 103 ou 138 kJ par jour et par kg de poids vif (Ortigues et Vermorel 1996). Cet exemple souligne la contribution importante de la station debout aux dépenses énergétiques journalières du muscle (environ 30 % chez les ruminants ; Lobley 1991).…”

La sous-alimentation chez les ruminants : ses effets sur la digestion

“…Or les résultats obtenus à des niveaux supérieurs à l'entretien ne peuvent être transposés à des niveaux inférieurs à l'entretien (figure 3). Pour des rations à base de fourrage, la réponse de la digestibilité de la Données de Lassiter et al 1958, McGraham 1964a, 1964b, 1964cet 1969, Keenan et al 1969, Leaver et al 1969, Nicholson et Sutton 1969, McGraham et Searle 1972, Grovum et Williams 1977, Gingins et al 1980, Doreau et al 1986, Bines et al 1988, Ortigues et al 1993, Agabriel et al 1995, Grimaud et Doreau 1995, Kabré et al 1995, Perrier et Doreau 1995, Ortigues et Vermorel 1996, Grimaud et al1998 et 1999 Une explication partielle tient à l'accroissement relatif du flux de matières endogènes dans les fèces par rapport à la quantité excrétée totale, en particulier avec des fourrages de faible qualité qui auraient un effet abrasif sur la muqueuse digestive. La quantité de matières fécales endogènes, qui est généralement considérée comme proportionnelle aux quantités ingérées, pourrait en effet être fortement sous-estimée chez les animaux sousalimentés (Ørskov et al 1989).…”