title: Effects of feed restriction and subsequent refeeding on energy utilization in growing pigs.
abstract: An experiment was carried out to evaluate the metabolic utilization of energy in crossbred barrows during feed restriction and subsequent refeeding. Ten pigs, initially weighing 52 kg, were used in 5 blocks of 2 littermates each. A 7-d adaptation period (P1) was used in which pigs were offered feed at 2.60 MJ of ME.kg of BW(-0.60).d(-1). This adaptation period was followed by a 7-d period (P2), in which 1 pig of each block continued to receive feed at the same level of feeding, whereas for its littermate a 40% reduction in feed intake was imposed (i.e., 1.55 MJ of ME.kg of BW(-0.60).d(-1)). During the subsequent 7-d period (P3), both pigs were offered feed at 2.60 MJ of ME.kg of BW(-0.60).d(-1). After P3, pigs were fasted for 1 d. Heat production (HP) was measured for all pigs during the last 3 d of P1 and on all days for P2 and P3. Heat production was measured using an open-circuit respiration chamber. Energy and N balances were determined for P1, P2, and P3. The HP was partitioned into HP due to physical activity, the short-term thermic effect of feeding, and resting HP. Feed restriction during P2 decreased (P < 0.01) total HP, resting HP, short-term thermic effect of feeding, and retained energy, whereas HP due to physical activity was not affected by feed restriction (P = 0.50). Likewise, fecal and urinary N loss, protein gain, lipid gain, and ADG were reduced during feed restriction (P < 0.01). There were no differences in components of HP and metabolic utilization of energy between the 2 groups during P1 and P3. Nevertheless, urinary N loss was decreased (P < 0.05) and ADG increased (P < 0.01) during P3 for pigs that were restricted in P2. Compensatory growth after a period of feed restriction does not seem to be related to a change in the metabolic utilization of energy for gain but more likely is due to gain in water and gut contents.
authors.affiliation: Universidade Federal de Santa Maria, Departamento de Zootecnia, Santa Maria, RS 97105-900, Brazil. lovatto@smail.ufsm.br
authors.forename: P A
authors.initials: PA
authors.lastname: Lovatto
authors.forename: D
authors.initials: D
authors.lastname: Sauvant
authors.forename: J
authors.initials: J
authors.lastname: Noblet
authors.forename: S
authors.initials: S
authors.lastname: Dubois
authors.forename: J
authors.initials: J
authors.lastname: van Milgen
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D004734:Energy Metabolism / Q000502:physiology*; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D013552:Swine / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D009584:Nitrogen