Metabolic utilization of energy and maintenance requirements in growing pigs: effects of sex and genotype.

Abstract

An experiment was conducted in which the metabolic utilization of energy was measured in individually penned pigs from seven groups that differed in genotype and(or) sex and ranged in body weight between 20 and 107 kg. The animals were fed a diet containing, on a DM basis, 14.7 MJ ME and at least 21% CP. Heat production was measured in an open-circuit calorimeter, and energy, nitrogen, and fat balances were determined at regular intervals over the growing period; a total of 177 measurements were performed. Body composition of the animals was measured by serial slaughter, and these data were used for estimating the body composition of an animal at a given weight through allometric regression. A factorial analysis procedure was used to estimate the utilization of ME by regressing the ME intake on the observed protein and lipid deposition rates. The intercept of this equation is the maintenance energy requirement (MEm) and was represented either as a function of body weight with group-specific parameters (MEm = a(i) BWb) or as a function of the muscle and visceral mass with an additional additive group effect (MEm = aM muscle(b) + a(v) viscera(b) + G(i)). With BW as dependent variable, the exponent b was close to .60 and differed significantly from .75. The regression coefficient (a(i)) averaged 1.02 MJ ME/kg.60 but it was different for most groups, indicating that different groups of animals have different maintenance requirements. Fixing the exponent to .75 consistently underestimated the maintenance requirement. When the exponent b was not fixed to .75 but estimated, the partial efficiencies for protein and lipid deposition were .62 and .84, respectively. Body muscle and visceral mass could explain a large part of the variation in MEm. Viscera contributed three times more to MEm (per kilogram of mass raised to the .70 power) than did muscle. Even though the muscle mass exceeds to a large extent the visceral mass in animals, the contribution of muscle to MEm was lower than that of viscera for most groups.

Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs

“…Nevertheless, in spite of this equal energy supply, the LR 3 LW pigs had consistently a greater rate of growth than IB pigs, as a result of comparatively increased protein deposition and efficiency of the nitrogen absorbed. As genotype differences in energy requirements for maintenance may be substantial (van Milgen et al, 1998;Noblet et al, 1999;Nieto et al, 2002;Barea et al, 2007), dietary energy available for production is expected to be greater in the obese genotype. It is well known that a low dietary CP supply may limit protein deposition (Campbell and Taverner, 1988;Rivera-Ferre et al, 2006).…”

Pigs that are divergent in feed efficiency, differ in intestinal enzyme and nutrient transporter gene expression, nutrient digestibility and microbial activity

“…When analysing the relationship between RFI and organ weights, RFI was positively correlated with weight of the large intestine (r = 0.57). The weight of organs, especially visceral organ mass contributes three times more to maintenance requirements than muscle mass (Noblet et al, 1999). The correlation between RFI and weight of the large intestine could partially explain the increased efficiency in LRFI pigs.…”

Effect of high dietary fat content on heat production and lipid and protein deposition in growing immunocastrated male pigs

“…NE was calculated as the sum of total RE and Energy metabolism in immunocastrated pigs fasting HP. All energy measurements were expressed relative to BW 0.60 (Noblet et al, 1999).…”