Maintenance Energy Requirements of Growing Pigs and Calves Are Influenced by Feeding Level

Abstract

The conventional regression method for partitioning heat production (HP) in growing animals between HP associated with either maintenance or growth assumes maintenance HP to be independent of feeding level (FL). However, there are indications that this assumption is not correct and an alternative method is proposed in this study from a reanalysis of 3 trials. In trial 1, 73-, 152-, and 237-kg calves received one milk replacer at 77, 84, 92, and 100% of their ad libitum metabolizable energy (ME) intake. In trial 2, 70-kg barrows received one diet at 60, 80, and 100% of their ad libitum ME intake {2600 kJ ME/[kg body weight (BW)(0.60) · d]}. In trial 3, 60-kg barrows received a basal diet [1700 kJ ME/(kg BW(0.60) · d)] or 4 diets consisting of the basal diet plus 850 kJ ME/(kg BW(0.60)·d) of starch alone or starch with corn gluten, casein, or vegetable oil. In the 3 trials (n = 48, 18, and 28, respectively), HP and activity-related HP were measured on individuals pigs and calves in respiration chambers for 6 d (fed state) and fasting HP (FHP; at zero activity) was calculated as the asymptotic value of HP kinetics on d 7 (feed-deprived state). The FHP changed by 0.22 kJ in calves and 0.14 kJ in pigs/kJ ME intake change during the previous days. The efficiency of using ME for maintenance and growth [k(mg); 1- (HP - FHP)/ME] was not affected by FL (calves: 84%, pigs in trial 2: 74%). In trial 3, k(mg) varied between diets in connection with variations in efficiencies between nutrients (from 55% for corn gluten to 85% for lipid). This new method of representing partitioning of ME intake considers FHP as variable with FL, does not require estimates of maintenance ME requirements, includes efficiencies that depend on diet characteristics, and is not biased by metabolic adaptations of the animal to FL.

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

“…IC/growth) in the present study (only for 20% of the difference). At a given stage of growth (or production), the ratio ME : DE is linearly related to dietary protein content (Noblet and Perez, 1993) and reflects the variation of N excretion in the urine with variation of LF diet = low-fat diet; HF diet = high-fat diet; IC = immunocastration; IC + growth = effect evaluated as the difference between group 1 in stage 1 and group 1 in stage 2; Diet = effect evaluated as the difference between group 1 and group 2 in stage 2; ME = metabolizable energy; NE = net energy; HP = heat production; corrected activity HP = activity of HP corrected for the difference in physical activity among animals (assuming a constant 8.7% activity HP:ME through experiment) according to Labussière et al (2011); DM = dry matter. For diet composition see Oxidation of nutrients and their contribution to lipid deposition were calculated according to Chwalibog et al (1992).…”

“…Total thermic effect of feeding was calculated as the sum of short-and long-term thermic effect of feeding. In addition, HP and its components were corrected for differences in physical activity among animals in each replicate (assuming constant ratio between activity HP and metabolizable energy (ME) throughout the experiment) as described by Labussière et al (2011). NE was calculated as the sum of total RE and Energy metabolism in immunocastrated pigs fasting HP.…”

Fasting heat production and metabolic BW in group-housed broilers

“…But the validity of the 0.75 exponent has been questioned in growing farm animals, and values of 0.60, 0.85 and 0.70 have been suggested for growing pigs (Noblet et al, 1999), growing calves (Labussière et al, 2008) and growing turkeys (Rivera-Torres et al, 2010), respectively. In addition, estimates of FHP vary with animal characteristics (e.g., genotype in pigs; van Milgen et al, 1998) and previous feeding conditions with a lower FHP at lower feeding levels in pigs, lambs or calves (Koong et al, 1982;de Lange et al, 2006;Labussière et al, 2011). Estimates of FHP also depend on the methods used for its measurement or calculation.…”

“…Estimates of FHP also depend on the methods used for its measurement or calculation. For instance, the method of extrapolating the heat production (HP) measured at different levels of energy intakes to zero energy intake has been criticized (Labussière et al, 2011) and may provide biologically unrealistic results such as FHP values not different from zero (Renaudeau et al, 2006). The adjustments of FHP for variation in physical activity of the animals or the duration of fasting are also of importance (e.g., Close and Mount, 1975).…”

“…The objective of the present work is to reassess FHP in modern broilers and especially the exponent for expressing the metabolic BW. To achieve that objective, 73 FHP measurements obtained between 2000 and 2012 in our laboratory on fast-growing male broilers over a wide BW range, under comparable environment conditions, and according to a common methodology validated in other growing farm animals (i.e., turkeys, pigs and calves) (Labussière et al, 2011) were combined.…”