Effects of ambient temperature on energy and nitrogen utilization in lipopolysaccharide-challenged growing pigs1

Abstract

High ambient temperature impacts feed intake, growth, and nutrient utilization in pigs. However, little is known on its effects on immune function and, therefore, on how or if it could modulate the utilization of nutrients in pigs exposed to an inflammatory challenge. The aim of this study was to evaluate the effects of high ambient temperature on energy and nitrogen utilization in pigs submitted to repeated injections of Escherichia coli lipopolysaccharide (LPS). Twenty-eight catheterized and pair-housed female pigs (55 kg BW) were assigned to 1 of the 2 thermal conditions: thermoneutrality (TN, 24°C) or high ambient temperature (HT, 30°C). Within each condition, pigs had a 2-wk adaptation period in climatic-controlled rooms and then were transferred to open-circuit respiration chambers. Pigs remained in respiration chambers for a period of 18 d, which was divided into a 7-d period without LPS (baseline) and a subsequent 11-d period with LPS administration (LPSperiod). The interaction between ambient temperature and period was not significant for most of the traits studied. At baseline, pigs kept at HT had lower ADFI (1,500 vs. 2,003 g/d; P < 0.01) and ADG (449 vs. 684 g/d; P = 0.01) and similar nutrient digestibility compared with those kept at TN. Pigs kept at HT also consumed less ME (1,651 vs. 2,170 kJ · kg BW(-0.60) · d(-1); P = 0.01) and produced less heat (1,146 vs. 1,365 kJ · kg BW(-0.60) · d(-1); P < 0.01) than those kept at TN. Furthermore, HT pigs retained less protein and fat than TN pigs (-61 and -57 g/d, respectively; P < 0.01 and P = 0.01). The LPS challenge reduced (P < 0.01) nitrogen (-13.7 and -7.4 g/d) and ME intake (-594 and -335 kJ · kg BW(-0.60) · d(-1)) in TN and HT conditions, respectively; fecal digestibility of nutrients was not affected by LPS. During the LPSperiod, total heat production (HP) was decreased (P < 0.01) in both TN and HT groups (-190 and -104 kJ · kg BW(-0.60) · d(-1), respectively), in connection with the lower short-term thermic effect of feeding (P = 0.01) and resting HP (P < 0.01). In addition, the LPS induced a reduction in protein (P < 0.01) and fat deposition (P = 0.01) in pigs kept at TN (-79 and -73 g/d, respectively) and at HT (-41 and -44 g/d, respectively). In conclusion, our study confirms that high temperature reduces feed intake, growth performance, and HP. Moreover, our results evidence that irrespective of thermal condition, an inflammatory LPS challenge affects energy utilization through changes in ME intake and maintenance requirements.

Lipopolysaccharide immune stimulation but not β-mannanase supplementation affects maintenance energy requirements in young weaned pigs

“…Just as feed intake did not influence the observed decrease in ADG of ISS pigs, nutrient digestibility was not different across treatments. This is in agreement with other studies reporting ATTD during a chronic LPS challenge [ 46 , 47 ].…”

“…However, in this study, ISS APP concentrations did not differ compared to CON. This was an unexpected result because LPS has been demonstrated to increase APPs such as haptoglobin [ 8 , 46 ] and C-reactive protein [ 55 ] in pigs. A less responsive APP, MBL has been demonstrated to attenuate LPS-induced pro-inflammatory cytokine production [ 56 ] and inhibit T-lymphocyte activation [ 57 ].…”

“…Campos et al [ 46 ] also evaluated HP components during an immune response and reported significant decreases in ADFI leading to decreased TEF compared to baseline values. In this study DMI did not differ, potential feed intake effects on TEF were removed by interpreting the data after normalizing to a constant feed intake, and TEF values were not affected by ISS.…”

“…Conversely, Labussière et al [ 68 ] and Campos et al [ 46 ] reported decreased HP in pigs during inflammatory challenges. Labussière et al [ 68 ] administered a single injection of complete Freund’s adjuvant to young weaned pigs but did not measured HP until the day after challenge and only re-entered the calorimetry chamber after visual recovery [ 68 ]; and this likely biased the response.…”

The relevance of functional amino acids to support the health of growing pigs

“…Inflammation-induced changes in nitrogen metabolism have been extensively documented. In growing pigs, inflammation reduces N retention in the body and increases urinary N loss (van Heugten et al, 1994;Litvak et al, 2013;Campos et al, 2014;Rakhshandeh et al, 2014;Kampman-van de Hoek et al, 2015). These changes result from: (a) decreased feed intake, (b) impaired digestion and absorption of nutrients, (c) enhanced catabolism of body proteins, and (d) increased oxidation of AAs, and are orchestrated by inflammatory cytokines and hormones.…”