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In growing pigs, reduced growth during heat stress (HS) is mainly related to decreased feed intake. The study aimed to determine whether the reported positive effects of live yeast (LY) supplementation in HS pigs were due to a modified feeding behaviour or energy metabolism, and if these can be replicated by imposing an increased meal frequency. The effect of LY supplementation (0 (NS) v. 100 (LY) g/ton of feed), and of feeding window (FW) (unlimited or Unli, 2FW of 1 h each and 8FW of 15 min each) were measured in entire male finishing pigs (n 36). Ambient temperature was at 22°C during the thermoneutral (TN) period (5 d) and at 28°C during the HS period (5 d). Heat exposure decreased DM intake (DMI) and retained energy (RE) (–627 and −460 kJ·kg BW–0·60 · d–1, respectively; P < 0·01). During HS, LY supplementation in Unli pigs decreased inter-meal intervals (P = 0·02) attenuating HS effect on DMI which tended to improve RE (P = 0·09). NS – 8FW had higher DMI and RE than NS – 2FW (P < 0·05) but protein deposition (PD) were similar. Supplemented pigs had higher PD during HS regardless of FW (+18 g · d–1; P = 0·03). Comparing the 2FW groups, improved heat tolerance of LY-supplemented pigs were due to improved insulin sensitivity (P < 0·05) and latent heat loss capacity after a meal (P < 0·05) allowing them to increase their DMI (via an increased number of meals) and thus their energy efficiency. Imposing an increased meal frequency improved DMI in HS pigs but did not replicate positive effects of LY on PD.

Immunocastration and rearing of entire males (EMs) are sustainable alternatives to surgical castration. However, these animal carcasses have variable risk of boar taint and should be identified at the slaughter line. We aimed to identify a simple and reliable indicator of androstenone-related boar taint by evaluating pelvic urogenital tract weight as a marker of boar-taint animals at the slaughter line. The pelvic urogenital tract, testes, and accessory sex glands of EMs and immunocastrates (ICs) were collected, dissected, and weighed, before colorimetric measurements of testicular tissue. Additionally, GnRH antibody titers and testosterone, androstenone, and skatole levels were determined. Our results showed that 81.8% of EMs had androstenone levels above the risk threshold (>0.5 µg/g fat; EM/Ahigh subgroup), whereas in ICs, the C/Ahigh subgroup with androstenone >0.5 µg/g fat accounted for only 4.3%. Androstenone levels correlated negatively with GnRH antibody titers and positively with testosterone levels and reproductive organ weights. Identification of ICs with androstenone levels above the threshold (IC/Ahigh subgroup) may be achieved via testes or pelvic urogenital tract weight measurements. However, in EMs, the latter is a more reliable parameter. A principal component analysis based on these variables and hierarchical clustering also distinguished the Ahigh from the Alow subgroup, irrespective of IC/EM. The findings highlight the possible use of pelvic urogenital tract weight along with testes weight as a simple, reliable, and efficient morphometric indicator for identifying androstenone-positive carcasses of different sex categories.

Pigs subjected to heat stress (HS) decrease their feed intake and growth. The objectives of the experiment were to determine the effects of live yeast (LY) supplementation (Saccharomyces cerevisiae var boulardii CNCM I-1079) on feeding behaviour, energy metabolism and faecal microbiota composition of finishing boars (n 10) housed in a respiration chamber at thermoneutrality (7 d at 22°C) or during HS (seven plus six days at 28°C). Dietary LY supplementation increased DM intake (P = 0·01) whatever the ambient temperature, whereas HS decreased feed intake whatever the dietary supplementation (P = 0·01). Dietary LY supplementation increased the number of meals (P = 0·02). Energy retention was higher with dietary LY supplementation (P < 0·01) but decreased during HS (P < 0·01). The skin temperature of the supplemented pigs was lower at thermoneutrality and increased during HS to a lesser extent than that of non-supplemented pigs (P < 0·01). Faecal microbiota composition was determined using 16S rRNA gene sequencing. Treponema, Christensenellaceae R-7, Ruminococcaceae UCG-002, Rikenellaceae RC9, Clostridium sensu stricto 1 and Romboutsia genera and some bacteria belonging to Alloprevotella, Oxalobacter and Anaeroplasma genera were more abundant under HS. LY supplementation attenuated HS effects on Romboutsia abundance, while decreasing the abundance of some bacteria from Ruminoccocus, Coprococcus, Peptococcus and Oxalobacter genera and increasing the abundance of beneficial bacteria from Lactococcus and Subdoligranulum genera. Our results suggest that higher level of the keystone species Ruminococcus bromii at thermoneutrality may be one of the causes for higher energy retention observed under subsequent HS.

Genetic and feeding factors were combined to improve various quality attributes of pork. Thirty Duroc (D) and thirty Pietrain NN (P) female crossbreeds received a control (C) or an R diet including extruded faba bean and linseed, from 30 to 115 kg. Growth, feed efficiency and slaughter weight were higher for P vs. D pigs and for R vs. C pigs. D pigs had fatter carcasses than P, whereas feeding did not affect carcass fatness. Compared with P, loin meat from D pigs had lower drip, higher ultimate pH and lipid content, and higher marbling, tenderness and juiciness scores (P 0.05). R feeding did not modify sensory traits but improved pork nutritional value by markedly reducing n-6:n-3 and saturated:n-3 fatty acid ratios (P 0.001). Combining D genotype and R diet is a favorable strategy for sensory, nutritional, technological properties and societal image of pork through relocation of feed resources, but requires a better market valorization to be implemented.

International audience; The use of diets with increased dietary fibre content (HF) from alternative feedstuffs is a solution to limit the impact of increased feed costs on pig production. This study aimed at determining the impact of an alternative HF diet on pig digestibility and at estimating genetic parameters of this trait. Digestibility coefficients (DC) of energy, organic matter and nitrogen were predicted from faecal samples analysed with near infrared spectrometry for 1,242 samples, and it represented 654 Large White pigs fed a conventional (CO) diet and 588 fed a HF diet. Growth and feed efficiency traits, carcass composition and meat quality traits were recorded. Pigs fed the HF diet had significantly lower DC than pigs fed the CO diet (−4.5 to 6.0 points). The DC were moderately to highly heritable (about 0.26 ± 0.12 and 0.54 ± 0.15 in the CO and the HF diet, respectively). Genetic correlations were favourable with feed conversion ratio, daily feed intake and residual feed intake, but unfavourable with average daily gain (ADG) and carcass yield (CY). To conclude, DC could be an interesting trait to include in future breeding objectives if pigs were fed diet with HF diets, but adverse genetic trends with ADG and CY would have to be taken into account.

International audience; Feed intake and its daily pattern are regulated both at a short and a long term by several control pathways, including energy balance regulation. This trial aimed to determine the effect of dietary fibre (DB) (mix of wheat, soy and sugar beet pulp fibres) and aleurone supplementation and their interaction on energy and nitrogen balances in growing pigs with ad libitum access to feed. Forty pigs (BW: 35 kg) were fed diets differing by fibre concentration (NDF concentration: 10% or 14% DM) and aleurone supplementation (0, 2 or 4 g/kg) during 3 weeks. Pigs were housed individually in a respiration chamber during the last week to record feeding behaviour and measure energy and nitrogen balances (n = 36). Glucose oxidation was studied on the 6th day with an injection of [U-13C] glucose and measurement of 13CO2 production. There was no significant interaction between DB inclusion and aleurone supplementation on any variables characterizing feeding behaviour. Pigs had less but longer meals with high level of DB, with an increased interval between two meals without effect on daily feed intake. The meal frequency significantly decreased when aleurone supplementation increased. Total tract apparent digestibility coefficient of DM, organic matter, ash, nitrogen and gross energy decreased when pigs received high DB level. Dietary fibre level increased significantly faecal excreted nitrogen. Aleurone supplementation decreased nitrogen retention. Free access to the feed induced a great individual variability not only in feed intake level (from 784 to 2290 g/day) but also in feeding behaviour (from 5.5 to 21.5 meals per day). This variability can be linked with the importance of underlying feed intake regulation pathways and difference in energy balance and metabolism efficiency. Several profiles of metabolism efficiency can be discriminate, thanks to a clustering based on feeding behaviour and pre-prandial concentrations of metabolites and hormones. In conclusion, DB inclusion decreased meal frequency, increased average meal size, decreased total tract apparent faecal digestibility coefficient of nitrogen and gross energy. Supplementation of aleurone decreased average daily feed intake with a reduction of the meal number per day, without modification of average meal size. Aleurone supplementation decreased nitrogen retention and nutrient deposition. Independently of experimental diets, the high individual variability permitted discriminating different profiles with different metabolic strategies. Efficient pigs with a high energy retention as protein and lipid seem to be able to adapt their metabolism according to energy sources.

Background: Nutritional requirements of heavy immunocastrated pigs (IM) and thus the appropriate feeding strategies have not been determined. Methods: The effects of a reduced net energy (NE) diet, achieved by including up to 10% dietary fiber were studied in 41 IM pigs fed ad libitum with an extended period between immunization and slaughter (i.e. 8 weeks). Traits assessed included growth performance (before and after immunization at 112 days of age), fat deposition, intestinal skatole and indole production, intestinal morphology, and cell proliferation. Results: From 84 days of age, IM pigs were fed diets with low, medium, or high NE content (LNE, MNE, and HNE diets; with 8.5, 9.3, and 10.0 MJ NE/kg). There was no effect (P > 0.10) of feed NE concentration on average daily gain or the ratio of BW gain to NE intake in any of the periods studied. However, in the period from 143 to 170 days of age, there was a tendency for a higher NE intake (P = 0.08) in pigs fed the HNE diet along with higher (P < 0.01) backfat gain. Dietary treatment affected carcass composition as lower backfat thickness (P = 0.01) and lower area of fat over the longissimus muscle (P = 0.05) were observed in LNE and MNE pigs. In addition, higher lean meat content (P = 0.04) was observed in LNE pigs. Reducing the NE of the diet with fiber addition resulted in lower indole production in the ascending colon (P < 0.01), and higher skatole production (P < 0.01) in the cecum. Greater villi area, width, height and perimeter, crypt depth, and thickness of the intestinal mucosa in the jejunum, ileum, ascending colon, and descending colon were found for the LNE group (P < 0.01) than for the HNE group, while the MNE group was intermediate. Cell proliferation was not affected by dietary treatment (P > 0.05). Conclusion: The present results show that despite improved absorptive capacity (indicated by histomorphological changes in the intestinal mucosa), a reduction in dietary NE concentration reduces lipid deposition, without affecting performance or energy efficiency in IM pigs.

Variations in feeding behaviour between animals result from individual variations in their metabolism as affected by diet composition. The study aimed to link the within-day dynamics of voluntary feed intake and those of blood metabolites and insulin in growing pigs havingad libitumaccess to feed and receiving diets differing in dietary fibre levels and aleurone supplementation. A total of forty pigs (body weight: 35 kg) had access to diets providedad libitum, which differed by fibre content (13 or 18 % neutral-detergent fibre) and aleurone supplementation (0, 2 or 4 g/kg). Feeding behaviour was individually recorded for 1 week. The kinetic of plasma metabolites and insulin was followed for 1 h after a voluntary test meal. Dietary fibre level did not affect the daily feed intake but increased meal size and meal duration. Aleurone supplementation (4 g/kg) decreased the daily feed intake and number of meals. Dietary fibre level only decreased insulin concentration measured 15 min after meal beginning. Aleurone supplementation (4 g/kg) decreased glycaemia in the first hour after the meal and insulinaemia 15 min after the meal. Free access to feed led to high variability in pre-prandial metabolites and insulin concentrations, resulting in different test meal size irrespective of diet composition. Animals were then spread over different profiles combining feeding behaviour and fasted status to explain different profiles of regulation of feed intake. Plasma metabolites and insulin kinetics were affected by diet composition but also by animal characteristics. Individual variability should be considered when diet composition is used to modulate feeding behaviour.

National audience; The objective of the study was to determine whether heat stress (HS) effects in pigs were caused directly by heat exposure (regardless of feeding level and pattern) or indirectly due to the reduction of feed intake, and to determine if splitting heat increments via increasing feeding frequency can improve pig response to HS. A total of 48 female pigs (66.1 ± 1.7 kg) were allotted to 4 groups in 3 replicates. After 7 d in thermoneutral conditions (TN; 22°C; P1), pigs were placed in either TN or HS (32°C) conditions for 20 d (P2). The diet was provided either ad libitum (AL; 2 distributions/d) or pair-fed (PF8; 8 distributions/d) using HS-AL pigs as the reference group. Thus, the 4 experimental groups were TN-AL, HS-AL, TN-PF8, and HS-PF8. Daily ration of PF8 pigs was distributed at every 90-min intervals from 09h00 to 19h30. Data was analyzed using the PROC MIXED procedure with replicate (n=3), experimental group (n=4), and their interactions as fixed effects and the REPEATED statement was used to for repeated measures data. Pigs had similar ADFI during P1 (P>0.05), while HS-AL and PF8 pigs had lower ADFI (-19%), ADG (-25%), and final BW (-6.1 kg) than TN-AL pigs (P0.05). Muscle temperature (Tmuscle) variation depended on feeding and physical activity for TN pigs while Tmuscle gradually increased throughout the day for HS pigs. Increase in Tmuscle for each meal was lower in HS-PF8 than TN-PF8 (P

International audience; With the increasing global mean temperature and more frequent summer heat waves, there is a need to find techniques to mitigate heat stress (HS) consequences on pig production. The aim of the study was to evaluate the effect of HS and of increasing feed provision frequency on performance and thermoregulation responses in finishing pigs. A total of 48 pigs (66.1±1.7 kg) were allocated to 4 experimental groups in 3 replicates. After being housed at thermoneutrality (TN; 22 °C) during 7 days (P1), pigs were subjected to either TN or HS (32 °C) conditions during 20 days (P2). In each environment, the diet (14.9%CP, 9.64 MJ NE/kg) was provided either ad libitum (AL; 2 distributions/day) or pair-fed (PF8; 8 distributions/day) with HS pigs fed-AL as the reference group. Thus, there were four experimental groups: TN-AL, HS-AL, TN-PF8, and HS-PF8. In PF8 groups, the calculated daily ration was divided into 8 feed provisions distributed at every 90-min intervals from 09:00 to 19:30. In P2, HS-AL and PF8 pigs had lower ADFI (-19% on average; P0.05). The PF8 groups had lower total viscera percentage than TN-AL pigs (-2.1% on average; P>0.05), while HS-AL had intermediate results. Pigs in HS-AL and in PF8 groups had similar slaughter BW (P

This study aimed to determine whether pig responses to heat stress (HS) were directly due to heat exposure (regardless of feeding level and pattern) or were indirectly due to the reduction of feed intake (FI) and to determine if increasing feeding frequency (splitting heat increments) can improve pig response to HS. A total of 48 pigs (66.1 ± 1.7 kg) were allocated to four groups in three replicates. After 7 d in thermoneutral (TN) conditions (22 °C; period 1 [P1; day −7 to −1]), pigs were placed in either TN or HS (32 °C) conditions for 20 d (period 2 [P2; day 0 to 19]). The diet was provided either ad libitum (AL; 2 distributions/d) or pair-fed (PF8; 8 distributions/d) using HS–AL pigs as the reference group. Thus, the four experimental groups were TN–AL, HS–AL, TN–PF8, and HS–PF8. The daily ration of PF8 pigs was distributed at every 90-min intervals from 0900 to 1930 hours. Data were analyzed using the PROC MIXED procedure with replicate (n = 3), experimental group (n = 4), and their interactions as fixed effects, and the REPEATED statement was used for repeated measures data. Pigs had a similar average daily feed intake (ADFI) during P1 (P > 0.05). In P2, HS–AL and PF8 pigs had lower ADFI (−19%), average daily gain (−25%), and final body weight (−6.1 kg) than TN–AL pigs (P < 0.01). TN–AL pigs had thicker backfat than TN–PF8 pigs (P < 0.05), while the HS pigs had intermediate results. HS pigs had a higher perirenal fat percentage based on the contrast analysis between PF8 pigs (P < 0.05). Thermoregulatory responses of pigs increased with HS exposure but did not differ between HS or between TN groups (P > 0.05). For TN pigs, variation in muscle temperature (Tmuscle) depended on feeding and physical activity, while for HS pigs, Tmuscle gradually increased throughout the day. The Tmuscle of PF8 pigs increased with each additional meal but plateaued earlier for HS–PF8 than TN–PF8 pigs; an increase in Tmuscle per meal was also lower in HS–PF8 than TN–PF8 (P < 0.05). Exposure to HS decreased plasma T3 and T4 (P < 0.05) and increased plasma creatinine (P < 0.05). Between the PF8 groups, HS pigs also had a transient increase in plasma insulin on day 8 (P < 0.05). The effect of HS on FI decreased the growth rate of pigs but there are heat-induced effects, such as altered physiological responses, which might explain the direct HS effects seen in other literature especially in terms of increased adiposity. The increased feed provision frequency in the present study did not improve the HS response of pigs.

National audience; Mesurer précisément l'ingestion individuelle journalière des animaux est essentiel à de nombreuses questions de recherches. Le challenge est plus difficile à relever pour des animaux élevés en groupe, et plus encore s'ils sont élevés à l'extérieur (parcours, pâturage). L'objectif de ce travail est de faire le bilan des méthodes existantes, de les hiérarchiser en termes de précision, de conditions d'utilisation, de pertinence, de faisabilité, et ceci pour les principaux animaux de rente (bovins, ovins, caprins, équins, porcins, lapins, volailles). Les méthodes existantes ont été développées essentiellement pour les ruminants au pâturage, et depuis plus de 50 ans pour les plus anciennes. Elles se classent en deux grands types: les méthodes directes et les méthodes indirectes. Les méthodes directes sont basées sur des pesées: 1) pesée de l'animal entier avant et après une séquence d'ingestion, avec correction des pertes et prise en compte de la durée effective d'ingestion sur la séquence, 2) pesée d'une partie de l'animal (jabot des volailles, contenu du rumen des ruminants), ou 3) "pesée"du couvert végétal avant et après pâturage, par fauche mécanique. Cette dernière méthode ne permet que la mesure de l'ingestion du groupe, sauf si chaque animal n'a accès qu'à une zone de pâturage. Elle peut être relativement précise pour des couverts homogènes moyennant une forte pression de mesures, notamment post-pâturage. Les méthodes indirectes sont les plus fréquemment utilisées et peuvent être classées en trois sous groupes: 1) par estimation de l'excrétion fécale et de la digestibilité, 2) par l'utilisation combinée d'alcanes internes et externes, et 3} par mesure des composantes du comportement animal. Toutes les méthodes répertoriées sont chronophages, au champ, sur l'animal, et/ou au laboratoire. Seules les méthodes indirectes basées sur l'emploi de marqueurs externes permettent une mesure relativement précise de l'ingestion journalière individuelle (erreur moyenne à l'échelle individuelle de 1 0%). En expérimentation, elles permettent de détecter des écarts d'ingestion de 5 à 10% entre traitements selon la puissance du schéma expérimental, et peuvent donc être considérées comme les méthodes de référence. L'application de ces méthodes de référence, développées sur ruminants et équins, au cas des porcins, lapins et volailles élevés en extérieur peut comporter de sérieuses limites pratiques concernant à la fois la distribution quotidienne des marqueurs et l'échantillonnage individuel des fèces. Cela nécessite dans tous les cas des études de validation en milieu confiné avec contrôle de l'ingestion et variations du régime alimentaire pour étudier notamment la récupération fécale des marqueurs et si besoin la prévision de la digestibilité. Pour les animaux élevés en groupe en bâtiment, dont les aliments sont dans une mangeoire ou une auge, la pesée en continu de la mangeoire couplée à l'identification automatique, via des puces RFID, de l'animal ayant accès à la mangeoire constitue la méthode de référence. Pour être appliquée à tous types de filières, cette méthode nécessite cependant d'importants travaux de développement techniques pour adapter les dispositifs au format et au comportement alimentaire de l'espèce considérée, ainsi que des travaux spécifiques de développement informatique pour traiter les données de façon automatique. Des dispositifs commerciaux existent, mais ne permettent pas toujours l'accès aux données individuelles journalières. Par ailleurs, même s'ils permettent le contrôle des quantités ingérées, voire le rationnement des animaux, nombreux sont les dispositifs qui isolent l'animal mesuré de ses congénères dans un couloir durant le repas. Même si la hiérarchie entre animaux influe probablement l'accès à la mangeoire, les conditions de la mesure ne permettent donc pas totalement l'expression des comportements sociaux observés sur le terrain. Les nombreuses méthodes d'estimation de l'ingestion individuelle des animaux élevés en groupe, sont toutes chronophages, et les méthodes de référence les plus précises sont partiellement invasives du fait de l'administration à l'animal d'un marqueur. Elles ne peuvent être utilisées directement au pâturage sans études préalables de calibration, et toutes ne sont pas transposables aux animaux de petite taille pour d'évidentes raisons pratiques.

International audience; In pigs, digestive disorders associated with weaning lead to antibiotic use to maintain intestinal health. Microalgae have been studied in humans and rodents for their beneficial effects on health. The nutritional value of microalgae in animal diets has been assessed, but results were not conclusive. Dietary supplementation with microalgae as an alternative to antibiotic use was studied in two trials (72 piglets with initial BW=9.1±1.1 kg in trial 1 and 24 piglets with initial BW=9.1±0.9 kg in trial 2). All piglets were weaned at 28 days of age and then housed in individual cages. Piglets were randomly allocated to one of the four diets during 2 weeks after weaning: a standard diet with no supplementation (NC) or the standard diet supplemented with 1% Spirulina (SP), with 1% Chlorella (CV), or with 0.2% of colistin as positive control (PC). Trial 1 was performed to determine the effect of microalgae supplementation from 28 to 42 days on performance and incidence of diarrhoea. Animals received then a standard diet from 42 to 56 days of age. Trial 2 was performed from 28 to 42 days of age to assess nutrient digestibility of the experimental diets and to determine inflammatory status and intestinal morphology at 42 days of age. In trial 1, 94% of the pigs had diarrhoea in the 1st week after weaning with no beneficial effect of colistin on diarrhoea incidence, average daily feed intake (ADFI), average daily gain (ADG), and gain : feed (G : F) ratio. This suggests that the diarrhoea was due to digestive disorders that did not result from enterotoxigenic Escherichia coli infection. Supplementation with either Spirulina or Chlorella did not affect ADFI, ADG and G : F in trials 1 and 2 (P>0.10). Diarrhoea incidence was reduced in CV pigs compared with NC, SP and PC pigs (P

To view supplementary material for this article, please visit https:/doi.org/10.1017/S175173111600286X; This review summarizes the results from the INRA (Institut National de la Recherche Agronomique) divergent selection experiment on residual feed intake (RFI) in growing Large White pigs during nine generations of selection. It discusses the remaining challenges and perspectives for the improvement of feed efficiency in growing pigs. The impacts on growing pigs raised under standard conditions and in alternative situations such as heat stress, inflammatory challenges or lactation have been studied. After nine generations of selection, the divergent selection for RFI led to highly significant ( P

Fever is one of the most common clinical signs of infection and systemic inflammation and is an important component of non-specific acute phase response. However, its activation results in increased metabolic rate and energy expenditure with negative consequences on animal growth and feed efficiency. This study aimed at investigating the effect of repeated administrations of Escherichia coli lipopolysaccharide (LPS) on the internal temperature of growing pigs and its associated impact on metabolic heat production. In response to LPS, internal temperature of the animals increased from 38.7 to 40 °C within 150 to 200 min after the LPS administration. The corresponding increase in maintenance energy requirements was estimated in 100 kJ/kg BW0.60/d which is equivalent to 10% of the basal metabolic rate of growing pigs.

International audience; Immunocastration, a technique to replace surgical castration of piglets, consists of two consecutive vaccinations to induce antibodies which transiently suppress testicular functions and avoid boar taint. It is a method to ensure both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively. While all aspects of sustainability have been studied separately, however, a contemporary global overview of different aspects is missing. In immunocastrates, performance results are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After second vaccination, immunocastrates switch from a boar- to a barrow-like status. Therefore, the timing of second vaccination is a fine-tuning tool to balance advantages of boars with environmental and economic benefits against increased risk of welfare problems and boar taint. Nevertheless, both synergic and conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products.

International audience; Due to the initiative to stop piglet castration, meat from entire male pigs is expected to take important share on the European market which can affect dry-cured ham industry. In the present study, hams of entire males (EM) and immunocastrates (IC) were submitted to dry-curing process. Sex category and salting regime were evaluated using standard (18days; HS) and shortened salting (6days; LS). At the end of processing, compared to HS, LS hams had lower (40%) salt content, were more proteolysed, were less salty, and had softer texture and different volatile profile. Sex effect was less evident; still, hams from EM exhibited higher processing losses and salt intake, and were drier, less marbled, harder, and more intensively coloured than IC hams. The panellists perceived higher off-flavours in hams with high boar taint compounds (correlation 0.67 and 0.53 for skatole and androstenone, respectively). The effect of sex category on volatile profile was negligible.

In the last decade, various applications of gaseous exchange measurements have been developed to quantify the production or consumption of particular gases by animals. Notably, booming research into methane emissions has led to an expansion of the number of facilities in which such measurements are made. Results of a ring test calibration of respiration chambers in the UK by Gardiner et al. (2015) confirmed our concern that not all research groups comply with the same standards of chamber operation.

Weaning of piglets is associated with important changes in gut structure and function resulting from stressful events such as separation from the sow, moving to a new facility and dietary transition from a liquid to a solid feed. This may result in post-weaning diarrhoea and a decrease in feed intake and growth. In humans, the cyanobacterium Spirulina platensis (SP) and the freshwater microalga Chlorella vulgaris (CV) are known for their beneficial health effects. This study aimed to determine the effects of early oral administration of Spirulina and Chlorella in piglets on mucosal architecture and cytokine expression in the intestine around weaning, and consequences on growth performance and diarrhoea incidence. The experiment was conducted on 108 suckling piglets of 14 days of age (initial BW = 4.9 +/- 0.7 kg) and weaned at 28 days of age (day 0). Animals received orally 385 mg/kg BW per day of SP or CV, or water (negative control (NC)) during 4 weeks from day -14 to day 14 and their growth performance was measured daily. After weaning, growth, feed intake and diarrhoea incidence were measured daily. Intestinal morphology and functionality were assessed at day -1, day 2, and day 14. During the suckling period, average daily gain (ADG) in SP piglets was higher, resulting in a higher weaning BW compared to NC and CV piglets (P < 0.05). No significant difference between treatments was observed for ADG, average daily feed intake, and gain to feed (G: F) ratio after weaning, but the extent of growth retardation after weaning was the lowest in piglets supplemented with Chlorella (P < 0.01). Supplementation with Spirulina reduced diarrhoea incidence by 50% from day 0 to day 14 (P < 0.05). Mucosal architecture at the jejunum was unaffected by Spirulina or Chlorella administration (P > 0.10). Shorter ileal villi were measured in SP and CV piglets than in NC piglets (P < 0.05). Cytokine expression did not differ between treatments in response to weaning. At day 14, IL-8 expression in the ileum was higher in SP piglets, while IL-1 beta expression in the jejunum was higher in CV piglets (P < 0.05). This study shows that Spirulina administration around weaning alleviates diarrhoea in weaned piglets, without marked modulation of local inflammation.

International audience; Microbial population in the gastrointestinal tract plays a central role in health and nutrient digestion. The objective of the present study was to investigate the relationships between microbiota and apparent digestibility coefficients with respect to age and diet. Pigs from Large-White, Duroc or Pietrain breeds were raised under the same housing conditions and fed alternately a low-fiber (LF) and a high-fiber diet (HF) during 4 successive 3-week periods. Data collection for digestibility measurements was achieved during the last week of each period. At the end of each period, fecal microbiota was collected for 16S rRNA gene sequencing. The microbiota remained stable across periods whereas digestibility of energy, crude proteins and cell wall components increased. The microbiota was resilient to diet effect and pigs fed the LF diet were discriminated to those fed the HF diet using 31 predicting OTUs with a mean classification error-rate of 3.9%. Clostridiaceae and Turicibacter were negatively correlated whereas Lactobacillus was positively correlated with protein and energy digestibility coefficients in the LF group. In addition, Lachnospiraceae and Prevotella were negatively correlated with cell wall component digestibility. In contrast, no significant correlation was found between microbiota composition and digestibility coefficients when pigs were fed the HF diet. Interestingly, it was also no longer possible to distinguish animals from different breeds once the animals were fed a HF diet, so that the microbiota could only trace the breed origin in the first period and in the LF group. In our experimental conditions, 3 weeks of adaptation to a new diet seems to be sufficient to observe resilience in growing pigs' microbiota. We demonstrated that fecal microbiota can be used to classify pigs according to their dietary treatment. Some bacteria are favorable or unfavorable to digestibility. This suggests that manipulations of bacterial populations can improve digestibility and feed efficiency.

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.

The effect of dietary fibre content on intestinal production of indolic compounds was studied in immunocastrated pigs (IC). In addition, entire males (EM) and IC were compared on control diet (with low fibre content). For the study 32 crossbred pigs were assigned, within a litter to 4 treatment groups; 24 pigs were immunocastrated (at the age of 77 and 112 days) and 8 pigs were kept as entire males (EM). IC were split into three groups (IC_H, IC_M and IC_L) fed three diets differing in crude fibre (34, 60 and 80 g/kg dry matter, respectively) and net energy (NE) (10.0, 9.3, 8.5 MJ NE/kg/DM, respectively). EM were fed high NE i.e. low fibre diet. The experiment started when pigs were 84 days old and finished at the age of 172 days, when pigs were sent to slaughter. Skatole and indole concentrations were determined in the samples of intestinal content taken from caecum (CE), ascending (AC) and descending colon (DC). The concentration of indole was the highest in CE and proximal part of the colon, while skatole concentration increased in the distal parts of the large intestine. Concentrations of indolic compounds did not differ between EM and IC that were fed the same diet. Lowering dietary NE by inclusion of high fibre ingredients reduced the production of indole in the intestinal content of IC pigs, whereas the production of skatole was not affected.

To view supplementary material for this article, please visit https://doi.org/10.1017/S1751731117001343; International audience; The optimization of dietary phosphorus (P) and calcium (Ca) supply requires a better understanding of the effect of dietary fiber content of co-products on the digestive utilization of minerals. This study was designed to evaluate the effects of dietary fiber content from 00-rapeseed meal (RSM) on P and Ca digestibility throughout the gastrointestinal tract in growing pigs fed diets without or with microbial phytase. In total, 48 castrated male pigs (initial BW=36.1±0.4 kg) were housed in metabolic crates for 29 days. After an 8-day adaptation period, pigs were allocated to one of the eight treatments. The impact of dietary fiber was modulated by adding whole RSM (wRSM), dehulled RSM (dRSM) or dRSM supplemented with 4.5% or 9.0% rapeseed hulls (dRSMh1 and dRSMh2). Diets contained 0 or 500 phytase unit of microbial phytase per kg. From day 14 to day 23, feces and urine were collected separately to determine apparent total tract digestibility (ATTD) and apparent retention (AR) of P and Ca. At the end of the experiment, femurs and digestive contents were sampled. No effect of variables of interest was observed on growth performance. Microbial phytase increased ATTD and AR of P (P

The regulation of lipogenesis mechanisms related to consumption ofn-3 PUFA is poorly understood. The aim of the present study was to find out whetherα-linolenic acid (ALA) or DHA uptake can have an effect on activities and gene expressions of enzymes involved in lipid metabolism in the liver, subcutaneous adipose tissue andlongissimus dorsi(LD) muscle of growing–finishing pigs. Six groups of ten pigs received one of six experimental diets supplemented with rapeseed oil in the control diet, extruded linseed, microalgae or a mixture of both to implement different levels of ALA and DHA with the same content in totaln-3. Results were analysed for linear and quadratic effects of DHA intake. The results showed that activities of malic enzyme (ME) and fatty acid synthase (FAS) decreased linearly in the liver with dietary DHA. Although the expression of the genes of these enzymes and their activities were poorly correlated,MEandFASexpressions also decreased linearly with DHA intake. The intake of DHA down-regulates the expressions of other genes involved in fatty acid (FA) metabolism in some tissues of pigs, such asfatty acid desaturase 2andsterol-regulatory element binding transcription factor 1in the liver and2,4-dienoyl CoA reductase 2in the LD muscle. FA oxidation in the LD muscle and FA synthesis decreased in the liver with increasing amount of dietary DHA, whereas a retroconversion of DHA into EPA seems to be set up in this last tissue.

In immunocastrated (IC) pigs, revaccination (V2) increases lipid deposition (LD) because of increased voluntary feed intake; but little is known on associated effect of diet composition on partitioning of nutrients in IC pigs. Digestibility measurements, N and energy balances in respiration chambers were performed in two subsequent stages in four replicates of two male littermates to determine the changes between 85 (stage 1) and 135 (stage 2) kg live weight due to combined effect of IC, growth and increased feed intake (IC/growth). During stage 1, pigs received a standard low-fat diet (LF diet; 2.5% dry matter (DM) of fat fed at 2.27 MJ metabolizable energy (ME)/kg BW0.60 per day), whereas during stage 2, feed intake was increased to 2.47 MJ ME/kg BW0.60 per day and one littermate was fed LF diet whereas the second received a fat-enriched diet (HF diet; 8.9% DM of fat) to determine the effect of increased dietary fat content on energy utilization in IC pigs. Results from N balance and measurements of gas exchanges were used to calculate respiratory quotient (RQ), heat production (HP), nutrient contribution to fat retention, components of HP, protein deposition (PD) and LD. Nutrients and energy apparent digestibility coefficients, methane losses and N retention (P

The use of indirect calorimetry as a means to quantify heat production (Q) and net substrate oxidation has increased rapidly since the pioneering work of Lavoisier, and today, indirect calorimetry is often used as a reference for other measures of Q. Simple equations were developed and widely adopted to calculate the production of heat from the measurement of the production of CO2 and CH4, the consumption of O2 and urinary nitrogen loss. The coefficients in these equations were derived from stoichiometry of the complete oxidation of carbohydrates, fat and protein. In this chapter, taking the Brouwer equation as an example, these calculations are explained and their validity to compute Q is discussed. Particular attention is paid to anaerobic fermentation and de novo lipogenesis from carbohydrates. It is concluded that Q can be predicted satisfactorily from the O2 consumed and CO2 produced using factors derived from oxidation of carbohydrates, fat and protein. Caution is required for corrections for CH4, particularly in ruminants, although quantitatively, the impact of these corrections on the estimates of Q seems limited. The approach is also valid when de novo lipogenesis from carbohydrates is substantial. As it is assumed that O2 and CO2 pools within the body do not change within a measurement period, a critical attitude towards this approach is required whenever pushing a biological system with e.g. a diet or infusate while using it to estimate short term variation in Q. Examples of these include strenuous exercise or an environmental challenge, e.g. heat stress, during which energy containing intermediates can be temporarily stored in the body and/or the bicarbonate pool fluctuates. Lastly, the measurement of retained energy based on indirect calorimetry in growing subjects is compared with other techniques. Comparison with the comparative slaughter technique in growing subjects reveals that measurement based on indirect calorimetry tends to lead to higher estimates of retained energy, but treatment differences within studies are quantified accurately. It can be argued that the bias reflects a true difference in Q, related to differences in e.g. housing conditions. Comparison of indirect calorimetry with the carbon-nitrogen balance technique and with direct calorimetry, reveal a very close match between these techniques. In conclusion, although a critical attitude is appropriate, Q can be accurately derived from gaseous exchange measurements using the simple equations developed in the previous century, with coefficients based on the complete oxidation of carbohydrates, fat and protein

The time dependent character of data generated by modern calorimetry equipment provides the unique opportunity to monitor short term changes in energy expenditure related to physical activity, feeding pattern and other experimental interventions. When timed recordings of physical activity are available, total heat production can be decomposed into heat production due to physical activity and resting metabolism. Based on additional measurements and assumptions, further separation of the thermic effect of feeding is possible. When separating total heat production into its components, the separation of activity energy is a key step, even if activity energy is not the main interest of the study. This chapter provides an overview of a current methodology used to measure physical activity within the setting of indirect calorimetry. An approach to decompose total heat production into activity related and resting metabolic rate, the latter including the short term effect of feeding, is presented. In regression analysis, the energetic costs of each unit of physical activity, as well as the resting metabolic rate are assumed to be constant. Improved methodology is available using penalized least squares regression to model time dependent variation in the resting metabolic rate. The impact of experimental variables and settings, e.g. sampling frequency and chamber washout time are discussed. In addition, housing conditions, including ambient temperature, and feeding methods can impact on the relationship between physical activity and total heat production, affecting the reliability with which total heat production can be decomposed into resting metabolic rate and heat production related to physical activity. Finally, single housing conditions, often difficult to avoid in indirect calorimetry experiments, can modify behaviour, induce stress and therefore substantially influence activity related heat production and the results of calorimetry experiments. The effect of single vs group housing in growing pigs extracted from previously unpublished data and from the literature, suggest that single housing may increase activity heat production possibly because of induced stress. From behavioural and calorimetry data obtained in calves it is also demonstrated that the energetic costs of stereotyped behaviours can be very high.

In the last decade, various applications of gaseous exchange measurements have been developed for quantifying the production or consumption of particular gases. Notably, booming research into methane emissions has led to an expansion of the number of facilities in which such mea-surements can be performed. Recent research by Gardiner et al. (2015) has confirmed our concern that not all research groups comply with the same standards, and it is alarming to read full system recoveries of six facilities in the UK, to be varying between 59% and 115% (six facilities, 22 individual chambers measured). We are convinced that such unac-ceptable recoveries also occur elsewhere. From two courses on indirect calorimetry that we organised, directly following the ISEP conferences in Davis in 2013 (USA) and Krakow in 2016 (Poland) we learnt that recovery tests are not con-sistently performed around the world. The urge for per-forming such tests has also recently been emphasized by Hammond et al. (2016).We are of the opinion that for all techniques aiming at quantification of gas exchange or production, either indirect calorimetry, methane emissions by chamber technique, ventilated hood or head box techniques, full system recovery tests of the relevant gas should be performed immediately before or following the measurements that are reported, and the results of these recovery tests for each chamber or unit are reported in the ‘Material and methods’ section of the manuscript. Currently, results of recovery tests are rarely reported. Procedures for recovery tests are fairly simple and can easily be found in references included below.

Little knowledge on the digestive and metabolic utilization of solid feed in veal calves is available. The objectives of the study were to determine the effects of 2 solid feeds offered at 2 feeding levels (FL90 and FL105) in addition to a milk replacer on heat production (HP) and protein and fat deposition in veal calves. Sixteen calves (148.0 +/- 3.7 kg) received milk replacer (75% of a reference DE allowance) and solid feeds that consisted of corn grain and pelleted hydrolyzed wheat gluten without (CO) or with (CS) chopped wheat straw. The solid feed supply provided 15 or 30% of the reference DE allowance to achieve FL90 or FL105, resulting in 4 treatments: CO90, CS90, CO105, and CS105. A fifth treatment consisted of using the milk replacer alone at FL90 (treatment M90) and was measured in 4 other calves. All calves were kept individually for 7 d in a respiration chamber to estimate energy and N balances and fasting HP. The digestibility coefficients of DM, OM, GE, and major nutrients were at least 94% for M90 and decreased when solid feed was added (P 0.05). Dietary treatment had no effect (P > 0.05) on activity HP (53 kJ/kg of BW(0.85) daily) but did affect thermic effect of feeding; efficiency of utilizing ME for maintenance and growth was greatest for the M90 calves (84.5%, P = 0.02). Fasting HP tended (P = 0.09) to increase at the greatest FL (308 vs. 298 kJ/kg of BW(0.85) daily). Maintenance ME requirement increased (P = 0.04) from 364 to 382 kJ/kg of BW(0.85) daily when feeding level increased (P = 0.04) but was not affected by ingestion of solid feed. The provision of solid feed to veal calves was associated with a reduced efficiency of N retention (P = 0.04), and energy retained as protein tended to decrease (P = 0.08), probably as a result of an imbalanced AA supply of the solid feeds. The data were used to calculate the energy contents of solid feed. The utilization of energy from solid feed differed from that of milk replacer.

The use of indirect calorimetry to measure the heat production of men and animals has increased rapidly since the pioneering work of Lavoisier. Measurement of the consumption of oxygen and production of carbon dioxide are the basis for the measurement of heat production. Today, applications of indirect calorimetry are available in many species. Combining these measurements with accurate climate control, recording of physical activity and feed intake, use of stable isotopes and sophisticated modelling techniques allow scientists to make progress in various research areas. This book provides a scientific basis for indirect calorimetry, dealing with smart ways to design calorimeters, gas measurements and computational techniques to deal with complex data. Novel techniques allow the connection between short term changes in energy expenditure, protein turnover and substrate oxidation, e.g. using stable isotopes. Various applications of

Selection of animals for improved feed efficiency can affect sustainability of animal production because the most efficient animals may face difficulties coping with challenges. The objective of this study was to determine the effects of an inflammatory challenge (using an intravenous injection of complete Freund’s adjuvant – CFA) in piglets from two lines of pigs divergently selected during the fattening period for a low (RFI−) or a high (RFI+) residual feed intake (RFI; difference between actual feed intake and theoretical feed requirements). Nitrogen and energy balances (including heat production – HP – and its components: activity-related HP – AHP, thermic effect of feeding, and resting HP) were measured individually in thirteen 20-kg BW castrated male piglets (six and seven from RFI+ and RFI− line, respectively) fed at the same level (1.72 MJ ME/kg BW0.60 per day) from 3 days before to 3 days after CFA injection. Dynamics of dietary U-13C-glucose oxidation were estimated from measurements of 13CO2 production on the day before and 3 days after the CFA injection. Oxidation of dietary nutrients and lipogenesis were calculated based on HP and O2 consumption and CO2 production. The data were analyzed as repeated measurements within piglets in a mixed model. Before CFA injection, RFI− piglets had a lower resting energy expenditure than RFI+ piglets, which tended to increase energy retention because of a higher energy retention as fat. The CFA injection did not affect feed intake from the day following CFA injection onwards but it increased energy retention (P=0.04). Time to recover 50% of 13C from dietary glucose as expired 13CO2 was higher in RFI+ piglets before inducing inflammation but decreased after to the level of RFI− piglets (P

National audience; Vacuum concentration and drying are valuable techniques for the removal of water and the resulting stabilization of most dairy and feed ingredients. In this study, we present methodology to calculate and compare the energy consumption for the production of dairy and feed powders at different processing stages of the dehydration process. The results show that the energy costs to produce 1 kg of dairy and feed powders were 6,120 and 20,232 kJ · kg−1 powder for pregelatinized starch and soy protein concentrate, respectively. For dairy products, the values were 9,072 and 15,120 kJ · kg−1 for fat-filled and demineralized whey powders, respectively. According to the type of product (biochemical composition, ratio of bound and free water) and process (demineralization, vacuum evaporation, lactose crystallization, roller and spray drying), the energy consumption for the production of powders could be calculated. These findings could be valuable for studies focusing on improvement of energy efficiency for dairy and feed processes.

In milk-fed calves, quantification of the milk that enters the rumen (ruminal milk volume, RMV) because of malfunction of the esophageal groove reflex may explain part of the variability observed between animals in their growth performance. The RMV can directly be quantified by adding an indigestible marker to the diet and measuring its recovery in the rumen at slaughter, but this technique cannot be repeated in time in the same animal. The objective of the study was to evaluate three indirect methods for estimating RMV. The first method was based on the assumption that ruminal drinking delays and limits acetaminophen appearance in blood after ingestion of milk supplemented with acetaminophen. The second method was based on a negative linear relationship between RMV and urinary recovery of non-metabolizable monosaccharides (3-O-methylglucose, l-rhamnose and d-xylose) added to the milk, owing to rumen fermentation. In the third method, RMV was calculated as the difference between total milk intake and the increase in abomasal milk volume (AMV) at feeding, measured through ultrasonography shortly after feeding, or estimated from the mathematical extrapolation of AMV to feeding time, based on consecutive measurements. These methods were tested in three experiments where calves (n=22, 10 and 13) were bucket fed or partly tube fed (i.e. by inserting milk replacer into the rumen via a tube to mimic ruminal drinking). In addition, Co-EDTA and Cr-EDTA were used as an indigestible marker in one experiment to trace bucket-fed or tube-fed milk replacer, respectively, to measure RMV. The relationship between AMV measured by ultrasonography and AMV measured at slaughter improved when kinetics of AMV were extrapolated to the time of slaughter by mathematical modeling (error between predicted and measured AMV equaled 0.49 l). With this technique, RMV during feeding averaged 17% and 24% of intake in Experiments 2 and 3, respectively. Plasma acetaminophen kinetics and recovery of non-metabolizable monosaccharides in urine were partly associated with ruminal drinking, but these techniques are not considered quantitatively accurate without further information of rumen degradation and absorption. The recovery of indigestible marker measured at slaughter gave a quantitative estimate of RMV (2% in Experiment 3), but improper measurement of emptying rate of fluid from the rumen may lead to underestimation. In conclusion, measuring changes in AMV by ultrasonography, in response to milk feeding, was the most promising indirect method to quantify RMV in veal calves.

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Immunocastration (IC) has been studied as one of the possible replacements for surgical castration of male pigs to block reproductive function and eliminate boar taint. It has a positive effect on performance (Batorek et al., 2012) but after IC, increased feed intake (FI) and fat deposition indicate changes at the metabolic level. The objective of the study was to determine the effects of IC and increase of dietary fat on energy (E) metabolism and relationships between digested nutrients and their final outputs for catabolic and metabolic process in fattening pigs.

Fasting heat production (FHP) of animals is indicative of their basal metabolic rate and is used to estimate the maintenance energy requirements and for calculating the net energy value of feeds. However, estimates of FHP vary with experimental conditions, as well as with measurement and calculation methods. In addition, FHP is often related to metabolic body weight (MBW) with the idea that FHP per unit of MBW is constant for a given group of animals over a large BW range. For comparing FHP in adult animals of different species, MBW is frequently expressed as BW0.75 but validity of the 0.75 exponent has been questioned for growing animals (Noblet et al., 1999; Labussiere et al., 2008). The objective of this study is to combine FHP measurements obtained according to a common methodology in four species of growing monogastric farm animals (veal calves, pigs, turkeys and broilers).

International Symposium on Modelling in Pig and Poultry Production 2013; absent

In growing pigs, the feed cost accounts for more than 60% of total production costs. The determination of efficiency of energy utilization through calorimetry measurements is of importance to sustain suitable feeding practice. The objective of this paper is to describe a methodology to correct daily heat production (HP) obtained from measurements in respiration chamber for the difference in energy expenditure related to physical activity between animals. The calculation is based on a preliminary published approach for partitioning HP between HP due to physical activity (AHP), thermic effect of feeding (TEF) and basal metabolic rate (fasting HP; FHP). Measurements with male growing pigs [mean body weight (BW): 115 kg] which were surgically castrated (SC), castrated through immunization against GnRH (IC), or kept as entire male (EM) were used as an example. Animals were fed the same diet ad-libitum and were housed individually in two 12-m(3) open-circuit respiration chambers during 6 days when fed ad-libitum and one supplementary day when fasted. Physical activity was recorded through interruption of an infrared beam to detect standing and lying positions and with force transducers that recorded the mechanical force the animal exerted on the floor of the cage. Corrected AHP (AHPc), TEF (TEFc), and HP (HPc) were calculated to standardize the level of AHP between animals, assuming that the ratio between AHPc and ME intake should be constant. Inefficiency of energy utilization (sum of AHPc and TEFc) was lower than the inefficiency estimated from the slope of the classical relationship between HPc and ME intake but was associated with higher requirements for maintenance. Results indicate that EM pigs had higher FHP but lower TEFc than IC and SC pigs. These results agree with the higher contents in viscera of EM pigs that stimulate their basal metabolic rate and with the reduced utilization of dietary protein to provide energy for maintenance energy requirements and fat deposition (FD).

When based on productive traits, genetic selection does not account for ‘non-productive functions’ such as the animal’s defense systems. Two lines of pigs were divergently selected with a low (RFI-) or a high (RFI+) residual feed intake (RFI), which is calculated as the difference between the actual and the theoretical feed intake required for maintenance and growth (Gilbert et al., 2007). In healthy growing animals, the immune system has low nutritional requirements, which can dramatically increase during inflammation. Whether selection for RFI affects the ability to partition nutrients between growth and immune response is not known. The objective of this study is to compare results obtained in 2 experiments, where the effect of RFI on energy and protein utilization was evaluated in pigs subjected to an inflammatory challenge.

Variation is inherent to living systems. Because feeding strategies are applied to groups of pigs, it contributes to the inefficient use of natural resources and may even amplify the variation among pigs at slaughter. Precision pork production and precision feeding, through management of the variation among individuals, may contribute to improving the efficiency of animal production systems. This approach relies on the prediction of the response of the animal to the nutrient supply, the continuous monitoring of the response, and a system to control nutrient supply. Most nutritional models of pig growth are based on the partitioning of nutrients between energy expenditure, and protein and lipid deposition. However, the link between chemical body composition and tissue growth, tissue composition and thus carcass quality remains a challenge in modeling. The potential of precision pork production also depends on the (real-time) information that can be obtained to control growth and carcass quality.

International audience; 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.

International audience; Energy requirements for veal calves have not been updated recently despite the increased age at slaughter and the predominance of the Prim'Holstein breed in Europe. The objectives of this study were to determine the effects of four feeding levels (FLs) on protein and fat deposition and heat production in milk-fed calves at three stages of fattening and to determine energy requirements of calves. At each stage, 16 Prim'Holstein male calves (mean body weight (BW): 73.4, 151.6 and 237.4 kg) were fed a milk replacer at 79%, 87%, 95% or 103% of a reference FL. Measurements for one stage were conducted over 4 successive weeks in two open-circuit respiration chambers and consisted of a 6-day nitrogen and energy balance followed by a fasting day for estimating fasting heat production (FHP) of the calves. Heat production (HP) measurements were analyzed using a modeling approach to partition it between HP due to physical activity (AHP), feed intake (thermic effect of feeding (TEF)) and FHP There was no effect of FL and stage on apparent digestibility coefficients except for a tendency for increased digestibility coefficient of fat as animals got older The metabolizable energy (ME)/digestible energy (DE) ratio did not depend on FL but decreased (P < 0.01) as animals got older in connection with marked increases in urinary glucose and urea excretion. The AHP and TEF components of HP were not affected by stage or FL and averaged 8.4% and 7.8% of ME intake, respectively. The FHP, expressed per kg BW(0.85) increased with increasing FL, suggesting that also ME requirement for maintenance (ME(m)) may depend on FL. For an average intake of 625 kJ ME/kg BW(0.85) per day (95% of the reference FL), FHP was 298 kJ/kg BW(0.85) per day. Energy retention as protein and fat increased with increasing FL resulted in higher BW gain. But the rate of increase depended on stage of growth. The slope relating protein deposition to FL was lower in the finishing phase than in the growing phase, while the slope for lipid deposition was greater Protein and fat contents of BW gain were not affected by FL but increased as animals got older From these results, the energy requirements of veal calves are proposed according to a new approach, which considers that ME(m) (expressed per kg BW(0.85)) depends on ME intake (kJ/kg BW(0.85)) according to the following relationship: ME(m) = 197 + 0.25 X ME intake. The corresponding marginal efficiencies of ME utilization for protein and fat deposition are then 82% and 87%, respectively.

International audience; Research on veal calf production has focused on maximizing lean tissue growth. Nevertheless, limited attention has been paid to the evolution of digestive and metabolic utilization of N and energy as calves get older, whereas age at slaughter increases. The objective of this study was to determine the effects of 4 concentrations of dietary crude protein (CP) content on protein and fat deposition and energy utilization in milk-fed calves at 3 stages of fattening using the balance technique combined with heat production measurements in a respiration chamber. At each stage, 16 Prim'Holstein male calves ( mean body weight at each stage: 72, 136, and 212 kg) received 4 isocaloric diets with CP contents of 76, 88, 100, and 112% of a reference CP content fixed at 20% during the first stage and 19% during the 2 later stages. After 2 wk of adaptation to their respective diets and housing conditions, the calves were placed for 1 wk in an open-circuit respiration chamber for N and energy balance measurements ( first 6 d) and measurement of the fasting heat production ( last day). Measurements for a stage were performed over 2 periods of 4 successive weeks. There was no effect of dietary CP on digestibility during the 2 later stages, but the low-protein diet resulted in lower digestibility coefficients for dry matter, organic matter, gross energy, CP, and crude fat during the first stage. Endogenous fecal N was estimated as 2.5 g/kg of dry matter intake irrespective of stage, and metabolic urinary N was estimated at 0.07 g/kg of body weight(0.85) per day. Maximum N retention was 32.8, 40.5, and 44.0 g/d at stages 1, 2, and 3, respectively. The effect of protein intake on protein deposition was dependent on age of the calves, because the marginal efficiency of digestible protein utilization decreased from 64 to 18% as animals got older. Fat deposition decreased with increasing dietary CP content irrespective of stage. Total energy retention was not modified by dietary CP content. The composition of body weight gain was affected differently for each stage, because the protein content of body weight gain increased with increasing dietary CP content during the first stage, whereas it remained constant during the other 2 stages. Fat and energy content in body weight gain decreased with increasing dietary CP irrespective of stage. These results provide a basis for estimating protein requirement of veal calves according to a factorial approach.