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The cost of feed represents an important part of the total cost in swine and poultry production (>60%) with energy accounting for at least 70% of feed cost. The energy value of ingredients or compound feeds can be estimated as digestible (DE), metabolisable (ME) and net energy (NE) in pigs and ME and NE in poultry. The current paper reviews the different methods for evaluating DE, ME and NE of feeds for monogastric animals and their difficulties and limits, with a focus on NE. In pigs and poultry, energy digestibility depends on the chemical characteristics of the feed, but also on technology (pelleting, for instance) and animal factors such as their health and body weight. The ME value includes the energy losses in urine that are directly dependent on the proportion of dietary N excreted in urine resulting in the concept of ME adjusted for a zero N balance (MEn) in poultry. For poultry, the concept of true ME (TME, TMEn), which excludes the endogenous fecal and urinary energy losses from the excreta energy, was also developed. The measurement of dietary NE is more complex, and NE values of a given feed depend on the animal and environmental factors and also measurement and calculation methods. The combination of NE values of diets obtained under standardised conditions allows calculating NE prediction equations that are applicable to both ingredients and compound feeds. The abundance of energy concepts, especially for poultry, and the numerous feed and animal factors of variation related to energy digestibility or ME utilisation for NE suggest that attention must be paid to the experimental conditions for evaluating DE, ME or NE content. This also suggests the necessity of standardisations, one of them being, as implemented in pigs, an adjustment of ME values in poultry for an N retention representative of modern production conditions (MEs). In conclusion, this review illustrates that, in addition to numerous technical difficulties for evaluating energy in pigs and poultry, the absolute energy values depend on feed and animal factors, the environment, and the methods and concepts. Finally, as implemented in pigs, the use of NE values should be the objective of a more reliable energy system for poultry feeds.

The aim of this study was to evaluate the associated effects of ambient temperature and inflammation caused by repeated administration of Escherichia coli lipopolysaccharide (LPS) on insulin, energy, and AA metabolism. Twenty-eight pigs were assigned to one of the two thermal conditions: thermoneutral (24 °C) or high ambient temperature (30 °C). The experimental period lasted 17 d, which was divided into a 7-d period without LPS (days −7 to −1), and a subsequent 10-d LPS period (days 1 to 10) in which pigs were administered 5 repeated injections of LPS at 2-d intervals. Postprandial profiles of plasma insulin and nutrients were evaluated through serial blood samples taken on days −4 (P0), 4 (P1), and 8 (P2). Before the LPS-challenge (P0), postprandial concentrations of glucose, lactate, Gln, Ile, Leu, Phe, Tyr, and Val were greater in pigs kept at 24 °C than at 30 °C (P < 0.05). In contrast, Arg, Asp, Gly, His, and Met postprandial concentrations at P0 were lower at 24 °C than at 30 °C (P < 0.05). At both 24 and 30 °C conditions, pigs had greater postprandial concentrations of insulin (P < 0.01) and lower concentrations of NEFA (P < 0.01) and α-amino nitrogen (P < 0.05) at P1 and P2 than at P0. Compared with P0, postprandial concentrations of glucose were greater (P < 0.05) at P1 in pigs kept at 24 °C, and at P1 and P2 in pigs kept at 30 °C. At both ambient temperatures, pigs had lower (P < 0.05) postprandial concentrations of Ala, Gly, His, Ile, Leu, Pro, Ser, Thr, Trp, and Val at P1 and P2 than at P0. Arginine postprandial concentration at P1 was lower than at P0 in pigs kept at 24 °C (P < 0.05), whereas no difference was observed in pigs at 30 °C. Relative to P0, Gln and Tyr concentrations were lower at P1 and P2 in pigs kept at 24 °C (P < 0.01), whereas lower Gln concentration was observed only at P2 (P < 0.01) and lower Tyr only at P1 (P < 0.01) in pigs kept at 30 °C. Our study shows a hyperglycemic and hyperinsulinemic state in LPS-challenged pigs and a greater magnitude of this response in pigs kept at 30 °C. Furthermore, LPS caused important changes in BCAA, His, Thr, and Trp profiles, suggesting the role these AA in supporting the inflammatory response. Finally, our results suggest that LPS-induced effects on postprandial profiles of specific AA (Arg, Gln, Phe, and Tyr) may be modulated by ambient temperature.

Using accurate nutrient values for ingredients is of vital importance for efficient diet formulation. The net energy (NE) system accounts for the real available amount of feedstuff energy for body maintenance and production as it considers energy dissipated as heat increment. The NE content of diets for pigs and broilers has been estimated from their nutrient contents. However, such estimates have not been made specifically for laying hens. This study reports the development of equations to predict NE for laying hens based on the chemical composition of 16 different diets meeting minimum nutrient specifications but varying in nutrient composition. Heat production and energy metabolism were measured in layers ranging from 32 to 62 weeks of age in closed-circuit calorimetry chambers with 8 replicates per diet in a randomized design. Each replicate consisted of a chamber with 3 layers that were adapted for 4 D to diets and chambers prior to measurement. The measurements included feed intake, metabolizable energy (ME) content, nitrogen balance, egg production, gas exchange, heat production, energy efficiency, and energy partition for a 3-D period. The average AME/GE and NE/AME ratios of the 16 diets were 77 and 74%, respectively. The latter ratio increased with energy efficiency (EE) content and decreased with CP content of diets. The results indicate that diet NE content can be predicted from AME, CP, and EE contents and the NE/AME ratio varied positively with EE and negatively with CP. A validation experiment with 2 diets fed to layers in calorimetry chambers confirmed the estimation from NE prediction equations. In conclusion, NE of diets can be predicted in laying hens from equations based on AME and CP and EE contents in laying hens being similar to those reported in broilers.

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 aim of the study was to evaluate the consequences of a divergent selection for residual feed intake (RFI) during growth in a temperate environment (TEMP) on sow performance in a tropical environment (TROP). Sows came from a selection experiment conducted at INRA in which 2 lines were selected for larger (RFI(+)) or smaller (RFI(─)) feed intake than predicted from performance. In the first analysis, a subsample of data obtained in TROP conditions (49 lactations) was compared to those obtained in TEMP on their sibs mated with the same boars (54 lactations). In the second analysis, data obtained in the TROP environment (82 lactations) were analyzed for testing the effect of season (warm vs. hot) and line on sow performance. Except for the lactation length, the interaction between line and climatic environment was not significant for the others traits (P > 0.05). The ADFI expressed per kilogram of litter BW gain tended to be higher in the RFI(+) line bred in the TROP environment (P = 0.080), together with piglet BW at weaning, which tended to be lower (P = 0.080). The ADFI was lower in TROP than in TEMP (4.56 vs. 5.86 kg/d; P = 0.003), with negative consequence on litter BW gain and maternal BW loss. The RFI(-) sows tended to eat less feed than RFI(+) sows during lactation (4.55 vs. 5.86 kg/d; P = 0.099). Litter BW at weaning was higher in the RFI(─) line. The RFI(─) sows ate significantly less feed to produce 1 kg of litter than the RFI(+) sows and tended to lose a larger amount of BW during lactation than the RFI(+) sows (2.40 vs. 3.02 kg/kg and -0.66 vs. -0.39 kg/d, respectively, P < 0.10). Whatever the line, ADFI was reduced by about 21% in the hot season (P < 0.05). Litter BW gain was depressed (P < 0.05) in the hot season (1.72 vs. 2.08 kg/d in the warm season; P = 0.023). Lactation maternal BW loss tended to increase in the hot season (1.10 vs. 0.71 kg/d in the warm season; P = 0.016), but back fat loss remained constant (P = 0.295). In the TROP environment, the amount of feed required to produce 1 kg of litter was not influenced by the line in the warm season (2.53 kg/kg on average; P = 0.99), but it tended to be lower in the RFI(─) line when compared to the RFI(+) line in the hot season (2.06 vs. 3.45 kg/kg; P = 0.050). This higher apparent efficiency in RFI(─) sows was mainly related to greater maternal body reserve mobilization (i.e., BW and back fat losses). In conclusion, selection for low RFI during growth in a TEMP environment did not impair sow and litter performance in tropical conditions.

Chantier qualité GA; Total tract digestive utilization of cassava (Manihot esculenta) leaves and leaves + stems, sweet potatoes (Ipomoea batatas) leaves and leaves + stems, cocoyam (Xanthosoma sagittifolium) leaves, and erythrina (Erythrina glauca) leaves was studied in three simultaneous Latin square designs with a total of nine castrated Creole growing pigs. Each dried foliage was included at 200 g/kg in a basal maize-soybean meal diet (MSBM) and the difference method was used to calculate the nutritional value of each of the six foliages. These leaves were characterized by a high fibre content and the presence of some anti-nutritional factors (such as tannins, 0.8–3.1%). Each of the foliage diets was measured on three animals (nine for the MSBM diet). Rate of passage variables of diets were also determined using a pulse dose of ytterbium. Mean retention time in the gastrointestinal tract was shorter (P0.05) for cassava and sweet potatoes. It is concluded that the high fibre content in addition to the presence of tannins are the main limiting factors of these tropical foliages in pig nutrition with a subsequent low energy value.

Castrated males from 2 lines of purebred French Large White obtained from a divergent selection experiment for their residual feed intake (RFI) over 7 generations were measured for their energy utilization during thermal acclimation to increased ambient temperature. The RFI(+) line consumed more feed than predicted from its performance, whereas the RFI- line consumed less feed. Each pig was exposed to 24°C for 7 d (P0) and thereafter to a constant temperature of 32°C for 3 consecutive periods of 7 d (P1, P2, P3). Feed intake, feeding behavior parameters, digestibility, components of heat production (HP; measured by indirect calorimetry in respiration chambers), and energy, nitrogen, fat, and water balance were measured in pigs offered feed and water ad libitum and individually housed in respiratory chambers. Two identical respiratory chambers were simultaneously used, and 5 pigs of each line were measured successively. Whatever the trait, the interaction between line and period was not significant (P > 0.10). On average, ADFI was greater in the RFI+ than in the RFI- line (1,945 vs. 1,639 g/d; P = 0.051) in relation to an increase of the mean size of each feeding bout (128 vs. 82 g/visit; P < 0.001). There was no line effect on nutrient and energy digestibility. Total HP tended to be greater in RFI+ than in RFI- lines (1,279 vs. 1,137 kJ·kg BW-0.60·d-1; P = 0.065), which tended to retain more energy (968 vs. 798 kJ·kg BW-0.60·d-1; P = 0.050). The sensible heat loss was greater in RFI+ compared with the RFI- line (644 vs. 560 kJ·kg BW-0.60·d-1; P = 0.020). The RFI+ pigs consumed more water (+981 vs. 657 g·kg BW-0.60·d-1; P = 0.085) and produced more urine (589 vs. 292 g·kg BW-0.60·d-1; P < 0.001) than RFI- pigs, whereas water evaporation was similar for both lines. On average, ME intake and HP declined by about 38% and 20%, respectively, from P0 to P1 (P < 0.001). In contrast to ME intake, HP gradually decreased (P < 0.05) from P1 to P3 in connection with a reduction of the activity related HP. The evaporative heat loss represented 30% on the total heat loss on P0, and this proportion significantly increased on P1 (61%; P < 0.001) and remained constant thereafter. In conclusion, our results suggest that thermal heat acclimation in pigs is mainly related to a biphasic reduction of HP rather than a change in the ability of losing heat, and it did not significantly differ between RFI+ and RFI- lines despite a decreased HP in the latter ones.

The aim of this study was to assess the effect of feed restriction applied to immunocastrated pigs in the period after the second vaccination (V2) against GnRH on hormonal status, performance, car- cass traits, and meat quality. Immunocastrated pigs (IC) were compared with entire males (EM) and surgical castrates fed ad libitum. Pigs (Large White × Landrace) × Pietrain were either left entire or surgically castrated within 1 wk after birth (SC, n = 22). At 83 d of age, the entire males were further allotted to treatment groups (individual housing) of ad libitum fed EM (n = 24), ad libitum fed IC (IC-L, n = 21), or restrictively fed IC (IC-R, n = 21). At that time, the fi rst vaccination (V1) was applied to IC-L and IC-R pigs. One week after V2 (age 130 d), feed restriction (≈80% of the ad libitum feed intake of SC pigs) was applied to IC-R pigs. The experiment ended 5 wk after V2, when pigs were 165 d old. Immunocastration successfully reduced boar taint compounds and size of reproductive organs. At 130 d, serum leptin concentrations were similar in all groups, whereas IGF-I concentration was less in SC (P ≤ 0.002) than in the other groups. Three weeks after V2, leptin concentrations of both IC groups were in between EM (least) and SC (greatest). The reverse was observed for IGF-I. Feed restriction had no effect on leptin or IGF-I concentrations in IC pigs. In the period V1 to V2, per- formance differed mainly between EM and SC, whereas both IC groups had feed intake and feed conversion ratio similar to EM and intermediate daily BW gain, not differing from either EM or SC. After V2, IC-L pigs increased their feed intake to the concentrations of SC, with faster growth compared with the other 3 groups (P < 0.05) and fatter carcasses compared with EM pigs (P = 0.007). Similar performance and carcass leanness were observed for IC-R and EM pigs. During preslaughter handling more carcass lesions were noted in EM and IC-R than in IC-L or SC pigs (P < 0.002). Neither immu- nocastration nor feed restriction had any effect on meat quality, but EM had greater drip loss, less intramuscular fat, and decreased tenderness than SC pigs. In conclu- sion, restricting feed intake can increase production effi ciency but also aggressiveness of IC pigs.

The effect of dietary NE content on feed intake and performance of pigs was investigated using crossbred barrows with initial and final BW of approximately 35 and 110 kg, respectively. Pigs were housed individually and allowed ad libitum access to feed. Pigs were randomly allotted to 6 wheat and soybean meal-based diets (8.1, 8.7, 9.3, 9.9, 10.5, and 11.1 MJ NE/kg) with 16 pigs/diet. Ratios between standardized ileal digestible AA and NE were similar in all diets. Over the entire experiment, increase in dietary NE concentration was associated with a decreased ADFI (3.216, 3.216, 3.122, 2.910, 2.732, and 2.684 kg/d, respectively, for diets containing 8.1 to 11.1 MJ NE/kg; linear, P < 0.01). The NE intake increased as dietary NE increased from 8.1 to 11.1 MJ NE/kg (26.04, 27.98, 29.03, 28.81, 28.68, and 29.77 MJ/d, respectively; linear, P < 0.01, and quadratic, P = 0.06). Average daily gain increased when dietary NE concentration increased (1.046, 1.126, 1.135, 1.177, 1.156, and 1.152 kg/d, respectively, for diets containing 8.1 to 11.1 MJ NE/kg; linear and quadratic, P < 0.01). The increase in dietary NE concentration was associated with an increase in dressing percentage (76.5, 77.0, 77.4, 78.0, 78.2, and 78.4% of BW; linear, P < 0.01) but no differences in lean percentage (58.3, 57.9, 58.0, 57.3, 58.1, and 56.4% of HCW, respectively, for diets containing 8.1 to 11.1 MJ NE/kg; P = 0.12). When dietary NE concentration increased from 8.1 to 11.1 MJ/kg, the G:F increased (0.326, 0.352, 0.364, 0.405, 0.425, and 0.428 kg/kg, respectively; linear, P < 0.01), but the G:F expressed using the NE system did not change (G:F, 39.97 g/MJ NE; P = 0.44). When adjusted to the same dressing yield and lean percentage, the differences in adjusted ADG increased among treatments, but the adjusted G:F expressed using the NE system was not influenced by dietary energy concentration. These results confirm the ability of individually housed pigs to adjust their spontaneous feed intake over a very wide range of NE concentrations (8.7 to 10.5 MJ/kg). Under commercial conditions, pigs may experience less variation in ADFI than the results obtained in this experiment because of differences in dietary energy concentrations. However, it seems that only a severe reduction in dietary energy concentration will be effective in restricting energy intake of pigs that are allowed ad libitum access to feed.

Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 ± 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 ± 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.

Two experiments were conducted to determine the total tract digestibility of energy and the DE and ME values of 10 European wheat dried distillers grains with solubles (DDGS) fed to growing pigs and adult sows. The wheat DDGS were obtained from European ethanol plants and selected to get a large variability. One control diet, based on wheat (87.2%), soybean meal (10.0%), and minerals and vitamins, and 10 experimental diets prepared from the control diet and 25% each of the 10 sources of DDGS, were fed to 66 crossbred barrows (6 per diet) according to a factorial arrangement or 6 adult sows according to a pseudo Latin square design. Animals were placed in metabolism cages that allowed for the total, but separate, collection of feces and urine for 8 to 10 d after a 7- to 11-d adaptation period. By subtracting the contribution from the control diet in the DDGS-containing diets (i.e., difference method), N and GE digestibilities and DE and ME values for each source of DDGS were calculated. The energy digestibility in wheat DDGS averaged 66.5% (56.3 to 76.0%) and 71.2% (59.7 to 78.2%) in growing pigs and adult sows, respectively. Consequently, average (range) DE values of DDGS were 14.0 (11.8 to 16.2) and 14.9 (12.5 to 16.4) MJ/kg of DM for growing pigs and adult sows, respectively. Our data show that DE content of wheat DDGS can be predicted from their ADF content or from the lightness score (L). By excluding the dark and overheated samples (L

Genetic selection on residual feed intake (RFI) can be used as an alternative method to G: F to improve feed efficiency in pigs. The objective of this study was to determine the effects of selection for RFI on digestive and metabolic utilization of energy in 2 lines of purebred French Large White castrated male pigs obtained from a divergent selection experiment over 6 generations. The RFI(+) (high RFI) line consumed more feed than predicted from performance compared with the RFI(-) (low RFI) line. Digestibility of energy and nutrients, total heat production (HP), HP related to physical activity, and energy and N balance were measured in respiration chambers for a 6-d period in pigs offered feed ad libitum. Pigs remained in the chamber for an additional day and did not receive any feed to estimate the fasting HP and calculate the thermic effect of feeding. Five pairs of 2 littermates from the same farrowing batch were used in each line. Because 2 respiration chambers were available for the trial, pigs were measured regularly during the 25- to 95-kg growing period. Two pigs per chamber were used until pigs reached 45 kg of BW, and 1 pig per chamber was used thereafter. Individual feed intake and BW gain were measured continuously from weaning to the end of the trial. Pigs were fed 3 diets with decreasing CP contents during the 25 to 45 (period 1), 45 to 65 (period 2), and 65 to 95 (period 3) kg of BW periods. Average daily feed intake was greater in RFI(+) pigs than in RFI(-) pigs between 25 and 65 kg of BW (2,128 vs. 1,891 g/d; P < 0.01) and G: F was 8% greater in RFI(-) pigs compared with RFI(+) pigs (P < 0.01). There was no line effect on digestibility coefficients or N retention, irrespective of the experimental period studied. Nitrogen retention was 31.2, 28.7, and 20.8 g/d at periods 1, 2, and 3, respectively (P < 0.001). The HP was greater in RFI(+) pigs than in RFI(-) pigs (1,497 vs. 1,383 kJ.kg of BW(-0.60).d(-1); P < 0.01), with no subsequent line effect on energy retention. The activity-related HP tended to be greater in RFI(+) pigs than in RFI(-) pigs (250 vs. 218 kJ.kg of BW(-0.60).d(-1); P = 0.09), and the fasting HP was 10% greater (P = 0.04) in RFI(+) pigs than in RFI(-) pigs (846 vs. 771 kJ.kg of BW(-0.60).d(-1)). The thermic effect of feeding, expressed as a percentage of ME intake, was the same for both lines of pigs (average, 14.7%). In conclusion, the RFI(+) pigs are energetically less efficient because of their greater HP related to physical activity and basal metabolic rate.

Eighty-six mixed-parity Large White sows were used to determine the effect of diets with reduced CP content or supplemented with essential AA on 28-d lactation performance under humid tropical climatic conditions. This experiment was conducted in Guadeloupe (West French Indies, latitude 16°N, longi- tude 61°W) between February 2007 and January 2008. Two seasons were distinguished a posteriori from cli- matic measurement variables continuously recorded in the farrowing room. The average minimum and maxi- mum ambient temperatures and average daily relative humidity for the warm season were 20.5 and 28.2°C, and 93.8%, respectively. The corresponding values for the hot season were 22.7 and 29.4°C, and 93.7%, re- spectively. The dietary experimental treatments were a normal protein diet (NP), a low protein diet (LP), and a NP diet (NP+) supplemented with essential AA. The NP and LP diets supplied the same levels of standard- ized digestible Lys (i.e., 0.80 g/MJ of NE), and the NP+ diet supplied 0.95 g/MJ of NE. No interaction between season and diet composition was noted on any response variable evaluated. The ADFI was decreased (P 0.08). In conclusion, the hot season in humid tropi- cal climates, which combines high levels of temperature and humidity, has a pronounced negative impact on performance of lactating sows. Diets with low CP con- tent or supplemented with essential AA can attenuate the effects of hot and humid season by increasing ADFI in lactating sows.

Forty-seven mixed-parity Large White sows were used to determine the effect of diets with reduced CP content or supplemented with essential AA on 28-d lactation feeding behavior under humid tropical climatic conditions. The study was conducted at the INRA experimental facilities in Guadeloupe, French West Indies (latitude 16 degrees N, longitude 61 degrees W) between February 2007 and January 2008. Two seasons were distinguished a posteriori from climatic measurements continuously recorded in the open-front farrowing room. The average ambient temperature and average daily relative humidity for the warm season were 23.6 degrees C and 93.8%, respectively. The corresponding values for the hot season were 26.1 degrees C and 93.7%. The dietary experimental treatments were a normal protein diet (17.3%), a low protein diet (14.1%), and a normal protein diet supplemented with essential AA (17.6%). No interaction between season and diet composition was found for all criteria. Average daily feed intake was less (P 0.10) by season or diet composition. Daily feed intake was greater for the sows fed the low protein diet when compared with normal protein treatments (P 0.05), and averaged 126 +/- 35 min/d. This study confirms that feeding behavior variables of the lactating sow are affected by seasonal pavariations of the tropical climate. Irrespective of season, the reduction of CP content improved feed consumption under tropical conditions.

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.

Parallèlement à l’accroissement rapide de la demande d’éthanol, essentiellement à base de blé en Europe, la disponibilité pour l’alimentation des animaux d’élevage des coproduits associés, tels que les drêches de blé s’est accrue. La synthèse réalisée dresse le profil moyen de la composition des drêches de blé et indique l’existence d’une forte variabilité de la composition des drêches pour certains paramètres. Ces modifications du profil moyen dépendent des spécificités de traitement du produit. La variabilité est ainsi très importante pour la teneur en parois végétales (NDF) et en amidon dont les teneurs moyennes (min-max) sont respectivement de 28 (23-33) et 4,7 (2,1-10,3)% de la MS. Les teneurs moyennes en énergie digestible de 14,2 MJ d’ED/kg MS et en phosphore digestible de 0,60% MS illustrent le potentiel des drêches pour l’alimentation des porcs. Ces valeurs varient selon les sources (12,8 à 16,0 MJ/kg pour l’ED). La teneur en lysine des protéines (0,83 à 3,0%) et la digestibilité iléale standardisée de la lysine (49 à 72%) sont les paramètres les plus variables, vraisemblablement en lien avec le procédé mis en œuvre (séchage notamment). La prise en compte des caractéristiques physiques (odeur et couleur) devrait permettre de prédire la valeur nutritionnelle et de conduire à l’inclusion de drêches à des niveaux plus importants dans l’aliment des porcs.

International audience; From results obtained over the last 20 years on energy and amino acid utilisation in reproductive sows, it has become possible to improve the determination of nutrient requirements (factorial approach) and the prediction of an animal's response to nutrient supplies (modelling). The objective of this project was to integrate the current state of knowledge in a nutritional model for growing pigs and for sows and make it available as a software tool to end-users, mainly nutritionists involved in the pig industry and students in animal nutrition. The aim of this paper is to describe the basis of the sow model. The sow is represented as different compartments that change over the reproductive cycle. Nutrient flows considered are those of energy and digestible amino acids. Nutrients are used with the highest priority for maintenance and uterine growth or milk production. Subsequently, deposition and/or mobilisation of body proteins and lipids are determined and used for estimating the changes in body weight and backfat thickness of the sow. A decision support tool was built from the set of equations given, with additional modules to describe animal's characteristics and adjust some model parameters to account for variations in genotypes and performance. This tool can be used to determine energy and amino acids requirements of sows according to production objectives, or to predict body composition changes according to a given feeding strategy. The use of the decision support tool is illustrated through some examples. (C) 2007 Published by Elsevier B.V.

The effects of season (hot vs. warm) in a tropical humid climate, parity (primiparous vs. multiparous) and breed (Creole: CR, Large White: LW) on rectal temperature (RT) were studied for a total of 222 lactations obtained in 85 sows (43 CR and 42 LW; 56 primiparous and 166 multiparous) over a 28-d lactation, between June 2002 and April 2005. Mean daily ambient temperature was higher during the hot season than during the warm season (26.0 vs. 24.1°C) and relative humidity was high and similar in both seasons (89% on average). At farrowing, BW was lower (172 vs. 233 kg) and backfat thickness was higher (37 vs. 21 mm) in CR than in LW sows (p

Corrigendum in [Anim. Feed Sci. Technol., vol. 159, 3-4, (2010) p.156] : modification de la table 2; International audience; The method of Boisen and Fernandez [Boisen, S., Fernandez, J.A., 1997. Prediction of total tract digestibility of energy in feedstuffs and pig diets by in vitro analyses, Anim. Feed Sci. Technol. 68, 277-286] for measuring in vitro fecal digestibility of organic matter (OMdv) or in vitro digestible organic matter content (DOMv, g/kg) was used on 113 compound feeds (79 as mash and 34 as pellets) and 66 ingredients (as mash) whose digestibility of organic matter (OMd) and energy (Ed) and digestible energy content (DE, MJ/kg) had been measured in 60 kg growing pigs for all compound feeds and ingredients, and in adult sows for about 2/3 of the compound feeds (as mash); net energy (NE, MJ/kg) of these feeds were estimated from digestibility information. The repeatability and accuracy of the method were evaluated. Data obtained on compound feeds fed as mash were used to establish prediction equations of OMd, Ed, DE NE from OMdv or DOMv and chemical criteria. The levels of accuracy and repeatability of OMdv measurement were satisfactory and values for OMdv and OMd of mash compound feeds were very close and highly correlated (r = 0.91). Apart from OMdv, the best prediction equations of OMd or Ed included ash content and a cell wall criterion (ADF or crude fiber); for prediction of DE, fat content had also to be considered. The coefficient of variation of all equations was below 0.02. The equations allow a satisfactory prediction of OMd, Ed or DE of the 66 ingredients fed as mash. However, the equations established on data obtained on mash feeds underestimate the in vivo nutritional value of pelleted feeds and are not applicable to prediction of energy value of feeds for adult pigs.

The impact of dietary fiber on fecal digestion is well-known and provides a comprehensive approach toward nutrient digestibility and availability. Little quantitative information is available on digestion of fiber in the different segments of the gastrointestinal tract (GIT). The objectives of this study were to obtain a method allowing the quantification of the digestive process in different segments of the GIT and to study the impact of dietary fiber on nutrient digestibility. Six barrows (average initial BW of 30 kg and fitted with a simple T-cannula at the proximal duodenum and caudal ileum) were used in a replicated 3 x 3 Latin square design. In each period, pigs were offered 1 of 3 diets differing in fiber content (low, medium, and high). Differences in fiber content were created by replacing wheat and barley with wheat bran. Titanium dioxide was included in the diet as an indigestible marker to determine the apparent digestibility coefficients in different segments of the GIT. The apparent digestibility of ash, CP, DM, and OM increased in the different segments of the GIT. Duodenal digestibility coefficients were negative for ash (e.g., -39.9% for the medium- and high-fiber diets), indicating important endogenous mineral secretions by the stomach and digestive glands. The duodenal digestibility of other nutrients and OM were positive but close to zero and numerically lower in the diets with the greater fiber contents. The fiber content in the diet did not affect the apparent ileal digestibility of nutrients. Increasing the fiber content in the diet affected the fecal digestibility of CP, ether extract, and energy (P < 0.01). The method used for studying sites of digestion in the digestive tract provides promising results, but it is limited due to the high variability that is likely caused by sampling limitations and variation between animals.

The effect of breed [Creole (CR) vs. Large White (LW)] on performance and physiological responses during acclimation to high ambient temperature was studied in 2 experiments involving 24 (12/breed) growing pigs each. Pigs were exposed to 24 degrees C for 10 d (d -10 to -1) and thereafter to a constant temperature of 31 degrees C for 16 d (d 1 to d 16) in Exp. 1 and for 20 d (d 1 to d 20) in Exp. 2. For both experiments, the temperature change was achieved over 4 h on d 0. The first experiment began at 105 d of age, and the average BW of CR and LW pigs was 36.6 +/- 2.5 kg and 51.7 +/- 3.0 kg, respectively. The second experiment was designed to compare both breeds at a similar BW (about 52 kg on d 0). Pigs were individually housed and given ad libitum access to feed. At 24 degrees C, ADG was lower (P < 0.01) in CR than in LW (602 vs. 913 g/d and 605 vs. 862 g/d in Exp. 1 and 2, respectively), but the ADFI was not affected by breed (190 and 221 g x d(-1) x kg(-0.60) in Exp. 1 and 2, respectively). Short-term thermoregulatory responses during the 4-h transition from 24 to 31 degrees C (d 0) were analyzed according to a linear plateau model to determine the break point temperature, above which rectal temperature (RT), cutaneous temperature (CT), and respiratory rate (RR) began to change. The CT increased linearly with temperature increase (0.22 degrees C/ degrees C) and was less (P < 0.05) in CR than in LW (by -0.3 degrees C on average). In both experiments, the break point temperature for RT was not affected by breed (27.6 degrees C on average), whereas for RR it was greater (P < 0.05) in CR than in LW (27.5 vs. 25.5 degrees C, P < 0.01). On average, ADFI declined by about 50 g x d(-1) x kg(-0.60) from d -1 to d 1 (P < 0.01), and thereafter at 31 degrees C, it gradually increased (23 g x d(-1) x kg(-0.60); P < 0.05), suggesting an acclimation to high exposure. This response was not influenced by breed. After the day that marked the beginning of the acclimation response (i.e., the threshold day), RR, CT, and RT declined over the duration of exposure to 31 degrees C (P < 0.05) in both experiments. During this period, RT and CT were less in CR than in LW pigs (39.6 vs. 39.9 degrees C and 37.9 vs. 38.2 degrees C, respectively; P < 0.05), whereas RR was not affected by breed. The threshold day at which RT began to decline was less in CR than in LW pigs (0.18 vs. 1.17 d and 0.39 vs. 0.93 d in Exp. 1 and 2, respectively; P < 0.05). In conclusion, this study suggests that short- and long-term physiological reactions during heat acclimation differed when CR and LW pigs were compared at the same age or BW.

Twenty-four castrated males were used to study the effect of breed (Large Whitev. Creole (LWv. CR)) and feeding level (0·70, 0·80, 0·90, and 1·00 ad libitum) on growth performance and protein deposition (PD) and lipid deposition (LD) between 30 and 60 kg in growing pigs under tropical climatic conditions; the CR pigs are raised in the Caribbean area and can be qualified as fat and slow growing pigs. Daily protein and amino acids supplies were calculated to be non-limiting for protein gain. Total PD and LD were measured according to the comparative slaughter technique. Digestibility coefficients of energy and nutrients were estimated over a 10-day period at 45 kg live weight. Neither the breed nor the feeding level influenced the apparent digestibility coefficients of dietary nutrients; only energy digestibility was increased at reduced feeding levels (Pv. 36·6 g per additional MJ ME). The food conversion ratio was not affected by feeding level but it was significantly higher in CR than in LW pigs (2·88v. 2·36 kg /kg;Pv. 4·2 g/MJ ME in CR and LW pigs, respectively;Pv. 6·4 g/MJ and 0·40v. 0·36 MJ/ MJ ME, respectively;P

A total of 179 lactations obtained on 71 multiparous sows [30 Creole (CR) and 41 Large White (LW)] between June 2001 and July 2004 were used to determine effects of breed (CR vs. LW) and season (hot vs. warm) in a tropical humid climate on performance during a 28-d lactation period. Mean daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8 degrees C), and relative humidity was similar in both seasons (85% on average). For both breeds, ADFI was reduced (-700 g/d, P < 0.01), sow BW loss was greater (17 vs. 12 kg, P < 0.01), and piglet growth was reduced (197 vs. 210 g/d, P < 0.05) during the hot vs. the warm season. At farrowing, LW sows were heavier (255 vs. 186 kg, P < 0.01) and had less backfat (21 vs. 40 mm, P < 0.01) than CR sows. The growth rate of CR piglets was lower than that of LW piglets (192 vs. 215 g/d, P < 0.01). A breed x season interaction was observed (P < 0.05) for ADFI and sow BW loss. During the hot season, the reduction of ADFI was more pronounced in LW than in CR sows (-910 vs. -470 g/d). Regardless of the season, BW loss of CR sows remained constant (14.2 kg), whereas it increased during the hot season for LW sows (10 kg). The weaning-to-estrus and the weaning-to-conception intervals were not affected by breed or season and averaged 4.8 and 6.1 d, respectively. The rectal temperature was greater (0.3 degrees C) during the hot season than during the warm season and greater in LW than in CR sows (39.1 vs. 38.8 degrees C, P < 0.10). This study confirms the negative effect of hot season in a tropical humid climate on performance of lactating sows and that breed can have a significant effect on lactation performance. The results also suggest that CR sows are more heat tolerant than LW sows.

The effects of breed and season on performance and feeding behavior were studied during 76 lactations in multiparous Large White (LW; n = 17) and Creole (CR; n = 23) sows reared in a humid tropical climate. The experiment was conducted in Guadeloupe (French West Indies, latitude 16 degrees N, longitude 61 degrees W) between May 2002 and July 2004. Average daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8 degrees C), but relative humidity was similar in both seasons (85% on average). The daily fluctuations of ambient temperature and relative humidity were similar for both seasons. At farrowing, BW was lower (187 vs. 265 kg) and backfat thickness was greater (40 vs. 22 mm) in CR than in LW sows (P < 0.01). Sows were offered feed ad libitum between the fifth and the 26th day of lactation. There was a breed x season interaction (P < 0.05) for ADFI. During the hot season the reduction of ADFI was more pronounced in LW than in CR sows (-1,100 vs. -300 g/d). Irrespective of breed and season, the daily number of meals was 9.0. The meal size and the rate of feed intake were greater in LW than in CR sows, respectively (555 g and 153 g/min vs. 390 g and 83 g/min; P < 0.01). The diurnal proportion of ADFI was greater in CR than in LW sows (0.60 vs. 0.41; P < 0.01). The reduction in ADFI in LW sows during the hot season was mainly related to a reduction in feed intake during the day rather than during the night (-1.3 vs. -0.2 kg; P < 0.01). Duration of standing was not affected by breed or season, and it averaged 120 min/day. This study confirms the negative effect of the hot season on feeding behavior of lactating sows. It also suggests a better acclimation to daily high temperatures and a greater heat tolerance in CR compared with LW sows, at least for eating behavior.

The effects of season in a tropical climate and parity on lactation performance of 106 Large White sows over several reproductive cycles (301 lactations in total) were studied in Guadeloupe (French West Indies, 16°N latitude, 61°W longitude) between January 1999 and March 2003. Two seasons were determined a posteriori from climatic parameters recorded continuously in a station close to the experimental unit. During the warm season, ambient temperature and relative humidity averaged 23-5°C and 0-831, respectively. In the hot season, the corresponding values were 26-0°C and 0-834, respectively. Over the 28-day lactation period, average daily food intake (ADFI) was lower (P < 0-001) and live-weight (LW) loss was higher (P < 0-05) during the hot season than during the warm season (3-9 v. 4-7 kg/day and 17 v. 12 kg, respectively). Growth rate and mean LW of piglets at weaning were lower (P < 0-05) during the hot season (203 v. 220 g/day and 7-0 v. 7-5 kg, respectively). However, the weaning-to-oestrus interval was not affected by season (5-4 days on average). The effect of season on ad libitum ADFI was less accentuated for primiparous than for multiparous sows (warm-hot 360 v. 2002 g/day). Irrespective of the season, ADFI was lower (P < 0-01) and piglet growth rate tended to be lower (P < 0-2) in primiparous than in multiparous sows (4-0 v. 4-4 kg/day and 205 v. 215 g/day, respectively). Moreover, the percentage of sows that returned to oestrus later than 5 days after weaning was higher in primiparous than in multiparous sows (25 v. 2%, P < 0-001). This study confirmed the negative effects of the hot season on performance of lactating sows raised in a humid tropical climate; the effects of season are dependent on parity number.

Twelve multiparous sows with an average initial weight of 182 kg were used in a randomized complete block design to determine the effects of feeding Carnichrome (50 mg of carnitine and 200 microg of chromium picolinate per kilogram of feed, as fed) on energy and nitrogen utilization in early, mid-, and late gestation. All sows were fed a diet with or without Carnichrome for the preceding 28-d lactation, the weaning-to-estrus period, and for the duration of gestation. Daily feeding allowances over pregnancy were based on calculated energy and nutrient requirements to achieve a target sow maternal weight gain of 20 kg and remained constant throughout gestation. Heat production (HP) and its partitioning (activity, thermic effect of feeding short term [TEFst], basal) were determined in early (wk 5 or 6), mid- (wk 9 or 10), and late (wk 14 or 15) pregnancy using indirect calorimetry. Net maternal weight gain and total number of fetuses averaged 21.6 kg and 16.4, respectively. Organic matter and energy digestibility for the Carnichrome diet was greater (P < 0.05), which resulted in greater DE and ME contents (0.6%, P < 0.05) compared with the control diet. The digestibility coefficient of energy in the current experiment for a typical corn and soybean meal diet (92%) was greater than that predicted from DE values of corn and soybean meal in feeding tables (88%). Carnichrome had no effect on total HP, energy retained as protein or lipid, and maternal energy retention in early, mid-, or late gestation. Heat production in late gestation increased linearly (4.0 kJ/[kg BW0.75 x d]) for each additional day from d 90 to 110, despite the reduction of ME intake per unit of BW0.75. Metabolizable energy requirement for maintenance was 405 kJ/(kg BW0.75 x d). On average, activity HP was 116 kJ/(kg BW0.75 x d), which was equivalent to 20% of ME intake; however, this value ranged from 11 to 37% between sows, which corresponds to duration of standing ranging from 210 to 490 min/d. Energy cost of standing activity averaged 0.30 kJ/(kg BW0.75 x min). In conclusion, Carnichrome had no effect on the components of heat production and maternal weight gain during gestation, although it improved energy and organic matter digestibility of the diet.

Sixty-two multiparous Large White sows were used to determine the effect of dietary fiber level on lactation performance according to season under conditions of a humid tropical climate. This experiment was conducted in Guadeloupe (West French Indies, lat 16 degrees N, long 61 degrees W) between October 1999 and January 2001. Two seasons were distinguished a posteriori from climatic measurements parameters continuously recorded in the farrowing room. During the warm season, ambient temperature and relative humidity averaged 25 degrees C and 86.8%, respectively. The corresponding values for the hot season were 27.5 degrees C and 83.5%. Experimental diets fed during lactation were a control diet (C; 14% neutral detergent fiber) and a high-fiber diet (HF; 20% neutral detergent fiber) obtained by substitution of wheat middlings by wheat bran. The two diets were formulated to provide the same ratios between essential amino acids and lysine and between lysine and net energy. No interaction between season and diet composition was found for all criteria studied. Over the 28-d lactation, average daily feed intake (ADFI) was lower and body weight loss was higher (P < 0.001) during the hot season compared to the warm season (3,447 vs 4,907 g/d and 33 vs 17 kg, respectively). The number of stillborn piglets was higher (P < 0.05) during the hot season than during the warm season (2.0 vs 1.1 piglets, respectively). Litter growth rate and mean BW of piglets at weaning were reduced (P < 0.01) during the hot season vs the warm season (2.1 vs 2.3 kg/d and 7.7 vs 8.3 kg, respectively). The ADFI was similar for both diets and digestible energy (DE) intake tended to be lower (P = 0.06) with the HF diet (54.9 vs 59.3 MJ of DE/d for C sows) in relation with its lower DE concentration. The body weight loss was greater (P < 0.01) for HF sows than for C sows (30 vs 21 kg). Compared with the C diet, the HF diet increased (P < 0.05) litter growth rate and piglet body weight at weaning (2.3 vs 2.1 kg/d and 8.3 vs 7.7 kg/d for HF vs C, respectively). Season and diet composition did not affect the weaning-to-estrus interval. In conclusion, the hot season in humid tropical climates, which combines high levels of temperature and humidity, has a major negative effect on the performance of lactating sows.

Two groups of three multiparous Large White x Landrace sows were used to investigate the direct effect of ambient temperature on mammary gland metabolism. Sows from the first group were exposed to temperatures of 28 degrees C between d 8 and 14 of lactation, and 20 degrees C between d 15 and 21; treatments were reversed in the second group. Four to six d after farrowing, an ultrasonic blood flow probe was implanted around the right external pudic artery and catheters were fitted in the right anterior mammary vein and in the carotid artery. After surgery all sows were fed 3.8 kg/d of a lactation diet. The arteriovenous (AV, mg/L) plasma samples were obtained every 30 min between 0915 and 1545 on d 5 of exposure to ambient temperature; the same day, milk samples were collected at 1630. Additional arterial samples were obtained between 1000 and 1100 on d 1, 4, and 6 of exposure. Milk yield was estimated from the body weight gain of the litter. Elevated temperature tended to reduce BW loss (2.44 vs 1.82 kg/d, P < 0.10), but did not affect milk yield (11.0 kg/d). Glucagon and leptin arterial concentrations increased (12 and 8%, respectively; P < 0.10), but thyroxin and triiodothyronine concentrations decreased (26 and 16%, respectively; P < 0.01) between 20 and 28 degrees C. Expressed as a percentage of total nutrients, AV difference, glucose, amino acids, triglycerides (TG), free fatty acids, and lactate A-V differences represented 60, 20, 11, 8, and 1%, respectively. Exposure to 28 degrees C increased the extraction rate of glucose, TG, and a-amino acid N (13, 8, and 2.5%, respectively; P < 0.10). The extraction rates of essential and nonessential amino acids were not affected by temperature. The right pudic artery mammary blood flow increased (872 vs 945 mL/min, P < 0.05) between 20 and 28 degrees C, whereas milk yield was unaffected by temperature. It is suggested that this apparent inefficiency of the sow mammary gland in hot conditions could be related to an increase of proportion of blood flow irrigating skin capillaries in order to dissipate body heat.

The effects of reducing CP level in combination with an increase in ambient temperature (29 vs 22 degrees C) on performance and carcass composition were studied in a factorial arrangement of treatments involving 66 Pietrain x (Landrace x Large White) barrows from 27 to 100 kg BW. Animals were fed at each temperature one of three experimental diets that provided 0.85 or 0.70 g of digestible lysine per megajoule of NE, in the growing (27 to 65 kg) and the finishing (65 to 100 kg) phases, respectively. Diet 1 was a corn, wheat, and soybean meal diet formulated without crystalline AA; CP levels were 20.3 and 17.6% for the growing and the finishing phases, respectively. In Diets 2 and 3, CP level was reduced by substituting part of the soybean meal with corn and wheat (Diet 2), or with corn, wheat, and 4% fat (Diet 3). Diets 2 and 3 were supplemented with AA and balanced according to the ideal protein concept. The CP levels of Diets 2 and 3 were, respectively, 15.8 and 16.3% in the growing phase, and 13.4 and 13.8% in the finishing phase. Pigs were housed individually and had free access to feed and water. The ADFI was measured daily, and animals were weighed weekly. Carcass composition was measured at slaughter (100 kg BW). Increasing ambient temperature from 22 to 29 degrees C resulted in a 15% reduction in ADFI and 13% lower ADG. Leaner carcasses (P 0.05). At 29 degrees C, ADFI was not different (P > 0.05) between diets and daily NE intake was higher (P 0.05) but increased mainly fat deposition. These results indicate that a 4 percentage unit reduction of dietary CP level reduces N excretion (minus 37%) but does not affect growth and carcass composition as long as the ratio between essential AA and NE are kept optimal. In addition, diets with reduced CP limit the effect of high ambient temperature on ADFI. Finally, our results demonstrate the significance of using NE, rather than DE or ME, for formulating diets.

Two replicates of three multiparous crossbred Large White x Landrace lactating sows were used to develop a technique for the continuous direct measurement of the blood flow through the mammary gland using transit time ultrasound. Four to six days after farrowing, an ultrasonic transit time flow probe was implanted around the right external pudic artery in order to measure the short-term variations of mammary blood flow through this vessel in response to postural change (standing vs lying), meal distribution, hand-milking, and weaning. After surgery, all sows were fed 3.8 kg/d of a lactation diet and housed either at 20 or 28 degrees C. The implantation of the ultrasonic blood flow probe was successful in all six operated sows. Postmortem examination did not indicate the presence of infection, any collateral bypassing the flow probe, or a reduction of artery diameter. The right pudic artery mammary blood flow (PMBF) was measured for 8.5 h over two periods of three days (d 11 to d 13 and d 18 to d 20 of lactation). The PMBF averaged 910 +/- 238 mL/min but was variable within 1 d. Compared with the lying position, PMBF was decreased (- 6%, P < 0.05) when sows were standing. Between 0 to 15 and 16 to 30 min after oxytocin injection (t = 0) and hand-milking, PMBF remained constant (P = 0.05; 801 vs 767 mL/ min) and increased (P = 0.02), respectively, in comparison with the mean calculated over the preceding 30-min period (982 vs 784 mL/min). The PMBF increased (P < 0.05) after meal distribution and reached a peak 65 min later (i.e., 980 mL/min). The PMBF decreased regularly after separation of piglets at weaning; at 8 and 16 h after weaning, PMBF was 60 and 40% of the value recorded before weaning, respectively. Assuming that PMBF drains one-quarter of the whole mammary gland, it can be calculated that blood flow through the entire mammary gland averages 3.6 L/min and that about 470 L of blood are required to produce 1 kg of milk. The proposed methodology constitutes a new technique to measure direct mammary blood flow and its short-term factors of variation.

Pour optimiser les performances de la truie et sa longévité, il est important d’adapter régulièrement les apports alimentaires de façon à contrôler l’état des réserves corporelles et éviter ainsi les situations d’engraissement ou d’amaigrissement excessif, qui sont préjudiciables à de bonnes performances de reproduction. La gestation apparaît la période privilégiée pour reconstituer un niveau de réserves corporelles adéquat. Pour cela il est nécessaire de disposer de critères objectifs d’évaluation des réserves, de fixer des objectifs en fonction du stade physiologique et de traduire ces objectifs en termes d’apports nutritionnels. La démarche proposée consiste à évaluer les besoins énergétiques de la truie en gestation sur la base d’une approche factorielle prenant en compte l’importance des réserves à reconstituer, ces réserves étant évaluées à partir du poids vif et de l’épaisseur de lard dorsal mesurée aux ultrasons. Sur la base des informations obtenues expérimentalement ou en élevage, on peut retenir, pour des femelles croisées Large White x Landrace, un objectif d’épaisseur de lard dorsal (mesuré au niveau de la dernière côte à 6,5 cm de la ligne médiane) de 16 à 19 mm au sevrage et de 19 à 22 mm à la mise bas, quel que soit le numéro de portée, l’écart entre ces deux objectifs devant se situer entre 2 et 4 mm. En pratique, le plus important pour atteindre ces objectifs est de favoriser au maximum la consommation pendant la lactation, l’alimentation pendant la gestation servant seulement à corriger l’état des réserves.

Forty-two multiparous Large White sows were used to investigate the effect of diurnally fluctuating temperature (T) on lactation performance and feeding behaviour. The animals were allocated to one of the four thermic treatments: constant T at 25°C (25C) and 29°C (29C) or equal-mean diurnal cyclic T varying from 21 to 29°C (25V) and from 25 to 33°C (29V). Photoperiod was fixed to 14 h of light. The sows were given food ad libitum between the 7th and the 19th day post partům. Lactation performance was measured for all sows whereas the feeding behaviour was recorded only on 28 sows. The ad libitum food intake was comparable at 25C and 25V (6•31 kg/day) as were milk production and body reserves mobilization. In contrast, food intake at 29V was higher than at 29C (4•53 v. 3•48 kg/day) with no difference in milk production between the two treatments. The increased daily food intake at 29V resulted from higher intakes over the coolest periods of the day and especially during the dark period. Neither meal size nor daily number of meals were significantly affected by T. Feeding behaviour was mainly diurnal but with differences between treatments: 0•90 of total food intake at 29C v. 0•78 at the other three T It appears that the effects of diurnally fluctuating T on lactation performance of sows depend on the mean level of T

40 ref.; International audience; Four replicates were conducted to determine the effects of tropical climate and season on voluntary feed intake and performance of pigs and their carcass characteristics at 90 kg, as compared to a control environment (CE). CE was characterized by ambient temperature of 20 degreesC and relative humidity (RH) of 75%. Under tropical climate, ambient temperature averaged 24.6 degreesC and RH 84% during the cool season (CTC) and 27.3 degreesC and 82% during the warm season (WTC) respectively. Ninety-six Large White pigs were used between 15 and 35 kg live weight (P1) and, as 36 of them were slaughtered at 35 kg, the remaining pigs were used from 35 to 90 kg (P2). In the CTC, neither voluntary feed intake, nor average daily gain, Feed:gain ratio or carcass characteristics significantly differed from CE in P1 and P2 pigs. In the WTC, the 13% decline in feed intake of P2 pigs (P < 0.001) induced a 13% diminution in growth rate (P < 0.05). In the WTC, fat percentage of the carcass was reduced by 3.2 units (P < 0.001), whereas less fat was deposited in backfat (P < 0.001) and more fat retained in leaf fat (P < 0.001), as compared to the CTC. Also in the WTC, the reduction in the weight of internal organs led to a 1.8 unit improvement in killing-out percentage (P

A low (L) and high-fibre (H) diet were fed to six multiparous sows during gestation in a 2 × 2 repeated Latin square design. A single meal per day was given that provided 37·2 MJ digestible energy/d. The kinetics of heat production (HP) and its partitioning (fasting HP, activity HP, and thermic effect of feeding (TEF)) were determined. The TEF was partitioned between a dynamic component (TEFst) and a constant component (TEFlt). Digestibility of energy and nutrients was lower for the diet H. In spite of the lower metabolisable energy (ME) intake (33·9 v. 35·4 MJ/d for diets H and L respectively), HP was higher for diet H (30·5 v. 28·9 MJ/d) resulting in a lower energy retention. The estimated fasting HP was 270 kJ/kg body weight0·75 per d at day 0 of gestation and increased with advancement of pregnancy. The TEFlt was not significantly different from zero for diet L, but represented 4·1 % of ME intake for diet H. The TEFst was not affected by the diet but diet H delayed the postprandial peak of HP. Total TEF was higher for diet H than for diet L (11·7 v. 8·2 % of ME intake). The longer duration of eating with diet H was compensated for by less physical activity between meals, so that activity HP was equivalent for both diets. The activity HP represented 20 % of ME intake but was variable between sows. The ME requirements for maintenance averaged 440 kJ/kg body weight0·75per d. Feeding high-fibre diets increases HP, delays the postprandial peak of HP and maintains the basal HP at a higher level.

The feeding behaviour of eight Pietrain boars (PP/M), eight Large White boars (LW/M) and nine barrows (LW/C), and six Meishan barrows (MS/C) was studied at three different stages of growth (S1, S2, S3) corresponding to average body weights (BW) of 23, 39 and 57 kg, respectively. The PP, LW and MS breeds were considered as lean, conventional and fat types of pigs, respectively. All animals were reared individually. The light pattern was 12 hours of artificial light. The type of pig significantly affected the daily voluntary feed intake (1659, 1746, 1970 and 1622 g/d in PP/M, LW/M, LW/C and MS/C, respectively). Daily number of meals was higher in PP/M (14.4) than in LW/M and LW/C (12.2 on average) and in MS/C (7.3) whereas meal size was lower in PP/M (125 g vs. 166 g in LW pigs and 250 g in MS/C). Feed intake increased linearly with BW; the increase was lower in PP/M and MS/C (+15 g per kg of BW gain) than in LW/M (+26 g per kg) and in LW/C (+35 g per kg). With increasing age, number of meals per day decreased. Simultaneously, their size increased but the increase was more important in MS/C than in other types of pigs. The pattern of feed intake was mainly diurnal and more pronounced with the increase of BW (57 and 66% of feed intake during the day at S1 and S3, respectively). The results obtained in the present experiment clearly indicate that differences observed in composition of BW gain between types of pigs are associated with differences in VFI but also with differences in feeding behaviour.

The aim of the present paper is to investigate the effect of energy supplies on growth characteristics in pigs when protein supplies are non-limiting. An experimental program was carried out at INRA between 1992 and 1994 and involved 60 pigs from three types fed at five energy levels. The effects of energy intake on protein deposition (PD) and lean gain on one hand and on lipid deposition (LD) and fat gain on the other hand were found to be very similar, which is logical with the fact that more than 55% of PD and 80% of LD are deposited in lean and fat tissues, respectively. Our results indicate that PD increases with energy supplies according to a linear–plateau relationship, which slope ( β p ) and maximum value are influenced by genotype, sex, and stage of growth. From our results and those of literature, β p is reported to vary between 2.9 and 6.1 g per MJ digestible energy (DE) intake over the 45–100 kg body weight (BW) range. Simultaneously, LD increases linearly with energy level but neither the genotype nor the sex influence significantly the slope of the relationship (14.5 g/MJ DE between 45–100 kg BW). Differences in growth response to energy intake between types of pigs result in an important variation in BW gain and its composition associated to energy intake. Therefore, characterisation of relationships between growth components and energy intake specific to each type of pig is necessary for modelling response to energy intake.

Development of mechanistic models of digestion is a means to account for interactions between different nutrients, and between nutrients and the animal. Although some digestion models for pigs have been proposed, quantitative information concerning the underlying processes is extremely limiting. The aim of this study was to determine the effect of dietary fibre on the transit of the solid and liquid phases of digesta in different segments of the gastro-intestinal tract (GIT) in growing pigs. Six barrows (initial BW 30 kg and fitted with two simple T-cannulas at the proximal duodenum and distal ileum) were used in a double 3×3 Latin square design. Pigs were offered diets differing in total dietary fibre content (17, 22 and 27%) at 4 h intervals. A single meal marked with YbO2 and Cr-EDTA was used to determine the passage kinetics of respectively the solid and liquid phases of digesta in different segments of the GIT. The mean retention time (MRT) averaged 1 h from the mouth to the proximal duodenum (stomach), 4 h from the proximal duodenum to the distal ileum (small intestine), and 35 h from the distal ileum to the faecal excretion (large intestine). Increase in dietary fibre content had no effect on MRT in the stomach, tended to decrease MRT of solid phase in the small intestine (P=0.07), and decreased MRT of both phases in the large intestine (43 to 29 h, P=0.06). For all diets, transit of the liquid phase in the large intestine was 4–8 h less than transit of the solid phase. © 2007 Elsevier B.V. All rights reserved.

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.

Twenty crossbred (Large Wliite × Piétrain) boars were used to investigate the effect of energy intake (0·71, 0·80, 0·90, 1·00ad libitum) and body weight (BW) on growth performance, and rates of protein (PD) and lipid (LD) deposition between 40 and 100 kg BW. Daily crude protein intake was kept constant. Total PD and LD were measured according to the comparative slaughter technique (CST) during total experiment and according to nitrogen and energy balance technique at 45, 65, 80 and 94 kg mean BW. Average daily gain increased linearly with metabolizable energy (ME) intake (+36 g/MJ ME) whereas food conversion ratio was not affected by energy level (28·0 M] ME per kg BW gain). Daily PD increased from 126 to 171 g/day, and LD from 70 to 187 glday between 0·71ad libitumandad libitumME intake. Maintenance ME requirement was constant when expressed per kg BW'60 (992 kJ/day). PD varied with ME intake above maintenance (MEp) according to a linear-plateau relationship. The slope decreased with BW (+11·5 g/MJ MEp at 65 kg BW and +9·0 g/MJ MEp at 94 kg BW). LD was linearly related to MEp (+16 g/M} MEp). The LD: PD ratio in marginal empty BW gain was constant within BW class, but increased from 1/5 to 1/9 between 65 and 94 kg BW.

Tissular and chemical body composition were measured for 85 pigs that were serially slaughtered between 15 and 110 kg BW and considered lean (boars from a Synthetic Line and the Pietrain breed), conventional (boars, gilts, and barrows from the Large White breed), or obese (Meishan barrows). These six groups were expected to be quite different with regard to their body composition. Tissular body composition was predicted from chemical body composition, according to nonlinear regression models. Common relationships were obtained for lean and conventional pigs (Group effect: P > .05). Empty body weight and the weight of adipose tissues were predicted directly from the amounts of body protein and lipid, whereas for estimation of weights of carcass, muscle, and lean, the prediction was improved when the weight of offals (visceral organs and blood) was also included in the model. Validation of prediction models on literature data indicated good agreement between calculated and measured values (R2 > .90). These relationships were not applicable to Meishan barrows. In pig growth modeling approaches, proposed equations can be used in order to predict the tissular composition of body weight gain and commercial value at slaughter.

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.

Digestible (DE), metabolizable (ME), and net (NE) energy values of seven diets were measured in castrated male pigs of 45 (Stage 1), 100 (Stage 2), or 150 (Stage 3) kg BW. Diets were prepared from a basal diet supplemented with cornstarch, or sucrose, or a protein mixture (referred to here as protein), or rapeseed oil, or a mixture of fibrous ingredients (referred to as fiber), or rapeseed oil+fiber. Diets were fed at similar levels (x maintenance) at the three stages. Heat production at different feeding levels, as measured by indirect calorimetry, allowed calculation of energy retained by each pig (equal to ME intake minus heat production) and an estimate of fasting heat production of all pigs (360 kcal/kg BW.42). Net energy intake was then calculated for each pig as retained energy plus 360 x BW.42. The amounts of DE digested before the end of the ileum (DEi) and in the hindgut (DEh) were measured. Formulation of diets allowed calculation of energy values of the ingredients added to the basal diet. Digestibility and metabolizability of diets increased significantly from Stages 1 to 3, with higher variations for low-energy diets. The NE:ME ratio (k, %) and dietary NE content were not affected (P > .05) by stage of growth. On average, k was 75%, with higher values for diets containing rapeseed oil or starch (77%) and lower estimates for the fiber diet (72%). As a consequence, k was approximately 90, 82, 80, 72, and 60% for rapeseed oil, cornstarch, sucrose, protein, and fiber, respectively. These values are consistent with the lower k value for ME from DEh (57 vs 78% for DEi). Present data confirm that the hierarchy between feeds is dependent on the energy system (DE vs ME vs NE) and that the NE concept is superior in predicting the "true" energy value. The present results combined with previous ones show that, under practical conditions, the same NE prediction equations based on digestible nutrient contents, or preferably DE or ME contents, can be applied at all stages of growth in pigs. However, attention should be paid to factors such as BW or feeding level that affect digestibility and metabolizability of feeds markedly. The effects are the most important for ingredients.

Digestible (DE), metabolizable (ME), and net (NE) energy values of 61 diets were measured in 45-kg growing Large White boars. Net energy was calculated as energy retained at an average ME intake equivalent to 540 kcal/kg BW.60 plus fasting heat production estimated from data of the present experiment as 179 kcal/kg BW.60. Retained energy was measured as the difference between ME intake and heat production obtained in respiration chambers. The amounts of DE digested before the end of the ileum (DEi) and in the hindgut (DEh) were also measured for each diet. Regression equations for predicting dietary NE content from digestible nutrient levels or from DE or ME and chemical characteristics or from chemical composition only were calculated. Efficiencies of utilization of ME for NE (k, %) were also obtained. The mean k value for the 61 diets was 74% (range: 69 to 77). Digestible nutrients were used differently for NE: k values varied from approximately 60% for digestible CP or digestible cell wall fractions to 82% for starch and 90% for digestible ether extract. Accordingly, k for ME associated with DEh was lower than ME from DEi (58 vs 76%). Equations for predicting NE content are proposed. Their applicability, the comparison with other available NE prediction equations, and the effects of energy system on diet formulation are discussed.

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.

Digestible (DE) and metabolizable (ME) energy values of 14 diets were measured in three groups of pigs: sows fed at a maintenance level; 45-kg growing pigs fed nearly ad libitum; and ileo-rectal anastomized (IRA) growing pigs. The energy digested in the hindgut was calculated as the difference between DE values in intact growing pigs or sows and DE measured in IRA pigs. Diets were prepared from ten ingredients (wheat, corn starch, soybean meal, rapeseed oil, meat and bone meal, corn gluten feed, wheat bran, wheat middlings, wheat straw and sugar beet pulp), the inclusion levels of ingredients being independent. The DE and ME values of ingredients were calculated by regression of DE or ME values of diets on levels of inclusion of ingredients. The DE values of ingredients were higher in sows than in growing pigs, the difference being greater for high-fibre diets. Apart from wheat straw, which contributed negatively to DE in growing pigs, the largest difference was obtained for sugar beet pulp, for which the DE value in growing pigs represented 60% of the value obtained with sows. No difference was observed for wheat and corn starch. The contribution of the hindgut was higher for sows than for growing pigs and more pronounced for high fibre ingredients (sugar beet pulp, soybean meal). Rapeseed oil was totally digested in the small intestine. Comparison of measured and tabulated DE values shows a good agreement for wheat, corn starch and soybean meal. But tabulated values overestimate the DE values of fibrous ingredients and rapeseed oil for growing pigs and underestimate the DE values of the same ingredients (except rapeseed oil) for sows. Conclusions are equivalent for ME. The consequences of these digestive interactions on the energy evaluation of pig diets are discussed.