Effect of sorghum distillers dried grains with solubles and microbial enzymes on metabolizable and net energy values of broiler diets.

There is generally no information regarding the influence of distillers dried grains with solubles (DDGS) on the net energy (NE) value of broiler diets. It was hypothesized that the ME content of DDGS may overestimate its productive energy, leading to higher heat increment when used in broiler diets. Furthermore, it was of interest to investigate the potential benefits of a mixture of carbohydrases and protease on energy partitioning in diets containing DDGS. In this study, 2 evaluations, comparative slaughter (CS) or indirect calorimetry (IC), were conducted using the same batch of birds and feed. Two levels of DDGS (0 or 30%) without or with an enzyme mixture were used in a 2 × 2 factorial arrangement of treatments. The CS evaluation used 240 male Ross 308 broiler chicks with 6 replicates (10 birds each) per treatment from d 18 to 28. Carcass energy values were examined in 2 birds per replicate on each of d 18 and 28 to determine heat production (HP), NE, and ME. The IC evaluation used 32 birds acclimatized to 16 closed-circuit calorimeters (2 birds per chamber) following energy partitioning measurement by gaseous exchange and total excreta collection from 18 to 24 d. Birds fed DDGS had increased feed efficiency during starter and grower phases (P < 0.001). The CS showed no difference in HP between birds fed diets with or without DDGS. When measured by IC, birds fed diets containing DDGS had higher HP and lower NE (P < 0.01). Enzyme supplementation had no effect on HP, ME, or NE:ME ratio measured using CS or IC but increased NE and NE intake (P < 0.01) from d 18 to 28. Carcass fat retention was decreased (P < 0.05) and there was a lower NE (P < 0.01) in birds fed the DDGS-diets. This study showed that 30% dietary DDGS affects energy partitioning in broilers with more heat produced, decreased dietary NE, and less fat retained in the carcass.

Changes in chemical composition in male turkeys during growth.

In growing animals, requirements for many nutrients (and energy) are determined by the retention of these nutrients. During growth, this retention changes in an absolute way and also between nutrients and energy, resulting in changing nutrient requirements. The objective of this study was to describe the changes in chemical composition in male growing turkeys. The serial slaughter technique was used to determine the composition of amino acids, lipid, ash, and water in feather-free body (FFB) and feathers in male turkeys offered feed ad libitum from 1 to 15 wk of age. Allometric relations were used to describe changes in body composition. The feather content in the body decreased from 6% at 1 wk of age to less than 3% at 15 wk of age. The water and protein content in FFB decreased with increasing FFB mass, with allometric scalars (b) of, respectively, 0.967 and 0.970, whereas the lipid content increased with increasing FFB mass (b = 1.388). The water, protein, and ash content in fat-free FFB was constant and represented, respectively, 71.6, 24.2, and 4.2% of the fat-free FFB mass. The amino acid content of FFB protein was relatively constant and only the Cys content decreased between 1 and 15 wk of age, whereas the Ile content increased. Feathers were mostly composed of protein, and the protein content did not change during growth. During growth, the Lys, Met, Trp, His, Tyr, Asp, and Glu contents in feather protein decreased, whereas the Cys, Val, and Ser contents increased. The contribution of feathers to whole-body amino acid retention ranged from 5% for His to 33% for Cys. On average, the weight gain of FFB contained 21.3% protein and 12.7% lipid, corresponding to an energy content of 10.1 kJ/g. The weight gain of feathers contained 87.4% protein, corresponding to an energy content of 20.4 kJ/g. The results of the present study can be used in a factorial approach to determine nutrient requirements in growing turkeys.

Standardised amino acid digestibility of wheat distillers' dried grains with solubles in force-fed cockerels.

1. In recent years, policies encouraging the production of ethanol from maize or wheat have stimulated an increased production of distillers' dried grains with solubles (DDGS) for which the nutritional value for poultry is poorly described, especially in the case of wheat DDGS. 2. DDGS samples (19) were obtained from 7 plants in Europe from June to September 2007. Each sample was analysed for chemical composition and 10 representative samples were measured for amino acid (AA) content and their standardised digestibility (SDD) in caecectomised cockerels. Lightness score (L) of each DDGS was also measured. 3. Results indicated a rather stable crude protein content (327 to 392 g/kg DM) but the AA profile was variable between samples. Lysine (LYS) was the most affected AA with contents ranging between 0·83 and 3·01 g/100 g CP. In addition, only 0·76 of total LYS were free if estimated by the fluoro-dinitro-benzene procedure and 0·85 of total LYS were free if estimated by the furosine procedure. 4. The SDD of LYS was also highly variable (-0·04 to 0·71) with the lowest values observed for DDGS samples with a low LYS content in CP; these latter samples had also a high occurrence of Maillard reactions and low L values (<50). Consequently, both LYS content in CP (r = 0·63) and SDD of LYS (r = 0·64) values were positively related with L. 5. Our data indicate that LYS SDD can be accurately predicted from LYS content in CP according to a quadratic (R(2 )= 0·94) or a linear-plateau model (R(2 )= 0·90; breakpoint for 1·9 g/100 g lysine in CP and a 0.63 plateau SDD value).

Energy partitioning in male growing turkeys.

Feed is one of the most important cost factors in poultry production, and energy represents the largest fraction of this cost. Surprisingly little is known about the energy utilization in turkeys. A better understanding of the energy utilization by growing turkeys may contribute to improve the efficiency of nutrient and energy utilization. The objective of the present study was to quantify the change in energy utilization in male turkeys during growth. Energy and nitrogen balances were performed in a respiration chamber in medium-type male turkeys to partition ME intake between heat production (HP) and energy retention as protein and lipid. The measurements consisted of 7-d balance periods during which the turkeys were offered feed ad libitum during 6 d, followed by 1 d of fasting. Total HP was partitioned into fasting HP, activity-related HP, and thermic effect of feeding. Results of the components of ME utilization were analyzed by ANOVA. Also, the maintenance energy expenditure and efficiencies of energy utilization were estimated by multiple regression analysis. Feed intake and growth were in line with the recommendations of the breeder. Fasting HP was proportional to BW raised to the power 0.75. The ME intake decreased with increasing BW and HP increased from 53 to 64% of ME intake at 0.5 and 13.5 kg of BW, respectively. The fasting HP represented the largest part of HP and averaged 449 kJ.(kg of BW)(-0.75).d(-1). The activity-related HP accounted for 9.1% of ME intake, whereas the thermic effect of feeding decreased with increasing BW and ranged from 17.9 to 14.5% of ME intake. Energy retained as protein decreased with increasing BW from 67 to 37% of energy retention. The maintenance energy expenditure was estimated at 641 kJ.(kg of BW)(-0.75).d(-1), whereas energy efficiencies for protein and lipid retention were 65 and 100%, respectively. This study contributes to the understanding of the changes in energy utilization in turkeys during growth.

Energy value of wheat dried distillers grains with solubles in roosters, broilers, layers, and turkeys.

Four experiments were conducted to measure total tract metabolizability of gross energy (GE), the AME, and AMEn or AME content corrected for a standardized N retention (AMEs) of 10 European wheat dried distillers grains with solubles (DDGS) in roosters, broilers (3 wk old), layers (25 wk old), and growing turkeys (10 wk old). The wheat DDGS were obtained from 7 European ethanol plants and selected to get a large variability in chemical composition. The AME, AMEn, or AMEs of wheat DDGS was obtained according to the difference method. The highest AMEn:GE was obtained for roosters with an average (minimum-maximum) value of 49% (43-55), the lowest in turkeys (43%; 34-50), and intermediate values (47%; 41-57 and 46%; 36-50) in broilers and layers, respectively. Corresponding AMEn values were 10.3 (9.0-11.3), 9.9 (8.5-11.7), 9.6 (7.8-10.5), and 9.6 (7.8-10.5) MJ/kg of DM for roosters, broilers, layers, and turkeys, respectively. The AMEs for N retention equal to 50% of N intake was about 0.6 MJ higher than the corresponding AMEn value. Our data indicate that the AMEn content of wheat DDGS can be predicted from either their acid detergent fiber content (R2=0.79) or the lightness score (L*; R2=0.77) with a common slope but different intercepts for the 4 poultry categories. If dark and overheated samples (L*<50; n=3) with the lowest AMEn:GE ratio and AMEn values are excluded, the average AMEn:GE ratio becomes 51, 49, 48, and 45% in roosters, broilers, layers, and turkeys, respectively, with corresponding AMEn values of 10.7, 10.2, 10.0, and 9.5 MJ/kg of DM that are more representative of a well-controlled process for DDGS preparation. The negative effect of L* on energy value and energy metabolizability indicates that overheating while drying should be minimized to maximize the energy value of wheat DDGS for poultry. Finally, equations for predicting AME values in layers, broilers, or turkeys from the AME values in roosters are proposed.

Transradial Woven EndoBridge device to treat a ruptured basilar tip aneurysm under conscious sedation.

We present a patient with a ruptured basilar tip aneurysm treated under conscious sedation via a right radial approach using the Woven EndoBridge device. We discuss the technical aspects of the case as the well as the available literature on the treatment of ruptured aneurysms treated without general anaesthesia. We discuss the potential benefits of the Woven EndoBridge device in such situations.

Energy efficiency and net energy prediction of feed in laying hens.

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.

Effects of dietary crude protein on protein and fat deposition in milk-fed veal calves.

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.

Review: divergent selection for residual feed intake in the growing pig.

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<0.001) line differences for RFI (-165 g/day in the low RFI (LRFI) line compared with high RFI line) and daily feed intake (-270 g/day). Low responses were observed on growth rate (-12.8 g/day, P<0.05) and body composition (+0.9 mm backfat thickness, P=0.57; -2.64% lean meat content, P<0.001) with a marked response on feed conversion ratio (-0.32 kg feed/kg gain, P<0.001). Reduced ultimate pH and increased lightness of the meat (P<0.001) were observed in LRFI pigs with minor impact on the sensory quality of the meat. These changes in meat quality were associated with changes of the muscular energy metabolism. Reduced maintenance energy requirements (-10% after five generations of selection) and activity (-21% of time standing after six generations of selection) of LRFI pigs greatly contributed to the gain in energy efficiency. However, the impact of selection for RFI on the protein metabolism of the pig remains unclear. Digestibility of energy and nutrients was not affected by selection, neither for pigs fed conventional diets nor for pigs fed high-fibre diets. A significant improvement of digestive efficiency could likely be achieved by selecting pigs on fibre diets. No convincing genetic or blood biomarker has been identified for explaining the differences in RFI, suggesting that pigs have various ways to achieve an efficient use of feed. No deleterious impact of the selection on the sow reproduction performance was observed. The resource allocation theory states that low RFI may reduce the ability to cope with stressors, via the reduction of a buffer compartment dedicated to responses to stress. None of the experiments focussed on the response of pigs to stress or challenges could confirm this theory. Understanding the relationships between RFI and responses to stress and energy demanding processes, as such immunity and lactation, remains a major challenge for a better understanding of the underlying biological mechanisms of the trait and to reconcile the experimental results with the resource allocation theory.

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

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<0.05) increased with IC/growth. Despite higher ME intake, total HP remained similar (1365 kJ/kg of BW0.60 per day; P=0.47) with IC/growth. Consequently, total retained energy (RE) increased with IC/growth (from 916 to 1078 kJ/kg of BW0.60 per day; P<0.01) with a higher fat retention (625 to 807 kJ/kg BW0.60 per day; P<0.01), originating mainly from carbohydrates associated with a higher lipogenesis (536 to 746 kJ/kg BW0.60 per day; P<0.01) and RQ (1.095 to 1.145; P<0.01). Both PD (from 178 to 217 g/day; P=0.02) and LD (from 227 to 384 g/day; P<0.01) increased due to IC/growth. Feeding HF diet after IC was associated with increased crude fat digestibility (P<0.01) and increased RE as fat (807 to 914 kJ/kg BW0.60 per day; P=0.03), originating mainly from dietary fat (P<0.01) and resulting in increased LD (384 to 435 g/day; P<0.01) and lower RQ (from 1.145 to 1.073; P<0.01). Altogether, present results indicate that increased fatness of IC pigs is a result of increased daily LD caused by higher energy intake and lower basal metabolic rate. In addition, LD is further enhanced by dietary energy enrichment with fat after V2.

Predicting feed digestibility from NIRS analysis of pig faeces.

Digestibility is a key parameter in the evaluation of feeds; however, the measurements on animals require heavy experimental trials, which are hardly feasible when large numbers of determinations are required - for example, in genetic studies. This experiment aimed at investigating the possibility to predict digestibility from NIRS spectra measured on faeces. A total of 196 samples were available from a digestibility experiment investigating the effects of age and genetic background of Large White pigs fed the same diet, rich in fibre (NDF=21.4% DM). Digestibility of dry matter (dDM), organic matter (dOM), nitrogen content (dN), energy (dE) and apparent digestible energy content (ADE) were calculated, as well as total N content of faeces (N). The faeces samples were submitted to reflectance NIRS analysis after freeze-drying and grinding. Calibration errors and validation errors were, respectively, 0.08 and 0.13% DM for total N in faeces, 0.97% and 1.08% for dDM, 0.79% and 1.04% for dOM, 1.04% and 1.47% for dN, 0.87% and 1.12% for dE and 167 and 213 kJ/kg DM for ADE. These results indicate that NIRS can account for digestibility differences due to animal factors, with an acceptable accuracy. NIRS appears to be a promising tool for large-scale evaluations of digestibility. It could also be used for the study of digestibility of different feeds, after appropriate calibration based on a wide range of feed types.

Fasting heat production and metabolic BW in group-housed broilers.

Fasting heat production (FHP) is used for characterizing the basal metabolic rate of animals and the corresponding maintenance energy requirements and in the calculation of net energy value of feeds. In broilers, the most recent FHP estimates were obtained in the 1980s in slow-growing and fatter birds than nowadays. The FHP values (n=73; six experiments) measured in 3 to 6-week-old modern lines of broilers weighing 0.6 to 2.8 kg and growing at 80 to 100 g/day were used to update these literature values. Each measurement was obtained in a group of fasting broilers (5 to 14 birds) kept in a respiration chamber for at least 24 h. The FHP estimate corresponds to the asymptotic heat production corrected for zero physical activity obtained by modeling the decrease in heat production during the fasting day. The compilation of these data indicates that FHP was linearly related to the BW(0.70) (in kg), which can be considered as the metabolic BW of modern broilers. The 0.70 exponent differs from the conventional value of 0.75 used for mature animals. The FHP per kg of BW(0.70) ranged between 410 and 460 kJ/day according to the experiment (P<0.01). An experiment conducted with a shorter duration of fasting (16 h) indicated that FHP values are higher than those obtained over at least 24 h of fasting. Our values are similar to those obtained previously on fatter and slow-growing birds, even though the comparison is difficult since measurement conditions and methodologies have changed during the last 30 years. The FHP values obtained in our trials represent a basis for energy nutrition of modern broilers.

Effect of inflammation stimulation on energy and nutrient utilization in piglets selected for low and high residual feed intake.

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<0.01). Oxidation of U-13C-glucose tended to slightly increased in RFI- piglets and to decreased in RFI+ piglets (P=0.10) because of CFA. Additionally, RFI- piglets had a lower respiratory quotient during the 1st day following the CFA injection whereas RFI+ piglets tended to have a higher respiratory quotient. In conclusion, selection for RFI during the fattening period also affected the energy metabolism of pigs during earlier stages of growth. The effects of CFA injection were moderated in both lines but the most efficient animals (RFI-) exhibited a marked re-orientation of nutrients only during the 1st day after CFA, and seemed to recover thereafter, whereas the less efficient piglets expressed a more prolonged alteration of their metabolism.

Estimation of sow milk nutrient output.

Ten replicates of two littermate gilts were used during a 21-d lactation in order to calculate relationships between milk nutrient intake and piglet growth rate and composition of gain. Gilts were fed 14.2 or 10.4 Mcal ME/d and litter size was standardized to 9 or 10 piglets. Piglets had no access to creep feed. Milk production was measured on 10 sucklings over 12 h on d 1, 5, 9, 13, 17 and 21 by the weigh-suckle-weigh method. Heat production of the piglets was measured (RQ method) on the same days in a confinement chamber. Milk composition was determined on the days following milk production measurements. Four to ten piglets/litter were slaughtered at weaning and their body composition was determined. Milk nutrient production during part of lactation was related closely to piglet weight gain and body weight (R2 = .80 to .96). Milk DM, energy and N output over the entire lactation were predicted from piglet ADG (R2 = .87 to .90) when, for each litter, the difference between energy in piglet daily weight gain measured by the slaughter technique and energy in piglet daily weight gain estimated by the RQ method was included in the model. This variable corrects for milk production measurement errors. The relationships were slightly improved, especially for energy output, when the composition of piglet weight gain was taken into account (R2 = .93 to .97).

Metabolic utilization of energy and maintenance requirements in lactating sows.

Metabolizable energy (ME), heat production (measured by indirect calorimetry in respiration chambers), milk energy output and body energy mobilization were measured in 20 gilts (10 replicates of two littermates) during a 21-d lactation. Two energy levels were used: 14.2 and 10.4 Mcal ME X d-1 X sow-1 in the high energy (HE) and low energy (LE) groups, respectively. The daily supply of other nutrients in the diets was identical in both treatments. Measurements of metabolic rate and energy balance of the litters were carried out. These data were used to estimate the maintenance requirements of the sows (MEm) and the efficiencies of utilization of energy of food (kl) and body reserves (krl) for energy production in milk. Nitrogen balance of the sows was also determined. Energy mobilization was increased by energy restriction (-5.35 vs -2.04 Mcal X d-1 X sow-1 for HE and LE gilts, respectively) and by the increment of milk production with the advancement of lactation. Energy restriction (LE vs HE gilts) resulted in increased weight loss consisting mainly of fat tissue depletion. Muscle depletion represented a rather large proportion of weight loss, even in sows fed the high energy level. Maintenance requirements amounted to 109 kcal ME X kg weight-.75 X d-1. The estimations for kl and krl were 72 and 88%, respectively. These results show that the overall efficiency of energy storage during pregnancy and its mobilization during lactation (68.6 to 70.9%) is similar to that of direct utilization of ME during lactation.

Effect of energy level in lactating sows on yield and composition of milk and nutrient balance of piglets.

The effects of energy level on milk yield, milk composition and growth of the piglets were studied in 20 gilts (10 replicates of two littermates) and their litters during a 21-d lactation. The metabolizable energy (ME) levels were 14.2 and 10.4 Mcal ME X d-1 X sow-1 in the high energy (HE) and low energy (LE) groups, respectively. The daily supply of other nutrients in the diets was identical in both treatments. Milk yield measured every 4 d was lower in the LE group. But fat (8.0 vs 6.9%), energy (1.27 vs 1.14 Mcal/g) and nitrogen (.78 vs .74%) contents of milk were significantly higher in the LE gilts compared with the HE gilts. The daily output of energy and nitrogen was therefore equivalent in both treatments (respectively, 8.28 Mcal and 51.8 g/d), but the fat output was higher in the energy-restricted gilts (532 vs 490 g/d). Growth rate of the litter was similar in both treatments, but piglets suckling LE dams had higher dry matter, fat and energy contents in their body at weaning. Piglets retained 89, 54 and 55% of nitrogen, fat and energy, respectively, of milk between birth and weaning. The results suggest that the ability of sows to mobilize body lipids in order to maintain the output of energy in milk is reduced as body fat reserves are depleted.

Effects of exposure to high ambient temperature and dietary protein level on sow milk production and performance of piglets.

The effects of high ambient temperature and level of dietary heat increment on sow milk production and piglet performance over a 28-d lactation were determined in 59 multiparous crossbred Large White x Landrace pigs kept at a thermoneutral (20 degrees C) or in a hot (29 degrees C) constant ambient temperature. Experimental diets fed during lactation were a control diet (NP; 17.6% CP) and two low-protein diets obtained by reduction of CP level (LP; 14.2% CP) or both reduction of CP and addition of fat (LPF; 15.2% CP); the NE:ME ratio was 74.3, 75.6, and 75.8% for NP, LP, and LPF diets, respectively. All diets provided 0.82 g of digestible lysine/MJ of NE, and ratios between essential AA and lysine were above recommendations. Creep feed was provided after d 21 of lactation. Reduction of CP level did not influence (P > 0.10) milk production, milk composition, or piglet performance. Despite higher nursing frequency (39 vs 34 sucklings per day), milk production decreased (P < 0.01) from 10.43 to 7.35 kg/d when temperature increased from 20 to 29 degrees C. At d 14, DM (18.6 vs 18.1%) and energy (4.96 vs 4.75 MJ/kg) contents in milk tended (P = 0.09) to be higher in sows kept at 29 degrees C. Over the 28-d lactation, piglet BW gain and BW at weaning decreased (P < 0.01) from 272 to 203 g/d and 9.51 to 7.52 kg, respectively, when temperature increased from 20 to 29 degrees C. Daily creep feed intake over the 4th wk of lactation was higher (P < 0.01) at 29 degrees C than at 20 degrees C (388 vs 232 g/litter, respectively), which was reflected in a greater increase in BW gain between wk 1 to 3 and wk 4 at the higher temperature (147 vs 130%); BW gain between weaning and d 14 postweaning was higher (P < 0.05) for piglets originating from sows kept at 29 degrees C (280 vs 218 g/d). In connection with their lower growth rate, DM (31.2 vs 33.0%), protein (15.5 vs 16.0%), lipid (12.3 vs 13.9%), and energy (8.39 vs 9.09 kJ/g) contents in weaned, slaughtered piglets were lower (P < 0.01) at 29 than at 20 degrees C. In conclusion, modification in the CP:NE ratio in order to decrease dietary heat increment did not affect milk production and piglet performance in thermoneutral or hot climatic conditions. Our results confirm the negative effect of high ambient temperatures on milk yield and emphasize the importance of creep feed supply to improve pre- and postweaning growth of piglets in these conditions, especially when weaning occurs after 3 wk of age.

Prediction of tissular body composition from protein and lipid deposition in growing pigs.

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 Piétrain 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.

Influence of high ambient temperatures on performance of multiparous lactating sows.

Multiparous Large White sows (n = 63) were used to investigate the effects of five ambient temperatures (18, 22, 25, 27, and 29 degrees C) and two dietary protein contents on their lactation performance. At each temperature treatment, ambient temperature was maintained constant over the 21-d lactation period. Dietary protein content was either 14 or 17% with essential amino acids levels calculated not to be limiting. The animals had ad libitum access to feed between the seventh and the 19th day of lactation. Diet composition did not influence lactation performance. Over the 21-d lactation, feed intake decreased from 5.67 to 3.08 kg/d between 18 and 29 degrees C. Between d 7 and 19, the corresponding values were 7.16 and 3.48 kg/d, respectively. This decrease was curvilinear; an equation to predict voluntary feed intake (VFI) from temperature (T, degrees C) and body weight (BW, kg) is proposed: VFI = -49,052 + 1,213 T - 31.5 T2 + 330 BW - .61 BW2 (residual standard deviation: 1,018). Skin temperature increased regularly with increased ambient temperature (34.6 to 37.4 degrees C between 18 and 29 degrees C), whereas udder temperature reached a plateau at 25 degrees C (38.3 degrees C). The gradient of temperature between skin and rectum was minimal (2 degrees C ) at 27 degrees C and remained constant at 29 degrees C. This constancy coincides with the marked reduction of feed intake. The respiratory rate increased from 26 to 124 breaths/min between 18 and 29 degrees C, and this indicates that the evaporative critical temperature was below 22 degrees C. The BW loss increased from 23 to 35 kg between 18 and 29 degrees C, but its estimated chemical composition remained constant. Pig growth rate was almost constant between 18 and 25 degrees C (241 g/d) and was reduced above 25 degrees C (212 and 189 g/d at 27 and 29 degrees C, respectively). In conclusion, temperatures above 25 degrees C seem to be critical for lactating sows in order to maintain their performance.