Increased Dietary Trp, Thr, and Met Supplementation Improves Performance, Health, and Protein Metabolism of Weaned Piglets under Mixed Management and Poor Housing Conditions

A sanitary challenge was carried out to induce suboptimal herd health while investigating the effect of amino acids supplementation on piglet responses. Weaned piglets of high sanitary status (6.33 ± 0.91 kg of BW) were distributed in a 2 × 2 factorial arrangement into two similar facilities with contrasting sanitary conditions and two different diets. Our results suggest that increased Trp, Thr, and Met dietary supplementation could support the immune systems of piglets under a sanitary challenge. In this manner, AA+ supplementation improved the performance and metabolism of piglets under mixed management and poor sanitary conditions. No major temporal microbiome changes were associated with differences in performance regardless of sanitary conditions or diets. Since piglets often become mixed in multiple-site production systems and facility hygiene is also often neglected, this study suggests that increased Trp, Thr, and Met (AA+) dietary supplementation could contribute to mitigating the side effects of these harmful risk factors in modern pig farms.

Evaluation of a mechanistic model that estimates feed intake, growth and body composition, nutrient requirements, and optimum economic response of broilers

Efficient meat production is crucial in addressing global market demands and sustainability goals. Modeling production systems has gained worldwide attention, offering valuable insights for predicting outcomes and optimizing economic returns. In the poultry industry, researchers have developed mathematical models to predict animal performance and maximize profits. These models incorporate theories to explain real-world processes and enable future event predictions. One such model is the Broiler Growth Model (BGM), which serves as a predictive tool for estimating feed intake, growth, and body composition of broilers. The BGM takes into account the genetic potential of the broilers, the feed they are provided, and several constraining factors that may prevent the animal from achieving their genetic potential. To evaluate the BGM, a series of simulations were performed: (i) model behavior was evaluated by simulating the response of males and females from 22 to 35 d to feeds differing in dietary protein content and nutrient density; (ii) model prediction was evaluated using the results of a protein response trial conducted at UNESP in which six dietary protein levels were fed to male and female broilers over a 56 d period; and (iii) model optimization was used to maximize economic returns in the above trial. The model behaved as expected when feeds differing in protein content were fed, with feed intake per kg of BW increasing as protein level was decreased, resulting in lower gains and higher body lipid contents. Increasing nutrient density resulted in higher feed intake in the second level, followed by a reduction in feed intake in the highest nutrient feed. The simulated response to nutrient density resulted in increasing body lipid deposition as the nutrient density increased. In comparing the simulated and actual results of the protein response trial, the overall error of prediction was up to 15% for feed intake, BW, and body protein. The optimization routine allows the simulation of different economic scenarios, helping in decision-making. The Broiler Growth Model emerges as a valuable tool for the poultry industry, offering predictive capabilities and economic optimization potential. While minor discrepancies between simulated and actual results exist, the BGM holds significant promise for enhancing efficiency and profitability in broiler production, contributing to the broader goals of sustainable broiler meat production.

A first model of the fate of dietary calcium and phosphorus in broiler chickens

To reduce P excretion and increase the sustainability of poultry farms, one needs to understand the mechanisms surrounding P metabolism and its close link with Ca metabolism to precisely predict the fate of dietary P and Ca and related requirements for birds. This study describes and evaluates a model developed to estimate the fate of Ca and P consumed by broilers. The Ca and P model relies on three modules: (1) digestion of Ca and P; (2) dynamics of Ca and P in soft tissue and feathers; and (3) dynamics of body ash. Exogenous phytase affects the availability of Ca and P; thus, to predict the absorption of those minerals, the model also accounts for the effect of phytase on Ca and P digestibility. We used a database to estimate the consequences of dietary Ca, P, and phytase over feed intake response. This study followed a four-step process: (1) Ca and P model development and its coupling with a growth broiler model; (2) model behavior assessment; (3) sensitivity analysis to identify the most influential parameters; and (4) external evaluation based on three databases. The proportion of P in body protein and the Ca to P ratio in bone are the most sensitive parameters of P deposition in soft tissue and bone, representing 91 and 99% of the total variation. The external evaluation results indicated that body water and protein had an overall mean square prediction error (rMSPE) of 7.22 and 12.3%, respectively. The prediction of body ash, Ca, and P had an rMSPE of 7.74, 11.0, and 6.56%, respectively, mostly errors of disturbances (72.5, 51.6, and 90.7%, respectively). The rMSPE for P balance was 13.3, 18.4, and 22.8%, respectively, for P retention, excretion, and retention coefficient, with respective errors due to disturbances of 69.1, 99.9, and 51.3%. We demonstrated a mechanistic model approach to predict the dietary effects of Ca and P on broiler chicken responses with low error, including detailed simulations to show the confidence level expected from the model outputs. Overall, this model predicts broilers' response to dietary Ca and P. The model could aid calculations to minimize P excretion and reduce the impact of broiler production on the environment. A model inversion is ongoing that will enable the calculation of Ca and P dietary quantities for a specific objective. This will simplify the use of the model and the feed formulation process.

A blend of functional amino acids and grape polyphenols improves the pig capacity to cope with an inflammatory challenge caused by poor hygiene of housing conditions

BACKGROUND

Dietary supplementation with a blend of functional amino acids (AA) and grape extract polyphenols contributes to preserve intestinal health and growth performance of piglets during the post-weaning period. In the present experiment, we assessed if a supplementation with a mix of AA and grape extract polyphenols during the post-weaning period would persist to improve the pig capacity to cope with a subsequent challenge caused by poor hygiene of housing conditions. Eighty pigs weaned at 28 days of age were fed a standard diet supplemented (AAP) or not (CNT) with 0.2% of a blend of AA (glutamine, arginine, cystine, valine, isoleucine, and leucine) and grape extract polyphenols during the post-weaning period (from week 0 to 6). At week 6, pigs were transferred to a growing unit where 50% of pigs previously fed AAP and CNT diets were housed in good and the other 50% in poor hygiene conditions for 3 weeks (from week 7 to 9; challenge period). All pigs were fed a standard growing diet that was not supplemented with AAP. We measured pig growth performance, plasma indicators of inflammation, digestive integrity, and oxidative status, and scored fecal consistency. Differences were considered significant at P ≤ 0.05.

RESULTS

One week post-weaning, pigs fed AAP had lower plasma concentrations of haptoglobin than CNT pigs (P = 0.03). Six weeks post-weaning, plasma concentrations of diamine oxidase (DAO) were lower (P = 0.03) whereas those of vitamin E and A were greater (P ≤ 0.05) in pigs fed AAP compared to CNT pigs. The prevalence of diarrhea was higher in CNT pigs compared to AAP pigs (P < 0.01). During the challenge period, only pigs previously fed CNT diet had lower growth rate in poor than good conditions (P ≤ 0.05). They had also greater plasma concentrations of haptoglobin and oxidative stress index (OSI) and lower plasma concentrations of vitamin E in poor than good hygiene conditions (P ≤ 0.05).

CONCLUSIONS

Pigs fed AAP diet during post-weaning had less diarrhea and plasma concentrations of a digestive integrity marker, as well as greater plasma concentrations of antioxidant indicators during the post-weaning period. The beneficial effects of AAP supplementation persisted after the post-weaning period as evidenced by the absence of effects of the hygiene challenge on growth and health indicators in pigs previously fed APP. This clearly indicated a greater ability of pigs fed AAP to cope with the poor hygiene conditions.

Effects of lowering dietary protein content without or with increased protein-bound and feed-grade amino acids supply on growth performance, body composition, metabolism, and acute-phase protein of finishing pigs under daily cyclic heat stress

This study investigated the effects of a low-protein diet with or without an increase in dietary protein and feed-grade amino acids (AAs) on the growth performance, body composition, metabolism, and serum acute-phase proteins of finishing pigs reared in thermoneutrality or cyclic heat stress conditions. A total of 90 gilts (67.7 ± 6.2 kg) were distributed in a 2 × 3 factorial arrangement (two ambient temperatures and three diets). Ambient temperatures (AT) were thermoneutral (TN, 22 °C for 24 h) and cyclic heat stress (CHS, 12 h to 35 °C and 12 h to 22 °C). The evaluated diets (D) were high crude protein (HP); low CP-free AA-supplemented diets (LPAAs); low CP-free AA-supplemented diets and digestible Lys level (+20%), and Lys:AA ratios above recommendations (LPAA+). The experimental period lasted 48 d (two experimental phases: days 0-27 and days 28-48, respectively). CHS pigs had higher skin temperature (P < 0.05) than TN pigs. Pigs in CHS had higher rectal temperature (P < 0.05) than TN pigs until day 38 but similar (P > 0.10) to TN pigs from 38 to 45 d. For the entire experiment, CHS pigs had lower (P < 0.05) final BW, average daily gain and daily feed intake, net energy intake, body lipid, bone mineral, lipid deposition, energy retention, Lys and CP intake, and nitrogen excretion than TN pigs. The level of CP intake impacted nitrogen excretion, nitrogen retention efficiency, and urea as pigs fed HP had the highest values, and pigs fed LPAA had the lowest values (P < 0.05). On day 27, CHS pigs had lower (P < 0.05) free triiodothyronine than TN pigs. LPAA+ pigs had lower (P < 0.05) insulin than LPAA. On day 48, CHS pigs had lower (P < 0.05) thyroxine, albumin, and lactate than TN pigs. On day 27, pigs fed LPAA+ had higher (P < 0.05) lactate than pigs fed HP or LPAA. Both AT and D were enough to stimulate the immune system as CHS pigs had lower (P < 0.05) transferrin and 23-kDa protein levels than TN pigs, and HP pigs had higher haptoglobin than LPAA on day 27. These results confirm the deleterious effects of high AT on performance, body composition, metabolism, and immune system stimulation in finishing pigs. These data also show that a diet with low levels of CP can be provided to pigs in CHS without affecting performance and body composition while reducing nitrogen excretion. However, the use of a diet with an AA level above the requirements obtained by increasing intact protein and free AA did not attenuate the impact of CHS on performance and body composition of pigs.

Increased dietary Trp, Thr, and Met supplementation improves growth performance and protein deposition of salmonella-challenged growing pigs under poor housing conditions

Highly intensified rearing conditions and precarious sanitary management predispose pigs to immune system activation, altered amino acid (AA) metabolism, and decreased growth performance. Thus, the main objective of this study was to evaluate the effects of increased dietary tryptophan (Trp), threonine (Thr), and methionine + cysteine (Met + Cys) supplementation on performance, body composition, metabolism, and immune responses of group-housed growing pigs under challenging sanitary conditions. A hundred and twenty pigs (25.4 ± 3.7 kg) were randomly assigned to a 2 × 2 factorial arrangement, consisting of two sanitary conditions (SC, good [GOOD] or salmonella-challenge and poor housing condition [Salmonella Typhimurium (ST) + POOR]) and two diets, control (CN) or supplemented with AA (Trp, Thr, and Met + Cys:Lys ratios 20% higher than those of the CN diet [AA>+]). Pigs were followed during the growing phase (25-50 kg) and the trial lasted 28 d. The ST + POOR SC pigs were challenged with Salmonella Typhimurium and raised in a poor housing condition. The ST + POOR SC increased rectal temperature, fecal score, serum haptoglobin, and urea concentration (P < 0.05) and decreased serum albumin concentration (P < 0.05) compared with GOOD SC. Body weight, average daily feed intake, average daily gain (ADG), feed efficiency (G:F), and protein deposition (PD) were greater in GOOD SC than in ST + POOR SC (P < 0.01). However, pigs housed in ST + POOR SC fed with AA+ diet had lower body temperature (P < 0.05), increased ADG (P < 0.05) and nitrogen efficiency (P < 0.05), and a tendency for improved PD and G:F (P < 0.10) compared with CN diet fed pigs. Regardless of the SC, pigs fed AA+ diet had lower serum albumin (P < 0.05) and tended to decrease serum urea levels (P < 0.10) compared with CN diet. The results of this study suggest that the ratio of Trp, Thr, and Met + Cys to Lys for pigs are modified by sanitary conditions. Furthermore, supplementation of diets with a blend of Trp, Thr, and Met + Cys improves performance, especially under salmonella-challenge and poor housing conditions. Dietary tryptophan, threonine, and methionine supplementation can modulate immune status and influence resilience to sanitary challenges.

Genetic selection modulates feeding behavior of group-housed pigs exposed to daily cyclic high ambient temperatures

This study was conducted to evaluate the effect of genetic selection (Lines A and B; Line A pigs have a greater proportion of Pietrain genes than those from Line B and therefore, selected for improved lean tissue accretion) on the feeding behavior of group-housed pigs exposed to daily cyclic high ambient temperatures. Feeding behavior of 78 barrows housed together in a single room was recorded in real time by five automatic feeders. The feeders registered each visit of each pig (day, hour, min, and second) and the amount of feed requested. Daily cyclic high ambient temperature was induced exposing pigs at 22°C from 18.00 to 10.00 h and 30°C from 10.01 to 17.59 h. From this temperature variation, day-period was divided into: 22°C(06-10h), from 6.00 to 10.00 h; 30°C(10-18h), from 10.01 to 17.59 h; and 22°C(18-06h), from 18.00 to 5.59 h. Meal criteria was estimated based on the probability of animals starting a new feeding event within the next minute since the last visit (Pstart). After defining the meal criteria, the number of meals (n), feed intake rate (g/min), feed intake (g/meal), feeder occupancy (min/meal), and interval between meals (min) of each animal were calculated. Greatest probability of starting to feed was observed at 22°C(06-10h), followed by 30°C(10-18h) and then 22°C(18-06h). Regardless of time period, pigs from line A had greater feed intake rate and lower feed intake, feed occupancy per meal and probability of starting a meal when compared with line B pigs. Only line A pigs had greater feed intake and feeder occupancy per meal at 22°C(18-06h) than remainder of the day. This indicates that pig feeding pattern is strongly related to the circadian rhythm. However, the genetic selection for improved lean tissue accretion may modulate pigs feeding behavior under daily cyclic high ambient temperatures.

Estimating Amino Acid Requirements in Real-Time for Precision-Fed Pigs: The Challenge of Variability among Individuals

Simple Summary

Precision feeding considers the difference in amino acid requirements among pigs and over time by providing daily tailored diets. This practice allows improving environmental and economic performances. Future systems should focus on maximizing nutrient use efficiency to move towards “green” pig production. This study explored a new method of providing amino acids to maximize their use, mainly focusing on understanding variations in the protein metabolism response among individuals to minimize variation in growth response. This study showed that even pigs fed the same amino acid level might use these nutrients differently, especially in protein deposition. Logically, pigs with the greatest protein deposition are the ones that use amino acids the most efficiently, thus exhibiting the lowest nitrogen excretion. This study helped identify some of the factors affecting the efficiency of nitrogen use in pigs. By improving the understanding of pigs’ nutrient response, pig production can become more resource-efficient.

Abstract

This study aimed to measure protein deposition (PD) in pigs fed with daily tailored diets where either dietary lysine (Lys) or threonine (Thr) were provided at independent levels (ignoring an ideal ratio). A total of 95 growing pigs (35 kg body weight (BW)) with electronic ear tags granting them access to automatic feeders were randomly assigned to treatments. The setup was an unbalanced 2 × 5 factorial arrangement with Lys and Thr provided at five levels (i.e., 60%, 80%, 100%, 120%, and 140% of the estimated individual requirements of Lys and Thr), resulting in 25 treatments for 21 days. The observed PD variation to Lys and Thr provisions was large, with Lys and Thr intake explaining only 11% of the variation. Cluster analysis discriminated pigs with low (167 g/d, n = 16), medium (191 g/d, n = 38), and high (213 g/d, n = 37) PD, but with a similar amino acid intake. Differences in PD were associated with differences in nutrient efficiency of utilization. Providing Lys and Thr in a factorial mode, ignoring an ideal ratio, did not decrease the variability in PD. Future research efforts should focus on identifying and investigating the sources of interindividual variability—a necessary step before final recommendations can be made for AA in precision-fed pigs.

Prandial Correlations and Structure of the Ingestive Behavior of Pigs in Precision Feeding Programs

Simple Summary

A better understanding of pig feeding behavior can provide critical information for improving feeding strategies, productivity, and animal well-being. However, the availability of information is very limited in this research field. Data collected using electronic feeders were used in this study to generate information on pig feeding behavior, such as the time, size, and duration of each visit and meal. Later, data were used to calculate prandial correlations that could be interpreted as hunger or satiety-regulating mechanisms. The results indicated that the hunger-regulating mechanisms were slightly stronger than the satiety-regulation mechanisms in the studied animals. A decrease in both regulating mechanisms was observed during animal growth. Feeding programs showed little influence on the feeding regulating mechanisms, with conventional feeding systems (a group of animals fed diets adjusted by phase) slightly differing from precision feeding programs (animals receiving diets adjusted daily to meet the individual nutritional requirements). The use of electronic feeders in research and field conditions is increasing, as well the variety of sensors available in the market. Thus, more studies focusing on pig feeding behavior must be developed in the coming years to further understand such a complex and interesting animal.

Abstract

The feeding behavior of growing-finishing pigs was analyzed to study prandial correlations and the probability of starting a new feeding event. The data were collected in real-time based on 157,632 visits by a group of 70 growing-finishing pigs (from 30.4 to 115.5 kg body weight, BW) to automatic feeders. The data were collected over 84 days, during which period the pigs were kept in conventional (by phase and by group) or precision (with daily and individual adjustments) feeding programs. A criterion to delimit each meal was then defined based on the probability of an animal starting a new feeding event within the next minute since the last visit. Prandial correlations were established between meal size and interval before meal (pre-prandial) or interval after meal (post-prandial) using Pearson correlation analysis. Post-prandial correlations (which can be interpreted as hunger-regulating mechanisms) were slightly stronger than pre-prandial correlations (which can be interpreted as satiety regulation mechanisms). Both correlations decreased as the animals’ age increased but were little influenced by the feeding programs. The information generated in this study allows a better understanding of pigs’ feeding behavior regulation mechanisms and could be used in the future to improve precision feeding programs.

Selection for feed efficiency elicits different postprandial plasma metabolite profiles in response to poor hygiene of housing conditions in growing pigs

This study was conducted to compare postprandial plasma concentrations of insulin, energy-related metabolites, and amino acids measured after a 6-week challenge consisting of exposure to good or poor hygiene of housing conditions of 24 growing pigs divergently selected for low-RFI (LRFI) and high-RFI (HRFI). Blood indicators of immune responses were assessed from samples collected before 0 (W0), and 3 (W3), and 6 weeks (W6) after pigs transfer to their respective hygiene of housing conditions. Plasma haptoglobin concentrations and blood neutrophil granulocyte numbers were greater in poor than in good hygiene of housing conditions at W3. Plasma concentrations of total immunoglobulin G were greater (p = 0.04) in poor than in good hygiene of housing conditions at W6. At W6, pigs were fitted with an intravenous catheter for serial blood samplings. Low-RFI pigs had greater insulin (p < 0.001) and lower triglyceride (p = 0.04) average plasma concentrations than HRFI pigs in both conditions. In poor hygiene of housing conditions, the peaks of insulin and glucose were observed earlier and that of insulin was greater in LRFI than in HRFI pigs. Irrespective of genetic line, average plasma concentrations of histidine, isoleucine, leucine, methionine, threonine, valine, and alanine were greater in poor compared with good hygiene of housing conditions. Only HRFI pigs had greater lysine, asparagine, proline, and tyrosine plasma concentrations in poor than in good hygiene of housing conditions. Conversely, arginine, tryptophan, proline, and tyrosine plasma concentrations were lower only for LRFI pigs housed in poor hygiene conditions. Our results suggest that, contrary to HRFI, LRFI pigs increase or maintain their utilization of tryptophan, arginine, and lysine when housed in poor hygiene conditions. This indicates that this difference may contribute to the better capacity of LRFI to cope with poor hygiene of housing conditions.

Performance and carcass composition of pigs from two sire lines are affected differently by ambient temperature

Context Differences among breeds or lines of pigs in terms of growth and carcass characteristics may be affected by rearing environment (genetic × environment interaction). Aims The present study compared the growth performance and carcass composition of pigs from two sire lines reared under constant thermoneutral (22°C; TN) or high ambient temperature (33°C; HT) conditions. Methods Hampshire (HAM) and synthetic-cross (SYN) castrated male pigs (n = 12 per group; 32.0 ± 2.0 kg) were kept in individual pens at either 22°C (TN) or 33°C (HT) for 55 days (two experimental phases: 0–27 and 28–55 days) following an adaptation period of 7 days. Throughout the experimental period, growth performance and body composition (by dual-energy X-ray absorptiometry on Days 27 and 55) were assessed, and a range of other measurements (serum parameters and physiological responses), which were divided into four measurement groups, was taken on 9 days. Key results Irrespective of genetic line (G), the pigs in the HT treatment had lower average daily feed intake values (P &lt; 0.001, by 29% and 41%) than did the pigs in the TN treatment during both experimental phases (0–27 and 28–55 days). During the second growth phase, the average daily gain of the SYN pigs in the HT treatment was reduced by 50%, whereas that of the HAM pigs was reduced by 24% (P &lt; 0.05 for G × ambient temperature (AT)). On Days 27 and 55, pig bodyweight was lower (P &lt; 0.05) in the HT treatment than in the TN treatment. On Day 27, a G × AT interaction was detected for backfat thickness (P &lt; 0.05); among the SYN pigs, the value of this trait was lower (16%; P &lt; 0.05) in the HT treatment than in the TN treatment, while for the HAM pigs, it was not influenced by treatment type. Conclusion Despite progeny from both genetic lines being affected negatively by high AT, the purebred HAM pigs were less affected by the high AT conditions than were the pigs from the synthetic line. Implication The present findings suggest that individual farm conditions and AT are among the most important factors to consider before implementing a G.

Corrigendum to: Performance and carcass composition of pigs from two sire lines are affected differently by ambient temperature

Context Differences among breeds or lines of pigs in terms of growth and carcass characteristics may be affected by rearing environment (genetic × environment interaction). Aims The present study compared the growth performance and carcass composition of pigs from two sire lines reared under constant thermoneutral (22°C; TN) or high ambient temperature (33°C; HT) conditions. Methods Hampshire (HAM) and synthetic-cross (SYN) castrated male pigs (n = 12 per group; 32.0 ± 2.0 kg) were kept in individual pens at either 22°C (TN) or 33°C (HT) for 55 days (two experimental phases: 0–27 and 28–55 days) following an adaptation period of 7 days. Throughout the experimental period, growth performance and body composition (by dual-energy X-ray absorptiometry on Days 27 and 55) were assessed, and a range of other measurements (serum parameters and physiological responses), which were divided into four measurement groups, was taken on 9 days. Key results Irrespective of genetic line (G), the pigs in the HT treatment had lower average daily feed intake values (P P P P P Conclusion Despite progeny from both genetic lines being affected negatively by high AT, the purebred HAM pigs were less affected by the high AT conditions than were the pigs from the synthetic line. Implication The present findings suggest that individual farm conditions and AT are among the most important factors to consider before implementing a G.

PSVI-13 Sequential feeding with diets varying in amino acid content improves body composition in growing-finishing pigs

This study evaluated the effect of conventional (CONV) and sequential feeding (SEQ) programs with diets varying in amino acid content over the day on body composition in growing-finishing pig. Sixty-eight 25-kg (±2.04) BW barrows were assigned to the following feeding programs: 1) CONV in which pigs received 100% of standardized ileal digestible (SID) AA recommendations for the entire day; 2) SEQ providing 80% SID AA recommendations from 2400 to 1159 h and 120% from 1200 to 2359 h (SEQ80-120); 3) SEQ providing 70% SID AA recommendations from 2400 to 1159 h and 130% from 1200 to 2359 h (SEQ70-130); and 4) SEQ providing 60% SID AA recommendations from 2400 to 1159 h and 140% from 1200 to 2359 h (SEQ60-140). The experimental period lasted 82 days. At days 0, 28, 54 and 82 body lean mass, fat and minerals were measured using a dual energy X-ray absorptiometry (DXA). Pigs fed SEQ80-120 had body composition variables similar to CONV pigs (P &gt;0.05). Whereas, pigs fed SEQ70-130 had greater (P&lt; 0.05) body fat mass (5.27 vs 4.48 kg), bone mineral content (0.656 vs 0.605 kg), fat mass gain (0.100 vs 0.073 kg/d) and bone mineral gain (6.92 vs 5.16 g/d) than CONV pigs during phase 1. Still during phase 1, SEQ60-140 fed pigs had greater (P&lt; 0.05) bone mineral content (0.655 vs 0.605 kg), lean mass gain (0.436 vs 0.374 kg/d) and bone mineral gain (7.48 vs 5.16 g/d) than CONV pigs. During phase 3, bone mineral content was higher (P&lt; 0.05) for SEQ70-130 than CONV (1.408 vs 1.269 kg). During the entire experimental period, body composition variables were not affected by SEQ (P &gt;0.05). According to our results, sequential feeding program improves body composition of pigs at the beginning of the growth period.

Feeding behavior of growing and finishing pigs fed different dietary threonine levels in a group-phase feeding and individual precision feeding system

Feeding behavior is an important aspect of pig husbandry as it can affect protein deposition (PD) in pigs. A decrease in plasma threonine (Thr) levels may influence feed intake (FI) due to amino acid imbalance. We set out to study whether different Thr inclusion rates of 70%, 85%, 100%, 115%, and 130% of the ideal Thr:lysine (Lys) ratio of 0.65 in two different feeding programs (individual precision feeding and group-phase feeding could affect pig feeding behavior and consequently PD. Two 21-d trials were performed in a 2 × 5 factorial setup (feeding systems × Thr levels) with 110 pigs in the growing phase [25.0 ± 0.8 kg of body weight (BW)] and 110 pigs in the finishing phase (110.0 ± 7.0 kg BW), which correspond to 11 pigs per treatment in each trial. Pigs were housed in the same room and fed using computerized feeding stations. The total lean content was estimated by dual x-ray absorptiometry at the beginning (day 1) and the end (day 21) of the trial. Multivariate exploratory factor analysis was performed to identify related variables. Confirmatory analysis was performed by orthogonal contrasts and Pearson correlation analysis. Graphical analysis showed no difference in feeding patterns between feeding systems during the growing or finishing phase. Pigs exhibited a predominant diurnal feeding, with most meals (73% on average) consumed between 0600 and 1800 h. Exploratory factor analysis indicated that feeding behavior was not related to growth performance or PD in growing or finishing pigs. Changes in feeding behavior were observed during the growing phase, where increasing dietary Thr resulted in a linear increase in the FI rate (P < 0.05). During the finishing phase, the duration of the meal and FI rate increased linearly as dietary Thr increased in the diet (P < 0.05). These changes in feeding behavior are, however, correlated to BW. In conclusion, the exploratory factor analysis indicated that feeding behavior had no correlation with growth performance or protein and lipid deposition in growing or finishing pigs. Dietary Thr levels and feeding systems had no direct effect on FI.

Interaction of space allowance and diet on growth performance and physiological responses of piglets raised in tropical conditions

Intensification of pig production in developing countries has resulted in increased number of animals per unit area leading to welfare and growth performance issues. This study was then performed to evaluate the effects of space allowance and dietary energy and amino acid content on growth performance and physiological parameters of piglets reared under tropical conditions. A total of 1280 piglets (castrated males and females) with initial body weight of 5.9 ± 0.4 kg were used. Animals were distributed in a 2 × 2 factorial arrangement composed by two space allowances (0.30 and 0.22 m²/animal) and two diets during 43 to 63 days of age (control and experimental diet with increased ME and AA content). The experimental period lasted 42 days subdivided into four phases according to the growth stage of the animals: pre-initial I (21 to 27 days of age), pre-initial II (28 to 34 days), initial I (35 to 42 days), and initial II (43 to 63 days). During pre-initial I and II, and initial I phases, pigs housed at a space allowance of 0.30 and 22 m²/animal had similar (P > 0.05) feed intake, weight gain, and feed conversion. During initial phase II, space allowance did not affect (P > 0.05) feed intake nor weight gain of the animals. Whereas, pigs fed the experimental diet had greater weight gain when compared to the control group (530 vs. 515 g/day, P = 0.03). According to our results, reducing space allowance from 0.30 to 22 m²/animal during the nursery phase (21 to 63 days of age) had negligible effects on piglet feed intake and weight gain, whereas feeding piglets with diets containing higher energy and amino levels resulted in greater weight gain.

100 Sequential feeding with diets that differ in amino acid content can significantly increase performance of growing and finishing pigs

Recent studies have shown that feed intake, nutrient metabolism and utilization may vary during the 24-h circadian period. In this regard, this study aimed at evaluating the impact on performance from the switching of conventional to sequential feeding programs with diets that differ in amino acid content over the day for growing–finishing pigs. Sixty-eight 25-kg (±2.04) BW barrows were assigned to 4 feeding programs (17 animals per treatment): 1) conventional feeding (CONV), in which pigs received 100% of standardized ileal digestible (SID) AA recommendations for the entire day; 2) sequential feeding (SEQ80-120), providing 80% SID AA recommendations from 2400 to 1159 h and 120% from 1200 to 2359 h; 3) sequential feeding (SEQ70-130) providing 70% SID AA recommendations from 2400 to 1159 h and 130% from 1200 to 2359 h; and 4) sequential feeding (SEQ60-140) providing 60% SID AA recommendations from 2400 to 1159 h and 140% from 1200 to 2359 h. The experimental period lasted 82 d and was subdivided in 3 phases: phase 1 (0 to 28 d), phase 2 (29 to 54 d) and phase 3 (55 to 82 d). The data were analyzed using the MIXED procedure in SAS (SAS Inst. Inc., Cary, NC). SEQ80-120 and SEQ60-140 did not improve performance compared to CONV (P &gt; 0.05). However, ADFI, ADG and BW was higher for SEQ70-130 than CONV during phase 1 (1.49 vs 1.3 kg/d; 0.74 vs 0.65 kg/d; 46.55 vs 43.40 kg, respectively; P &lt; 0.05). During phase 2, BW tended to be higher for SEQ70-130 than CONV (69.20 vs 63.60 kg; P = 0.08). In the entire experimental period, ADFI tended to be higher for SEQ70-130 than CONV (2.08 vs 1.89 kg/d; P = 0.10). According to our results, sequential feeding program improves performance of growing–finishing at the beginning of the period.

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119 Bioavailability of L-Methionine in comparison to DL-Methionine for nitrogen retention of weaned and growing pigs

Two nitrogen (N) balance studies were conducted to compare the relative bioavailability (RBV) of L-Met with DL-Met as Met sources in young pigs. In each experiment, 42 barrows (PIC; initial BW in Exp. 1: 10.7 kg and Exp. 2: 20.5 kg) were allotted to 7 experimental diets with 6 pigs per treatment. The basal diets (diet 1) were formulated based on corn and soybean meal being deficient in Met, but adequate for the other AA (Exp. 1: 0.24% standardized ileal digestible [SID] Met; 0.53% SID Met + Cys; 1.30% SID Lys; Exp 2: 0.23% SID Met; 0.47% SID Met + Cys; 1.15% SID Lys). Three graded levels of DL-Met and L-Met (0.03, 0.06 and 0.09%) were supplemented to the basal diet on top to create diets 2 to 7 for both studies. In Exp.1, N retention (% of N absorbed) increased linearly (P < 0.05) with supplementation with both Met sources. The slope-ratio regression estimated the RBV of 106% [95% confidence interval (CI): 39 to 173%] for N retention (% of absorbed) on an equi-molar basis. In Exp. 2, N retained (g/d), N retention (% of N intake and % of N absorbed) increased linearly (P < 0.05) by supplementing with both Met sources. There was no effect of Met sources on all N balance parameters in both studies. The slope-ratio estimated the RBV of 89% (95% CI: -28 to 206%) for N retained (g/d), 95% (95% CI: 13 to 177%) for N retention (% of N intake) and 94% (95% CI: 20 to 167%) for N retention (% of N absorbed), respectively on an equi-molar basis. In conclusion, the 95% CI for the RBV of L-Met covers 100%, indicating the RBV of L-Met is not different from that of DL-Met as a Met source for weaned and growing pigs.

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Sequential feeding with high-fat/low-crude protein diets for two lines of growing-finishing pigs under daily cyclic high ambient temperature conditions1

This study was conducted to evaluate the effects of sequential feeding technique in two genetic lines (GL; Line A [cross having a greater proportion of Pietrain] and Line B [cross having a lower proportion of Pietrain]) of growing-finishing pigs reared under daily cyclic high ambient temperature conditions. Seventy-eight castrated male pigs (22 ± 2.5 kg BW) were housed in a single group and were allocated to one of the three feeding programs: control (CON, 24 h control diet), high-fat/low-crude protein (HF/LP, 24 h high-fat/low-crude protein diet), and sequential feeding (SEQ, control diet from 1800 to 1000 h and HF/LP diet from 1001 to 1759 h). Cyclic high ambient temperature was induced by exposing the pigs to 22ºC ambient temperature from 1800 to 1000 h (time-period 22ºC, TP22) and to 30ºC from 1001 to 1759 h (TP30). The experimental period lasted 84 days and was divided into 3 growth phases, growing 1 (from day 0 to 20), growing 2 (from day 21 to 48) and finishing (from day 49 to 83). Feed intake was recorded in real time using an automatic feeder system. Pigs were weighed at the beginning and end of each experimental phase. Animal body composition was measured through dual-energy X-ray absorptiometry on days 0, 35, and 70. The ambient temperature averaged 22.3 ± 0.4ºC during TP22 and 30.2 ± 0.5ºC during TP30, characterizing the condition of daily ambient temperature variation that which pigs are usually exposed in tropical climate areas. During growing phase 1, the feeding programs had negligible effects on pig performance (P > 0.05), whereas during growing phase 2, ADG was greater in SEQ than in CON pigs (7%; P = 0.04). During the finishing phase, HF/LP pigs had greater ADFI (+ 10%) and ADG (+ 8%) than CON pigs. Lean mass and gain did not differ among feeding programs (P > 0.05). Overall, fat mass and gain were similar between SEQ and HF/LP pigs (P > 0.05), and both were greater than those of CON pigs (P < 0.05). On the basis of pig performance per phase, the supply of high-fat/low-crude protein diets (SEQ and HF/LP feeding) improved the performance of pigs under daily cyclic high ambient temperature. However, the use of these techniques resulted in fatter carcasses and in higher energy cost of gain. Finally, pigs with greater proportion of Pietrain genes had decreased growth performance in our experimental conditions.

Precision feeding strategy for growing pigs under heat stress conditions

This study evaluated the responses of individual daily precision (IPF) and conventional 2-phase (CON) feeding systems (FS) in terms of pig growth performance, nutrient balance, serum parameters, and meal patterns of growing pigs reared under thermoneutral (TN: 23 °C) and heat stress (high temperature [HT]: 30 °C) conditions. The animals in each treatment were assigned on the basis of equal BW to the experimental treatments (12 animals per treatment at 41.0 ± 4.87 kg of BW). The experiment lasted 55 d (phase 1 from days 0 to 27 and phase 2 from days 28 to 55). Pigs fed CON received within each phase a constant blend of diets with high and low nutrient density supplying the estimated nutrient requirements of the group, whereas the IPF pigs received daily a personalized blend providing the estimated amount of nutrients according to individual feed intake and body weight information. Body mineral content, and lean and fat masses were assessed through dual-energy X-ray absorptiometry at the beginning and end of each phase. Data were analyzed using a linear mixed-effect model, with fixed effects of the FS, temperature (AT), and the 2-way interaction between FS and AT and random effects of blocks. In relation to CON pigs, IPF pigs reduced (P < 0.05) Lys (19%), protein (16%), and P (14%) intake without impairing (P > 0.05) body composition. Nitrogen excretion was 24% lower (P < 0.05) in IPF pigs than in CON pigs; however, both groups had similar N retention efficiency thoroughly the trial. Amount of time feeding, feed intake rate, and feed intake per meal were 15% lower (P < 0.05) in pigs raised under HT than under TN conditions. During the phase 2, only amount of time feeding, feed intake rate, and feed intake per meal were decreased (P < 0.05) in pigs under HT conditions during nocturnal (2000 to 0500 h) and diurnal (0501 to 1959 h) periods. Haptoglobin levels were affected by the AT, showing an increase of 70% and 43% in HT at 28 and 55 d of the experiment, respectively. Pigs raised under HT conditions had 10% lower (P < 0.05) serum albumin concentration at day 55 than those under TN conditions. For serum urea concentrations, IPF pigs had 28% lower (P < 0.01) levels than CON pigs. Even though HT conditions considerably reduced growth performance and activated inflammatory responses in growing pigs, IPF was not able to rescue performance during HT; however, it was equally effective at improving nutrient utilization and maintaining body composition in HT and TN conditions.

Environmental impacts of precision feeding programs applied in pig production

This study was undertaken to evaluate the effect that switching from conventional to precision feeding systems during the growing-finishing phase would have on the potential environmental impact of Brazilian pig production. Standard life-cycle assessment procedures were used, with a cradle-to-farm gate boundary. The inputs and outputs of each interface of the life cycle (production of feed ingredients, processing in the feed industry, transportation and animal rearing) were organized in a model. Grain production was independently characterized in the Central-West and South regions of Brazil, whereas the pigs were raised in the South region. Three feeding programs were applied for growing-finishing pigs: conventional phase feeding by group (CON); precision daily feeding by group (PFG) (whole herd fed the same daily adjusted diet); and precision daily feeding by individual (PFI) (diets adjusted daily to match individual nutrient requirements). Raising pigs (1 t pig BW at farm gate) in South Brazil under the CON feeding program using grain cultivated in the same region led to emissions of 1840 kg of CO2-eq, 13.1 kg of PO4-eq and 32.2 kg of SO2-eq. Simulations using grain from the Central-West region showed a greater climate change impact. Compared with the previous scenario, a 17% increase in climate change impact was found when simulating with soybeans produced in Central-West Brazil, whereas a 28% increase was observed when simulating with corn and soybeans from Central-West Brazil. Compared with the CON feeding program, the PFG and PFI programs reduced the potential environmental impact. Applying the PFG program mitigated the potential climate change impact and eutrophication by up to 4%, and acidification impact by up to 3% compared with the CON program. Making a further adjustment by feeding pigs according to their individual nutrient requirements mitigated the potential climate change impact by up to 6% and the potential eutrophication and acidification impact by up to 5% compared with the CON program. The greatest environmental gains associated with the adoption of precision feeding were observed when the diet combined soybeans from Central-West Brazil with corn produced in Southern Brazil. The results clearly show that precision feeding is an effective approach for improving the environmental sustainability of Brazilian pig production.

Development of sustainable precision farming systems for swine: estimating real-time individual amino acid requirements in growing-finishing pigs

The objective of this study was to develop and evaluate a mathematical model used to estimate the daily amino acid requirements of individual growing-finishing pigs. The model includes empirical and mechanistic model components. The empirical component estimates daily feed intake (DFI), BW, and daily gain (DG) based on individual pig information collected in real time. Based on DFI, BW, and DG estimates, the mechanistic component uses classic factorial equations to estimate the optimal concentration of amino acids that must be offered to each pig to meet its requirements. The model was evaluated with data from a study that investigated the effect of feeding pigs with a 3-phase or daily multiphase system. The DFI and BW values measured in this study were compared with those estimated by the empirical component of the model. The coherence of the values estimated by the mechanistic component was evaluated by analyzing if it followed a normal pattern of requirements. Lastly, the proposed model was evaluated by comparing its estimates with those generated by the existing growth model (InraPorc). The precision of the proposed model and InraPorc in estimating DFI and BW was evaluated through the mean absolute error. The empirical component results indicated that the DFI and BW trajectories of individual pigs fed ad libitum could be predicted 1 d (DFI) or 7 d (BW) ahead with the average mean absolute error of 12.45 and 1.85%, respectively. The average mean absolute error obtained with the InraPorc for the average individual of the population was 14.72% for DFI and 5.38% for BW. Major differences were observed when estimates from InraPorc were compared with individual observations. The proposed model, however, was effective in tracking the change in DFI and BW for each individual pig. The mechanistic model component estimated the optimal standardized ileal digestible Lys to NE ratio with reasonable between animal (average CV = 7%) and overtime (average CV = 14%) variation. Thus, the amino acid requirements estimated by model are animal- and time-dependent and follow, in real time, the individual DFI and BW growth patterns. The proposed model can follow the average feed intake and feed weight trajectory of each individual pig in real time with good accuracy. Based on these trajectories and using classical factorial equations, the model makes it possible to estimate dynamically the AA requirements of each animal, taking into account the intake and growth changes of the animal.

Meta-analytical study of productive and nutritional interactions of mycotoxins in broilers

A meta-analysis was carried out to study the association of mycotoxins with performance, productive indices, and organ weights in broilers. Ninety-eight papers published between 1980 and 2009 were used, totaling 1,401 diets and 37,371 animals. Meta-analysis followed 3 sequential analyses: graphical, correlation, and variance-covariance. The mycotoxin presence in diets reduced (P < 0.05) feed intake by 12% and weight gain by 14% compared with control group. Ochratoxins and aflatoxins were the mycotoxins with the greatest effect on feed intake and bird growth, reducing (P < 0.05) feed ingestion by 17 and 11%, respectively, and weight gain by 20 and 11%, respectively. The mycotoxin concentration in diets and the animal age at challenge were the variables that more improved the coefficient of determination for equations to estimate mycotoxin effect on weight gain. The mycotoxin effect on growth proved to be greater in young poultry. The residual analysis revealed that 65% of the variation in weight gain was explained by feed intake. The variation in weight gain of challenged broilers in relation to nonchallenged broilers was also influenced by ingestion of nutrients such as protein and methionine. Mortality was 8.8 and 2.8 times greater (P < 0.05) in groups that received diets with deoxynivalenol and aflatoxins, respectively. Mycotoxins also increased (P < 0.05) the relative weight of liver by 15%, of kidneys by 11%, of lungs by 9%, and of gizzard by 3%. Mycotoxins influenced broiler performance, productive indices, and organ weights. However, the magnitude of the effects varied with type and concentration of mycotoxin, animal age, and nutritional factors.

Alimentação de porcas lactantes com dietas contendo silagem de grãos úmidos de milho e ácido fumárico

Estudou-se o efeito de dietas elaboradas com silagem de grãos úmidos de milho e ácido fumárico sobre os desempenhos de porcas lactantes e suas leitegadas. Foram utilizadas 20 porcas de genética comercial em um delineamento de blocos ao acaso com quatro tratamentos - dieta basal (DB), elaborada a cada 24h; DB + 0,3% de ácido fumárico - (AF); DB + 0,6% AF; e DB + 0,9% de AF, e cinco repetições. As dietas contendo ácido fumárico foram elaboradas a cada 48 horas. O consumo médio diário da dieta das porcas lactantes foi de 7,42kg de matéria natural e não houve diferença (P>0,05) entre os tratamentos. A adição de 0,9% de ácido fumárico às dietas reduziu (P<0,01) em 6% o pH do leite em relação à dieta-basal. A média de ganho diário e a média de peso dos leitões não diferiram (P>0,05) entre os tratamentos. A adição de ácido fumárico às dietas não alterou os desempenhos de porcas lactantes e de suas leitegadas. A adição de ácido fumárico às dietas de lactação elaboradas com silagem de grãos úmidos de milho reduziu o pH do leite e aumentou a frequência de fezes normais dos leitões lactentes.

Alimentação de leitões com dietas contendo soro de leite fermentado mais zinco e cobre orgânico

Um experimento foi realizado com o objetivo de avaliar o desempenho de leitões alimentados com dietas contendo soro de leite fermentado mais Zn e Cu complexados a aminoácidos. Foram utilizados 64 leitões, meio-irmãos paternos em um delineamento de blocos ao acaso com dois tratamentos. Um tratamento consistiu de uma dieta controle (DC) com ZnO e CuSO4 e o outro foi a DC sem CuSO4 e com adição de soro de leite fermentado mais Zn e Cu complexados a aminoácidos (SLFLact+ZnCuAA). Cada tratamento teve oito repetições e quatro animais por unidade experimental. A presença de SLFLact+ZnCuAA na dieta de leitões não alterou (p>0,05) o peso vivo dos leitões no experimento. No entanto, o peso vivo diferiu (p

Alimentação de leitões em creche com dietas contendo ácido ascórbico e bioflavonóides

Foi realizado um experimento para avaliar o desempenho de leitões em creche alimentados com dietas contendo ou não extratos cítricos. Foram utilizados 32 leitões, meio-irmãos paternos, com peso vivo médio inicial de 6,2 kg (± 0,87), durante 42 dias. O delineamento experimental foi o de blocos ao acaso, com dois tratamentos: dieta controle (DC) e DC + 750 mg kg-1 de um composto contendo extratos cítricos (ácido ascórbico + bioflavonóides), com oito repetições e dois animais por unidade experimental. O peso vivo final foi 4% superior (p

Alimentação de leitoas pré-púberes com dietas contendo aflatoxinas ou Zearalenona

Um experimento foi realizado para avaliar o desempenho, a morfologia vulvar e os pesos de órgãos viscerais e de trato reprodutivo em leitoas pré-púberes alimentadas com dietas contendo aflatoxinas ou zearalenona durante 28 dias. Foram utilizados 18 animais com peso médio inicial de 11 quilogramas. Três tratamentos (dieta controle - DC; DC + 1 mg kg-1 de aflatoxinas; DC + 2 mg kg-1 de zearalenona) foram utilizados em um delineamento inteiramente casualizado com seis repetições. As aflatoxinas reduziram (p0,05) o consumo de ração (DC x DC + zearalenona: 1,087 x 0,986 kg), a conversão alimentar (1,85 x 1,86), o ganho de peso (0,608 x 0,539 kg) e o peso vivo dos animais (27,4 x 25,5 kg) em relação ao grupo controle. Os pesos relativos de fígado e coração também não foram alterados (p>0,05) pelas micotoxinas. Porém, a zearalenona aumentou (p

Alimentação de leitoas pré-púberes com dietas contendo zearalenona

O desempenho, o peso de alguns órgãos e a morfologia vulvar de leitoas pré-púberes, alimentadas por 28 dias com dietas contendo zearalenona, foram avaliados. O delineamento experimental utilizado foi inteiramente ao acaso, com dois tratamentos, dieta controle (DC) e dieta controle + 2mg kg-1 de zearalenona (DZ), e seis repetições cada. Não houve diferença (P>0,05) entre os tratamentos para consumo médio diário de ração (1,24 x 1,19kg), ganho médio diário de peso (0,68 x 0,71kg), conversão alimentar (1,86 x 1,71) e peso vivo (PV); (30,9 x 30,4kg). A zearalenona não alterou (P>0,05) os pesos absoluto e relativo do coração (137 x 141g e 0,45 x 0,45% PV), fígado (699 x 699g e 2,31 x 2,26%PV), rins (47 x 49g e 0,15 x 0,16%PV) e baço (166 x 171g e 0,55 x 0,55%PV). Houve aumento (P<0,05) no comprimento (17 x 27cm) e no peso (23 x 157g e 0,07 x 0,51%PV) do trato reprodutivo das leitoas do grupo DZ. O volume vulvar ao final do período foi 820% maior (P<0,05) nos animais alimentados com zearalenona (941 x 8658mm³/kgPV0,6). Os resultados indicam que em suínos a zearalenona e seus metabólitos possuem atividade estrogênica, mas não interferem no desempenho dos animais.

Utilização do triticale e de enzimas em dietas para suínos: digestibilidade e metabolismo

Avaliou-se o efeito da inclusão de níveis de triticale sobre o valor nutritivo de dietas para suínos com ou sem enzimas. Foram utilizados 24 suínos machos, castrados, com peso inicial de 59kg, alojados em gaiolas metabólicas. O delineamento foi de blocos ao acaso em arranjo fatorial 3 x 2 (níveis de triticale, 0, 30 e 60%, com ou sem enzimas), com quatro repetições cada. A inclusão de triticale na dieta em até 60% e a adição de enzimas não influenciou (P>0,05) a digestibilidade da matéria seca, fósforo, energia bruta, metabolização da energia, energia digestível e metabolizável e o balanço do N. Os valores médios de energia digestível e metabolizável foram de 3.537 e 3.435kcal. Houve interação triticale x enzimas na proteína digestível aparente (PDa) (P<0,01). Na dieta com 60% de triticale sem adição de enzimas a PDa foi 6% inferior à controle. Na dieta com 30 e 60% de triticale com enzimas, a PDa foi similar à controle e 5% superior à dieta com 60% de triticale sem enzimas. A inclusão de 60% de triticale em dietas para suínos reduz a PDa. A adição de enzimas melhora a PDa em dietas com 30 e 60% de triticale.

Substituição de milho por sorgo baixo tanino em dietas para suínos: digestibilidade e metabolismo

Um experimento foi realizado para avaliar os efeitos digestivos e metabólicos da substituição de milho por sorgo em dietas para suínos. Foram utilizados 12 suínos machos castrados, meio-irmãos paternos, com peso vivo médio inicial de 40,8kg, mantidos em gaiolas metabólicas. O delineamento experimental foi inteiramente casualizado com três tratamentos (T1 = dieta controle; T2 = substituição de 50% do milho por sorgo e T3 = substituição de 100%) e quatro repetições. As digestibilidades da proteína e da energia brutas foram 5 e 4% superiores (P<0,05), respectivamente, nos suínos alimentados com a dieta que tinha 50% de substituição, comparadas àquela com substituição total do milho por sorgo. A substituição total do milho por sorgo reduziu (P<0,05) as digestibilidades, em relação à dieta-controle, em 3% para MS, 8% para PB e 5% para EB. O N fecal foi 25% maior (P<0,05), o N absorvido 10% menor (P<0,05) e a excreção fecal de energia 15% maior (P<0,05) para a dieta com substituição total, em relação à dieta-controle. A excreção fecal de N e energia e a absorção de N são influenciadas negativamente pela substituição total de milho por sorgo nas dietas. A substituição em até 50% do milho por sorgo em dietas para suínos não influi na digestibilidade das dietas e no metabolismo dos animais.