Update and evaluation of the egg production model in laying hens.

The egg production model (EPM) described here is a mechanistic and stochastic model that simulates the amino acid and energy requirements of laying hens. It takes into account their potential rate of laying, and egg weight over time, and the composition of the feed provided. The model predicts feed intake based on the assumption that hens will consume enough feed to reach their genetic potential. The environment is assumed to be non-limiting, although feed intake may be constrained by bulk capacity when bulky feeds are offered. The simulation model integrates a least-cost feed formulator, which enables the prediction of a feeding program that maximizes economic returns. A series of simulations were conducted to demonstrate the model behavior, external evaluation, and the economic optimization routine. The model behavior showed that as the energy content in the feed decreased, the simulated feed intake increased to compensate. Consequently, feeds with lower energy concentrations led to an overconsumption of nutrients, resulting in increased egg component weights (yolk and albumen). However, when the balanced protein was reduced while maintaining a constant energy-to-protein ratio, there was no change in egg components, consistent with published literature. The external evaluation indicated that feed intake, egg production, and egg weight were estimated with low error, and there was a similar trend observed between the estimated and observed data. This demonstrates the reliability of the model. Additionally, the paper provides a demonstration of how to use and interpret the results from the egg production model, including the economic optimization routine. The study found that a feed containing 7.8 g/kg of digestible lysine maximized economic returns. This optimization tool can be valuable in making nutritional decisions to optimize economic returns in an egg production system.

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.

Energy utilization and requirement of broiler breeders during the production phase.

This study aimed to evaluate energy utilization and propose models for metabolizable and net energy requirements in broiler breeders during the egg production phase. Sixty Cobb500 broiler breeders aged between 29 and 65 wk were randomly assigned to 3 feeding levels. At each age, 6 birds were adapted for 8 d to 3 levels of metabolizable energy intake (MEi), established based on the amount of feed allocated: 1) the amount of feed recommended in the guideline, 2) 25% above, and 3) 25% below. The birds were housed in respirometry chambers for 6 d (1 adaptation, 4 feeding state, 1 fasting) to measure oxygen consumption and carbon dioxide production to calculate heat production (HP) and fasting HP (FHP). Daily measurements of feed intake, egg weight, egg production, and total excreta were recorded. Variables of MEi, HP, and retained energy (RE) in the egg were calculated, while RE in the body and its partitioning into fat and protein in the egg and body were calculated from MEi, total HP (THP), and RE in the egg. Statistical analysis involved linear regression of multiple factors with MEi and age (categorical) as the independent variables. Pearson correlation analysis was conducted to investigate the relationship between visceral mass and the evaluated variables. The study proposed mixed models for developing models of energy requirements for both metabolizable (ME) and net systems (NE). The study found that FHP (average 259 ± 20.08 kJ/kg0.75*d) remained constant throughout the production cycle regardless of the MEi level (P > 0.05). The efficiency of energy utilization for depositing protein and fat in the body changed with the bird's age. The lower error model was considered to select ME requirements for maintenance, egg, and gain efficiencies, disregarding the effect of age. The efficiencies were 0.89, 0.78, and 0.80 for maintenance, gain, and egg production, respectively. The NE was unaffected by age and showed a lower error than the ME model. The NE system was found to be more accurate in expressing the energy requirements of broiler breeders.

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.

Eimeria maxima infection impacts the protein utilisation of broiler chicks from 14 to 28 days of age.

In floor-raised broilers, coccidiosis is responsible for reducing the use of nutrients, mainly by impairing intestinal tissue function and activating the immune system. Understanding and quantifying how balanced dietary protein (BP) is used when birds are challenged will allow nutritionists to make decisions regarding challenged flocks. This study aimed to determine the effects of Eimeria maxima on broiler performance and body composition, and to calculate changes in the maintenance and efficiency of protein utilisation (Ep). A total of 2 400 male 14-day-old Cobb500 broiler chickens were randomly allotted to ten groups with six replications of 40 birds each, with a 5 × 2 factorial arrangement of treatments. Five levels of BP in reference to digestible lysine (3.6, 7.2, 10.8, 14.4, and 18.0 g/kg) were fed to unchallenged (NCH) and challenged (CH) broilers with 7 × 103E. maxima sporulated oocysts from 14 to 28 days of age. Performance and body deposition were measured using a comparative slaughter technique to compare BP maintenance requirements and Ep. ANOVA followed by a posthoc test was performed to compare the effects of BP levels, challenge, and their interactions. A monomolecular model describing the responses of NCH and CH broilers to BP intake, maintenance, and maximum protein deposition was compared. There were significant interactions between body weight gain and digestible lysine intake among the factors studied. Infection had a negative impact on all variables analysed, proving the efficacy of the challenge. The maintenance did not differ between the CH and NCH groups. Increased levels of dietary BP did not recover the maximum protein deposition in CH broilers. Eimeria maxima significantly reduced Ep by a factor of 0.09 times on Ep compared to the control group. The Eimeria maxima challenge was responsible to modify the use of BP altering the body composition and impairing broilers performance.

Energy cost of physical activities in growing broilers.

1. The time-energy budget method estimates the energy used for physical activity (PA) by integrating behaviour PA patterns with energy cost for specific PAs. Nevertheless, information about individual energy cost by type of PA are not available and so this study estimated the energy cost of PA for growing broilers.2. An indirect calorimetry system for single birds was constructed to measure the variation in the rate of O2 consumption (V˙O2, L/min) and rate of CO2 production (V˙CO2, L/min) produced by these PAs.3. A total of five birds were used in a replicated trial where their body weight (BW) ranged from 1.5 to 2.5 kg to measure the increase in heat production (HP) above resting levels as a result of PA. The procedure in the chamber was divided into five steps: (1) initial baselining, (2) resting metabolic rate, (3) PA such as feeding, drinking and other standing activities, (4) removal of gas exchange produced in step 3, and (5) final baselining. The PA was recorded using a video camera fixed at the chamber's top (and outside).4. The area under V˙CO2 and V˙O2 curves was used to calculate the CO2 production (vCO2, L) and O2 consumption (vO2, L). Then, the HP (cal/kg-0.75) was calculated according to the Brouwer equation. Two observers analysed the video records to estimate the time spent for each PA (seconds and frequency).5. To calculate the energetic coefficients, the HP was regressed with the function of time spent to perform each PA allowing to estimate the energy cost for eating, drinking and stand activities, which were 0.607, 0.352 and 0.938 cal/kg-0.75/s, respectively.

Composition of feathers and pulp of two broiler genotypes.

1. Cobb and Ross broilers (200 of each sex and breed) were fed four phases of diets ad libitum formulated with balanced protein to match their amino acid requirements throughout growth. Ten birds per genotype were sampled and euthanised at two-weekly intervals from 14 to 112 d of age. All feathers were dry-plucked from each of the seven tracts (specific skin areas) and pulp (the centre of the feather filament) was removed from primary and secondary remiges.2. Daily losses of feathers were collected from an additional 20 individually-caged broilers of each breed. These feathers were separated into natal down, contour feathers, remiges and rectrices and then pooled by type, sex and genotype to quantify water and protein contents. Only those feathers collected from male Cobb 500 MX broilers were analysed for amino acid content.3. Amino acid contents of feathers from the seven tracts were measured only in Cobb males on days 1, 28 and 70; for pulp on days 28 and 70; and for the four types of moulted feathers.4. Protein content on a dry matter basis remained relatively constant over all ages and tracts during growth. Water content decreased with age in both sexes and genotype. Lysine and methionine content in feathers decreased with age while cystine, valine, leucine and serine increased. Lysine, methionine and histidine levels were higher in pulp than in mature feathers whereas cystine and valine were higher in mature feathers than in pulp.5. These results, together with information about moulting patterns in broilers, enabled the effects of age of the bird and of the type of feather, to be taken into account when determining the rate of deposition of amino acids in feathers.

Gut capacity of broiler breeder hens.

1. Broiler breeders are subjected to qualitative or quantitative feed restrictions to prevent obesity, which causes major health and welfare problems. Diluting their feed by adding inert or low nutrient, bulky materials can reduce obesity, but the capacity of the gut needs to be determined to apply this strategy successfully. Two trials were conducted to measure the bulk capacity of Ross 308 broiler breeders prior to and after the onset of lay. The trial was completely randomised, with nine individually-caged breeders, with each cage as a replicate, totalling 189 birds per trial2. Birds were given ad libitum access to one of 21 maize-soyabean based feeds, an undiluted control or progressive dilution (10, 20, 30 and 40%) with either cellulose fibre, rice husk, sand, vermiculite or sawdust. Feeds were analysed for density, crude-, acid detergent- and neutral detergent-fibre, water-holding capacity (WHC), cation-exchange capacity and oil-holding capacity.2. In general, feed intake (scaled to body weight0.67) increased and then declined as the proportion of each diluent increased. Intake increased linearly when rice hulls and sand were used as diluents.3. Water holding capacity was the most appropriate measure to define the gut capacity of broiler breeders.4. The trial data was used to estimate the maximum-scaled feed intake (SFImax) in broiler breeders, which was 240-56.1WHC + 4.34WHC2 g/kg0.67/d.

The response of reproducing Japanese quail to dietary valine.

1. A feeding trial was conducted to measure the responses of Japanese quail to dietary valine. In total, 280 Japanese quail were randomly assigned to eight treatments giving seven replicates (cage - 35 cm length, 35 cm width × 15 cm high). Experimental diets were formulated using a dilution technique to give a range dietary Val concentration (1.97 to 9.85 g/kg).2. Feed intake was maximised at 6.66 g Val/kg and above, but declined linearly below this level. Body weight reached a maximum of 170 g on 6.66 g Val/kg. Egg output peaked at 9.5 ± 0.3 g/bird/d with an egg weight of 11 g for the 6.66 g Val/kg diet. Rate of laying for the group that received the feed with the lowest Val content was close to zero (1.40%), but egg weight on this treatment was 70% of the maximum egg weight. Valine required per gram of egg output was estimated as 10.6 mg/g, whereas the maintenance requirement was 159 mg/kg body weight. Val required for maximum egg output was estimated in 154 mg/d.3. The marginal cost of Val in Brazil currently is negative below a level of 8.0 g/kg feed, which is above that required for maximum egg output. Consequently, Val cannot be regarded as a limiting amino acid currently, as the optimum economic intake exceeds the requirements of all the individuals in the population. The price of a quail egg weighing 11 g in Brazil at the time of the experiment was R$ 0.021. Even if the marginal revenue for these eggs was doubled to 0.4 c/g, there would be no reason to increase the intake of Val.

Rate of feed passage in Japanese quail.

The rate of passage (ROP) in the gastrointestinal tract (GIT) influences the exposure time of food to the digestion and absorption processes. Consequently, ROP affects the efficiency of nutrient utilization and energy from the diet. This study aimed to determine the physiological parameters that characterize the digestive response, such as first appearance time (FAT), ROP, mean retention time (MRT) and transit time (TT) in adult Japanese quail (Coturnix coturnix japonica), and to evaluate the effects of sex, apparent metabolizable energy corrected for nitrogen balance (AMEn) content in the diet and different types of markers on these parameters. In the first trial, we investigated the effects of sex and AMEn level (high- and low-energy diet) on the FAT parameter. Thirty-two male and 32 female Japanese quail were randomly allocated to 8 battery cages and assigned to 4 treatments in a 2 × 2 factorial design with 4 replicates of 4 birds for each treatment. To determine the FAT, ferric oxide (1%) was added to the diet, and the excreta of the quail was monitored until the first appearance of the marker. The results indicated significant differences (P < 0.05) in the FAT between males (100 min) and females (56 min), regardless of the AMEn content. In the second trial, thirty-two 32-week-old female Japanese quail in the laying phase were assigned to four treatments in a 2 × 2 factorial design, in which the main independent variables were type of marker (Cr or Ti) and AMEn level (high- and low-energy diets). In order to determine ROP (ET1%), MRT and TT (ET100%), the markers (0.5%: Cr2O3 and 0.5%: TiO2) were added to the diets, and the excreta were collected for 750 min. The excretion times for 1% (ET1%), 25% (ET25%), 50% (ET50%), 75% (ET75%) and 100% (ET100%) were estimated using cumulative excretion curves. No effect was detected for the AMEn level (P > 0.05); however, the effect of different marker types was significant (P < 0.05). This difference increased with time and ET100% was estimated to occur at 59 min. The ROP was estimated to be 68 min. The TT was estimated to be 540 min using Cr and 599 min using Ti, with an average MRT value of 0930 h. Taken together, our findings support the hypothesis that Japanese quail digestion through the GIT can be dynamic and differ based on sex or marker type.

Stable isotopes to study sulfur amino acid utilization in broilers.

Nutritionists have been discussing whether the dietary supplementation of cyst(e)ine is required as a part of the dietary methionine (Met) in the total sulfur amino acid (TSAA) requirement to achieve optimum performance in broilers. Part of Met is converted to cysteine (Cys) to meet the Cys requirement, especially for feather growth. The TSAA requirement has been determined by using graded levels of free Met in the diet, without supplementation of free cyst(e)ine. It has also been argued that the Met to Cys ratio (Met : Cys) changes with age and even with different Met sources. The objective of this study was to evaluate the two sources of Met, while determining the proportion of Met and Cys in total dietary TSAA that optimize the performance of broilers. A performance assay was carried out in a factorial arrangement (5 × 2) using 1080 broilers from 42 to 56 days of age fed diets having different dietary proportions of Met and Cys (44 : 56, 46 : 54, 48 : 52, 50 : 50 or 52 : 48) while maintaining the same dietary TSAA in the diets. Two synthetic Met sources (dl-Met or l-Met) were used for each of the diets with different dietary Met : Cys ratios. Twenty-one broilers of the same age were fed the diets 44 : 56, 48 : 52 and 52 : 48 by supplementing the diet with L-(15N) Met or L-(15N2) Cystine to study the metabolism of TSAA. No differences were observed between Met sources for feed intake, BW gain and feed conversion ratio (FCR; P > 0.05); however, FCR was numerically improved at 50 : 50 Met : Cys. Regarding TSAA utilization, the conversion of Met to Cys increased with increase in Met : Cys ratios, but the concentration of Met intermediates decreased. Broiler chickens responded to different dietary proportions of sulfur amino acids by altering their sulfur amino acid metabolism, and diets containing 50 : 50 Met : Cys is recommended for broilers of age 42 to 56 days.

Metabolisable energy partition for Japanese quails.

Knowing how energy intake is partitioned between maintenance, growth and egg production (EP) of birds makes it possible to structure models and recommend energy intakes based on differences in the BW, weight gain (WG) and EP on commercial quail farms. This research was a dose-response study to re-evaluate the energy partition for Japanese quails in the EP phase, based on the dilution technique to modify the retained energy (RE) of the birds. A total of 300 VICAMI® Japanese quail, housed in climatic chambers, were used from 16 weeks of age, with averages for BW of 185 g and EP of 78%, for 10 weeks. To modify the RE in the bird's body, a qualitative dilution of dietary energy was used. Ten treatments (metabolisable energy levels) were distributed in completely randomised units, with six replicates of five quails per experimental unit. Metabolisable energy intake (MEI), egg mass (EM) and RE were expressed in kJ/kg0.67. The utilisation efficiency (kt) was estimated from the relationship between RE and MEI. The metabolisable energy for maintenance was given by RE = 0. The net energy requirement for WG was obtained from the relationship between RE in the BW as a function of the BW. The utilisation efficiency for EP (ko) was obtained from the relationship between EM and RE corrected MEI for maintenance and WG. Based on these efficiencies, the requirements for WG and EM were calculated. The energy intake by Japanese quails was partitioned according to the model: MEI = 569.8 × BW0.67 + 22 × WG + 13 × EM. The current study provides procedures and methods designed for quails as well as a simple and flexible model that can be quickly adopted by technicians and poultry companies.

Weight gain responses of laying-type pullets to methionine plus cystine intake.

Each individual in the population has a distinct maximum growth potential, and the growth curve may vary depending on the response to nutrient intake, growth phase and variability among animals. The present study aimed to (1) model weight gain (WG) response to methionine+cystine (Met+Cys) supply using different mathematical functions, (2) identify functions that better fit the growth responses of pullets, (3) determine the Met+Cys requirements that maximize WG based on breeding standards and (4) partition the Met+Cys requirements for WG and maintenance. Three trials were performed using 1448 laying-type pullets. We adopted a completely randomized design with eight treatments and six replicates. The first trial (2 to 6 weeks, P1) used 15 pullets per experimental unit. The second and third trials (8 to 12 weeks, P2; 14 to 18 weeks, P3) were used eight pullets per replicate. The Met+Cys levels were obtained using a dilution technique. The mathematical functions used to describe WG responses to Met+Cys intake were broken line, broken line with curvilinear ascendancy, Michaelis-Menten, saturation kinetics and three logistic and three exponential models. Models were selected using the Bayesian information criterion and evaluated by residual analysis. It was possible to model the responses using the studied functions. The best functions were obtained by logistic and sigmoidal models in P1 and P2, and with the broken line by the curvilinear ascendancy model in P3. The Met+Cys intake that determined the maximum potential for WG (WGmax) in P1, P2 and P3 were 313, 381 and 318 mg/day, respectively. The Met+Cys requirements for WG were 20, 22 and 27 mg/g, and for maintenance were 214, 53 and 30 mg/kgBW0.75 for P1, P2 and P3, respectively.

A description of the growth and moulting of feathers in commercial broilers.

1. Changes in feather length and weight and daily losses of down, contour feathers, remiges and retrices were studied in two commercial broiler strains to determine feather growth and moult in broilers up to 112 d of age. 2. Ten pens of 20 chicks for each sex x strain were fed adequate amounts of dietary protein in a four-phase feeding programme. Ten birds were sampled per genotype at 14, 28, 42, 56, 70, 84, 98 and 112 d. Feather loss was determined for individual birds caged within a nylon net. 3. All feathers were dry-plucked from each of seven tracts, with representative feathers from the capital-cervical, dorsopelvic and interscapular, pectoral and femoral tracts being randomly selected. Three rectrices of the dorsocaudal tract and three primaries and secondaries of the humeral-alar tract of the right wing were evaluated. 4. The length of the selected feathers was measured, and the feathers from each tract and from the whole bird were weighed. 5. A wide range of rates of maturing (0.0250-0.0907/d) and mature weights (9.62-52.9 g) were evident between sampled tracts. 6. Feather weight failed to predict some moults which were detected by the measurement of feather losses. From the weight data, moulting was evident only in the humeral-alar and dorsocaudal tracts, whereas, when daily losses were measured, contour feathers accounted for over 0.7 proportion of feather losses. Logistic equations adequately described the cumulative losses of down, contour feathers and remiges. 7. Feather loss needs to be considered when feather growth is determined from feather weight at different ages. 8. The rate of maturing (B) of feathers was numerically higher in Ross males and females than in the Cobb strain. In females, B was higher than in males (0.0483 vs. 0335/d) but the mature weight was lower (162 vs. 230 g).

A description of the potential growth and body composition of two commercial broiler strains.

1. The potential growth of feathers and feather-free body and their chemical components was measured in two commercial broiler strains. 2. A total of 200 chicks of each sex x strain were fed adequate amounts of dietary protein using a four-phase feeding programme. Ten birds per genotype were sampled at 14, 28, 42, 56, 70, 84, 98 and 112 d of age. They were weighed before and after being dry-plucked to determine the weight of feathers, and the feather-free body was then minced and analysed for water, protein and lipid. 3. Body weights and chemical composition of males of the two strains were similar throughout the trial. Females of the two strains differed only in their body lipid contents, with mature Cobb females being higher than Ross (1371 vs. 1210 g). 4. Mature body weights of males and females from both strains averaged 8420 g and 6650 g; mature body protein weights averaged 1555 g and 1030 g; and mature body lipid contents averaged 908 and 1290 g, respectively. 5. Rates of maturing per day of body weights of males and females of both strains averaged 0.0385 and 0.0368; feather-free body protein was 0.0316 and 0.0348 and body lipid was 0.0503 and 0.0375, respectively. The rates for body lipid differed between Cobb and Ross females (0.0352 vs. 0.0397/d). Separate equations were required for males and females to describe the allometric relationship between lipid and protein in the feather-free body. 6. The rate of maturing of feathers in females was higher than in males (0.0526 vs. 0398/d) and the mature weight was lower (205 vs. 266 g), respectively. Mature body weights of broilers in this trial were considerably higher than those measured using the same protocol 24 years ago, whereas rates of maturing remained the same.

Growth performance and carcass yield of broiler chickens in response to carbohydrases and its association with phytase / Desempenho e rendimento de carcaça de frangos de corte em resposta à associação de carboidrase com fitase

An experiment was conducted to evaluate broiler chicken performance and carcass yield in response to carbohydrase supplementation (Xylanase and Betaglucanase; XB) and association of carbohydrase and phytase (PHY). A total of 1,920 day-old male broiler chicks (Cobb 500) were distributed in a completely randomized design with 8 treatments and 8 replicates each, allocated in 64 pens with 30 chicks each. The treatments were: Positive Control (PC); Negative Control (NC): reduced ME [-120kcal/kg (Starter) and -170kcal/kg (Finisher)]; NC + XB [50g/ton]; NC + XB [100g/ton]; NC + XB [150g/ton]; NC + XB [50g/ton] + PHY [100g/ton]; NC + XB [100g/ton] + PHY [100g/ton]; NC + XB [150g/ton] + PHY [100g/ton]. The inclusion of XB (150) and XB (50, 100, and 150) associated with phytase increased feed intake than positive control when considering the total rearing phase. The feed conversion ratio of all broilers fed diets with energy reduction were worse than positive control, even with the addition of enzymes, and did not differ between them. There was no significant effect of treatments on carcass parameters.(AU)

O experimento foi conduzido para avaliar o desempenho e o rendimento de carcaça de frangos de corte em resposta à suplementação de carboidrase (Xilanase e Betaglucanase; XB) e à associação de carboidrase com fitase (PHY). Um total de 1.920 frangos de corte, machos, com 1 dia de idade (Cobb 500), foram distribuídos em um delineamento experimental inteiramente ao acaso, com oito tratamentos e oito repetições, totalizando 64 unidades experimentais (boxes) com 30 aves cada. Os tratamentos foram: controle positivo (PC); controle negativo (NC): redução de EM [-120kcal/kg (fase inicial) e -170kcal/kg (fase final)]; NC + XB [50g/ton]; NC + XB [100g/ton]; NC + XB [150g/ton]; NC + XB [50g/ton] + PHY [100g/ton]; NC + XB [100g/ton] + PHY [100g/ton]; NC + XB [150g/ton] + PHY [100g/ton]. A inclusão de XB (150) e a associação de fitase com XB (50, 100 e 150) aumentaram o consumo de ração em relação ao tratamento controle positivo, considerando-se a fase total de criação. A conversão alimentar de todos os frangos que receberam dietas com redução de energia foi pior que o controle positivo, mesmo com a adição das enzimas, e não diferiu entre elas. Não houve efeito significativo dos tratamentos sobre os parâmetros de carcaça.(AU)

An update on the cecectomy technique in roosters anesthetized with isoflurane used in subsequent amino acid digestibility experiments.

This work aims to study an alternative technique of cecectomy in roosters using inhalation anesthesia for subsequent use in digestibility experiments. A total of 30 adult chickens of Leghorn breed were used with an average age of 27 wk. The birds were preoxygenated, and the anesthetic induction was performed using isoflurane diluted in oxygen. After proper muscle relaxation, endotracheal intubation was performed using a Murphy catheter and kept in anesthesia under mechanical ventilation with a constant monitoring of electrocardiography variables, heart rate, oxyhemoglobin saturation, and body temperature during the surgical procedure. An incision of approximately 3 cm was made between keel and cloaca in order to expose and extirpate the cecum followed by a simple ligature. The opening of the peritoneal cavity was closed in 2 ways: Sultan suture technique was used for closing the abdominal wall and modified Cushing intradermic continuous points for closing the skin. The time for anesthesia induction and preoperational period noted to be 10 ± 2 min. Surgical procedures completed in 7 ± 1.5 min. No intraoperatively and postoperatively harm observed in animals. Water was immediately provided after the birds returned to cages and feed offered after 24 h of surgery. In remaining birds, no abnormalities were observed during and after the experimental period (3 mo). The present study describes a promising update on cecectomy technique regarding anesthesia induction and surgical procedures in roosters using potential drugs and safer surgical materials without any trans- and postoperative complications.

Insoluble fibres, satiety and food intake in cats fed kibble diets.

Fibre is generally considered to dilute food energy, alter intestinal transit time and promote satiety; however, in cats, conflicting results have been found. In this study, two insoluble fibres were evaluated in four feline diets: control (no added fibre); diet with 10% sugar cane fibre; diet with 20% sugar cane fibre; and diet with 10% cellulose. The experiment was conducted with 32 cats, eight animals per diet, over 42 days: 1-7 for diet adaptation; 8-14 for total collection of faeces for digestibility; 15-17 for fresh faeces collection for fermentation products measurements; 18-20 for gastrointestinal transit time determination; 21 and 37 to evaluate the pattern of food intake; and 22 and 42 to assess satiety. Means were compared by analysis of variance and orthogonal contrasts, and the pattern of food intake was compared by repeated-measures analysis of variance (p < 0.05). The cats exhibited increased food intake after fibre addition to the diets (p < 0.05), achieving similar energy consumption. Cellulose and the two levels of sugar cane fibre reduced nutrient availability and energy digestibility, but only sugar cane fibre reduced fat digestibility (p < 0.05). Faecal output and the number of defecations per day increased with fibre inclusion (p < 0.05). Gastrointestinal transit time did not change with sugar cane fibre inclusion, but it was reduced with cellulose addition (p = 0.032). The pattern of food intake did not change, but cats fed fibre-supplemented diets exhibited greater consumption of a challenge meal, increasing energy intake (p < 0.01) when exposed to a palatable, energy-dense food.

Optimal in-feed amino acid ratio for broiler breeder hens based on deletion studies.

An ideal amino acid ratio (IAAR) for breeder hens is needed for maximum nitrogen retention (NR) taking into account nitrogen deposition in body (NDB ), feathers (NDF ) and egg mass (NEM) to improve dietary protein efficiency. Thus, the aim of this study was to apply the deletion method to derive the IAAR for broiler breeder hens. The nitrogen balance trials were performed from 31 to 35 weeks and from 46 to 50 weeks. Twelve treatments with eight replicates and one hen per cage were used. A balanced diet (BD) was formulated to meet the requirement of all nutrients. The other diets were formulated diluting 55% of BD with corn starch and refilled with amino acids (AAs) and other ingredients, except the AA tested. Each trial lasted 25 days. Feather losses, egg production and egg weight were recorded daily, and the samples were stored to further determine NEM and nitrogen in feather losses (NDFL ). At the start and the end of each period, a group of birds were slaughtered to further determine NDB and NDF . The NR was calculated as the sum of NDB , NDF , NDFL , NEM and the nitrogen maintenance requirement (NMR). The deletion of valine greatly depressed the NR in peak production (31 to 35 weeks) while the deletion of the isoleucine greatly depressed the NR of the hens from 46 to 50 weeks of age. The percentual reduction in NR and the per cent of the AA to delete from the BD were used to calculate the AA requirement. The average IAAR was Lys 100, Met+Cys 86, Trp 23, Thr 80, Arg 113, Val 90, Ile 91, Leu 133, Phe+Tyr 108, Gly+Ser 94 and His 35. The IAAR was in line with the recommendation from the literature, validating deletion method with the advantages from a rapid and low-cost procedure.