Effects of dietary calcium and phosphorus restrictions on growth performance, intestinal morphology, nutrient retention, and tibia characteristics in broiler chickens.

1. This study evaluated the effects of dietary calcium (Ca) and available phosphorus (aP) restrictions on growth performance, intestinal morphology, nutrient apparent total tract retention (ATTR), and tibia characteristics.2. A total of 1296, one-day-old male Ross-308 broilers were reared for 42 d. During the starter phase (1-10 d), all birds were fed a nutrient-adequate diet (C). Diets fed during the grower phase (11-24 d) included: 1. C; 2. 15% of the Ca and aP in C; 3. 30% of the Ca and aP in C. At the beginning of the finisher phase (25 d), chickens fed the C diet were divided into two subgroups including C, and C+ phytase (500 FTU/kg). Restricted treatments were divided into eight subgroups as 1. C; 2. 10% of the Ca and aP in C; 3. 20% of the Ca and aP in C; 4. 30% of the Ca and aP in C; 5. C+ phytase; 6. 10% of the Ca and aP in C+ phytase; 7. 20% of the Ca and aP in C+ phytase and 8. 30% of the Ca and aP in C+ phytase. 3. On d 24 and 42, ATTR of Ca and phytate phosphorus (pP) were linearly increased by decreasing Ca and aP levels (P < 0.05). Birds receiving phytase showed higher nutrient ATTR compared to those fed non-phytase supplemented diets (P < 0.05). Tibia Ca and P were linearly decreased at 24 d (P < 0.05) and tibial ash was linearly decreased (P < 0.05) at 42 d by decreasing levels of Ca and aP in finisher diets (without phytase) . By decreasing the levels of Ca and aP in the finisher diets (with phytase) with a 30% reduction of Ca and aP in the grower phase, tibia ash linearly decreased (P < 0.05). Using 500 FTU/kg phytase improved tibia traits compared to non-phytase supplemented treatments (P < 0.05).4. In general, decreasing dietary Ca and aP (up to 30%) during grower and finisher phases increased ATTR of minerals and decreased Ca, P and breaking strength (BS) of tibia without any negative effect on growth performance or intestinal morphology. Reduced dietary Ca and aP decreased tibial ash content, although 500 FTU/kg phytase improved ATTR of minerals and tibia attributes.

Effects of methionine and guanidinoacetic acid supplementation on performance and energy metabolites in breast muscle of male broiler chickens fed corn-soybean diets.

1. Guanidinoacetic acid (GAA) is the single endogenous precursor of creatine, which plays a critical role in energy homeostasis of cells. Since GAA is endogenously converted to creatine by methylation, it was hypothesised that the effects of dietary GAA supplementation might determine the methionine (Met) availability in corn-soybean based diets. 2. A total of 540, one-day-old male Ross 308 broilers were allocated to nine dietary treatments with six replicates (10 birds each) in a 3 × 3 factorial arrangement with three graded levels of supplementary Met (+0.4 g/kg per level), whilst cystine was equal across groups, resulting in a low, medium and high level of total sulphur amino acids, and with three levels of GAA (0, 0.6 and 1.2 g/kg). Birds were fed for 42 days. 3. Increasing levels of supplemental Met enhanced performance indices in all rearing periods, although there was no effect on feed conversion ratio in the grower or feed intake in the finisher periods. Final body weight was 8.8% and 14.6% higher in the birds fed medium and high Met diets, respectively, compared to the low Met level. Relative breast weight and protein content in muscle on d 25 linearly increased with higher levels of Met. At low and high Met levels, growth in the finisher phase was negatively affected by supplementing GAA at 1.2 g/kg. It was suggested that disturbances in methylation homeostasis and/or changes in Arg metabolism might explain these findings. At the end of the grower phase, muscle creatine content was higher when feeding GAA at 0.6 and 1.2 g/kg (4464 and 4472, respectively, vs. 4054 mg/kg fresh muscle in the control group). 4. The effects of dietary GAA supplementation were influenced by the dietary Met level only in the finisher period, which indicates the need for proper sulphur amino acid formulation in diets when feeding GAA.

Conditioning time and sodium bentonite affect pellet quality, growth performance, nutrient retention and intestinal morphology of growing broiler chickens.

1. The present study was conducted to evaluate the effects of conditioning times and processed sodium bentonite (PSB)-based pellet binder (G. Bind™) on pellet quality, performance, small intestine morphology, and nutrient retention in growing broiler chickens (d 11-24).2. A total of 540, one-day-old male broiler chicks were fed a commercial starter diet (d 1-10). On day 11, birds were assigned to a 2 × 3 factorial arrangement including two conditioning times (2 and 4 min) and three levels of PSB (0, 7.5 and 15 g/kg) with six replicates of 15 chicks each. Feed intake and weight gain were recorded to calculate growth performance. The jejunal segment and excreta samples were collected to determine intestinal morphology and nutrient retention, respectively.3. Diets produced with 2 min conditioning time and containing 15 g/kg PSB increased (P < 0.05) pellet durability index and hardness. Conditioning time and PSB levels had no significant effect on growth performance. The inclusion of PSB to broilers diet increased (P < 0.05) energy usage of the pelleting machine. Chickens fed the diet conditioned for 2 min and containing 15 g/kg PSB had the lowest (P < 0.05) relative jejunal length. Two minutes conditioning of diets containing 15 g/kg PSB increased (P < 0.05) apparent metabolisable energy retention in broilers.4. It was concluded that 2 min conditioning of diet containing 15 g/kg PSB improved pellet quality and nutrient retention of broiler chickens, while the main effects of conditioning time and PSB levels were controversial in most evaluated parameters.

Effects of conditioning time and sodium bentonite on pellet quality, growth performance, intestinal morphology and nutrient retention in finisher broilers.

1. This study was carried out to evaluate the effect of steam-conditioning time and different levels of processed sodium bentonite (PSB) on pellet quality, growth performance, intestinal development and morphology, and nutrient digestibilities in broilers during finisher period (d 24-45). 2. A total of 810 male chicks were reared in commercial conditions on floor pens till d 24. Then, birds were weighed and used in a completely randomised design experiment with a 3 × 3 factorial arrangement, including three levels of conditioning times (0, 2 and 4 min) and three PSB levels (0, 7.5 and 15 g/kg diet). Each of the 9 diets fed to 6 replicates group of 15 birds each. 3. The results showed that 2-min steam conditioning and 15 g/kg PSB supplementation significantly increased pellet durability index (PDI) and hardness, and decreased electrical consumption of pelleting. Diets had no significant effects on body weight, feed intake and feed conversion ratio. Although dietary treatments did not influence relative weight and length of three segments of small intestine, 2-min steam conditioning significantly improved villus height (VH) and crypt depth. Steam conditioning of diet for 2 min significantly increased apparent metabolisable energy (AME), ether extract (EE), calcium (Ca) and dry matter (DM) retention in birds measured during 38-42 d of age. 4. It could be concluded that 2-min steam conditioning improved PDI and hardness, VH and nutrient retention (AME, EE, Ca and DM), but did not affect growth performance in broilers during finisher period.

Guanidinoacetic acid supplementation in broiler chickens fed on corn-soybean diets affects performance in the finisher period and energy metabolites in breast muscle independent of diet nutrient density.

(1) Guanidinoacetic acid (GAA) is the single immediate endogenous precursor of creatine (Cr). It was hypothesised that dietary GAA would have different effects on performance and energy metabolites in breast muscle depending on the nutrient density (ND) of corn-soybean-based diets. (2) A total of 540 one-day-old male Ross 308 broilers were allocated to 9 dietary treatments with 6 replicates (10 birds each) in a 3 × 3 factorial arrangement with three levels of ND (low, 2800; medium, 2950 and high, 3100 kcal metabolizable energy (ME)/kg; and with the other nutrients being constant relative to ME) and supplemented with three levels of GAA (0, 0.6 and 1.2 g/kg) in a 42-d feeding trial. (3) In the starter and grower periods, increasing levels of ND improved body weight (BW), average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR), with the exception of ADFI in the starter period. GAA supplementation did not affect performance characteristics. All performance indicators responded markedly to increasing ND in the finisher period, whereas the highest GAA level reduced ADFI compared to the unsupplemented control (156 vs. 162 g/d) and concomitantly FCR (1.81 vs. 1.93). No interactive effects were noted for any performance trait. The high ND diet resulted in more breast meat yield on d42, associated with higher fat content and darker colour compared to the other ND levels. The GAA supplementation did not affect carcass and breast traits. At the end of the experiment, Cr was elevated when feeding GAA at 1.2 g/kg (5455 vs. 4338 mg/kg fresh muscle). (4) To conclude, ND had a substantial effect on performance and carcass traits, whereas any effect of GAA was limited to FCR in the finisher period and independent of diet ND level.

The effect of n-6/n-3 fatty acid ratios on broiler breeder performance, hatchability, fatty acid profile and reproduction.

This experiment was conducted to study the effect of dietary omega6 (n-6) to omega3 (n-3) fatty acid (FA) ratios on performance and reproduction of broiler breeders. In experiment 1, 400 females and 40 males (30 week age) of Ross 308 broiler breeder (20 females and two males in each pen) were randomly assigned to one of the four diets with n-6/n-3 FA ratios of 4, 6, 8 and 16 (control). As a measure of hatchability, fertility of eggs and general incubation traits, 1,200 eggs (60 eggs from each pen) were collected and incubated for 21 days and embryo liver and brain fatty acid profile in 14 and 21 days were determined. In experiment 2, 48 males (three males in each pen) randomly assigned to one of the four diets with n-6/n-3 FA ratios of 4, 6, 8 and 16 (control). Semen was collected twice weekly, and semen volume, spermatozoa concentration and motility and alive and dead spermatozoa were estimated. Egg production and egg mass were decreased by n-6/n-3 FA ratios of 4:1 and 6:1 (p < .05). There were no significant differences between treatments on breeder's body weight, eggs fertility and hatchability, embryonic mortality and semen features. Linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and total n-3 of egg yolk, semen, testis and liver and brain of embryo and day-old chicken were increased while concentration of linoleic acid, arachidonic acid and docosatetraenoic acid of mentioned tissues were decreased by increasing n-6/n-3 FA ratios (p > .05). In conclusion, absolute amount of n-3 and n-6 FAs in broiler breeder diet may be more important than n-6/n-3 FA ratios and to consider reproductive and performance traits of breeders, it is necessary to supply higher levels of n-3 and n-6 FA with respect to n-6/n-3 FA ratios.

Mitochondrial biogenesis and PGC-1α gene expression in male broilers from ascites-susceptible and -resistant lines.

Ascites is a cardiovascular metabolic disease characterized by accumulation of fluid around the heart and in the abdominal cavity that eventually leads to death. This syndrome is the end-point result of a series of metabolic incidents that are generally caused by impaired oxygen availability. Mitochondria are the major sites of oxygen consumption, therefore major contributors to oxidative stress. Genetic, metabolic and dietary factors can influence variations in mitochondrial biogenesis (mitochondrial size, number and mass) that might have an effect on oxygen consumption and reactive oxygen species production. This study evaluated the effect of genotype on PGC-1α mRNA gene expression and mitochondrial biogenesis. These parameters were examined in male broiler chickens at 22 weeks of age from the SUS and RES lines divergently selected for ascites phenotype. From each line, five birds were sampled for right ventricle and breast muscle. Gene expression and mtDNA copy number were assessed by quantitative PCR. Results showed that birds from SUS had significantly higher PGC-1α mRNA gene (p = .033) and mitochondrial DNA copy number (p = .038) in breast muscle. There was no difference in right ventricle PGC-1α expression or mitochondrial DNA copy number between the two lines. These findings indicate that mitochondrial biogenesis and PGC-1α mRNA gene expression differ between male broiler chickens from RES and SUS lines in a tissue-specific manner.

Effects of in ovo injection of chrysin, quercetin and ascorbic acid on hatchability, somatic attributes, hepatic oxidative status and early post-hatch performance of broiler chicks.

An experiment was conducted to evaluate the effects of in ovo injection of chrysin, quercetin and ascorbic acid on hatchability, somatic attributes, hepatic antioxidant status and early post-hatch growth performance of broiler chicks. Four hundred and eighty embryonated broiler breeder eggs containing live 18-day-old embryos were divided into six groups of 80 eggs each. One group remained intact and served as a control group (i), whereas the other five groups were injected with the prepared injection solutions as follows: (ii) 0.05 ml distilled water; (iii) 0.05 ml distilled water containing 6 mg ascorbic acid; (iv) 0.05 ml dimethyl sulfoxide (DMSO); (v) 0.05 ml DMSO containing 4.5 mg quercetin; and (vi) 0.05 ml DMSO containing 4.5 mg chrysin. The hatchability rate, hatching weight, residual yolk sac weight, yolk sac-free body weight, liver weight, hepatic glutathione peroxidase and total superoxide dismutase activities, as well as malondialdehyde concentrations, were not affected by the injected solutions. There were no differences between chicks hatched from the control and in ovo injected eggs in weight gain, feed intake and feed conversion ratio from 0 to 11 days of age. However, the specific contrast performed between the in ovo injected groups and intact eggs revealed that in ovo injection significantly increased hatchability rate (p = .0493). This finding also implies that our injection procedure was harmless. In conclusion, the intra-egg injection of chrysin, quercetin or ascorbic acid at the injection rates used in this study did not have a significant effect on hatchability, somatic characteristics, early growth performance and hepatic antioxidant status of broiler chicks. However, the overall hatchability was higher in the in ovo injected eggs as compared to non-injected ones. These findings also confirmed the harmlessness of the procedure developed for in ovo injection in this study.

Effect of adjuvants on in ovo vaccination against Newcastle disease on hatchability, performance and antibody titres in commercial pullets.

This study was conducted to investigate the efficacy of in ovo administration of aluminium hydroxide (AH) and/or mannan oligosaccharide (MOS) adjuvants along with lentogenic VG/GA strain-Avinew to alleviate the embryonic pathogenicity of Newcastle disease virus. Six hundred and thirty fertilized Bovans eggs were divided into nine groups of 70 each incubated in a commercial hatchery and administered with eight types of in ovo injections in a factorial design of 2 × 2 × 2 including with/without AH, MOS and Newcastle disease vaccine (NDV), and one uninjected group on day 18 of incubation. Hatchability was higher in the eggs received MOS and/or AH adjuvants plus NDV compared those injected with NDV alone which confirmed the attenuation of NDV. However, the average daily feed intake and feed conversion ratio of pullets hatched from NDV-injected eggs were significantly reduced, but did not affect growth performance during 0-42 days of age. The performance of pullets hatched from eggs injected with AH, MOS or their mixture with NDV was not significantly different during all growth periods. Pullets from MOS + vaccine injected eggs had significantly higher antibody titres against NDV compared to those hatched from either injected with saline or uninjected on d 28 (p < .05). In addition, AH plus vaccine and MOS significantly improved total anti-SRBC and IgG respectively. Histological observation revealed that injection of MOS adjuvant into eggs led to increase crypt depth, whereas AH injection caused a reduction in villus surface area of jejunum in chicks on d 14 post-hatch. It is concluded that in ovo MOS injection as compared to AH may be more effective to attenuate the embryonic pathogenicity of in ovo NDV injection.

Interactive effects of temperature and dietary supplementation of arginine or guanidinoacetic acid on nutritional and physiological responses in male broiler chickens.

1. The aim of this experiment was to study the interactive effect of rearing temperature and dietary supplementation of arginine (Arg) or guanidinoacetic acid (GAA) on performance, gut morphology and ascites indices in broiler chickens raised under the same condition in the first 2 weeks and then reared under normal (23-26°C) or subnormal (17°C) ambient temperatures for the next 3 weeks. 2. This experiment was conducted as a split plot with 900 Ross 308 male broiler chicks that were allocated to two houses (as main plots); each consisted of 5 treatments (as sub-plots) with 6 replicates of 15 birds. The 5 diets were (1) control, (2) control + 0.60 g/kg GAA, (3) control + 1.20 g/kg GAA, (4) control + 0.86 g/kg Arg and (5) control + 1.72 g/kg Arg. 3. Feed intake (0-35 d) of birds fed on a diet containing 1.2 g GAA/kg and reared under normal temperature was reduced compared to control fed birds. Birds fed on a diet containing 1.72 g/kg Arg and reared under subnormal temperature had higher weight gain compared to those fed on control or GAA-added diets in overall study period. 4. Supplementation of diets with Arg alleviated the adverse effect of cold stress as reflected by reduction in blood haematocrit (41% vs. 37%), and right ventricle to total ventricle ratio (0.28 vs. 0.25) at 35 d of age. Addition of Arg to the diet of birds reared under cold stress resulted in a higher jejunal villus surface area compared to those fed on control or GAA-added diets. 5. Findings of this study revealed that Arg or GAA supplementation of diets did not affect performance of birds under normal temperatures, but Arg supplementation of the diet significantly alleviated the adverse effect of cold stress on performance, gut development and ascites syndrome. In addition, GAA supplementation at 1.2 g/kg improved jejunal villus surface area in birds raised under subnormal temperature.

Growth, immune, antioxidant, and bone responses of heat stress-exposed broilers fed diets supplemented with tomato pomace.

A study was conducted to investigate the effects of supplementation of dried tomato pomace (DTP) on growth performance, relative weights of viscera, serum biological parameters, antioxidant status, immune response, and bone composition of broilers exposed to a high ambient temperature. A total of 352 one-day-old male broiler chickens were randomly divided into four groups consisting of four replicates with 22 birds each. One group was reared under the thermoneutral zone and fed a corn-soybean meal basal diet. The other three groups were subjected to a cyclic heat stress from 29 to 42 days of age (34 ± 1 °C, 55 % RH, 5 h/day). These birds were fed corn-soybean meal basal diet or the same diet supplemented with 3 % DTP (420 mg lycopene/kg diet) or 5 % (708 mg lycopene/kg diet) of DTP. Blood samples were collected on days 28 and 42, and the birds were slaughtered at the same times. Supplementation of 5 % of DTP increased body weight and production index and decreased feed conversion ratio during 1-28 days of age. On day 28, the broilers supplemented with 5 % DTP had lower serum triglycerides and higher high-density lipoprotein (HDL) cholesterol concentration than those on the other dietary treatments. The activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were higher and the concentration of malondialdehyde (MDA) was lower in the broilers fed 5 % TP than those of the broilers fed other diets at 28 days of age. The effects of heat stress (HS) were impaired body weight, enhanced serum activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lipase, and MDA concentration while reducing the activities of GPx and SOD. Dried tomato pomace supplementation did not influence growth performance under HS but ameliorated the negative effects of HS on the serum enzyme activities, GPx activity, and lipid peroxidation. Heat stress did not change the relative weights of the lymphoid organs but reduced the total and IgG titers for secondary antibody response to sheep red blood cells and titer against Newcastle disease virus and increased the heterophil/lymphocyte ratio. The supplementation with 5 % of DTP completely alleviated the negative effects of HS on immune responses. The ash, Ca, and P contents of the tibia bone were decreased under HS. The ash and Ca contents of the tibia were not significantly different between thermoneutral and heat-stressed broilers supplemented with 5 % DTP. In conclusion, dietary supplementation of DTP, particularly 5 % DTP, to broiler diet attenuated the detrimental effects of HS on the activities of serum enzymes, oxidative status, immune response, and bone composition.

Effect of digestible methionine + cystine concentration on performance, egg quality and blood metabolites in laying hens.

The estimation of sulphur amino acid requirement is a vital key to providing appropriate nutrition in poultry. The estimation of amino acid requirement depends on what production parameter is taken into consideration for optimisation. A complete randomised block design was performed with 5 treatments and 6 replicates of 8 Hy-line layers (W-36) each from 32 to 44 weeks of age. The blocks were made to have a replicate of each treatment. The dietary treatments were consisted of 5 concentrations of digestible sulphur amino acid (DSAA) at 5.1, 5.6, 6.1, 6.6 and 7.1 (g/kg). Egg production, egg mass, egg weight and feed conversion ratio (FCR) were significantly affected by an increase in DSAA intake. However, feed intake, egg component yield, Haugh unit, specific gravity, eggshell thickness, egg protein and dry matter (DM) were not altered by DSAA intake. A significant increment in plasma high-density lipoprotein was concomitant with a reduction in low-density lipoprotein when DSAA intake was increased. However, triglyceride, cholesterol, uric acid and total protein in plasma were not affected by DSAA intake. The DSAA requirements estimated by the linear broken-line model to optimise egg production, egg mass, egg weight and FCR were 678, 673, 641 and 656 mg/bird.d in the whole experimental period, respectively. The DSAA requirement estimated by the quadratic broken-line model to optimise egg production, egg mass, egg weight and FCR were 4.71%, 7.87%, 8.73% and 7.62% higher than those estimated by linear broken-line fit model in the whole experimental period, respectively.

Optimisation of broiler chicken responses from 0 to 7 d of age to dietary leucine, isoleucine and valine using Taguchi and mathematical methods.

Three experiments were conducted to evaluate the applicability of the Taguchi method (TM) and optimisation algorithms to optimise the branch chain amino acids (BCAA) requirements in 0 to 7 d broiler chicks. In the first experiment, the standardised digestible (SID) amino acids and apparent metabolisable energy (AME) values of maize, wheat and soya bean meal were evaluated. In the second experiment, three factors including leucine (Leu), isoleucine (Ile) and valine (Val), each at 4 levels, were selected, and an orthogonal array layout of L16 (4(3)) using TM was performed. After data collection, optimisation of average daily gain (ADG) and feed conversion ratio (FCR) were obtained using TM. The multiobjective genetic algorithm (MOGA) and random search algorithm (RSA) were also applied to predict the optimal combination of BCAA for broiler performance. In the third experiment, a growth study was conducted to evaluate the applicability of obtained optimum BCAA requirements data by TM, MOGA and RSA, and results were compared with those of birds fed with a diet formulated according to Ross 308 recommendations. In the second experiment, the TM resulted in 13.45 g/kg SID Leu, 8.5 g/kg SID Ile and 10.45 g/kg SID Val as optimum level for maximum ADG (21.57 g/bird/d) and minimum FCR (1.11 g feed/g gain) in 0- to 7-d-old broiler chickens. MOGA predicted the following combinations: SID Leu = 14.8, SID Ile = 9.1 and SID Val = 10.3 for maximum ADG (22.05) and minimum FCR (1.11). The optimisation using RSA predicted Leu = 16.0, Ile = 9.5 and Val = 10.2 for maximum ADG (22.67), and Leu = 15.5, Ile = 9.0 and Val = 10.4 to achieve minimum FCR (1.08). The validation experiment confirmed that TM, MOGA and RSA yielded optimum determination of dietary amino acid requirements and improved ADG and FCR as compared to Aviagen recommendations. However, based on the live animal validation trial, MOGA and RSA overpredicted the optimum requirement as compared to TM. In general, the results of these studies showed that the TM may be used to optimise nutrient requirements for poultry.

Antioxidant enzyme activities, plasma hormone levels and serum metabolites of finishing broiler chickens reared under high ambient temperature and fed lemon and orange peel extracts and Curcuma xanthorrhiza essential oil.

The negative effects of high ambient temperature during some months of the year on poultry production have been of great concern in many countries. Dietary modifications are among the most practical ways to alleviate the effects of high temperature. Possible effects of dietary supplementation with 200 or 400 mg/kg feed of lemon peel extract (LPE), orange peel extract (OPE) and Curcuma xanthorrhiza essential oil (CXEO) under hot conditions (34 °C with 50% relative humidity for 5 h daily starting from day 28 until day 38 of age) on blood antioxidant enzyme activities, biochemical parameters and antibody titres of broiler chickens were investigated. All extracts are rich in phenolic compounds and highly available. Compared to control, supplementation with OPE at 400 mg/kg and CXEO significantly increased erythrocyte glutathione peroxidase and superoxide dismutase activity, plasma growth hormone concentrations and serum phosphorus, total protein and chloride concentrations and decreased serum low-density lipoprotein and cholesterol concentrations in chickens at 38 days of age. Regarding antibody titres, CXEO supplementation at 400 mg/kg caused a significant increase in bronchitis antibody titres. Supplementation with LPE and OPE gave more inconsistent results. Most interesting, 400 mg/kg LPE significantly increased 3,5,3'-triiodothyronine and GH concentration as compared to the control. In conclusion, the herbal extracts tested in this study, in particular CXEO at 400 mg/kg, may relieve some of the changes in blood composition induced by increased ambient temperatures.

Gene expression of heat shock protein 70 and antioxidant enzymes, oxidative status, and meat oxidative stability of cyclically heat-challenged finishing broilers fed Origanum compactum and Curcuma xanthorrhiza essential oils.

Heat stress in poultry is a serious problem in many countries and has been associated with oxidative stress. Hence, nutritional interventions with antioxidants might be beneficial. Therefore, the effects of dietary Curcuma xanthorrhiza (CX) and Origanum compactum (OC) essential oils on mRNA levels of heat shock protein 70 and antioxidant enzymes, oxidative status, and meat oxidative stability of heat-challenged broilers were studied. Starting on d 25 of age, a control diet and 4 diets containing 200 or 400 mg/kg feed of CX or OC (CX200, CX400, OC200, OC400 diets) were fed to 3 pen replicates of 20 Ross 308 chickens each. From d 28 of age on, the temperature was increased from 22 to 34°C with 50% RH for 5 h daily during 2 wk. Dietary CX or OC did not affect zootechnical performance. Feeding CX400 and both levels of OC increased the a* value in stored breast meat (P < 0.05), and OC diets tended to decrease the thiobarbituric acid reactive substances values in fresh breast meat (P = 0.061). Compared with control, at d 31, feeding CX400 and OC400 reduced mRNA levels of heat shock protein 70 and increased mRNA levels of catalase in kidney and liver (P < 0.05). The mRNA levels of superoxide dismutase were increased at d 31 on the OC400 diet in kidney and on the CX400 diet in heart (P < 0.05). In heart, at d 31, both dietary levels of CX and OC200 resulted in higher glutathione peroxidase activity (P < 0.05). Feeding CX400 increased superoxide dismutase activity in liver, kidney, and heart at d 31 (P < 0.05). Catalase activity was increased in the CX200 and OC400 groups at d 42 (P < 0.05). Feeding CX at both levels and OC200 decreased plasma malondialdehyde concentrations at d 42 (P < 0.05). In conclusion, dietary essential oils rich in simple phenolic compounds offer potential for improving the antioxidant defense against heat stress-induced changes.

Alternative growth functions for predicting body, carcass, and breast weight in ducks: Lomolino equation and extreme value function.

In this study, 2 alternative growth functions, the Lomolino and the extreme value function (EVF), are introduced and their ability to predict body, carcass, and breast weight in ducks evaluated. A comparative study was carried out of these equations with standard growth functions: Gompertz, exponential, Richards, and generalized Michaelis-Menten. Goodness of fit of the functions was evaluated using R(2), mean square error, Akaike information criterion, and Bayesian information criterion, whereas bias factor, accuracy factor, Durbin-Watson statistic, and number of runs of sign were the criteria used for analysis of residuals. Results showed that predictive performance of all functions was acceptable, though the Richards and exponential equations failed to converge in a few cases for both male and female ducks. Based on goodness-of-fit statistics, the Richards, Gompertz, and EVF were the best equations whereas the worst fits to the data were obtained with the exponential. Analysis of residuals indicated that, for the different traits investigated, the least biased and the most accurate equations were the Gompertz, EVF, Richards, and generalized Michaelis-Menten, whereas the exponential was the most biased and least accurate. Based on the Durbin-Watson statistic, all models generally behaved well and only the exponential showed evidence of autocorrelation for all 3 traits investigated. Results showed that with all functions, estimated final weights of males were higher than females for the body, carcass, and breast weight profiles. The alternative functions introduced here have desirable advantages including flexibility and a low number of parameters. However, because this is probably the first study to apply these functions to predict growth patterns in poultry or other animals, further analysis of these new models is suggested.

Application of the Taguchi method in poultry science: estimation of the in vitro optimum intrinsic phytase activity of rye, wheat and barley.

1. In poultry investigations, the main interest is often to study the effects of many factors simultaneously. Two or three level factorial designs are the most commonly used for this type of investigation. However, it is often too costly to perform when number of factors increase. So a fractional factorial design, which is a subset or a fraction of a full factorial design, is an alternative. The Taguchi method has been proposed for simplifying and standardising fractional factorial designs. 2. An experiment was conducted to evaluate the applicability of the Taguchi method to optimise in vitro intrinsic phytase activity (IPA) of rye, wheat and barley under different culture conditions. 3. In order to have a solid base for judging the suitability of the Taguchi method, the results of the Taguchi method were compared with those of an experiment that was conducted as a 3(4) full factorial arrangement with three feed ingredients (rye, wheat and barley), three temperatures (20°C, 38°C and 55°C), three pH values (3.0, 5.5 and 8.0) and three incubation times (30, 60 and 120 min), with two replicates per treatment. 4. After data collection, a Taguchi L 9 (3(4)) orthogonal array was used to estimate the effects of different factors on the IPA, based on a subset of only 9 instead of 81 treatments. The data were analysed with both Taguchi and full factorial methods and the main effects and the optimal combinations of these 4 factors were obtained for each method. 5. The results indicated that according to both the full factorial experimental design and the Taguchi method, the optimal culture conditions were obtained with the following combination: rye, pH = 3, temperature = 20 °C and time of incubation = 30 min. The comparison between the Taguchi and full factorial results showed that the Taguchi method is a sufficient and resource saving alternative to the full factorial design in poultry science.

Effects of carboxy methyl cellulose and thymol + carvacrol on performance, digesta viscosity and some blood metabolites of broilers.

This study was conducted to evaluate the effects of thymol + carvacrol as plant essential oils on performance, digesta viscosity and some blood metabolites of broilers fed diets supplemented with carboxy methyl cellulose (CMC) and/or thymol+carvacrol. In a completely randomized design with a 2 × 3 factorial arrangement, two levels of CMC (0% and 2%) and three levels of thymol+carvacrol (0, 100 and 200 mg/kg) were used. Each of the six dietary treatments was fed to five replicate pens of 12 birds each from 0 to 42 days of age. Body weight gain (BWG), feed intake, feed conversion ratio (FCR), intestinal digesta viscosity and pH, plasma lipids and some blood metabolites were recorded. The inclusion of 2% CMC decreased (p < 0.05) BWG by 2.2% and increased FCR by 2.3% at 42 days of age. Carboxy methyl cellulose significantly increased the digesta viscosity and decreased serum total cholesterol, but had no significant effect on triglyceride, pH, HDL, LDL and other blood metabolites measured in this experiment. Thymol+carvacrol had no effect on feed intake, but significantly increased (p < 0.05) BWG from 1 to 42 days of age and improved FCR (p < 0.05) by the addition of 100 and 200 mg/kg thymol+carvacrol respectively. Inclusion of thymol+carvacrol at levels of 100 and 200 mg/kg in the diets decreased digesta viscosity and serum total cholesterol (p < 0.05) and also increased AST at a 200 mg/kg thymol+carvacrol without any effect on creatine kinase (CK). Thymol+carvacrol significantly increased total protein (TP), albumin and globulin (p < 0.05). In conclusion, CMC at an inclusion level of 2% of diet increased digesta viscosity and reduced growth performance. However, thymol+carvacrol decreased digesta viscosity and consequently improved the performance of broilers fed the CMC-based diet. Therefore, thymol+carvacrol addition to viscose-based diets might be helpful to alleviate the negative effects of viscous compounds in poultry diets.

Effect of thymol and carvacrol feed supplementation on performance, antioxidant enzyme activities, fatty acid composition, digestive enzyme activities, and immune response in broiler chickens.

This trial was conducted to evaluate the effects of dietary supplementation of phytogenic product containing an equal mixture of thymol and carvacrol at 4 levels (0, 60, 100, and 200 mg/kg of diet) on performance, antioxidant enzyme activities, fatty acid composition, digestive enzyme activities, and immune response in broiler chickens. Each of the 4 diets was fed to 5 replicates of 12 chicks each from d 0 to 42. The inclusion of thymol + carvacrol linearly decreased (P < 0.05) feed intake, but the highest (P < 0.05) BW gain (ADG) and feed efficiency was observed in broilers offered 200 mg/kg of phytogenic product. The phytogenic product linearly increased (P < 0.05) superoxide dismutase and glutathione peroxidase activities and decreased (P < 0.05) malondialdehyde level in thigh muscle at d 42 and serum and liver at d 24 and 42. Total saturated fatty acids were depressed (P < 0.05) and total polyunsaturated fatty acid and n-6 were linearly increased (P < 0.05) in serum and thigh by the inclusion of phytogenic product compared with the control diet. Supplementation with thymol + carvacrol also increased intestinal and pancreatic trypsin, lipase, and protease activities in 24-d-old (linear, P < 0.05) but not in 42-d-old birds. Thymol + carvacrol modified (linear, P < 0.05) immune response by increasing hypersensitivity response, total and IgG anti-sheep red blood cell titers, and decreasing heterophil to lymphocyte ratio compared with the control group. However, hematological parameters and lymphoid organ weight were not affected by thymol + carvacrol. Thus, feed supplementation with thymol + carvacrol enhanced performance, increased antioxidant enzyme activities, retarded lipid oxidation, enhanced digestive enzyme activities, and improved immune response of broilers.

Study of broiler chicken responses to dietary protein and lysine using neural network and response surface models.

1. In this study, neural network (NN) and response surface (RS) models were developed to investigate the response [average daily gain (ADG) and feed efficiency (FE)] of young broiler chickens to dietary protein and lysine. For this purpose, data on their responses to dietary protein and lysine were extracted from the literature and separate NN and RS models were constructed. 2. Comparison between the NN and RS models revealed higher accuracy of prediction with the NN models compared to the RS models. In terms of R (2) values, the NN models developed for both ADG (R (2) = 0.923) and FE (R (2) = 0.904) were far superior to the RS models (R (2) for ADG = 0.511; R (2) for FE = 0.67). This suggests that the NN models can serve as an alternative option to conventional regression approaches including use of RS models. 3. Optimisation of the NN models developed for response to protein and lysine showed that diets containing 220.7 (g/kg of diet) protein and 12.85 (g/kg of diet) lysine maximise ADG, whereas maximum FE is achieved with diets containing 241.3 and 13.12 (g/kg) protein and lysine, respectively. Based on the optimisation results, optimal dietary protein and lysine concentrations for maximum FE in broiler chickens during the starting period are higher than for ADG.