Effects of feeding guanidinoacetic acid on oxidative status and creatine metabolism in broilers subjected to chronic cyclic heat stress in the finisher phase.

Dietary guanidinoacetic acid (GAA) has been shown to affect creatine (Cr) metabolic pathways resulting in increased cellular Cr and hitherto broiler performances. Yet, the impact of dietary GAA on improving markers of oxidative status remains equivocal. A model of chronic cyclic heat stress, known to inflict oxidative stress, was employed to test the hypothesis that GAA could modify bird's oxidative status. A total of 720-day-old male Ross 308 broilers were allocated to 3 treatments: 0, 0.6 or 1.2 g/kg GAA was added to corn-SBM diets and fed for 39 d, with 12 replicates (20 birds each) per treatment. The chronic cyclic heat stress model (34°C with 50-60% RH for 7 h daily) was applied in the finisher phase (d 25-39). Samples from 1 bird per pen were taken on d 26 (acute heat stress) and d 39 (chronic heat stress). GAA and Cr in plasma were linearly increased by feeding GAA on either sampling day, illustrating efficient absorption and methylation, respectively. Energy metabolism in breast and heart muscle was greatly supported as visible by increased Cr and phosphocreatine: ATP, thus providing higher capacity for rapid ATP generation in cells. Glycogen stores in breast muscle were linearly elevated by incremental GAA, on d 26 only. More Cr seems to be directed to heart muscle as opposed to skeletal muscle during chronic heat stress as tissue Cr was higher in heart but lower in breast muscle on d 39 as opposed to d 26. The lipid peroxidation marker malondialdehyde, and the antioxidant enzymes superoxide dismutase and glutathione peroxidase showed no alterations by dietary GAA in plasma. Opposite to that, superoxide dismutase activity in breast muscle was linearly lowered when feeding GAA (trend on d 26, effect on d 39). Significant correlations between the assessed parameters and GAA inclusion were identified on d 26 and d 39 using principal component analysis. To conclude, beneficial performance in heat-stressed broilers by GAA is associated with enhanced muscle energy metabolism which indirectly may also support tolerance against oxidative stress.

Guanidinoacetic acid supplementation improves feed conversion in broilers subjected to heat stress associated with muscle creatine loading and arginine sparing.

It was hypothesized that dietary guanidinoacetic acid (GAA), the precursor of creatine (Cr), would be beneficial to heat-stressed finisher broilers owing to improved cellular energy status and arginine sparing effects. A total of 720 one-day-old male Ross 308 broilers were allocated to 3 treatments, 0 (control), 0.6, or 1.2 g/kg of GAA added to complete corn-soybean meal diets, and were fed for 39 D, with 12 replicates (20 birds each) per treatment. A chronic cyclic heat stress model (at a temperature of 34°C and 50 to 60% relative humidity for 7 h daily) was applied in the finisher phase (day 25-39). Samples were taken on day 26 and 39 to determine thrombocyte, white blood cell, corticosterone, protein and amino acid levels in blood and Cr, phosphocreatine (PCr), and adenosine triphosphate levels in the breast muscle. Meat quality was assessed on day 40 after overnight fasting. Guanidinoacetic acid at a dose of 1.2 g/kg decreased feed-to-gain ratio compared with the control in the grower phase (1.32 vs. 1.35, respectively; P <0.05). In the finisher period, the supplementation of 1.2 g/kg of GAA reduced feed intake compared with the control (-3.3%, P <0.05), whereas both GAA supplementation levels improved feed efficiency markedly (1.76, 1.66, and 1.67 for 0 [control], 0.6, and 1.2 g/kg of GAA, respectively, P <0.05). Mortality outcomes highlight that GAA feeding improved survival during heat stress, supported by lower panting frequency (linear effect, P <0.05). Plasma arginine was higher with increase in dietary GAA concentration on day 26 (+18.3 and + 30.8% for 0.6 and 1.2 g/kg of GAA, respectively; P <0.05). This suggests enhanced availability of arginine for other metabolic purposes than de novo GAA formation. In the breast muscle, PCr (day 39, P <0.05), free Cr (day 39, P <0.05), total Cr (both days, P <0.05), and PCr-to-adenosine triphosphate ratio (day 39, P <0.05) levels were increased with higher GAA content in diet. Guanidinoacetic acid supplementation improved feed conversion and survival during chronic cyclic heat stress, which may be associated with enhanced breast muscle energy status and arginine sparing effect.

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 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.

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.

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.

Effect of in ovo injection of threonine on immunoglobulin A gene expression in the intestine of Japanese quail at hatch.

The objective of this study was to investigate the effect of in ovo injection of threonine (THR) on immunoglobulin A (IgA) gene expression of Japanese quail on hatch day. A total of 540 Japanese quail eggs were assigned into nine groups of 60 each and were set in a single-stage incubator. Treatments were as follows: non-injected (control), two diluent levels (0.05 or 0.1 ml saline), two sites of injection (in or under the air sac) and with or without nutrients (0.5 mg/ml THR). Eggs were injected on d 11 of incubation. On hatch day, after euthanizing hatched quail chicks, the intestine was removed and the jejunum was separated. The relative mRNA expression of jejunal IgA increased (p < 0.05) by the injection of 0.05 ml THR under the air sac when compared to the control group or other treatments of injection. Compared to the control group, no differences were imputable to treatments of 0.1-ml injections on IgA gene expression. Differences with other injected groups were not significant. It was concluded that injection of 0.05 ml saline containing 0.5 mg THR/ml under the air sac can improve jejunal IgA mRNA expression in newly hatched Japanese quail chicks.

The suitability of some blood gas and biochemical parameters as diagnostic tools or early indicators of ascites syndrome in broiler sire lines.

In recent few years, there have been some attempts to find a reliable indicator trait as a selection criterion against susceptibility to ascites syndrome (AS). Blood parameters were of great interest as they could be measured in live animals without implementing an ascites-inducing challenge (AIC). In this work, the suitability of some blood parameters was evaluated for diagnosing AS-susceptible chicks in later steps of the disease in trial 1 as well as their early predictive ability in trial 2. In the first trial, one hundred 1-day-old chicks from two pure broiler lines namely S1 and S2 and, in the second trial, 226 1-day-old chicks from line S2 were subjected to AIC. Saline drinking water (1200 mg/l) and lower-than-standard ambient temperatures were the implemented AICs in trials 1 and 2 respectively. The blood parameters including pH, partial pressure of O2 (pO2 ), partial pressure of CO2 (pCO2 ), bicarbonate ion concentration (BIC), percentage of haematocrit (HCT) and saturated haemoglobin (SaO2 ) were measured twice per each bird at days 28 and 35 in trial 1 and once in trial 2 at day 21. The results of the first trial revealed that in line S2 some of the blood parameters differed significantly between the ascitic and non-ascitic groups following exposure to AIC. In this line, the incidence of AS was accompanied by a lower pO2 , SaO2 and BIC, while with higher pCO2 and HCT values. In the second trial, however, although almost all of the parameters showed meaningful differences between the ascitic and non-ascitic broilers, only mean difference of BIC parameter was statistically significant. The general conclusion of this study is that the blood parameters can somewhat have diagnostic ability in the condition in which the AIC is already present, whereas the results did not approve their usefulness as early predictors of AS.

Effect of in ovo injection of threonine on Mucin2 gene expression and digestive enzyme activity in Japanese quail (Coturnix japonica).

A total of 540 Japanese quail eggs were assigned to 9 treatments of 4 replicates to investigate the effect of in ovo injection of threonine (THR) on mucin2 (MUC2) mRNA expression and digestive enzyme activity. Treatments were (non-injected) eggs and those in ovo injected with saline (0.05 or 0.1 ml) with or without THR (5 mg/ml) in two sites (in or under the air sac). On hatch day, 0.05 ml in ovo injected (under the air sac: TUAS) hatchlings were divided into three groups based on NRC recommendations for THR, while all 0.1 ml in ovo injected chicks were removed due to low hatchability. The remaining treatments received the NRC recommended diet until day 10 post-hatch. Treatments had no effect on protease and amylase activities, while TUAS increased MUC2 gene expression. In conclusion, the in ovo injection of THR increased MUC2 gene expression but had no effect on enzyme activity.

Effects of chromium and chromium + vitamin C combination on metabolic, oxidative, and fear responses of broilers transported under summer conditions.

A total of 240 female broilers (42 days old) were randomly assigned to four groups with six replicates and fed either a basal diet (two control groups) or a basal diet supplemented with either 1,200 µg Cr(+3) from chromium (Cr) methionine/kg (Cr group) or 1,200 µg Cr(+3) from Cr methionine plus 800 mg vitamin C (Vit C)/kg of diet (Cr + Vit C group). After 7 days on the dietary treatment, all groups except one of the controls were transported for 3 h under the summer conditions. Performance parameters were not influenced by dietary treatments. The plasma concentrations of insulin, triiodothyronine, triglyceride, and the ratio of triiodothyronine/thyroxin were decreased and the ratio of glucose/insulin was increased due to transport process. Road transportation also increased the plasma concentrations of protein, cholesterol, aspartate aminotransferase, and creatine kinase and decreased the concentration of low-density lipoprotein cholesterol in the Cr + Vit C group. The pretransport concentrations of insulin and triiodothyronine were highest in the Cr + Vit C group. The concentration of phosphorous was lower in the Cr group than that in the other groups after transport. No significant effects of dietary treatments were observed on the other biochemical parameters. Transport increased malondialdehyde concentration in the control group and did not change plasma total antioxidant capacity and erythrocyte glutathione peroxidase activity. Either in combination or alone, Cr increased plasma total antioxidant capacity (before transport P ≤ 0.05, after transport P = 0.07) but did not affect the concentration of malondialdehyde and activity of glutathione peroxidase. The duration of tonic immobility (TI) was similar between nontransported control chicks and transported chicks without any supplements. Pretreatment with Cr + Vit C significantly reduced the duration of TI.

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.

Effects of supplemental vitamin C and chromium on metabolic and hormonal responses, antioxidant status, and tonic immobility reactions of transported broiler chickens.

Three hundred female broilers were assigned to five groups with six replicates and were fed with either a basal diet (two control groups) or the basal diet supplemented with 800-mg vitamin C/kg (Vit C group), 1,200-µg Cr(+3) from chromium (Cr) chloride/kg (Cr group) or 800-mg Vit C and 1,200-µg Cr(+3) from Cr chloride/kg (Vit C + Cr group) from 42 to 49 days of age. Treatments did not affect performance. Transport decreased insulin level in the control and Cr groups and increased glucose/insulin (G/I) ratio in the groups. The level of insulin was higher in the Vit C + Cr group than those in the control and Cr groups after the transport. The G/I ratio was lowest in the Vit C + Cr group after the transport. The transport significantly decreased triiodothyronine (T3) concentration in the groups except the Vit C + Cr group and only increased thyroxin (T4) concentration in the Vit C + Cr group. The T3/T4 ratio was significantly decreased in the groups except the Cr group by transport. The T3/T4 ratio was greatest in the Vit C + Cr group before the transport. Alkaline phosphatase activity was decreased in the Vit C + Cr group due to transport. Transport decreased triglyceride levels in the groups and also decreased low-density lipoprotein cholesterol levels in the Vit-C-supplemented groups. Transport increased malondialdehyde concentration in the control and Vit C groups and also increased glutathione peroxidase (GPx) activity in the Cr-fed groups. The GPx activity was higher in the Vit C + Cr group than those in the control and Cr groups after the transport. Ferric reducing/antioxidant power (FRAP) value was decreased in the Vit C and Cr groups by transport. Either alone or in combination, Cr increased the FRAP value before the transport. Neither transport nor treatments had significant effects on the duration of tonic immobility (TI) and number of inductions to induce TI.

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.

The effects of dietary 1, 25-dihydroxycholecalciferol and hydroalcoholic extract of Withania somnifera root on bone mineralisation, strength and histological characteristics in broiler chickens.

1. This study was carried out to investigate the effects of 1, 25-dihydroxycholecalciferol (1, 25 (OH)2 D3) and a hydroalcoholic extract of Withania somnifera (WS) root on performance, mineral retention, bone mineralisation, bone mechanical and bone histological characteristics of broiler chicks. 2. A 2 × 3 × 2 factorial experiment consisted of a positive control diet with adequate Ca and a negative control diet (Ca concentration reduced by 30%), three concentrations of WS (0, 75 and 150 mg/kg diet), and two concentrations of 1, 25 (OH)2 D3 (0 and 0.5 µg/kg diet). 3. A total of 600 male one-d-old Ross 308 broiler chicks were randomly distributed into 60 floor pens, with 10 birds each. Each treatment was replicated 5 times (50 birds). Diets were given ad libitum from one to 42 d of age. On d 21 and 42, one bird per replicate was killed and tibiae were removed. 4. Dietary treatments did not affect feed intake and feed conversion. The maximum body weight gain (2475 g) was noted in birds fed on a diet adequate in Ca and supplemented with 75 mg/kg WS. 5. The Ca and P retentions were significantly higher in birds that were given a diet with 30% less Ca. Supplementation of 150 mg/kg WS significantly improved Ca retention in birds receiving a negative control compared to those given a positive control diet (83.0% vs. 66.3%). Ca retention was significantly improved with the addition of 0.5 µg/kg 1, 25 (OH)2 D3 to the diet containing 75 mg/kg WS, regardless of dietary Ca concentration (79.5 vs. 73.3 and 77.9 vs. 68.9). 6. On d 21, birds that received WS had significantly higher tibia Ca compared to those of controls. No significant effects on tibia Ca were noted at 42 d. Birds given a negative control diet supplemented with 75 mg/kg WS and 0.5 µg/kg 1, 25 (OH)2 D3 displayed a similar tibia Ca compared to those given only 150 mg/kg WS. Dietary supplementation of 1, 25 (OH)2 D3 significantly increased tibia Ca and tibial mineralised zone width in birds at 42 d of age. 7. Tibia shear force and stiffness were significantly increased by supplementation of WS. Administration of 1, 25 (OH)2 D3 resulted in a significantly lower width of the proliferative zone at 21 d of age. Reduction of the Ca supply significantly reduced the mineralised zone and cortical thickness at this age. 8. The present study showed that WS supplementation improved Ca retention, bone calcification and mechanical properties with no adverse effects on performance. Also, synergistic effects of WS and 1, 25 (OH)2 D3 were observed on Ca retention and bone calcification.

The effects of turmeric supplementation on antioxidant status, blood gas indices and mortality in broiler chickens with T(3)-induced ascites.

1. A total of 320 one-day-old Ross male broiler chickens were used to investigate the effects of 0·0, 2·5, 5·0 and 7·5 g/kg turmeric rhizome powder (TRP) in the diet, on antioxidant status, biochemical gas indices and mortality in broiler chickens with triiodothyronine (T(3)) induced ascites. 2. The TRP supplementation had no effect on blood pH, pO(2) or pCO(2) during the whole period of study. Moreover, supplementation of TRP did not influence the heart weight, right ventricle, left ventricle, or total ventricle weights, all relative to total live weight; RV/TV (right ventricle to total ventricle) ratio; or serum GPX (glutathione peroxidase) or SOD (superoxide dismutase) activities at week 6. 3. TRP supplementation influenced the blood [Formula: see text] and O(2) saturation during the whole period of study, total mortality due to ascites, and serum total tocopherol and malondialdehyde (MDA) contents. Blood [Formula: see text] and serum total tocopherol increased linearly as dietary TRP level increased. Blood O(2) saturation increased quadratically as dietary TRP increased. 4. Total ascites mortality and serum MDA content decreased linearly with increasing TRP level to 5 mg/kg and then reached a plateau. 5. The results of the study indicate that the addition of 5·0 g/kg TRP is sufficient to increase the blood O(2) saturation and bicarbonate ([Formula: see text]) concentration, and reduce the mortality due to ascites and serum MDA content.

The effect of dietary n-6:n-3 ratio and sex on broiler breeder immunity.

A study was conducted with male and female adult broiler breeders to determine the effect of feeding a fish oil supplement on selected immune activities. The fish oil was added to the diet such that the n-6:n-3 ratios could meet certain levels. Four hundred Ross 308 broiler breeder hens and 48 Ross 308 broiler breeder roosters at 30 wk of age were randomly assigned to diets containing 3.5% fat with n-6:n-3 ratios of 4, 6, 8, and 16. As a measure of cell-mediated immunity, thickness of the toe web was measured at 4, 8, 24, and 48 h after injection of phytohemagglutinin-P (PHA-P) at 32 wk of age. Total antibodies were quantified 6 and 9 d after the injection of SRBC at 33 wk of age. Blood lymphocyte proliferation was assayed after in vitro stimulation with PHA-P at 34 wk of age. The fatty acid profile of the spleen was determined in roosters. The effects of dietary n-6:n-3 ratios on total antibodies and in vitro lymphocyte proliferation were not significant (P > 0.05). However, the birds fed diets containing an n-6:n-3 ratio of 8 showed the greatest toe web thickness (P < 0.05). Total antibodies in hens at 9 d after SRBC injection were significantly greater than those of roosters. Conversely, toe web thickness in roosters was greater than that of hens (P < 0.05). Although the increase in the dietary n-6:n-3 ratio of polyunsaturated fatty acids significantly decreased the concentrations of eicosapentaenoic acid, docosahexaenoic acid, total n-3 (P < 0.05), linoleic acid, arachidonic acid, and total n-6, the n-6:n-3 fatty acid ratios of the entire spleen were significantly increased (P < 0.05). Results indicated that under the conditions of this study, the n-6:n-3 ratios seemed to influence the toe web response to PHA-P, but not the antibody response or the cell proliferation response in vitro.

Changes of biochemical parameters and enzyme activities in broiler chickens with cold-induced ascites.

An experiment with 250 one-day-old male broilers (Ross 308) was conducted to investigate the differences of some blood parameters of cold-induced ascitic and healthy broiler chicks in a 6-wk period. The chickens were divided into 2 groups of 5 replicates each. One group of these chickens was raised in normal temperature (NT) treatment and the other in cold temperature (CT) treatment to induce ascites. Mortality was necropsied daily to determine cause of death. At the end of the experiment (wk 6), 5 chickens from each replicate were randomly selected and slaughtered. The heart was removed; the right ventricle was dissected away from the left ventricle and septum. Weights of right and left ventricles were determined separately. Average BW gain and average feed intake were measured weekly, and weekly average feed conversion ratio was calculated. Serum glucose, total protein, cholesterol, triglyceride, activity of lactate dehydrogenase, as-partate aminotransferase, and alanine aminotransferase were determined. Throughout the study, the right ventricle-to-total ventricle ratio and total mortality percentage due to ascites of CT-treated birds at the end of experiment was greater (P < or = 0.05) than those of NT-treated ones. Fasting blood sugar of CT-treated birds in wk 4 and 6 was greater (P < or = 0.05) than NT-treated birds. Total blood protein of CT treatment was lower than NT-treated birds in every week and whole period, but this difference was only significant (P < or = 0.05) in wk 6. There was not a significant difference between 2 treatments for triglyceride and cholesterol, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase. It was concluded that cold-induced ascites could affect serum protein and fasting blood sugar of broiler chickens.

Study the effects of different levels of fat and L-carnitine on performance, carcass characteristics and serum composition of broiler chicks.

An experiment was conducted in order to study the effect of 3 levels of fat (1, 3, 5%) and 2 levels of L-camitine (0 and 250 mg kg(-1)) on 360 male Ross broiler chicks in a factorial arrangement (2 x 3) with completely randomized design with 6 treatments, 4 replicates and 15 chicks in each replicates. All diets were isocaloric and isonitrogenous and were fed to chicks from 1 to 42 days of ages. During the experiment feed intake, body weight gain and feed conversion ratio were measured weekly. Mortality was measured throughout the experiment. At 42 days of ages 4 birds from each treatment were slaughtered for determination of carcass characteristics and serum composition. Data of the experiment were analyzed by GLM procedure of SAS. Increasing of fat in the diets significantly improved performance of chicks in grower (22 to 42 days) and whole period (1 to 42 days) of the experiment (p < 0.05). Chicks fed with diets containing 3% fat had the highest breast meat and lowest abdominal fat percentage (p < 0.05). Adding L-carnitine to diets had not significant effect on performance and carcass characteristics. Interaction between fat and L-carnitine was significant on liver weight (p < 0.05). The levels of triglyceride (TG) and glucose in blood serum were affected by increasing of dietary fat (p < 0.05). Adding L-carnitine to diets significantly decreased the level of serum triglyceride, cholesterol and VLDL (p < 0.05). Dietary treatments had not significant effect on mortality.