Effect of dietary clenbuterol and cimaterol on muscle composition, beta-adrenergic and androgen receptor concentrations in broiler chickens

Illegal dietary supplementation with beta(2)-agonists has been shown to increase protein deposition and decrease fat accretion in domestic animals. In poultry the metabolic and endocrine responses to beta(2)-agonists are not fully elucidated. In this trial the effects of dietary clenbuterol (1 p.p.m.) and cimaterol (1 p.p.m.) on muscle composition and endocrine response of male broiler chickens were studied. Dietary clenbuterol induced a slight, but in general not significant, improvement of zootechnical performances and carcass yields. Chemical composition of muscle was not influenced by dietary treatments, even if a slight improvement of protein content was observed in treated groups. No effects on fatty acid composition of meat were detected. Both clenbuterol and cimaterol treatments caused a downregulation in testicular androgen receptors and in pulmonary, cardiac and central nervous system beta-adrenergic receptors.     

Effect of different dietary ideal protein concentrations on broiler performance

1. The aim of the study was to examine the response of male broilers of different age categories to different dietary ideal protein (IP) concentrations and to compare the effects to IP recommendations based on single lysine (Lys) requirement studies from the literature. 2. Two experiments were carried out, in which diets containing different IP concentrations (9.0 to 14.4g apparent faecal digestible (AFD) Lys/kg) were fed to male broilers from 14 to 34 (Exp. 1) and 28 to 41 d of age (Exp. 2). The diets (12.88MJ AMEN/kg) were prepared by the dilution technique. The effect of dietary IP concentrations on weight gain, feed intake, feed conversion efficiency (FCE) and slaughter characteristics were studied in both experiments. 3. In Exp. 1, weight gain and FCE increased linearly and fat concentration in the carcase decreased with increasing IP concentration. In Exp. 2, weight gain and FCE improved exponentially, whereas breast meat yield improved linearly with increasing dietary IP concentration. On the basis of these results, it was concluded that the weight gain and FCE of male broilers respond to higher dietary IP levels than would be expected from single lysine requirement studies in the literature.     

The effects of benzoic acid supplementation on the performance of broiler chickens

To determine the efficiency of benzoic acid, a feeding experiment was carried out with 240 one‐day old ROSS 308 cockerels. Birds were divided into three dietary treatments: I (C) – no additives, II (B1) – 0.1% inclusion of benzoic acid, III (B2) – the inclusion of 0.2% benzoic acid. The performance results were similar in birds fed the control diet and the diet with 0.1% of benzoic acid. The dietary inclusion of benzoic acid at 0.2% depressed the growth of broiler chickens (p < 0.05). The dry matter of the digesta increased in the crop and caeca after benzoic acid supplementation. The pH of the caecal contents decreased following benzoic acid supplementation and was the lowest in the B2 group. No differences were found in the pH of the crop, ileal, gizzard digesta and rectum content. Lactic acid bacteria populations were the lowest in the caeca of the B1 group (p < 0.05). Coliform bacteria decreased in the caeca contents following increased benzoic acid supplementation.     

Production performance and plasma metabolite concentrations of broiler chickens fed low crude protein diets differing in Thr and Gly

The aim of the study was to test the interaction between Thr and Gly in low crude protein (CP) diets in 7 to 28 d broilers on production performance and plasma metabolites. A total of 2,040 broilers were allocated to 17 treatments. A positive control (PC) diet (20.5% CP) was formulated to be adequate in dietary Thr and Gly. A negative control (NC) diet (18.5% CP, deficient in Thr and Gly) was supplemented with crystalline l-Thr and Gly to obtain a 4 Thr × 4 Gly design. Dietary Thr was tested at an apparent faecal digestibility (AFD) Thr-to-Lys ratio, which was 55%, 58%, 61% or 64%, and dietary Gly was tested at an AFD (Gly + Ser)-to-Lys ratio, which was 135%, 142%, 149% or 156%. Plasma samples were collected at 28 d. The low CP diet, formulated at 64% Thr and 156% Gly, resulted in a higher body weight gain (BWG) (P < 0.01) and similar feed conversion ratio (FCR) as the high CP treatment (PC). FCR was improved (P < 0.001) by l-Thr supplementation. Quadratic response to dietary Thr was significant for feed intake (FI), BWG and FCR (P < 0.01). A near-significant interaction for Thr × Gly was observed for FI and BWG (P_linear = 0.091 and P = 0.074, respectively). Gly did not affect production performance. An interaction between Thr × Gly on plasma free AA level was observed (P < 0.05). Free AA concentration in plasma linearly decreased with increase in AFD Thr-to-Lys ratio, and increased with increase in AFD (Gly + Ser)-to-Lys ratio. Plasma uric acid concentration was higher in PC than in all of the other diets, and plasma triglyceride concentration was decreased by l-Thr supplementation, but not by Gly. In conclusion, Gly was not limiting for growth at low dietary CP level unless Thr was deficient, showing that adequate amounts of Thr in broiler diets can overcome marginal supply of Gly and Ser and allow reduction of dietary CP from 20.5% to 18.5% for broilers from 7 to 28 d of age.     

Effect of clenbuterol on growth,carcase and skeletal muscle characteristics in broiler chickens

1. Male and female broiler chickens (144 in total) were given diets supplemented with clenbuterol (CB) at 0 (control) and at 1 mg/kg between 28 and 49 d of age to study the effect of CB on growth, carcase and skeletal muscle.

2. CB improved growth in males by increasing daily weight gain and final live weight and by lowering food conversion ratio. In females it changed the carcase composition by reducing abdominal fat pad and by increasing the proportion of protein. Consequently, carcase protein gain was increased in both sexes (11% and 16%, respectively).

3. Skeletal muscle weights were enhanced by between 6% and 22%. Muscle fibre diameters were increased in extensor hallucis longus (EHL) but not in gastrocnemius (GAS) muscle. This increase was more pronounced in females. EHL total muscle fibre number remained unchanged. The proportion of fast‐twitch glycolytic fibres was increased at the expense of fast‐twitch oxidative fibres in males only. Nuclear/cytoplasm and DNA/protein ratios tended to be decreased by CB.

4. From the elevated EHL muscle RNA/DNA, unchanged protein/RNA and translation activity it is suggested that CB stimulated protein synthesis at the pretranslational level. Reduced protein degradation is deduced from decreased neutral calcium‐dependent proteolytic activity.

5. It is concluded that broiler chickens respond to long‐term CB treatment as has been shown in various mammals. However, the sex‐specific response in growth, carcase composition and skeletal muscle cellularity is more clearly apparent in broiler chickens.     

Effects of chitosan on growth performance and energy and protein utilisation in broiler chickens

1. Two experiments were conducted to investigate the effects of dietary chitosan on growth performance, energy availability and protein retention in broilers. 2. Experiment 1 was a 42-d growth assay, in which 294 1-d-old male broilers were given one of 7 dietary treatments. A control feed was supplemented with 5 levels of chitosan (0.2, 0.5, 1.0, 3.0 and 5.0 g/kg) or 50 mg/kg chlortetracycline (CTC). 3. Increasing chitosan inclusion gave a nonlinear increase (P< 0.001) in feed conversion efficiency (FCE). Optimal growth and feed conversion were obtained with 0.5-1.0 g/kg chitosan. 4. In experiment 2, 42 1-d-old male broilers (6/treatment) were individually housed but fed on the same diets as in experiment 1. Excreta were collected from d 19-21 and d 40-42. 5. The addition of 0.5-1.0 g/kg chitosan increased nitrogen retention compared with the control group (P< 0.01), while apparent metabolisable energy in the diets was not altered.     

Comparative effects of zinc-nano complexes,zinc-sulphate and zinc-methionine on performance in broiler chickens

1. Micronutrients, especially zinc, have an important role in normal metabolism and growth of broilers. Using novel technologies helps to synthesise novel zinc complexes to deliver this micronutrient more efficiently.

2. In the present study, the effects of different zinc complexes and nano complexes on broiler performance were compared. Broilers in 6 groups were given basal diet (without zinc) and basal diet supplemented with zinc-sulphate, zinc-methionine, zinc-nano-sulphate, zinc-nano-methionine and zinc-nano-max (that was synthesised based on nanochelating technology) at a concentration of 80 mg/kg of diet.

3. At 1–42 d of age, dietary zinc-nano-sulphate supplementation decreased weight gain and feed intake. However, feed conversion ratio was not influenced by treatments. Carcass yield (%) of birds in the zinc-nano-sulphate and control groups were dramatically reduced at 42 d of age and abdominal fat (%) increased in these groups.

4. Relative to the control group, the antibody titre, spleen and bursa of Fabricius (%) were significantly higher in groups supplemented with zinc. Heterophil (%) was also significantly higher in the zinc-nano-methionine group in blood on d 42 compared to the control, zinc-sulphate and zinc-nano-sulphate.

5. Compared to the controls, the mean malondialdehyde content in thigh tissue was significantly reduced in groups supplemented with zinc at the time 0, 50, 100 and 150 min after oxidation.

6. Tibia zinc concentration in nanoparticle zinc samples was significantly higher relative to the control and zinc-sulphate groups.

7. Taken together, our data indicate that delivery of zinc in the structure of zinc-nano-methionine and zinc-nano-max at concentrations of 80 mg/kg of diet improves growth performance. However, dietary zinc-nano-sulphate decreased growth performance in broilers.

     

Tissue concentrations and pharmacokinetics of florfenicol in broiler chickens

1. Florfenicol (30 mg/kg body weight) was administered to broiler chickens via intravenous (iv), intramuscular (im) and oral routes to study its plasma concentrations, kinetic behaviour, systemic bioavailability and tissue content.

2. Following a single iv injection, the kinetic disposition of florfenicol followed a 2‐compartmental open model with an elimination half‐life of 173 min, total body clearance of 26.9 ml/kg/min and a steady state volume of distribution of 5.11 1/kg.

3. The highest plasma concentrations of florfenicol were 3.82 and 3.20 μg/ml following single im and oral administration, respectively. The systemic bioavailability was 96.6% and 55.3% after im and oral administration. The plasma protein binding of florfenicol was 18.5%.

4. Following its administration, the highest tissue concentrations of the drug were found in the kidney bile, lung, muscle, intestine, heart, liver, spleen and plasma. Low concentrations of the drug were found in brain, bone marrow and fat. No florfenicol residues were detected in tissues and plasma after 72 h except in the bile from where it disappeared after 96 h.     

Combined effects of guanidinoacetic acid,coenzyme Q10 and taurine on growth performance,gene expression and ascites mortality in broiler chickens

High levels of guanidinoacetate acid (GAA) deteriorate growth response in broiler chickens. We propose using coenzyme Q₁₀, an antioxidant, and taurine (TAU), a methyl donor, to cope with the situation when high level of GAA included in diet. GAA was supplemented at 0 (control), 0.75, 1.5 and 2.25 g/kg in isoenergetic and isonitrogenous diets and fed to broilers (Cobb 500) from 1 to 40 days post‐hatch. Three additional diets were prepared by adding CoQ₁₀ (40 mg/kg), TAU (40 mg/kg) or their combination (both CoQ₁₀ and TAU at 40 mg/kg) to the 2.25 g/kg GAA group. The experimental design used was a completely randomized design. While weight gain (p = 0.038) and feed conversion ratio (p = 0.024) improved when GAA added at 1.5 g/kg, higher supplementation (2.25 g/kg) deteriorated these responses. These responses, however, were significantly restored by using CoQ₁₀, TAU or their combination. Abdominal fat deposition was significantly decreased when TAU added to broiler diets by virtue of upregulating peroxisome proliferator‐activated receptor alpha. Supplementing broiler diets with CoQ₁₀ and TAU or their combination significantly decrease ascites mortality. In conclusion, CoQ₁₀ and TAU have shown beneficial effects when high level of GAA included in broiler diets.     

Growth performance and carcase quality in broiler chickens fed on bacterial protein grown on natural gas

1. The effects of increasing concentrations (0, 40, 80 or 120 g/kg) of bacterial protein meal (BPM) and bacterial protein autolysate (BPA) grown on natural gas on growth performance and carcase quality in broiler chickens were examined. 2. Adding BPM to diets reduced feed intake and improved gain: feed from 0 to 21 d and overall to 35 d, but did not significantly affect weight gain compared to the soybean meal based control diet. 3. Increasing concentrations of BPA significantly reduced growth rate, feed intake, gain: feed, carcase weight and dressing percentage, but significantly increased carcase dry matter, fat and energy content. 4. Adding BPM to diets had no effect on viscosity of diets and jejunal digesta, and minor effects on litter quality, whereas BPA increased the viscosity of diets and jejunal digesta, improved litter quality at 21 d, but decreased litter quality at 32 d. 5. To conclude, broiler chickens performed better on a BPM product with intact proteins than on an autolysate with ruptured cell walls and a high content of free amino acids and low molecular-weight peptides.     

Effects of increasing dietary concentrations of specific structured triacylglycerides on performance and nitrogen and energy metabolism in broiler chickens

Specific structured triacylglycerides (STG) containing medium chain fatty acids in sn-1,3 positions and a long chain fatty acid in sn-2 position were prepared from rapeseed oil and capric acid (C10:0). A total of 80 female broiler chickens (Ross 208) were randomly allocated into five dietary treatments as two series of 40 chicks: a basal diet with graded levels of STG of 0, 20, 40, 60 and 80 g/kg diet at the expense of rapeseed oil were fed to the chickens in groups of four. At 12 d of age the chickens were placed pair-wise in metabolism cages. The grower period (d 13-36) was divided into four consecutive balance periods each of 6 d. Two 24 h measurements of gas exchange in two open-air circuit respiration chambers were performed during the second and third day of each balance period. During the whole experiment there was a negative effect of the inclusion of STG on average feed intake. However, this only slightly affected average daily weight gain. Feed conversion efficiency improved linearly with the inclusion level of STG. Daily gain adjusted to mean daily feed intake increased linearly with inclusion rate of STG, indicating that the weight gain was affected by both feed intake and the enhancing effect on digestibility of STG. Weight of small intestine and colon decreased with increasing inclusion of STG. Utilisation of dietary protein relative to intake increased while that of retained fat tended to decrease resulting in a decreased utilisation of metabolisable energy (RE/ME) in birds receiving STG. Heat production (HE) was slightly lower in the STG groups. More of the dietary fat was oxidised when more STG was added, although the total amount of fat in the diets was kept constant.     

The effects of fructo-oligosaccharides or whole wheat on the performance and digestive tract of broiler chickens

1. The objective of this experiment was to study two feeding methods, which could potentially act on the gut microflora, the structure and/or the function of the digestive tract and thereby improve the performance of broilers. 2. Four dietary treatments were studied: a negative control (wheat based) with no additives (C), a positive control with 0.01 g/kg avilamycin (AV), a treatment with 0.6 g/kg fructo-oligosaccharides (FOS) and a treatment with the same composition as treatment C but in which a part or all (400 g/kg) of the wheat was given as whole wheat and a concentrate supplement (WW). The measurements were: the performance from 0 to 6 weeks, the bacterial counts at 3 and 6 weeks, the digestive tract morphology and the activity of some intestinal enzymes at 3 weeks. 3. The birds given AV had better daily live weight gain (DLWG) and feed conversion ratio (FCR) compared to treatment C. The birds given FOS had a lower feed intake and a lower DLWG than the birds on treatment C but their FCR was significantly improved. WW resulted in a numerically lower feed intake and a significantly lower DLWG than treatment C. With AV, the number of aerobic mesophilic bacteria in the caeca was reduced at 3 weeks. With WW, gizzard and pancreas weights were greater and the surfaces of the ileal crypts were larger. An increased activity of leucine aminopeptidase (LAP) in the duodenum was found for treatments AV, FOS and WW. 4. In conclusion, in this study, treatments WW and FOS reduced DLWG, which may have been due to a lower feed intake during the whole period. With WW, the FCR was not affected, maybe because of both positive and negative effects on digestive tract (higher gizzard and pancreas development and LAP activity; larger crypts). However, FOS improved FCR, which may be partly explained by the higher LAP activity.     

Effect of dietary protein and environmental temperature on growth performance and water consumption of male broiler chickens

1. Male broilers were reared in individual cages from 23 to 44 d of age. The effect of 2 temperatures (22° and 32°C) and 2 crude protein (CP) levels (160 and 200 g/kg) were studied. The low protein diet was supplemented with lysine, methionine, arginine, threonine and valine in order to meet requirements.

2. At 22°C, a reduced CP content did not affect growth rate and breast muscle but slightly increased adiposity and food to gain ratio (FCR). Water consumption was reduced.

3. High temperature reduced growth rate and absolute and proportional breast muscle weight, and increased adiposity and FCR. These effects were more pronounced with the low CP diet. Water consumption was also reduced.

4. It was concluded that reducing CP content did not seem a good way to help broilers to withstand hot conditions. This experiment suggests that amino acids other than lysine, methionine and cystine are probably involved in the detrimental effect of high temperature.     

Effects of dietary concentrations of methionine on growth performance and oxidative status of broiler chickens with different hatching weight

1. A study was conducted to evaluate the effects of two hatching weight (HW) levels and two dietary concentrations of methionine on the growth performance and oxidative status of broilers. Male Arbor Acres chickens were divided into two groups on their HW (low and high HW, H and L). Each HW group was then distributed into two subgroups, of similar HW, receiving either low or high dietary concentrations of methionine (4.9 g methionine/kg, LM; 5.9 g methionine/kg, HM). Thus, all day-old birds were distributed into 4 treatments (H-LM, H-HM, L-LM, L-HM) × 6 replicates × 10 birds for 21 d.

2. Broilers with high HW were heavier than those with low HW during the 21 d assay, which appeared to result from increased body weight gain rather than improved feed conversion efficiency. A higher dietary concentration of methionine (5.9 g/kg) improved growth performance of broilers with low HW in terms of body weight gain and feed conversion ratio.

3. Broilers with different HW had similar antioxidant status both in serum and liver.

4. Broilers given a diet containing 5.9 g/kg methionine had enhanced serum superoxide dismutase (SOD) activity and decreased hepatic malondialdehyde (MDA) content at day 7.

5. Broilers given a diet containing 5.9 g/kg methionine had a higher hepatic reduced glutathione (GSH):glutathione disulphide (GSSG) ratio than those given a diet containing 4.9 g/kg methionine at day 21. High dietary methionine concentration reduced hepatic GSH content and glutathione peroxidase (GPX) activity of broilers with high HW at day 7 and at day 21, respectively, but increased hepatic GSH content of broilers with low HW at day 7.

6. Although broilers with different HW had similar oxidative status as indicated by several parameters in blood and liver, HW can have positive effects on the subsequent growth performance of broilers, and a higher dietary methionine concentration (5.9 g/kg) can improve growth performance and antioxidant status in broilers exhibiting low HW.     

Responses of broiler chickens to dietary protein: effects of early life protein nutrition on later responses

1. A study was conducted with modern broiler chicks to test the effects of early life protein nutrition and sex on responses in growth and body composition to dietary protein at a later age. Effects on the incidence of metabolic disorders were also evaluated. 2. From 11 to 26 d of age (EXP1), birds were given 8 diets varying in balanced protein to energy ratio (BPE ratio) between 0.575 and 1.100 g digestible lysine per MJ AMEn. Birds from two treatment groups in EXP1 (BPE ratio of 0.725 and 1.025 g/MJ, respectively) were subsequently used in a test from 26 to 41 d of age (EXP2). In EXP2, 8 diets were used, varying in BPE ratio between 0.500 and 1.025 g/MJ. 3. Responses in weight gain and feed conversion to BPE ratio in EXP2 changed considerably when BPE ratio in EXP1 was modified, irrespective of sex. Up to 10% improvement in both weight gain and feed conversion in EXP2 was observed if BPE ratio in EXP1 was 0.725 compared with 1.025 g/MJ. With males, however, the effect of treatment in EXP1 on weight gain in EXP2 was present only at high BPE ratios. 4. For the relative gain of breast meat and abdominal fat, but not for carcase, the responses of male broilers to BPE ratio in EXP2 were altered by the BPE ratio in EXP1. With females, responses in composition of the gain to diet in EXP2 were independent of BPE ratio in EXP1. 5. The incidence of metabolic disorders was low, irrespective of treatment in EXP1. The lower BPE ratio in EXP1 increased mortality in EXP2 from 0.8 to 3.6%. 6. Our findings show that broiler responses to dietary protein depend on previous protein nutrition and sex. Effects of early life protein nutrition on incidence of metabolic disorders were not observed. The results strongly suggest that protein levels in grower and finisher diets should not be optimised independently, but simultaneously.     

Effect of feeding diet with alternate protein sources and quality protein maize on performance and nutrient utilization in broiler chickens

Tropical Animal Health and Production - The experiment was conducted to study the effect of feeding diets with quality protein maize (QPM) along with cottonseed meal (CSM) and guar meal (GM) on...     

Dietary effects of commercial probiotics on growth performance,digestibility, and intestinal morphometry of broiler chickens

This study compared five commercially available probiotics vis-à-vis antibiotic growth promotant (AGP) supplementation and absence of feed additive based on efficiency, intestinal morphometry, and energy digestibility in improving broiler chicken production. A total of 630 straight run (Cobb) day-old broiler chicks were distributed to seven treatments following a completely randomized design, with ten replicates per treatment and nine birds per replicate per cage. Dietary treatments consisted of basal diet in combination with the following: without probiotics and AGP supplementation (treatment 1); 75 ppm each of chlorotetracycline (CTC) and Zn bacitracin (treatment 2); probiotic A, Bacillus subtilis (treatment 3); probiotic B, Bacillus subtilis (treatment 4); probiotic C, Enterococcus faecium (treatment 5); and probiotic D, Bacillus subtilis (treatment 6); probiotic E, Enterococcus faecium, Bifidobacterium spp., Pediococcus spp., and Lactobacillus spp. (treatment 7). At day 42, energy digestibility was determined by fasting three randomly selected birds from each treatment for 12 h and then subjecting them to their corresponding dietary treatments. Excreta were collected and pooled after 24 h of feeding. Pooled excreta were weighed, oven-dried, and subjected to energy analyses after 3-day collection. Apparent total tract metabolizable energy was then computed. At day 47, three birds were randomly selected per treatment for intestinal morphometry (villi height and crypt depth) of the duodenum, jejunum, and ileum. Dietary supplementation using probiotics showed no significant effect on overall body weight, weight gain, feed consumption, feed efficiency, dressing percentage, mortality, harvest recovery, carcass quality parameters (e.g., meat to bone ratio and abdominal fat content), intestinal morphometry, and energy digestibility. Birds under treatment 7 (basal feed + probiotic E) generated the highest income over feed and chick cost.

     

Effect of dietary lysine to crude protein ratio on performance of male Ross 308 broiler chickens

Two experiments were conducted to determine the effect of dietary lysine to crude protein ratio on performance of male Ross 308 broiler chickens. In each experiment the diets were isocaloric and isonitrogenous but with different lysine to crude protein ratios. A complete randomized design was used in both experiments, the starter (1–21 days) and grower (22–42 days) experiments. The three starter diets, based on lysine to crude protein ratios, were L₀ (0.055), L₁ (0.066) and L₂ (0.077), while grower diets were L₃(0.047), L₄(0.061) and L₅(0.074). A quadratic type equation was used to determine ratios for optimum growth rate, feed conversion ratio, breast meat yield and breast meat nitrogen content. Dietary lysine to crude protein ratios of 0.066 and 0.077 supported optimum growth rate and feed conversion ratio, respectively, during the starter period. Dietary lysine to crude protein ratios of 0.073, 0.073, 0.069 and 0.079 supported optimum growth rate, feed conversion and breast meat yield and nitrogen content during the grower phase. Dietary lysine to crude protein ratio had no effect on diet intake and digestibility. The results indicate that at each phase a single dietary lysine to crude protein optimized both growth rate and feed conversion ratio. However, the ratio for optimum breast meat yield was lower than that for optimum growth rate and feed conversion ratio. These findings have implications on ration formulation for broiler chickens.