Effects of supplemental different clay minerals in broiler chickens under cyclic heat stress

The objective of this study was to investigate the effect of supplementing clay minerals and organic chromium in feed on broiler chicken under heat stress (HS). A total of 90 one-day-old broiler chicken (Arbor Acres) with an initial body weight of 45.0 ± 0.2 g were assigned to five treatment groups (six replications, three birds each cage): 1) NC group, basal diet under room temperature environment; 2) PC group, basal diet under high temperature (HT) environment; 3) ILT group, basal diet + 1% illite + HT; 4) ZLT group, basal diet + 1% zeolite + HT; 5) OC group, basal diet + 400 ppb/kg organic chromium + HT. The ILT and ZLT groups had significantly higher body weight than the PC group in 4 weeks. Apparent total tract digestibility of gross energy was increased in the ILT, ZLT, and OC groups compared to the PC group. The NC group had lower foot-pad dermatitis score than other groups. Escherichia coli population in the cecum and feces was decreased in the ZLT group than in the PC group. Lactobacillus in cecum and feces was significantly increased in the ZLT group than in the PC group. Regarding blood profiles, blood cortisol was decreased in the NC and ILT groups compared to the PC group. Water holding capacity and pH were increased in the ZLT group than the PC group. In conclusion, according to the results of growth performance, nutrients digestibility, bacteria counts, and meat characteristics, supplementation of the ZLT in broiler diet can alleviate HS.

Chromium Supplementation on the Growth Performance, Carcass Traits, Blood Constituents, and Immune Competence of Broiler Chickens Under Heat Stress: a Systematic Review and Dose-Response Meta-analysis

Several studies have been conducted to assess the effects of supplemental dietary chromium (Cr) on broiler chickens under heat stress (HS) conditions, but the shape and strength of the associations between Cr supplementation and broiler chickens' responses to HS remain unclear. Therefore, the current systematic review and meta-analysis investigated the effectiveness and dose-response relationship of Cr. The results indicated non-linear dose-response associations between Cr supplementation and body mass gain (BMG), feed intake (FI), feed conversion ratio (FCR), carcass, breast, leg, and abdominal fat relative weight (P_{non-linearity} < 0.05). The maximum BMG, FI, and the relative weight of carcass, breast, and leg would be achieved with 1200, 1100, 900, 800, and 800 ppb of Cr, respectively, while the lowest FCR and abdominal fat relative weight might be obtained with the supplementation of 1100 and 1000 ppb of Cr, compared with no Cr supplementation. Referring to BMG, supplementation with 1200-1700 ppb inorganic Cr or 2700 ppb or less organic Cr had a significant beneficial effect on the BMG, while NanoCr supplementation did not influence this outcome variable. A non-linear association was observed for blood total cholesterol concentration (TC, P_{non-linearity} < 0.05), with the maximum reduction of TC concentration observed at approximately 900 ppb of Cr. The cholesterol-lowering effect of Cr (≤ 2400 ppb) was only found in severe HS conditions. Moreover, supplemental Cr caused a significant linear reduction in the blood triglycerides and glucose concentrations (P < 0.05). The blood concentrations of triiodothyronine, thyroxine, and insulin increased linearly, and the corticosterone concentration reduced, with increasing supplemental Cr (P < 0.05). There was a non-linear inverse association between Cr supplementation and cortisol level (P_{non-linearity} < 0.05), and the lowest concentration of cortisol was observed with the supplementation of 1000 ppb of Cr. Meanwhile, significant positive linear associations between Cr supplementation and bursa percentage, thymus percentage, infectious bronchitis vaccine titer, avian influenza vaccine titer, Newcastle disease vaccine titer, cutaneous basophil hypersensitivity response, and serum immunoglobulin G level were found (P < 0.05). However, Cr supplementation caused a linear reduction in the heterophil/lymphocyte ratio (P < 0.05). Based on the obtained results, the recommended optimum amount of supplemental Cr is 1100 ppb.

Effects of Supplemental Chromium Nanoparticles on IFN-γ expression of Heat Stress Broilers

The aim of present study was to investigate the beneficial effect of chromium (III) picolinate (CrPic) and chromium (III) picolinate nanoparticles (NCrPic) addition on growth performance, stress-related hormonal changes, and serum levels of various immunity biomarkers, as well as the gene expression of IFN-γ in broilers exposed to heat stress conditions. Treatments included T1 which received the basal diet with no feed additive; T2 exposed to heat stress; T3, T4, and T5 containing 500, 1000, and 1500 ppb CrPic; as well as T6, T7, and T8 containing 500, 1000, and 1500 ppb NCrPic, respectively. After 2 weeks from CrPic and NCrPic supplementation, IFN-γ mRNA expression was assayed using the RT-PCR technique. The results showed that the lower body weight, daily weight gain, daily feed intake by heat stress, and the feed conversion ratio were recovered remarkably by CrPic and NCrPic supplements. The stress-elevated levels of cortisol and immunoglobulin were reduced significantly using CrPic and NCrPic supplementation (P ≤ 0.05). The gene expression profile showed that the upregulated expression of IFN-γ was regulated by the addition of CrPic and NCrPic, in particular, to the diet; however, a full downregulation of IFN-γ expression was observed after week 2 of NCrPic supplementation. In conclusion, the results indicated that nanoparticle supplementation could be effective in reducing heat stress-induced detrimental alterations, thereby attributing to substantial changes to the immune system, including IFN-γ expression.

The Impact of Bacillus subtilis PB6 and Chromium Propionate on the Performance, Egg Quality and Nutrient Metabolizability of Layer Breeders

The objective of this study was to evaluate the effects of Bacillus subtillis PB6, chromium propionate or a combination of the two on the performance, egg and eggshell quality, nutrient metabolizability and serum biochemistry of layer breeders. White Plymouth Rock and Red Rhodes Island breeder hens at 55 weeks of age were allocated in individual cages using a completely randomized block design with 16 replicates. Hens were fed control, control + probiotic (500 g/ton of Bacillus subtilis PB6), control + CrProp (50 g/ton of chromium propionate) and control + probiotic + CrProp diets from 55 to 70 weeks of age. Productive parameters and eggshell quality as well as cortisol and blood biochemistry were grouped each 28 d as well as for the overall period. The metabolizability of nutrients and energy was determined at 70 weeks of age. In the overall period, hens fed the control + probiotic or control + probiotic + CrProp diets had significantly higher egg production, egg mass, shell percentage, thickness and shell strength. The metabolizability of dry matter, nitrogen and energy increased in hens that were fed the control + probiotic + CrProp diet. In conclusion, diets supplemented with Bacillus subtillis PB6 and chromium propionate resulted in improved productive performance, eggshell quality and nutrient metabolizability of layer breeders, without modifying serum cortisol, albumin and triglycerides.

Thermal stress and high stocking densities in poultry farms: Potential effects and mitigation strategies

Environmental changes pose significant threats to agricultural activities particularly animal production. These changes have induced major concerns which will negatively affect the poultry health and productivity under the current climate changes. Moreover, they also alter the immunological status of the exposed birds and make them susceptible to different diseases. The adverse effects of environmental stress also include poor performance of birds (reduced feed intake, growth, feed efficiency, immunity, and egg production) and inferior product quality. The adverse effect of heat stress on different quail breeds like Japanese quail, bobwhite quail, scaled quail, and Gambel's quail ranged from decreased growth rates (11.0-14.5%), body weight (7.7-13.2%), feed intake (6.1-21.6%), feed efficiency (4.3-8.6%), and egg production (6.6-23.3%). Also, birds reared under heat stress (34 °C) had significantly decreased Haugh units by 10.8% and egg weight by 14.3% in comparison with the control group (reared at 22 °C). On the other hand, increasing stoking density from 30 to 45 kg/m² also negatively affected the feed intake and body weight. Recent studies have focused on evaluating the potential adverse effects of different environmental stresses on poultry performance, behavior, welfare, and reproduction. It is imperative to understand better the interaction of different environmental factors and their subsequent effects on avian physiology, to spotlights on the effective management and nutritional strategies to alleviate the adverse effects of different stresses in poultry. This review aims to present a comprehensive overview of physiological manifestations of major environmental stresses including thermal stress (heat and cold stress) and high stocking densities on poultry health and production. Moreover, we have also critically evaluated the scope and efficacy of some potential strategies to mitigate the influences of these environmental stressors in different poultry species.

Effects of different concentration of organic and inorganic trace minerals (zinc, selenium, and chromium) supplementation on expression of chTLR4 gene and humoral immune response in broilers

BACKGROUND AND AIM

Poultry production is the fastest-growing livestock sector in developing countries. In the poultry diet, trace minerals (zinc [Zn], selenium [Se], and chromium [Cr]) are normally administered in the inorganic form which has been traditionally considered as the most cost-effective and easily available but organic forms of these trace minerals have a higher bioavailability, lower dietary inclusion and cause less environmental pollution as compared to inorganic form. This study aimed to investigate the effect of different concentrations of organic and inorganic forms of trace minerals (Zn, Se, and Cr) supplementation (0-35 days) on expression of chTLR4gene and humoral immune response in broilers.

MATERIALS AND METHODS

A total of 216 broilers were randomly divided into 12 groups and each group divided into three replicates consisting of six broilers each. T1 (R1, R2, and R3) group was kept as control. T2, T3, and T4 (R1, R2, and R3) groups were supplemented with inorganic form of Zn at 40 mg/kg of feed, organic form of Zn at 40 mg/kg of feed, and 50% organic form of Zn at 20 mg/kg of feed, respectively. T5, T6, and T7 (R1, R2, and R3) groups were supplemented with inorganic form of Se at 0.3 mg/kg of feed, organic form of Se at 0.3 mg/kg of feed, and 50% organic form of Se at 0.15 mg/kg of feed, respectively. T8, T9, and T10 (R1, R2, and R3) groups were supplemented with inorganic form of Cr at 2 mg/kg of feed, organic form of Cr at 2 mg/kg of feed, and 50% organic form of Cr at 1 mg/kg of feed, respectively. T11 and T12 (R1, R2, and R3) groups were supplemented with a combination of all three minerals from inorganic and organic forms, respectively.

RESULTS

Reverse transcriptase-polymerase chain reaction gene expression analysis revealed that in bursa of Fabricius, maximum upregulation of chTLR4 (3.0214 fold) was observed in T6 group, and in spleen, maximum upregulation of chTLR4 (3.2140 fold) was observed in T3 group as compared to control group. On day 35, the maximum plasma immunoglobulin G concentration was observed in organic trace minerals (OTMs) supplemented, whereas the minimum concentration was recorded in control group. On day 28 and 35, the overall mean heterophil:lymphocyte ratio showed a significant difference (p<0.05) between control and OTM supplemented groups. A significantly higher immune organ weight (spleen and bursa of Fabricius) was recorded in OTM supplemented group as compared to control and other supplemented group.

CONCLUSION

Supplementation of organic form of Zn, Se, and Cr either alone or in combination increase humoral immune response and upregulation of chTLR4 gene expression in bursa and spleen indicates a beneficial effect of OTM in augmentation of immune system in broilers.

Research Note: Responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate in heat-stressed broilers

This study was conducted to investigate the dose responses of growth performance, immune traits, and small intestinal morphology to dietary supplementation of chromium propionate (CrPro) in heat-stressed broilers. A total of 252 1-day-old Cobb 500 male broilers were randomly assigned to 6 treatments with 7 replicate cages of 6 birds per cage. The dietary treatments consisted of a basal diet supplemented with 0, 0.2, 0.4, 0.8, 1.6, and 3.2 mg/kg Cr in the form of CrPro. The birds had ad libitum access to feed and tap water for an experimental period of 42 D. For induction of heat stress, the house temperature was set at 35°C ± 2°C from 22 to 42 D of age. No differences were detected among treatments in growth performance during the experimental period (P > 0.05). Serum IgA concentrations were not affected by treatment (P > 0.05). However, a quadratic response was detected for serum IgG (P < 0.01) and IgM (P < 0.01) concentration as dietary Cr supplementation was increased. The highest response of IgG and IgM in serum was observed for broilers fed a diet supplemented with 0.2 mg of Cr/kg. Dietary supplementation of Cr had no impacts on villus height, crypt depth, or the ratio of villus height to crypt depth in the jejunum and ileum. A quadratic response of villus height and the ratio of villus height to crypt depth and a linear response of crypt depth to increased dietary Cr supplementation were observed in the duodenum (P < 0.01). The results indicate that CrPro supplementation could modify the intestinal morphology of the duodenum and influence serum IgG and IgM concentrations in heat-stressed broiler chickens. Based on the results of this experiment, the 0.2-mg Cr/kg diet from CrPro increases immune response and intestinal health in heat-stressed broilers.

Effects of Combined Supplementation of Conjugated Linoleic Acid, Methionine Chromium, Betaine, and Cysteamine on Meat Tenderness of Rats

A systemic design was carried out to investigate the optimal combination of BET, Met-Cr, CLA, and CS for improving the meat tenderness in rats. A total of 104 six-week old male Sprague-Dawley rats were randomly assigned to 13 treatments with 4 replicates of 2 rats each. The experiments lasted for 5 weeks. The results showed that inclusion of Met-Cr decreased the contents of intramuscular fat (IMF), fat among muscle cells, and lipid droplets inside muscle cells (P < 0.05), and inclusion of CLA or Met-Cr increased the contents of IMF, fat among muscle cells, and lipid droplets inside muscle cells (P < 0.05). CS increased the contents of total collagen (TC) and soluble collagen (SC), and CLA decreased the contents of TC and SC (P < 0.05). The combination of BET and CLA increased IMF and SC contents and decreased TC contents (P < 0.05). The combination of BET and CS could increase fat contents among muscle cells and decrease TC and SC contents (P < 0.05). The combination of CLA and Met-Cr decreased IMF contents (P < 0.05). The combination of CLA and CS, as well as Met-Cr and CS, decreased fat contents among muscle cells (P < 0.05). These combinations may regulate lipogenesis and decrease the deposition of fat in muscles. There existed a significant positive correlation between IMF and SC content, which might indicate that IMF content improves meat's tenderness partly by increasing SC content in muscle.

Effect of synbiotics on thyroid hormones, intestinal histomorphology, and heat shock protein 70 expression in broiler chickens reared under cyclic heat stress

This study examined effect of a dietary synbiotic supplement on the concentrations of plasma thyroid hormones, expressions of heat shock protein 70 (HSP70), and intestinal histomorphology in broiler chickens exposed to cyclic heat stress (HS). Three hundred and sixty day old male Ross 708 broiler chicks were randomly distributed among 3 dietary treatments containing a synbiotic (PoultryStar meUS) at 0 (control), 0.5 (0.5×), and 1.0 (1.0×) g/kg. Each treatment contained 8 replicates of 15 birds each housed in floor pens in a temperature and lighting controlled room. Heat stimulation was established from days 15 to 42 at 32°C for 9 h daily. The results indicated that under the HS condition, both synbiotic fed groups had lower liver and hypothalamus HSP70 levels (P < 0.001) compared to control group; however, HSP70 mRNA expression was not different among treatments (P > 0.05). There were no treatment effects on the levels of triiodothyronine (T3) and thyroxine (T4) as well as T3/T4 ratio (P > 0.05). Compared to controls, 1.0× HS broilers had greater villus height in the duodenum (P < 0.01), and greater villus height and villus height:crypt depth ratios in the ileum (P < 0.01). There were no differences among treatments on the measured intestinal parameters in the jejunum (P > 0.05). The results suggest that the synbiotic may ameliorate the negative effects of HS on chicken health as indicated by the changes in the intestinal architecture and the levels of HSP70. Dietary synbiotic supplement could be a feasible nutritive strategy for the poultry industry to improve the health and welfare of chickens when exposed to hot environmental temperature.

The palliative role of Eruca sativa leaves dietary supplementation against oxidative stress, immunosuppression, and growth retardation in temperature-stressed Oreochromis niloticus

This study was conducted to investigate the effects of dietary dried Rocket Leaves meal (DRLM) supplementation on growth performance, immune response, and antioxidant capacity of Oreochromis niloticus reared under different water temperature. For this purpose, five hundred and forty apparently healthy O. niloticus were allocated into nine groups fed three DRLM-supplemented diets (0,1, and 3%) and reared at three water temperature (18, 24, and 32°C) in a 3 × 3 total randomized factorial design. The results revealed that exposure of fish to low (18°C) or high (32°C) temperatures for 30 days evoked significant growth retardation, depleted antioxidant enzymes activities (Catalase; CAT and super oxide dismutase; SOD), lipid peroxidation (malondialdehyde; MDA), immunosuppression, altered cortisol level compared to those reared at 24°C. Moreover, a marked down-regulation of oxidative stress related genes with up-regulation of interleukin 1β gene were apparent. In contrast, DRLM incorporation, particularly at 3%, in heat or cold stressed fish diets significantly enhanced growth, restored IgM and lysozymes levels, and SOD and CAT activities. Also, both the MDA and cortisol levels were significantly depressed. Furthermore, both antioxidant and immune-related genes expression were significantly corrected. Conclusively, 3% DRLM dietary supplementation in tilapia diet could be a promising strategy to alleviate the temperature stress-induced negative impacts on fish health and performance.

Systematic Review of the Effects of Chromium(III) on Chickens

Chromium supplementation has been proposed to have beneficial effects in farm animals, particularly when under stress. The last two decades, in particular, have seen an emphasis on examining the effects of supplemental chromium on a variety of variables in chicks and chickens. Thus, given the recent approval of a Cr(III) compound for use in chicken feed in the United States and the recent surge in papers on the use of Cr in chicken feed, the need for a systematic review of studies utilizing chickens is extremely urgent and timely. With the exception of studies on cold-stressed laying hens, the results of studies of Cr supplementation of chickens, whether broilers or laying hens, were found to be too inconsistent for any firm conclusions to be drawn other than that Cr supplementation generally leads to accumulation of Cr in tissues. Few potential trends in terms or beneficial or deleterious effects from Cr supplementation were found regardless of strain of chicken, Cr source, Cr dose, duration of supplementation, or variable examined. Hence, in summary, no recommendation for the use of Cr as a supplement for the diet of chickens can be made at this time.

Palliative effects of extra virgin olive oil, gallic acid, and lemongrass oil dietary supplementation on growth performance, digestibility, carcass traits, and antioxidant status of heat-stressed growing New Zealand White rabbits

This study explored the effects of supplemental dietary extra virgin olive oil (EVOO), gallic acid (GA), or lemongrass essential oil (LGEO) on growth performance, nutrient digestibility, carcass traits, lipid peroxidation, hematological, and antioxidative status in growing rabbits under heat stress conditions. A total of 48 male growing New Zealand White rabbits were randomly divided into four equal groups, which received a basal diet without any supplementation or supplemented with 15 g EVOO, 500 mg GA, or 400 mg LGEO/kg of diet, for eight consecutive weeks. Results revealed that the overall mean of temperature humidity index was 84.67 ± 0.35, reflecting a state of severe heat stress. Moreover, dietary supplementation with EVOO, GA, or LGEO significantly increased live body weight and daily body weight gain but decreased both feed conversion ratio and daily water consumption. Additionally, a significant increase in both organic matter and crude protein digestibility besides a remarkable elevation in the nutritive values of digestible crude protein, total digestible nutrients, and digestible energy, as well as an increase in the numbers of WBCs, lymphocytes, and heterophils was significant in EVOO-supplemented rabbits. Supplementation with EVOO, GA, or LGEO in the heat-stressed growing rabbit's diet enhanced catalase activity and reduced glutathione content, whereas EVOO-treated rabbits had the highest values. Also, malondialdehyde activity was reduced in response to all tested additives. In conclusion, these findings suggested that addition of EVOO, GA, or LGEO in growing rabbit's diet could be used effectively to alleviate negative impacts of heat stress load on performance, nutrient digestibility, oxidative status, and hemato-biochemical features. Furthermore, among these additives, EVOO achieved the best effects.

Dietary chromium methionine supplementation could alleviate immunosuppressive effects of heat stress in broiler chicks

The present study was conducted to investigate the effects of dietary supplementation of chromium methionine (CrMet) on performance, immune responses, and stress status of broiler chicks subjected to heat-stress conditions. A total of 450 day-old Ross 308 broiler chicks were randomly distributed between 5 replicate pens (15 birds each) of 6 experimental treatments according to a 2 × 3 factorial arrangement of treatments including 2 temperature conditions (thermoneutral and heat stress) and 3 supplemental Cr levels (0, 500, and 1,000 μg/kg as CrMet). For induction of heat stress, the house temperature was set at 35 ± 2°C from 15 to 42 d of age. Results showed that the chicks subjected to heat-stress condition had lower (P < 0.01) feed intake, BW gain, and deteriorated (P < 0.05) feed conversion values compared with those kept in the thermoneutral house. Dietary supplementation with CrMet increased (P < 0.01) feed intake and improved (P < 0.01) weight gain and feed efficiency. There were significant Cr level × temperature interactions, so that inclusion of CrMet into the diets was more effective in heat-stressed chicks. Exposure to heat stress suppressed (P < 0.01) cutaneous hypersensivity response to phytohemagglutinin-P injection at 30 d of age, and dietary supplementation of 500 μg Cr/kg induced (P < 0.05) this response, with the greater impacts in heat-stressed chicks, resulting in a significant (P < 0.01) Cr × temperature interaction. Antibody responses against Newcastle and infectious bronchitis disease viruses were diminished (P < 0.01) in heat-stressed chicks. Dietary inclusion of CrMet improved (P < 0.05) antibody responses to different immunostimulants, and this effect was more pronounced in heat-stressed chicks. Exposure to heat stress caused a significant (P < 0.05) decrease in the proportion of helper (CD4+) T lymphocytes and increased cytotoxic (CD8+) T lymphocytes, resulting in a decreased (P < 0.01) CD4+ to CD8+ ratio in peripheral blood circulation. Supplementation of CrMet to heat-stressed chicks modulated (P < 0.01) plasma corticosterone level. The present findings indicate that dietary CrMet supplementation could alleviate heat-stress-induced growth retardation in broiler chicks. Moreover, supplemental CrMet modulated suppressive effects of heat stress on cellular and humoral immune responses.

Effect of Supplementing Organic Forms of Zinc, Selenium and Chromium on Performance, Anti-Oxidant and Immune Responses in Broiler Chicken Reared in Tropical Summer

Two experiments were conducted to study the effect of supplementing organic forms of zinc (Zn), selenium (Se) and chromium (Cr) on performance, anti-oxidant activities and immune responses in broiler chickens from 1 to 21 days of age, which were reared in cyclic heat-stressed condition under tropical summer in open-sided poultry house. A total of 200 (experiment I) and 450-day-old (experiment II) broiler male chicks (Cobb 400) were randomly distributed in stainless steel battery brooders (610 mm × 762 mm × 475 mm) at the rate of five birds per pen. A maize-soybean meal-based control diet (CD) containing recommended (Vencobb 400, Broiler Management Guide) concentrations of inorganic trace minerals and other nutrients was prepared. The CD was supplemented individually with organic form of selenium (Se, 0.30 mg/kg), chromium (Cr, 2 mg/kg) and zinc (Zn, 40 mg/kg) in experiment I. In experiment II, two concentrations of each Zn (20 and 40 mg/kg), Se (0.15 and 0.30 mg/kg) and Cr (1 and 2 mg/kg) were supplemented to the basal diet in 2 × 2 × 2 factorial design. A group without supplementing inorganic trace minerals was maintained as control group in both experiments. Each diet was allotted randomly to ten replicates in both experiments and fed ad libitum from 1 to 21 days of age. At 19th day of age, blood samples were collected for estimation of anti-oxidant and immune responses. Supplementation of Se, Cr and Zn increased (P < 0.05) body mass gain (BMG) and feed intake compared to those fed the CD in experiment I. The feed efficiency (FE) in Cr-fed group was higher (P < 0.05) compared to the CD-fed group. Se or Cr supplementation reduced lipid peroxidation (LP) compared to broilers fed the CD. In experiment II, BMG was not affected (P > 0.05) by the interaction between levels of Zn, Se and Cr in broiler diet. The FE improved (P < 0.05) with supplementation of the trace minerals tested at both concentrations except in group fed 40 mg Zn, 0.5 mg Se and 1 mg Cr/kg. Reduction in lipid peroxidation (LP, P < 0.05) and increased (P < 0.05) activity of superoxide dismutase were observed in broiler fed organic Zn, Se and Cr compared to the CD-fed group. The dietary concentrations of Zn, Se and Cr did not influence (P > 0.05) the immune responses (Newcastle disease titre and cell-mediated immune response to phytohaemagglutinin-P) in both the experiments. Based on the results, it is concluded that supplementation of organic form of Se, Cr and Zn (0.30, 2 and 40 mg/kg, respectively) either alone or in combination significantly improved performance and anti-oxidant responses (reduced LP and increased superoxide dismutase) in commercial broiler chicks (21 days of age) reared in cyclic heat stress conditions in open-sided poultry house during summer.

Effects of Supplemental Chromium Source and Concentration on Growth Performance, Carcass Traits, and Meat Quality of Broilers Under Heat Stress Conditions

The objective of this study was to investigate the effects of dietary supplemental chromium (Cr) on growth performance, carcass traits, and meat quality of broilers reared under heat stress. A total of 252 1-d-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involving a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate, CrPro; Cr picolinate, CrPic; Cr chloride, CrCl3) and two concentrations of added Cr (0.4, or 2.0 mg of Cr/kg) plus a Cr-unsupplemented control group. Feed and distilled-deionized water were available ad libitum for an experimental phase of 42 days. For induction of heat stress, the house temperature was set at 33 ± 2 °C from 15 to 42 days of age. Results showed that birds supplemented with Cr, regardless of Cr source, had increased ADG (P = 0.032) than controls. Birds fed 2.0 mg Cr/kg diet had greater ADG (P = 0.005) than birds fed 0.4 mg Cr/kg diet. Compared to controls, birds fed with Cr had greater dressing percentage (P = 0.021). Percentage of abdominal fat decreased (P = 0.013), whereas, breast intramuscular fat (IMF) remained unaffected (P = 0.147) in Cr supplemented vs control broilers. Broilers supplemented Cr had decreased b* values of meat color (P = 0.042) in breast muscle. B*values were also lesser (P = 0.049) in birds fed CrPro than birds supplemented with CrCl3 or CrPic. Regardless of Cr source, the percentage of cooking loss was decreased (P = 0.025) with Cr supplementation in breast muscle when compared to controls. Results from this study indicate that Cr supplementation, independent of its source, could promote growth and improve carcass traits and meat quality of broilers under heat stress conditions. Chromium propionate seems to have greater beneficial effects on meat color in comparison with CrPic and CrCl3.

Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions

An experiment was conducted to investigate the effects of dietary chromium (Cr) source and concentration on growth performance, carcass traits, and some serum lipid parameters of broilers under normal rearing conditions for 42 days. A total of 252 1-day-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involved in a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate (CrPro), Cr picolinate (CrPic), Cr chloride (CrCl3)) and two concentrations of added Cr (0.4 and 2.0 mg of Cr/kg) plus a Cr-unsupplemented control diet. The results showed that dietary Cr supplementation tended to increase the breast muscle percentage compared with the Cr-unsupplemented control group (P = 0.0784), while Cr from CrPic tended to have higher breast muscle percentage compared with Cr from CrCl3 (P = 0.0881). Chromium from CrPic also tended to increase the breast intramuscular fat (IMF) compared with Cr from CrCl3 (P = 0.0648). In addition, supplementation of 0.4 mg/kg Cr tended to decrease low-density lipoprotein cholesterol (LDL-C) (P = 0.0614). Compared with the control group, broilers fed Cr-supplemented diets had higher triglyceride (TG) (P = 0.0129) regardless of Cr source and Cr concentration. Chromium from CrPro and CrPic had lower total cholesterol (TC) compared with Cr from CrCl3 (P = 0.0220). These results indicate that dietary supplementation of Cr has effects on carcass characteristics and serum lipid parameters of broilers under normal rearing conditions, while supplementation of organic Cr can improve carcass characteristics and reduce the cholesterol content in serum.

Influence of chromium propionate on the carcass characteristics and immune response of commercial broiler birds under normal rearing conditions

The study investigated the effect of supplementation of chromium propionate at different dosage levels (100 to 3,200 µg/kg of elemental chromium in feed) on the performance, carcass characteristics, and immune response of broiler birds. The study was conducted on male broiler chickens (Cobb 400) for a period of 42 d as per the completely randomized design. Seven hundred 1-d-old birds were randomly segregated into 7 treatment groups, each with 10 replicates, and each replicate having 10 birds. Weight gain, feed intake, carcass characteristics, immune response, and the serum biochemical parameters of birds were studied during the supplementation period. There was no significant response to chromium supplementation on weight gain, feed intake, FCR, and lymphoid organ weights for the overall study period of 42 d. With increased chromium dosage, the breast meat yield improved linearly (P = 0.045). Antibody response to Newcastle disease vaccination improved quadratically (P = 0.001) with increased dose of chromium in the diet. Improved cell-mediated immune response was indicated by the increase (quadratic, P = 0.00) in lymphocyte proliferation ratio with increased dose of chromium supplementation. Heterophil:lymphocyte ratio decreased (quadratic, P = 0.004) with chromium propionate dosage, suggestive of reduced stress levels. Chromium propionate supplementation also reduced serum glucose levels (quadratic, P = 0.008) and improved (quadratic, P = 0.016) the total protein levels.