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Heat stress presents a substantial challenge for the poultry industry, negatively impacting broilers' health, growth, and productivity. Optimizing dietary crude protein (CP) levels is a viable approach to reduce the heat generated during birds' amino acid oxidation process. Additionally, supplementing diets with Selenium (Se), a potent antioxidant, can help counteract the detrimental effects of heat stress on broiler growth performance. To explore the effects of varying CP and Se levels on growth performance, carcass characteristics, blood parameters, immune function, and blood leukocyte profiles in broiler chickens under heat stress, a 42- day experiment was conducted. It involved 528 male broiler chicks (Ross 308), divided into six groups with 11 chicks each, fed diets with 100%, 94%, or 88% of the recommended CP levels, and two Se levels (0 and 0.04 mg/kg). The findings indicated that reducing dietary CP levels led to an improvement in daily weight gain (DWG) without affecting feed intake (FI), feed conversion ratio (FCR), or carcass traits. There was a significant interaction between CP and Se levels regarding glucose, albumin, uric acid, cholesterol, triglyceride levels, antibody titers against Newcastle disease virus (NDV), and monocyte counts. Se supplementation increased NDV antibody titers at 14 days, whereas reducing CP lowered these titers at 21 days. The study concluded that lowering dietary CP did not adversely affect growth performance, carcass quality, or blood parameters; it even enhanced DWG compared to a normal protein diet and influenced some blood parameters. [ABSTRACT FROM AUTHOR]

The pre-starter diet is critical for providing adequate nutrition to newly hatched chicks, whose digestive systems are not yet fully developed to handle solid feeds. Different levels of dietary energy can impact the growth and development of broilers. Hence, providing the right energy to meet their requirements is necessary. A study was conducted to examine the effect of different levels of metabolizable energy (ME) (3025, 2904, and 2783 kcal/kg) in the pre-starter diet (1 to 10 days) of broiler chickens on their growth performance traits. The experiment involved 450 broilers of the Ross 308 breed, divided into three treatments and six replications. The results of the study showed that reducing dietary energy levels increased the feed intake (FI) and body weight (BW) of broiler chickens, although it did not affect their feed conversion factor (FCR). Based on the results of the current study, reducing the recommended energy levels by up to 5% had no negative impact on growth performance. This can be useful in reducing the feed expense in broiler production. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of dietary guanidinoacetic acid (GAA) on performance, enzyme activity and biochemical variables of broilers with cold-induced ascites. A total of 640 day-old male broiler chicks (Cobb 500) were randomly assigned to four treatments (with 8 replicates of 20 birds) including a control and diets supplemented with 0.6, 1.2 and 1.8 g of GAA per kg of feed. On day 14, the temperature was reduced to 17°C during the daytime and 14°C at night. Dietary inclusion of 0.6 g/kg GAA decreased BWG in compared to those fed other levels in the grower period (P < 0.05). The ratio of right to total ventricle, mortality and relative weights of liver were lower in birds fed the diet with 1.2 g/kg GAA compared to bids fed other levels (P < 0.05). The plasma activity of creatine kinase (CK) increased in the birds fed with 1.2 and 1.8 g/kg GAA compared to chicks fed the control diet. It can be concluded that dietary supplemental 1.2 g/kg GAA would be a beneficial way to decrease the mortality rate of broiler reared under cold stress conditions. In addition, the blood levels of HDL-C increased in broilers fed the 1.2 g/kg GAA diet. [ABSTRACT FROM AUTHOR]

Background: Organic products of animals are getting more accepted by consumers. Using herbal additives may lead to more health animal products. In this research it is hypothesized that Lavandula angustifolia and/or Mentha spicata essential oils would be helpful to enhance production performance in laying hens. Objectives: This experiment was conducted to evaluate the effects of Lavandula angustifolia and Mentha spicata essential oils on performance, egg traits and blood variables in laying hens. Methods: 144 Lohmann LSL‐Lite laying hens from 42 until 56 weeks of age were used in a completely randomized design in four treatments and six replicates (six birds per replicate). The treatments consisted of: (a) control group (basal diet), (b) basal diet supplemented with 250 mg/kg diet lavender essential oil (LEO), (c) basal diet supplemented with 250 mg/kg diet mint essential oil (MEO), and (d) basal diet supplemented with both LEO and MEO. Results: Using LEO and/or MEO did not affect body weight changes, feed intake, egg weight, egg index, yolk index, Haugh unit, egg shell weight and egg shell thickness. Feeding LEO, individually or in combination with MEO, did not affect FCR compared with the control group (p <.05), however, feeding MEO individually increased feed conversation ratio (FCR) compared to LEO and the control group during 42–56 weeks (p <.05), as well as decreasing egg mass compared to LEO (p <.05). Feeding LEO increased egg production compared to MEO and combination of MEO and LEO (p <.05). Conclusions: In conclusion, dietary supplemental MEO (250 mg/kg) may increase FCR, and LEO (250 mg/kg) is more effective than MEO (250 mg/kg) for egg production and egg mass purposes; besides MEO (250 mg/kg) negatively affected FCR compared with the control group. In addition, no specific beneficial effect of dietary supplemental MEO and/or LEO on the other measured variables was detected. [ABSTRACT FROM AUTHOR]

A total of 288 32-wk-old Lohmann Selected Leghorn (LSL-Lite) laying hens were fed on corn-soyabean meal-based diets containing three concentrations of rice bran (RB; 0, 75 and 150 g/kg; equivalent to 1.8, 2.7 and 3.5 g/kg phytate phosphorus), two of non-phytate phosphorus (NPP; 2.5 and 3.5 g/kg) and two of microbial phytase (Phyzyme® XP 5000G; 0 and 150 FTU/kg) in a 10-wk trial under high temperature condition. The average minimum and maximum room temperatures were 26.0 ± 1.9 and 36.0 ± 1.8 °C, respectively, with relative humidity ranging from 42.3 ± 1.8% to 55.1 ± 2.1%. Each dietary treatment was fed to four cages (six birds/cage) from 32 to 42 wk of age. Egg production, egg weight and feed intake were recorded daily. Egg quality traits were recorded every 5 wk. Leukocyte subset counts and blood lipid profile were evaluated at the end of experiment. The results showed that inclusion of 150 g/kg RB negatively influenced ( P < 0.05) egg production (EP), feed conversion ratio (FCR), shell weight and shell thickness. Significant reductions ( P < 0.05) in the blood triglyceride and total cholesterol were observed with increasing dietary inclusion levels of RB. Although, dietary NPP levels did not influence any of the performance traits, the low-NPP diets caused a decrease ( P < 0.05) in shell weight and shell thickness when compared with normal-NPP diets. The H/L ratio, as a stress indicator, was also increased ( P < 0.05) by low-NPP diets. These adverse effects were partially overcome by the addition of microbial phytase (PHY). Supplemental PHY improved ( P < 0.05) EP, FCR and unmarketable eggs but the magnitude of the responses was greater in low-NPP and high-RB treatments, resulting in significant RB × NPP × PHY interactions. Egg mass, shell weight and shell thickness were also improved ( P < 0.05) by PHY addition but the response was greater at the highest concentration of RB, resulting in a significant RB × PHY interaction. Responses were also greater ( P < 0.05) in low-NPP diets as indicated by significant NPP × PHY interaction. It can be concluded that the positive effects of PHY supplementation were clearly evident for laying hens reared under the high ambient temperatures pertaining to this study. At high concentration of phytate (high-RB diet) and/or low level of NPP (2.5 g/kg), response to supplemental PHY appears to be increase in terms of performance and egg quality in heat-stressed laying hens. [ABSTRACT FROM AUTHOR]