Effects of dietary chromium picolinate supplementation on broiler growth performance: A meta-analysis

Objective A meta-analysis was conducted to assess the effects of dietary chromium picolinate (CrPic) supplementation on broiler growth performance and to determine whether such effects are regulated by broiler strains, sex, environmental stress, or contextual factors including study area and years. Methods Eligible studies were identified by searching the Web of Science, Springer, Elsevier, ScienceDirect, Taylor & Francis Online databases. Weighted average differences with corresponding 95% confidence intervals were computed with a random-effects model. We performed subgroup analysis stratified by study area, published years, broiler strains and sex, and environmental stress. Publication bias was assessed with Egger’s test method. A total of 15 studies eligible for inclusion. Results The results indicated that CrPic supplementation significantly improved broiler growth performance and subgroup analysis confirmed this conclusion. We also found that Ross 308 or male broilers might be more sensitive to CrPic supplementation and showed better growth performance. A model was used to obtain the amount of chromium addition under the optimal growth performance, which suggested that the maximum value of average daily gain (ADG) was reached when chromium addition was 1810 μg/kg. The results of the sensitivity analysis showed low sensitivity and high stability of the meta-analysis. Conclusions CrPic supplementation had a positive effect on the growth performance of broilers, and this meta-analysis provides a more accurate value of chromium addition, which may be beneficial for the practice of the broiler industry.

Effects of dietary inorganic chromium supplementation on broiler growth performance: a meta-analysis

Background A meta-analysis was conducted to assess dietary inorganic chromium supplementation on broiler growth performance and determine if these effects are regulated by strains, sex, or contextual factors such as study area and time. Methods Eligible studies were identified by searching Web of Science, Springer, Elsevier, Science Direct, Taylor & Francis online databases. The weighted average difference with corresponding 95% confidence interval was computed with a random-effects model. We performed subgroup analyses stratified by study locations, published years, broiler sex, and strains. The publication bias was assessed with Egger’s test method. A total of nine studies were eligible for inclusion. Results The meta-analysis results indicated that inorganic chromium supplementation significantly improved the broiler’s growth performance, with a lower feed conversion ratio (FCR) and a higher average daily feed intake (ADFI). Through subgroup analyses, we found that the result of average daily gain (ADG) in Iran or published in the 2010s, the results of ADFI in Egypt, and the results of FCR in China had significant responses to chromium supplementation. We also found that Cobb 500 broilers and male broilers might be more sensitive to the addition of inorganic chromium by subgroup analyses. A model was used to obtain the amount of chromium addition under the optimal growth performance. The results showed that the adjusted ADFI and FCR presented a quadratic relationship with chromium supplementation except for average daily gain (ADG). The growth performance improved when the inorganic chromium addition ranged from 1.6 to 2.3 mg/kg. The result of sensitivity analyses showed low sensitivity and high stability. Also, there was little indication of publication bias for studies. Conclusions Our study showed that the males and Cobb 500 broilers might be more sensitive to chromium supplementation and provided more accurate inorganic chromium supplementation for broiler management practice. The fewer included studies may lead to higher heterogeneity, and no subgroup analyses of environmental stress conditions was conducted due to the lack of related information. Therefore, this study still has some limitations, and we look forward to the follow-up researches.

On the Support Effect and the Cr Promotion of Co Based Catalysts for the Acetic Acid Steam Reforming

This work focuses on the support effect of the performances of Co based catalysts for acetic acid steam reforming. SBA-15, a well ordered hexagonal mesoporous silica structure, and CeO2 have been selected as the supports, with the impact of chromium addition also being investigated. Better acetic acid steam reforming performances have been recorded for CeO2 compared to SBA-15 supported catalysts and, in particular, the 7Co/CeO2 catalyst showed the highest values of acetic acid conversions with enhanced H2 yields below 480 °C, in comparison to the other investigated catalytic formulations. In addition, more pronounced coke depositions and acetone concentrations have been obtained with CeO2 supported catalysts, due to the tendency of ceria to catalyse the ketonization reaction. Chromium addition to Co/SBA-15 catalysts led to an enhancement in the activity towards acetic acid steam reforming, while on CeO2 supported catalysts no improvement in the catalysts’ activity was observed. However, on both SBA-15 and CeO2 supported catalysts, Cr addition reduced the amount of coke deposited on the catalysts surface.

An Experimental Study of the Acetic Acid Steam Reforming Over Co-Based Catalysts

This work focuses on the support effect on the performances of Co-based catalysts for the acetic acid steam reforming. SBA-15, a well ordered hexagonal mesoporous silica structure, and CeO2 have been selected as the supports, with the impact of chromium addition also being investigated. Better acetic acid steam reforming performances have been recorded for CeO2 compared to SBA-15 supported catalysts and, in particular, the 7Co/CeO2 catalyst showed the highest values of acetic acid conversions with enhanced H2 yields below 480°C, in comparison to the other investigated catalytic formulations. In addition, more pronounced coke depositions and acetone concentrations have been obtained with CeO2 supported catalysts, due to the tendency of ceria to catalyse the ketonization reaction. Chromium addition to Co/SBA-15 catalysts led to an enhancement in the activity towards acetic acid steam reforming, while on CeO2 supported catalysts no improvement in the catalysts activity was observed; however, on both SBA-15 and CeO2 supported catalysts, Cr addition reduced the amount of coke deposited on the catalysts surface.