Feng Chao, Lin Hua, Li Jie, Xie Bin
Department of Life Sciences, Hulunbuir University, Hulunbuir, Inner Mongolia Autonomous Region, China.
Department of Anesthesiology, Tianjin Medical University General Hospital Airport Site, Tianjin, China.
PeerJ. 2021 Mar 16;9:e11097. doi: 10.7717/peerj.11097. eCollection 2021.
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.
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.
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.
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.
进行了一项荟萃分析，以评估日粮中添加无机铬对肉鸡生长性能的影响，并确定这些影响是否受品种、性别或研究地区和时间等背景因素的调节。
通过检索Web of Science、Springer、Elsevier、Science Direct、Taylor & Francis在线数据库确定符合条件的研究。采用随机效应模型计算加权平均差异及相应的95%置信区间。我们按研究地点、发表年份、肉鸡性别和品种进行了亚组分析。用Egger检验方法评估发表偏倚。共有9项研究符合纳入标准。
荟萃分析结果表明，添加无机铬显著改善了肉鸡的生长性能，降低了料重比（FCR），提高了平均日采食量（ADFI）。通过亚组分析，我们发现伊朗或2010年代发表的研究中平均日增重（ADG）的结果、埃及研究中ADFI的结果以及中国研究中FCR的结果对添加铬有显著反应。我们还通过亚组分析发现，科宝500肉鸡和雄性肉鸡可能对添加无机铬更敏感。使用一个模型来获得最佳生长性能下的铬添加量。结果表明，除平均日增重（ADG）外，调整后的ADFI和FCR与铬添加量呈二次关系。当无机铬添加量在1.6至2.3mg/kg范围内时，生长性能得到改善。敏感性分析结果显示敏感性低、稳定性高。此外，研究几乎没有发表偏倚的迹象。
我们的研究表明，雄性肉鸡和科宝500肉鸡可能对添加铬更敏感，并为肉鸡养殖实践提供了更准确的无机铬添加量。纳入研究较少可能导致异质性较高，且由于缺乏相关信息未对环境应激条件进行亚组分析。因此，本研究仍有一些局限性，期待后续研究。
