Vitamin A, a fat-soluble vitamin, is the basic substance required to maintain healthy vision and the main physiological functions of cattle. The results from previous studies regarding the effect of vitamin A on intramuscular fat varied. This meta-analysis aimed to generate a more comprehensive understanding of the relationship between vitamin A and intramuscular fat content and to provide potential clues for future research and commercial practice. Electronic databases such as MEDLINE and Ovid were systematically searched, and studies investigating the relationship between vitamin A and intramuscular fat content were included. Standardized mean differences (SMDs) in intramuscular fat percentage and intramuscular fat score, with their respective 95% confidence intervals (CIs), were calculated. The heterogeneity and publication bias were evaluated. A total of 152 articles were identified through searches of databases. Seven articles were confirmed for inclusion in this meta-analysis. The SMD of IMF percentage derived from the analysis was−0.78 (-2.68, 1.12) (Q = 246.84, p < 0.01). The SMD of the IMF score was 1.25 (-2.75, 5.25) (Q = 87.20, p < 0.01). Our meta-analysis indicates that the addition of vitamin A could decrease intramuscular fat in cattle steers.

中文翻译：

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维生素 A 对肉牛肌内脂肪发育的影响：荟萃分析

维生素A是一种脂溶性维生素，是维持牛健康视力和主要生理机能所需的基本物质。先前关于维生素 A 对肌内脂肪影响的研究结果各不相同。该荟萃分析旨在更全面地了解维生素 A 与肌内脂肪含量之间的关系，并为未来的研究和商业实践提供潜在线索。系统地检索了 MEDLINE 和 Ovid 等电子数据库，并纳入了调查维生素 A 与肌内脂肪含量之间关系的研究。计算肌内脂肪百分比和肌内脂肪评分的标准化均值差 (SMD) 及其各自的 95% 置信区间 (CI)。评估了异质性和发表偏倚。通过数据库搜索，共识别出 152 篇文章。七篇文章被确认纳入该荟萃分析。从分析得出的 IMF 百分比的 SMD 为−0.78 (-2.68, 1.12) (Q = 246.84,p< 0.01）。IMF评分的SMD为1.25（-2.75，5.25）（Q=87.20，p< 0.01）。我们的荟萃分析表明，添加维生素 A 可以减少阉牛的肌内脂肪。