Animal Molecular Breeding, 2025, Vol.15, No.1, 9-18 http://animalscipublisher.com/index.php/amb 10 2 The Growth Characteristics of Nile Tilapia 2.1 Key growth parameters: body weight, body length and specific growth rate Body weight, body length and specific growth rate (SGR) are key indicators for evaluating the growth performance of Nile tilapia. These parameters are listed as routine observation indicators in scientific research and aquaculture management, and are used to test the effectiveness of nutrition programs, genetic improvement and breeding strategies. Kamble et al. (2024) found that supplementing guava leaves and currant extracts in the feed could increase the body length growth rate of fish by 23% and the daily weight gain rate by 18%, verifying the effectiveness of the nutritional regulation strategy. Integrated analysis indicates that plant essential oil additives can increase the terminal body length by 15%~20% and significantly enhance the SGR value, highlighting their crucial role in growth assessment (Orzuna-Orzuna and Granados-Rivera, 2024). Gene editing technology has a significant regulatory effect on the above indicators. The group modified by myostatin gene had a 49.45% increase in body weight compared with the control group, and the body length increased by 12%~15% simultaneously with SGR, confirming the targeted improvement ability of genetic engineering on growth traits (Figure 1) (Wu et al., 2022). Statistical analysis showed a strong correlation between body length and body weight (r=0.89), emphasizing the necessity of multi-trait collaborative breeding (Kamble et al., 2024). Figure 1 The morphological and growth alterations in mstnb / tilapia compared with their wild type (WT) siblings at 5 mah (Adopted from Wu et al., 2022) Image caption: (A) Photos of WT and mstnb KO tilapia at 5 mah. (B) The average body weights of tilapia with different genotypes at 2 mah and 5 mah. Comparison of the average body lengths (C), body heights (D) and body widths (E) between mstnb+/+and mstnb/tilapia at 5 mah. Data are shown as mean ± SD. *p<0.05. mah, months after hatching (Adopted from Wu et al., 2022) 2.2 Feed conversion efficiency and sexual maturity regulation Feed conversion rate (FCR) is a core efficiency parameter for measuring the conversion of feed nutrients into biomass in fish. A lower FCR value indicates a better nutrient conversion efficiency. Studies have shown that nano-phosphorus complexes and plant essential oil additives can reduce FCR by 0.3~0.5, simultaneously shorten
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