The comparative studies on growth rate and disease resistance between improved grass carp and common grass carp

Grass carp (Ctenopharyngodonidella, GC) is one of the most economically important freshwater fishes in China. In this study, we use the ultraviolet-treated haploid sperm of koi carp (Cyprinuscarpiohaematopterus, KOC, 2n=100) to activate the eggs of GC with the treatment of 0–4 °C cold shock, and obtain all-female gynogenetic grass carp (GGC). Subsequently, we mated the mature female GGC with the common male GC, and produce the improved grass carp (DR-GC) with the disease-resistance. The experimental results show that the DR-GC has 22.18% higher survival rate than GC and 16.31% faster growth rate than GC. The input–output ratio of DR-GC to GC is 1.00:1.30, demonstrating significant cost-saving, efficiency-increasing, and higher-breeding benefits in DR-GC. The results regarding the morphological characteristics, DNA content, and chromosomes in DR-GC and their parents show that the DR-GC have a greenish-gray body with golden yellow scales on the back of the body, have the 58.01 as the DNA content, and have 48 as the number of chromosome in each somatic cell. DR-GC also has a high fertilization rate (95.30%) and a hatching rate (92.10%). The above results indicate that DR-GC is improved grass carp with some advantages in phenotypes and genotypes, which are significant for fish aquaculture. •We obtained lots of DR-GC with the disease-resistance.•The DR-GC had 22.18% higher survival rate than GC and 16.31% faster growth rate than GC.•Input–output ratio of DR-GC to GC was 1.00:1.30, indicating significant cost-saving, efficiency-increasing, and higher-breeding benefits in DR-GC.