Safety Assessment Of Meat From MSTN Edited Cattle By 90-day Feeding Study In Rats

Myostatin(MSTN)is a negative regulator of skeletal muscle growth and development.The MSTN mutated animals will increase muscle mass and show double muscle traits.The MSTN gene mutation can also be achieved through gene editing.In the previous work,our laboratory have obtained the MSTN gene edited cattles,which grow normally and produce high lean meat and less fat.The evaluation of edible safety is an important part of safety evaluation of gene edited cattle.In this study,a 90 day Wistar rat feeding experiment was conducted to evaluate the safety of MSTN gene edited beef.A total of 50 Wistar rats,half males and half females,with 5 weeks old were randomly divided into 5 groups respectively according to their sex and body weight.Five groups of the rats were fed with 15%,7.5% MSTN gene edited beef and ordinary beef,while the control group was fed with AIN-93 base feed.The animal behaviors were observed during the experiment and the weights were measured weekly and the consumption of feed was recorded.On the ninetieth day,blood tests were taken to detect blood routine and biochemical criteria,the organs were weighed and the organ coefficient was calculated.In addition,the main organs were observed histopathologically.The results showed that the rats in each group had good mental state,normal behavior,bright hair,limbs and tail strongand sensitivity to external stimuli.No loss of appetite and lethargy were found in all of the rats,and no death occurred.Data analysis showed that compared with ordinary beef feed group and AIN-93 group,the weight gain,food consumption,liver function,renal function,heart function,blood routine,pathological tissue and organ coefficient of MSTN edited beef feed group rats had no biological significance.Although there are statistical differences in individual indicators,there is no dose correlation and sex correlation and no biological significance.The results showed that the addition of MSTN edited beef did not have subchronic toxicity to Wistar rats and had no long-term adverse effects.This study provides reference data for the comprehensive safety assessment of MSTN gene edited beef cattle.