| The law of weight gain and the change of coat color of meat rabbits are two important traits in breeding and production of meat rabbits.The body weight of California rabbit×New Zealand white rabbit(F1)and F1 self-bred population(F2)at 35-84 days old was fitted by three non-linear animal growth curve models,which refers to Logistic,Gompertz and Von Bertallanffy.The growth characteristics of the two populations were compared and analyzed.The coat color of meat rabbits is mainly controlled by one or more genes.In this experiment,24 Tianfu black rabbits,Sichuan white rabbits,Fujian yellow rabbits and Sichuan castor rabbits were used as experimental materials.Five candidate genes controlling coat color were analyzed:MC1R,MLPH,TYRP1,MITF and TYR.(1)Growth trial:The average body weight of 35 day-old weaning population was lower than that of F2 group,but the difference was not significant(p>0.05).From 42 day-old,the average body weight of F1 population was higher than that of F2 population.,except that of70 day-old group(p<0.05).The average daily gain of F1 and F2 population was 25.67 g/d and 24.66 g/d at the age of 0-84 days,respectively.The growth rate of F1 population at the age of 35-49 days and 70-84 days was faster than that of F2 population.In conclusion,the weight and growth rate of F1 population were better than those of F2 population.(2)Growth curve fitting:In F1 population,the fitting effect of Logistic model is the best,the fitting degree(R~2)is 0.993,the age of inflection point is 44.17 day,the weight of inflection point is 1150.46 g,and the fitting limit weight is 2300.92 g.In F2 population,the fitting effect of Logistic model is the best,the fitting degree(R~2)is 0.995,the age of inflection point is 45.92 day,the weight of inflection point is 153.96 g,and the predicted value of extreme weight is 2307.92 g.(3)MC1R:In this study,two mutation sites(1)c.284-285del,(2)c.292-295del were found in the CDS coding region of MC1R.There were no mutations in Fujian yellow rabbit and Sichuan hemp rabbit.The distribution of MC1R in Tianfu black rabbit and Sichuan white rabbit was complex.Therefore,MC1R could not completely control the expression of coat color,presumably regulated by other genes.(4)MLPH:In this study,three mutation sites(3)c.693 C<G,(4)c.851 A<G,(5)c.911G<were found in exon 3 of MLPH.The mutations of c.693 C<G and c.851 A<G in Tianfu black rabbits were identical and had a linkage effect,but no mutations were found in Sichuan white rabbits.The distribution of three mutations in Sichuan white rabbits was uneven.We speculate that the simultaneous mutation of MLPH c.693 C<G,c.851 A<G and c.911 G<A results in the black expression of rabbit fur.Therefore,the three mutation sites of MLPH can be used as screening markers for black rabbits.(5)TYRP1:In this study,only one mutation site(6)g.4137286 G<A was found in exon2 of TYRP1.The allele A of Sichuan White Rabbit and Fujian Yellow Rabbit had the highest frequency and was the dominant gene.We speculated that TYRP1 was a gene affecting rabbit fur color,but it was not the main gene.It might control the expression of fur color together with other genes.(6)MITF:In this study,three mutation sites(7)g.232587 A<G,(8)g.232650 C<G,(9)g.232766 A<T were detected in exon 7 of MITF.All three mutations occurred in Tianfu Black Rabbit,and all mutations were detected at g.232766 A<T.The first two mutations did not occur in Sichuan White Rabbit,and only one mutation at g.232766 A<T was found in Fujian Yellow Rabbit,and only one mutation at g.232587 A<G was detected in Sichuan Ma Rabbit.None of them happened.Therefore,the MITF g.232766 A<T can be identified as one of the screening markers for black rabbits.MITF is one of the effective genes affecting the black expression of rabbit fur.(7)TYR:In this study,five mutation sites(10)c.185G<A,(11)c.465C<T,(12)c.498T<C,(13)c.669 C<T,(14)c.775 G<A were detected in exon 2-5 of TYR.Five mutations were found in Tianfu Black Rabbit,one in Sichuan White Rabbit and two in Sichuan Rabbit.Therefore,it can be determined that TYR is one of the effective genes affecting rabbit fur color,and the interaction with other genes affects the formation of fur color.The growth curve model of California rabbit×New Zealand white rabbit hybrid F1generation was established.The distribution of SNP loci of five major genes controlling the fur color of meat rabbits was also analyzed,we found that MITF?TYR?MLPH?MC1R regulated the expression of rabbit fur black.MITF and MLPH were the main genes.The mutation of these two genes resulted in the formation of rabbit fur black.The interaction of TYRP1?MLPH?TYR resulted in the formation of rabbit fur white.TYRP1 was the main gene regulating rabbit fur yellow and TYR is the main gene controlling the expression of castor in rabbit fur. |
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