Genetic Studies on Growth Hormone as A Physiologgical Indicator in Rabbits

Abstract: The aim of the present study was to evaluate the effects of GH gene polymorphisms on reproduction and growth traits and identify its variability in the rabbits.
A total of 218 blood samples collected from rabbits were used to evaluate the allele frequency distribution for GH gene polymorphisms and its association with reproductive and growth traits in rabbits. The samples included 16 rabbits of the different breeds (Middle-Egypt native breed, Gabali Sinai, Baladi Black, Baladi Red and New Zealand White) and 202 rabbits (118 female and 84 male) from APRI rabbits. The traits tested were: (1) body weight (BW) at 5, 6, 8,10 and 12 weeks from birth, (2) daily bodyweight gain (DBG), (3) reproductive traits included age at puberty (AP), Kindling interval (KI), litter size at birth (LS), litter weight (LW) at birth, Litter size at weaning (LSW) and litter weaning (LWW), (4) milk yield. For this purpose, DNA was extracted from rabbit blood samples and used in PCR amplification. The c.-78C >T SNP was genotyped by PCR-RFLP using the digestion by restriction enzyme Bsh1236I (BstUI).
Association analysis between the GH C >T SNP and body weight, growth and reproductive traits was tested in the rabbits population using SAS program. The heterozygous genotype was associated with heavy weight of rabbits in different ages during the growth period. This increase in weight was significant (P < 0.05) at 8 weeks of age. DBG through 5-8 week interval was significantly associated (P < 0.05) with the T/C genotype. The heterozygous genotype (T/C) exhibited higher values in the DG compared to C/C and T/T genotypes. The estimated dominant genetic effect (d) was significant (P < 0.05) in 8 weeks. The C/C genotype showed significant value (P<0.05) associated with early age of puberty. The estimated additive genetic effect (a) and estimated dominant genetic effect (d) in a population was insignificantly associated (P<0.05) within all the investigated reproductive traits in rabbits. Polymorphism of heterozygous genotype T/C was associated with milk yield traits of rabbits during the first two weeks in suckling period. Estimated additive genetic effect (a) in a population was significant (P<0.05) within milk yield at the second week of suckling period of rabbits. Estimated dominant genetic effect (d) was significant (P < 0.05) within milk yield at the first week of suckling period of rabbits. In conclusion, the polymorphism of growth hormone (GH) gene in rabbits may has over dominance at the locus c.-78C >T. Positive effects of the heterozygous genotype were recorded compared to both homozygous genotypes on body weight, body gain and milk yield at the first two week. The effect of the C allele of GH gene decreased the age of puberty in rabbits.
Effects of the heterozygous genotype in c.-78C > T of GH polymorphisms on the tested traits in current study and on the fmishing weight in previous study could be selected as a favorable genotype in rabbits and may be used in Marker-assisted selection (MAS) programs to improve growth performances rabbits.
Key words: Rabbit, GH , association study SNP , reproductive, growth traits.
Publication year 2015
Pages PP. 89
Availability location مكتبة معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى- جيزة
Availability number 1339
Organization Name
Country Egypt
Author(s) from ARC
Publication Type Master Thesis