Analysis of restriction fragment length polymorphism in the kappa-casein gene related to weight expected progeny difference in Nellore cattle

Fernando H Biase,Analia Del V Garnero,Lúcia Martelli,Arthur J.M Rosa,Luiz A.F Bezerra,Raysildo B Lôbo

doi:10.1590/s1415-47572005000100014

Fernando H Biase, Analia Del V Garnero + Show 4 more

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https://doi.org/10.1590/s1415-47572005000100014

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Abstract

Restriction fragment length polymorphism (RFLP) has been detected at the bovine kappa-casein locus. The polymorphism has been analyzed for its effects in cattle production, mostly for milk traits and even for maternal effect on pre-weaning weights. We used polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) to genotype 408 Nellore animals for the non-silent mutation (Thr/Ile136 and Asp/Ala148) that characterizes the A and B variants of the polymorphism and compared expected progeny difference (EPD) for a maternal effect on 120 and 210 days weights and direct EPD for 120, 210, 450 and 550 day weight between AA and AB animals. The EPD values were obtained from the University of São Paulo (Brazil) Nellore Cattle Breeding Program, which evaluated 266,272 animals in 2001. Analysis of Variance was used to compare weight expected progeny differences (EPDs) between animals genotyped as AA and AB. The A allele frequency was 0.911. Although the AA animals had higher weight EPDs than AB animals the differences were not statistically significant (p > 0.05).

Highlights

The use of DNA polymorphic markers allows the determination of individual genotypes at many loci and provides information on population parameters such as allele frequencies as well as improving selection by marker assisted selection. Medrano and Aguilar-Cordova (1990) identified a restriction fragment length polymorphism (RFLP) at the kappa-casein (CSN3) bovine locus and detected two alleles (A and B) which, according to Lin et al (1992), differed by two amino acid substitutions, tyrosine/isoleucine at position 136 and asparagine/alanine at position 143 of the kappa-casein protein.The known participation of kappa-casein in the composition of milk protein (Bordim et al, 2001) justifies investigations correlating this polymorphism with milk production and composition
Bovenhuis et al (1992) reported that dairy cattle with the BB genotypes produced less milk in kilograms but that the milk produced had 0.8% more protein and 5.28 kg less fat in the first lactation than AA animals, these authors having reviewed the association of CSN3 polymorphisms with kilograms of milk produced per lactation, percentage fat and protein and kilograms of fat and protein per lactation demonstrated a divergence regarding genotypes and their association with these traits
All the animals are included in the 2001 Nellore Cattle Breeding Program (NCBP) of the University of São Paulo (São Paulo state, Brazil) that predicted the breeding value for 266,272 calves, cows and bulls from herds distributed over 12 Brazilian states

Summary

Introduction

The use of DNA polymorphic markers allows the determination of individual genotypes at many loci and provides information on population parameters such as allele frequencies as well as improving selection by marker assisted selection. Medrano and Aguilar-Cordova (1990) identified a restriction fragment length polymorphism (RFLP) at the kappa-casein (CSN3) bovine locus and detected two alleles (A and B) which, according to Lin et al (1992), differed by two amino acid substitutions, tyrosine/isoleucine at position 136 and asparagine/alanine at position 143 of the kappa-casein protein.The known participation of kappa-casein in the composition of milk protein (Bordim et al, 2001) justifies investigations correlating this polymorphism with milk production and composition. Haenlein et al (1987) found no differences in milk traits between kappa-casein genotypes there have been many analyses of the kappa-casein CSN3 polymorphism or linked markers and their direct effects on milk production. Ojala et al (1997) demonstrated that the B allele alone did not have a positive effect on milk or protein production but, as compared to other haplotype combinations, the alpha, beta and kappa casein genotypes ABA1A2BB increased protein content and resulted in an increase milk yield of 86 kg for the first lactation. Quantitative trait loci screening in bovine chromosome 6, where the casein genes are located, have identified markers related to milk fat and milk protein yield (Kühn et al, 1999) and percentage protein, milk yield and fat yield (Velmala et al, 1999)

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