The impact of a leptin gene SNP on beef calf weaning weights

Leptin gene contributes to beef marbling standard, meat brightness, meat firmness, and beef fat standard of the Kumamoto sub-breed of Japanese Brown cattle

The Kumamoto sub-breed of Japanese Brown cattle has unique characteristics, such as great growth rate, and their contribution as future breeding materials is expected. To develop a DNA marker for their breeding, we investigated the effects of Leptin gene, controlling energy homeostasis, on carcass traits of the Kumamoto sub-breed. Sequence comparison identified five single nucleotide polymorphisms (SNPs): four linked synonymous mutations and one nonsynonymous mutation. Statistical analysis revealed that c.239C > T (p.A80V) had significant effects on the traits related with quality grade: beef marbling standard (p = 0.0132), meat brightness (p = 0.0383), and meat firmness (p = 0.0115). The C allele showed favorable effects; these scores of the C/C cattle were significantly higher than those of the C/T cattle. On the other hand, the effect of c.399T > C was observed on meat firmness (p = 0.0172) and beef fat standards (BFS) (p = 0.0129). The C/C cattle showed higher values of these traits than the T/T cattle. Our data suggested that these SNPs in Leptin gene could be used as a DNA marker for breeding of the Kumamoto sub-breed.

Leptin in farm animals: where are we and where can we go?

Fat affects meat quality, value and production efficiency as well as providing energy reserves for pregnancy and lactation in farm livestock. Leptin, the adipocyte product of the obese (ob) gene, was quickly seen as a predictor of body fat content in animals approaching slaughter and an aid to assessing reproductive readiness in females. Its participation in inflammation and immune responses that help animals survive infection and trauma has clear additional relevance to meat and milk production. Furthermore, almost a decade of discoveries of nucleotide polymorphisms in the leptin and leptin receptor genes has suggested useful applications relating to feed intake regulation, the efficiency of feed use, the composition of growth, the timing of puberty, mammogenesis and mammary gland function and fertility in cattle, pigs and poultry. The current review attempts to summarise where research has taken us in each of these aspects and speculates on where future research might lead.

Association of bovine leptin polymorphisms with energy output and energy storage traits in progeny tested Holstein-Friesian dairy cattle sires

Background

Leptin modulates appetite, energy expenditure and the reproductive axis by signalling via its receptor the status of body energy stores to the brain. The present study aimed to quantify the associations between 10 novel and known single nucleotide polymorphisms in genes coding for leptin and leptin receptor with performance traits in 848 Holstein-Friesian sires, estimated from performance of up to 43,117 daughter-parity records per sire.

Results

All single nucleotide polymorphisms were segregating in this sample population and none deviated (P > 0.05) from Hardy-Weinberg equilibrium. Complete linkage disequilibrium existed between the novel polymorphism LEP-1609, and the previously identified polymorphisms LEP-1457 and LEP-580. LEP-2470 associated (P < 0.05) with milk protein concentration and calf perinatal mortality. It had a tendency to associate with milk yield (P < 0.1). The G allele of LEP-1238 was associated (P < 0.05) with reduced milk fat concentration, reduced milk protein concentration, longer gestation length and tended to associate (P < 0.1) with an increase in calving difficulty, calf perinatal mortality and somatic cells in the milk. LEP-963 exhibited an association (P < 0.05) with milk fat concentration, milk protein concentration, calving difficulty and gestation length. It also tended to associate with milk yield (P < 0.1). The R25C SNP associated (P < 0.05) with milk fat concentration, milk protein concentration, calving difficulty and length of gestation. The T allele of the Y7F SNP significantly associated with reduced angularity (P < 0.01) and reduced milk protein yield (P < 0.05). There was also a tendency (P < 0.1) for Y7F to associate with increased body condition score, reduced milk yield and shorter gestation (P < 0.1). A80V associated with reduced survival in the herd (P < 0.05).

Conclusions

Several leptin polymorphisms (LEP-2470, LEP-1238, LEP-963, Y7F and R25C) associated with the energetically expensive process of lactogenesis. Only SNP Y7F associated with energy storage. Associations were also observed between leptin polymorphisms and calving difficulty, gestation length and calf perinatal mortality. The lack of an association between the leptin variants investigated with calving interval in this large data set would question the potential importance of these leptin variants, or indeed leptin, in selection for improved fertility in the Holstein-Friesian dairy cow.

Lack of an association between single nucleotide polymorphisms in the bovine leptin gene and intramuscular fat in Bos taurus cattle

Leptin contributes to the regulation of adiposity and metabolism, and single nucleotide polymorphisms (SNPs) in the leptin gene have been associated with intramuscular fat (IMF) levels in beef. Our objectives were to estimate the frequency of four SNPs in the leptin gene in nine purebred cattle (n=430), to test for linkage disequilibrium and infer haplotypes, and to determine if individual genotypes or estimated haplotypes were associated with IMF values in crossbred cattle (n=244). The four SNP loci were found to be in linkage disequilibrium and thus, the frequencies of each of the 16 possible haplotypes were inferred by maximum likelihood. No significant association between any individual SNP and haplotype was found with the divergent IMF values. Our results suggest that these SNPs are not influential on the divergent IMF levels in the crossbred population tested.