A SNP in the ovine cathepsin K (CTSK) gene is associated with yearling growth performance in a crossbred sheep population.

Cathepsin K (CTSK) is a lysosomal protease existent in the skeletal muscles which is involved in biochemical processes related to obesity. Several studies have reported the effects of CTSK gene on body weight and fat deposition in human, mice and pigs. However, information about its structure and functions in sheep is very limited. Thus, this study was performed to evaluate the association between CTSK gene variants and yearling growth performance in Afshari × Booroola-Merino crossbred sheep. A fragment of 500 bp in exon 6 and partial of intron 5 of CTSK gene was amplified with polymerase chain reaction (PCR). All animals were genotyped by single-stranded conformation polymorphism (SSCP) and further confirmed by sequencing. Association analysis using a fixed linear model indicated that g.106510225G > A SNP was significantly related to average daily weight gain (ADWG) per year, fat-tail weight to carcass weight ratio (FW/CW), muscle thickness (MT) and muscle cross-sectional area (MCSA) of animals (p < 0.05). Due to the low polymorphic information content (PIC <0.25) for targeted locus in studied population, more association studies are needed to confirm the CTSK gene effects on growth traits in sheep.

Comparison of the growth performance between pure Moghani sheep and crosses with Texel or Booroola sheep carrying major genes contributing to muscularity and prolificacy.

This study aimed to compare growth performance between Moghani sheep and crossbred lambs resulting from crossbreeding between Moghani pure breed ewes and the lines of rams e.g., Texel Tamlet, Texel Dalzell, Booroola Merino, and Booroola Romney. The first visible phenotypic characteristic was the presence of lean tail in all F1 crossbred lambs, whereas Moghani pure sheep is a well-known large fat-tailed breed. Moreover, the first generation of backcross (BC1) lambs from mating four types of F1 crossbred rams with Moghani pure ewes revealed lean-tailed to short fat-tailed. Comparative results showed that the F1 crossbred lambs had significantly (p < 0.0001) greater birth weight (BW) than the Moghani pure breed lambs. Despite no significant differences observed between Moghani pure breed sheep and its F1 crossbred lambs for body weight at pre-weaning, but F1 crossbred lambs achieved significantly (p < 0.0001) greater body weight after weaning compared to Moghani sheep. The growth performance of BC1 lambs was outperformed than F1 crossbred and Moghani sheep. These results encourage the continuation of the Moghani sheep crossbreeding programs to improve overall lamb growth, particularly post-weaning and to benefit from a better reproductive efficiency by elimination or reduction of the fat tail.

Survey of mutations in prolificacy genes in Santa Ines and Morada Nova sheep / Pesquisa de mutações em genes da prolificidade em ovelhas Santa Inês e Morada Nova

Polymorphisms in the BMP-15 gene related to Galway (FecXG) and Inverdale (FecXI) and in the BMPR-1B gene known as Booroola (FecB) mutations were investigated using the Polymerase Chain Reaction - Restriction Fragment Length Polymorphism (PCR-RFLP) method, on sheep from the breeds Santa Inês (n= 574) and Morada Nova (n=282). DNA was extracted and amplified through PCR with specific primers that introduced a restriction site in association with the mutation. The PCR products were submitted to endonucleases. The experiment found no FecXG and FecXI mutations. Six samples of animals with multiple offspring/birth history presented polymorphism for FecB similar to control samples, but this pattern was not confirmed by nucleotide sequencing. Although the absence of these mutations in the studied breeds, other factors related to prolificacy should be investigated to explain the inherent prolificity mechanisms.(AU)

Polimorfismos Galway (Fec XG ) e Inverdale (Fec XI), relacionados ao gene BMP-15, e Booroola (FecB), localizado no gene BMPR-1B, foram investigados usando-se a técnica de reação em cadeia da polimerase - polimorfismo de comprimento de fragmentos de restrição (PCR-RFLP), em ovelhas Santa Inês (n= 574) e Morada Nova (n=282). O DNA foi extraído e amplificado por PCR com iniciadores específicos, que introduziram um sítio de restrição associado à mutação, em seguida os amplicons foram submetidos à ação de endonucleases. Não foram observadas as mutações Fec XG e Fec XI nas amostras estudadas. Amostras de seis animais com histórico de partos gemelares apresentaram polimorfismo para FecB semelhantes às amostras controle, mas esse padrão não foi confirmado pelo sequenciamento de nucleotídeos. Apesar da ausência dessas mutações nos animais das raças estudadas, outros fatores relacionados à prolificidade devem ser pesquisados para explicar os mecanismos da alta prolificidade desses animais.(AU)

Allelic and genotypic frequencies in polymorphic Booroola fecundity gene and their association with multiple birth and postnatal growth in Chhotanagpuri sheep.

AIM: Chhotanagpuri breed of sheep reared for mutton in Jharkhand, India, having problem of low litter size and body weight. The response of genetic improvement for traits with low heritability through traditional selection method is time-consuming. Therefore, marker-assisted selection based on a polymorphism study of suitable candidate gene can response quickly. Thus, this study was aimed at identification of different allelic and genotypic frequencies of Booroola fecundity (FecB) gene and its association with multiple birth and postnatal growth in Chhotanagpuri sheep. MATERIALS AND METHODS: DNA isolation and gene-specific amplification of FecB gene was performed from blood samples of from 92 Chhotanagpuri lambs maintained under similar feeding and management conditions. Custom nucleotide sequencing and single-strand conformational polymorphism analysis were performed to identify different genotypes with respect to the target gene. Statistical analysis was performed for determination of allelic and genotypic frequencies of FecB gene polymorphisms and its association with multiple birth and postnatal growth of lambs from birth to 52 weeks age. RESULTS: "AA," "AB," and "BB" genotypes were found at locus-1 as it is polymorphic for FecB gene while locus-2 was found to be monomorphic for FecB gene. Higher frequency of "A" allele at locus-1 was found in single born lambs, whereas "B" allele was predominant among multiple born lambs. The lambs having "BB" genotype weighed significantly (p≤0.01) heavier than those of "AB" and "AA" genotype at 52 weeks of age. CONCLUSION: "BB" genotype has emerged as favored genotype for multiple births and better growth indicator. Therefore, homozygous lambs for "B" allele should be selected and utilized in breeding program for better growth rate.