Honeybees show inbreeding depression for various traits both in queens and in workers. Increased homozygosity at the complementary sex determination locus due to inbreeding produces lethality or sterility in males, and consequently reduces the productivity of the colony. In the present study, assuming a condition where mating is controlled by artificial insemination, we consider the following four mating systems for reducing the harmful effects of inbreeding in the maintenance of honeybee colonies. In the first system (RS-RM), parents of the next generation are randomly selected from the progeny pooled over colonies, and breeding groups are established by randomly dividing the selected progeny. In the second system (WS-RM), selection is carried out within a colony, and breeding groups of the next generation are established from the selected individuals in the same way as for RS-RM. In the third system (WS-RGM), after the within-colony selection as in WS-RM, males selected from the same colony are randomly assigned to each queen to establish breeding groups. The final system (WS-NGM) is similar to WS-RGM, but breeding groups are formed so as to completely avoid sib-mating. These systems are compared here by deterministic simulation in terms of the inbreeding coefficient and effective population size. Compared to RS-RM, the three systems with within-colony selection (WS-RM, WS-RGM and WS-NGM) effectively reduce the inbreeding coefficient in the initial generations. Among these three systems, WS-NGM gives the lowest initial inbreeding coefficient. Although the largest effective population size is attained under WS-RGM, many generations are required for achieving a lower inbreeding coefficient than WS-NGM. It is concluded that WS-NGM is the most highly recommended system for practical use.
The fatty acid composition of adipose tissue in beef affects to fat-melting point. The beef, which unsaturated fatty acids content is high, is lower fat-melting point, and is thought favorable. Stearoyl-CoA desaturase (SCD) is enzyme that converts saturated fatty acids into mono-unsaturated fatty acids (MUFA). It was reported that alanine type SCD for c.878C>T (p. A293V) elevates MUFA content and lowers fat-melting point, and it is known that alanine type was superior allele. It was also reported that c.878C>T did not associated with major carcass traits on Japanese Black cattle. However, it was indicated that g.7534G>A on 3’UTR associated with BMS in a Japanese Black cattle × Limousin reference population. Therefore, we validated an association between SCD and carcass traits, using c.878C>T, g.7534G>A and g.7864C>T. It was indicated that these SNPs associated with brightness, firmness and texture of meat. Since, linking alleles of the three SNPs indicated same effect for these traits, it was thought that these effects for traits were caused by c.878C>T, which was non-synonymous SNP. Although, the allele C of c.878C>T was superior allele which elevates MUFA content, the allele indicated negative effect for brightness, firmness and texture. Firmness and texture is thought to relate with flavor of beef. Therefore, it was suggested that the information of c.878C>T is need to use with caution.
Pesisir cattle are one of the Indonesian native cattle in West Sumatra that are adapted to the local tropical environment. The aim of the present study is to investigate genetic characteristics of the Pesisir cattle by genotyping the SNPs within SREBP1, SCD1, EDG1, NCAPG, DGAT1, and MC1R genes by PCR or PCR-RFLP. We also determined the mitochondrial DNA and Y-chromosomal haplotypes by direct sequencing of PCR products. The results showed that SREBP1, SCD1, and DGAT1 genes are monomorphic while EDG1, NCAPG, and MC1R genes are polymorphic in the population of Pesisir cattle. The sequence analysis of the D-loop region of mitochondrial DNA indicated that the population of Pesisir cattle possesses five haplotypes that are classified into the I1 and I2 haplogroups of zebu cattle type haplotypes. The sequence analysis of the SRY gene on male specific region of Y chromosome also indicates that the cattle population possesses the zebu type Y-chromosomal haplotype. The present findings first report the presence of the desirable allele of NCAPG gene in zebu cattle, which is associated with increased carcass weight. These findings will be informative for future selective breeding of the Indonesian native cattle to increase their meet productivity.