Effect of polymorphic variants of GH, Pit-1, and beta-LG genes on milk production of Holstein cows.

Effect of polymorphic variants of growth hormone (GH), beta-lactoglobulin (beta-LG), and Pit-1 genes on milk yield was analyzed in a Holstein herd. Genotypes of the cows for these genes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Allele frequencies were 0.884 and 0.116 for L and V variants of GH, 0.170 and 0.830 for A and B variants of Pit-1, and 0.529 and 0.471 for A and B variants of beta-LG, respectively. GLM procedure of SAS software was used to test the effects of these genes on milk yield. Results indicated significant effects of these genes on milk yield (P < 0.05). Cows with LL genotype of GH produced more milk than cows with LVgenotype (P < 0.05). Also, for Pit-1 gene, animals with AB genotype produced more milk than BB genotype (P < 0.05). In the case of beta-LG gene, milk yield of animals with AA genotype was more than BB genotype (P < 0.01). Therefore, it might be concluded that homozygote genotypes of GH (LL) and beta-LG (AA) were superior compared to heterozygote genotypes, whereas, the heterozygote genotype of Pit-1 gene (AB) was desirable.

Genetic diversity in mazandaranian native cattle: a comparison with Holstein cattle, using ISSR marker.

This study was carried out to investigate genetic diversity in Mazandaranian native cattle population comparised to the Holstein breed, using Inter Simple Sequence Repeats (ISSR) marker. A total of 175 animals, including 71 native and 104 cattle of Holstein breed were screened. The extraction of DNA samples were carried out, using modified salting out method. A 19-mer oligonucleotide, (GA)9C, was used as primer in PCR reactions. The PCR products showed 15 different fragments with length ranged from 120 to 1600 bp in the two breeds.. Genetic variation indexes, including effective number of alleles, Shannon index, Nei's gene diversity and standard genetic distance were estimated, using POPGene software. Generally, the estimated genetic variation indexes showed low levels of diversity in the two breeds. However, Nei's gene diversity and Shannon index estimation was observed almost two folds in native cattle compared to Holstein breed. Less levels of diversity in Holstein cattle may be because of applying intensive selection programs. Conversely, native cattle have been less affected by selection. Therefore, it seems that Mazandaranian native cattle probably are better for breeding programs than Holstein cattle. Results showed that ISSR Markers are reliable and can be used in genetic diversity investigations.

A breeding program for balanced improvement of performance and health in broilers.

To illustrate the consequences of including health related traits in a sustainable broiler breeding program, two scenarios were simulated using the SelAction program. In the first scenario (economic), selection was only for production traits and Gait Score (GS) and Heart Failure (HF) were ignored in the breeding goal. In the second scenario (sustainable), GS and HF as well as production traits were included in the breeding goal. Economic values of GS and HF were determined using desired-gain approach to obtain a zero response in GS and HF. The results indicate that, despite improved responses for production traits in the economic scenario, there was an unfavorable reduction in GS of about 0.13 points and an unfavorable increase in HF of about 0.025 points. In the sustainable scenario, the deterioration of GS and HF was stopped. In the economic scenario with zero economic values for GS and HF, the total monetary response was higher (0.104 euros) than sustainable scenario (0.097 euros). Due to negative correlations between health and production traits, increased emphasis on health traits in the sustainable scenario resulted in a reduction in the total monetary response. In conclusion to stop the increased incidence of diseases, health traits should be included in the breeding goal and assigned appropriate values.