Problem statement:A wide range of studies for the assessment of genetic diversity in livestock breed were conducted using genetic distance. For high-accuracy and unbiased estimation sampling methods, criteria of choosing type of DNA markers, distance measurement strategies, cluster analysis will be important for any genetic diversity projects. Approach: Main objective of this short review is focusing on application statistical procedures and methods in analysis of genetic diversity data in animals. Results: There is no simple strategy to address for best and effectively genetic diversity results by the way regarding to some important factors can make reliable results for next analysis. Conclusion: There is still a distinct need for developing comprehensive and user-friendly statistical packages that facilitate an integrated analysis of different data sets for generating reliable information about genetic relationships, genome diversity, and favorable allele variation. Equally important and perhaps more challenging, is the concerted and planned utilization of genome information in animal breeding programs on the basis of knowledge accrued from studies on genetic diversity.

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We designed this project to determine the nutritional potential and ruminal microbial fermentation properties of eight rangeland plants (Dracocephalum moldavica L., Melissa officinalis L., Ruta graveolens L., Perovskia abrotanoides Kar., Cichorium intybus L., Borago officinalis L., Peganum harmala L., and Teucrium polium L.) collected from the semi-arid region of Iran at two consecutive years (2019 and 2020) for ruminant diets. Medicago sativa as a common forage was also considered as control. We determined the chemical-mineral composition, buffering capacity, in vitro gas yield, ruminal fermentation, and protozoa population in a culture medium with the standard laboratory methods. A significant difference in chemical-mineral compounds was observed among the studied plants (p < 0.05). A lower crude protein range (6.28% for Cichorium intybus L. to 18.4% for Melissa officinalis L.) was observed rather than Medicago sativa (20.3%). The amount of calcium was highest in Peganum harmala L. (23.5–24.2 g/kg DM) and lowest in Ruta graveolens L. (1.15–1.25 g/kg DM). Dracocephalum moldavica L. exhibited the highest acid–base buffering capacity (235–242 mEq×10−3) among other plants. The highest decrease in total protozoa and other protozoan populations was observed when Perovskia abrotanoides Kar. was added to the culture medium. Teucrium Polium L. had the greatest potential gas yield and its total volatile fatty acid was comparable with Medicago sativa. It seems that eight plants are nutritionally suitable for partial replacement of the conventional plants such as Medicago sativa in diets of small ruminants, however dietary supplementation of Peganum harmala L. due to its alkaloids content should be done with caution.

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This study estimated the genetic parameters of productive and reproductive traits of Iranian Holstein cattle from data recorded between 2006 to 2018. The data analysis was performed using an animal model, including the record of the first parity and the first three lactation records. Heritability values for milk, fat, and protein traits using a single record animal model were 0.29 ± 0.005, 0.22 ± 0.005, and 0.24 ± 0.005, respectively. The heritability of these traits based on a repeated records animal model was estimated to be 0.19 ± 0.001, 0.15 ± 0.005, and 0.17 ± 0.006, respectively. Furthermore, the heritability of age at first calving (AFC) and length of lactation (LL) traits were 0.16 ± 0.004 and 0.02 ± 0.002, respectively. Estimated repeatability for milk, fat, and protein production was 0.38 ± 0.002, 0.34 ± 0.002, and 0.36 ± 0.002, respectively. Positive genetic changes occurred over the years of the study for production traits. Evaluation of the effect of herd-year-season (HYS) on the productive traits revealed that the management and environmental conditions improved. The average estimate of heritability for milk, fat, and protein yields and AFC indicates the possibility of genetic improvement for these traits. Furthermore, the repeatability values show that the selection process can be performed based on the first lactation record. The positive genetic trend of productive traits validates the positive response to selection in Iranian Holstein cattle. Consequently, improving environmental and management conditions in Iranian dairy cattle herds is recommended, which will positively affect reproductive traits.

Inbreeding depression, the reduction of fitness and performance, is due to an increase in the mating of related individuals. Based on the purge hypothesis, inbreeding and breeding over generations reduce the effect of deleterious alleles responsible for inbreeding depression. Thus, recent inbreeding is assumed to be more harmful than ancestral inbreeding. This study aimed at evaluating the effects of new and ancestral inbreeding on milk, fat and protein production in Iranian Holstein cattle. The secondary objective was to examine the changes in predicted breeding values when the inbreeding effect was included in the model's analysis. To this end, inbreeding coefficients were calculated using the pedigree of 2,394,517 Holstein cattle to achieve these goals. In addition, 419,132 records of milk, fat and protein yields of first parity cows were collected to assess inbreeding depression and breeding values. The average inbreeding coefficients were 0.83% and 1.68% for the whole population and the inbred animals, respectively. A 1% increase in classical pedigree-based inbreeding coefficient was associated with a decrease of 11.99 kg in milk, 0.39 kg in fat and 0.29 kg in protein. The effect of ancestral inbreeding was more detrimental to performance traits than the effect of new inbreeding. This result contradicted the hypothesis of purging. By including the inbreeding coefficient in the model, the rank of animals remained unchanged, but the average predicted breeding values increased. In general, inbreeding depression was observed in Iranian Holstein cows; however, no evidence of purging was observed. The average of inbreeding coefficients was not high in this population, although accounting for inbreeding coefficients in the analytical model did significantly increase the predicted breeding values. It is recommended that the analytical model incorporate the inbreeding coefficient to improve the accuracy of genetic evaluation. In future studies, inbreeding depression should be assessed using genomic data for performance and reproduction traits.