The aim of the study was to establish morphometric, biochemical and hematological values for the endangered Balkan donkey breed (Serbia) and to explore the possible age dependence of the parameters tested. Inter-breed similarity of morphometric parameters was assessed by comparing the data obtained for the Balkan donkey with morphometric measurements of several previously characterized domestic donkey breeds. The study population included 74 donkeys, divided in two age groups (group A ≤ 3 years; group B > 3 years). In total, 18 morphometric, 13 hematological and 14 biochemical parameters were assessed. Significant morphometric differences (p<0.05) in body length, head length, chest circumference and body weight were found between the two age groups. Significant differences in morphological parameters were revealed among the Balkan donkey and other donkey breeds (Catalonian, Croatian and Albanian), but results of cluster analysis demonstrated the smallest distance between the Balkan donkey and Albanian donkeys. The results of morphometric analyses showed consistency of the obtained values within the breed, and diversity as compared to other donkey breeds, and, thus, could be taken as referent for the Balkan donkey. Hematological and biochemical profiles obtained for the Balkan donkey were consistent with previous reports and within the recommended reference ranges. White blood cell, mid cell and granulocyte counts, showed significantly higher (p<0.05) values in donkeys under 3 years of age, while the only biochemical parameter affected by age was alkaline phosphatase. The information gained through characterization of the Balkan donkey breed provides a basis for conservation and development of the breed standard.

The problem of the erosion of animal genetic resources is evident in certain local donkey breeds, and their long-term sustainability can be achieved by economically repositioning them. To develop alternative and sustainable commercial programs, the meat and milk production characteristics of Istrian donkey and Littoral Dinaric donkey breeds were investigated. The meat production characteristics were examined in mature males, whose carcasses were dissected, and meat composition was determined using NIT spectrophotometry and gas chromatography. Milk yield and milk composition were determined in jennies in second or subsequent lactations by measuring milk volume and using infrared spectrometry and gas chromatography. Compared to the Littoral Dinaric donkey, the Istrian donkey has a higher carcass weight and dressing percentage (p < 0.001). The share of boneless meat in relation to live weight was 28.27% in the Istrian donkey and 26.18% in the Littoral Dinaric donkey. The absolute masses of primal cuts of meat in E, I, and II classes were significantly greater in Istrian donkeys than in Littoral Dinaric donkeys (p < 0.01), although the differences in the proportions of primal cuts were not significant. The breed did not have a significant impact on the color, pH, or meat composition. A significant influence of breed on milk yield, lactose, protein, and the fat content of milk was observed (p < 0.01). A significant influence of breed on the ratio of n-6/n-3 PUFA fatty acids in donkey milk was observed (p = 0.002). The values of the atherogenic and thrombogenic indexes were favorable, considering potential beneficial effects of donkey milk and meat on consumer health. The findings of this research suggest that local donkey breeds hold significant potential for meat and milk production, focusing on the uniqueness and quality of their products rather than the quantity of meat and milk they can produce.

This article reviews current knowledge on candidate genes and fatty acids in beef meat. It highlights the general situation of beef cattle in the world, the anatomy, and genetics of cattle, and discusses fatty acid groups in beef and their percentage in musculus longissimus dorsi and the musculus longissimus thoracis. Some selected genes that have been most researched in recent years are discussed in terms of many fatty acids that are associated with as well as sensory attributes of meat and the influence of the fatty acids themselves on sensory evaluation of meat.

Over the past three decades, the scientific and public interest has been initiated by studies in which the negative effect of milk consumption of beta-casein A1 variant has been observed on consumers’ health. The production of "A2 milk" is one of the ways to economically increase the competitiveness of small and medium-sized dairy farms. Breeders of endangered local breeds are also interested in reaffirmation through production of “A2 milk”. The aim of this study is to determine frequencies of A1 and A2 variants of beta-casein in three commercial and three local breeds of cattle in Croatia, and their relationship with production indicators of commercial breeds in the first three lactations. The genomic DNA was extracted from hair by using a commercial kit, used for determination of CSN2 genotypes by means of PCRRFLP method. Data for milk yield and chemical composition were provided by the central database. The dominant presence of A2 variant beta-casein in the investigated cattle breeds (0.650-0.758) and the increase in the frequency of A2 beta-casein in the population of Simmental and Istrian cattle were determined. The association of A2A2 and A1A1 genotypes of beta-casein with lactation production and milk fat content in the first and second lactation was observed (p <0.05). The dominance of the A2 allelic variation of beta-casein makes the researched conventional and local breeds suitable for the production of "A2 milk. The breeding extension of A2 allelic variation of beta-casein within local breeds of cattle should be carried out carefully not to lose part of the existing genetic variability.