In this study, the authors focused on the evaluation of the genetic parameters of longevity, milk yield traits, and type traits in dairy cattle populations in the Republic of Serbia. The total dataset used consisted of production records and pedigree data for 32,512 Holstein cows that calved from 1981 to 2015. The animal model was applied to determine the variance and covariance components and genetic parameters of the analyzed traits by applying the restricted maximum likelihood (REML) approach and using the programs VCE6 and PEST. The heritability of longevity traits was estimated using the Survival Kit V6.0 software package. Variance and covariance were estimated for five production traits: milk yield (MY), fat yield (FY), protein yield (PY), milk fat content (MC), and protein content (PC), and three longevity traits: length of productive life (LPL), lifetime milk yield (LMY), and the number of lactations achieved (NL) as well as for 18 standard type traits. Heritabilities for the milk, fat, and protein yield traits were 0.20 (MY), 0.15 (FY), and 0.19 (PY), respectively. The estimated coefficients of heritability for the longevity traits were higher when using the Weibull proportional hazards model compared to the traditional linear methods and ranged from 0.08 for NL to 0.10 for LPL. Heritability values for the type traits varied from a low of 0.10 (RLSsv—rear legs set–side view) to medium values of 0.32 (ST-stature). Genetic correlations were found between MY and the following longevity traits: LPL, LMY, and NL with values of −0.18, −0.11, and −0.09, respectively. Genetic correlations were found between MY and a number of linear type traits and varied from 0.02 (between MY and RUH-rear udder height) to 0.28 (between MY and FUA-fore udder attachment). Genetic correlations between the 18 investigated type traits ranged from −0.33 between TL (top line) and RTP (rear teats position) to 0.71 between AN (angularity) and RUH (rear udder height). Genetic correlations between most linear type traits and longevity traits (LPL, LMY, and NL) were generally negative and very low. The highest positive genetic correlation was found between UD and LPL (r_xy = 0.38).

The quality and yield of milk, and therefore of dairy products as well, depends directly on their protein composition. Milk gene proteins represent structural locuses that are functionally associated with milk production. In cattle selection a special importance is attached to the variability of kappa casein (?-CN) as one of the four casein milk proteins. Genotypes of 21 Simmental breed cows, 20 crossbred cows obtained by crossing of Simmental and Red Holstein breed, and 25 cows of autochthonous Busha breed were determined for kappa casein by restriction fragment length polymorphism analysis (PCR- RFLP) of amplified DNA. The ?-CN genotype frequencies for Simmental breed were: 42.8; 47.6 and 9.6 % for AA, and BB genotype, for crossbreds: 75.0; 25.0 and 0.0% and for Busha individuals: 41.7; 50.0 and 8.3 %, respectively. Frequencies of A and B alleles, assessed on the basis of genotypic frequencies were 0.667 and 0.333 for Simmental breed, 0.875 and 0.125 for crossbreds and 0.667 and 0.333 for autochthonous Busha cattle breed, respectively. For confirming the phenotypic variability of milk yield in standard lactation, yield of milk fat and the content of milk fat per ?-CN genotypes within breeds observed the fixed model which included the breed effect, lactation in order and effect of ?-CN genotype (AA, and BB) was used. The ?-CN genotype statistically significantly (p ?0.05) influenced milk yield and highly significantly (p ?0.01) milk fat yield, while the content of milk fat was not statistically significantly (p>0.05) influenced in examined animals.

Estimation of genetic variability and genetic correlations between production traits (milk yield, fat yield, fat content, protein yield, and protein content) and selected type traits (angularity, fore udder height, rear udder height, front teat placement, teat length, and udder depth) was done using data sets of 10,860 first-calving Holstein-Friesian cows raised in the territory of the Republic of Serbia. Genetic variance and covariance were obtained using the Restricted Maximum Likelihood (REML) method, VCE v6 software, and the multi-trait mixed [...] ABSTRACT Estimation of genetic variability and genetic correlations between production traits (milk yield, fat yield, fat content, protein yield, and protein content) and selected type traits (angularity, fore udder height, rear udder height, front teat placement, teat length, and udder depth) was done using data sets of 10,860 first-calving Holstein-Friesian cows raised in the territory of the Republic of Serbia. Genetic variance and covariance were obtained using the Restricted Maximum Likelihood (REML) method, VCE v6 software, and the multi-trait mixed

Preserving local autochthonous domestic animal populations and the products derived from them is a crucial aspect of managing human utilization of the biosphere. This management approach aims to ensure sustainable benefits for both present and future generations. The diversity of autochthonous domestic animal populations plays a vital role in the functionality and sustainability of the food production system. It encompasses both productive and non-productive aspects, contributing significantly to the overall health, nutrition, and food security of the landscape by providing a wide range of animal-derived food resources. Based on the data contained in the Draft Program of Rural Development, a significant presence of more than 44 autochthonous and local breeds of domestic animals has been noted in Serbia. In order to enable the sustainable preservation of local domestic animals, the competent Ministry of Agriculture of the Republic of Serbia has, through a number of projects, implemented models for the preservation of local breeds on farms (in situ), as well as provided technical assistance to small farms that keep animal collections. It also helps the local population to procure animals, conducts product quality research, and provides opportunities to integrate conservation programs through tourism. Given that molecular characterization is a key factor for the preservation of autochthonous breeds, in the Republic of Serbia, DNA markers are used for identification and to investigate the belonging to a specific breeds or strain. All the mentioned activities led to an immediate increase in the number of animals, which is especially true for the autochthonous breeds of cattle (Busha), sheep (Sjenicka, Svrljiska, and Vlach-vitohorn) and pigs (Mangalitsa, Moravka, and Resavka) that are discussed in this paper. In addition to the significant measures undertaken to preserve animal genetic resources (AnGR), it is necessary to continue to work primarily on ex situ conservation in order to prevent the loss of their gene pools. However, regardless of the evident effort that has been made to preserve autochthonous genetic resources in Serbia, we believe that there is still a lot of room for further improvement. This primarily refers to advanced technologies that have not been applied so far, mostly related to the identification of genomic regions associated with economic traits, resistance to diseases, and adaptability to emerging climate changes. In this way, the production capacity and functional characteristics of autochthonous species and breeds of domestic animals in Serbia will be improved.

In order to examine the biased milk production depending on the sex of calves, data on calving and milk yield characteristics of 15,181 Holstein type cows in PK Belgrade, Serbia were analyzed. A total of 30,362 lactations that were realized in the period from 1985 to 2017 were analyzed. Data were prepared and analyzed using the SAS software package (SAS Institute Inc. Software License 9.3, 2012). The expression and variability of investigated traits were determined using the PROC MEANS procedure, while the effect of individual factors on milk yield traits was analyzed using the PROC GLM procedure. Obtained results deviate from the views of the Trivers–Willard (TW) hypothesis. The results indicate that mothers invest more in female offspring by producing a higher milk and fat yield in the first and second lactation compared to male offspring. This is especially emphasized under better environmental conditions. The highest milk yield (7788 kg) and fat yield (271 kg) in the second lactation were achieved in the combination with two consecutive female calves in the group of higher-than-average milk production farms, and lowest in the combination of two consecutive male calves (6783 kg for the MY and 243 kg for the FY), respectively.

The objective of this research was to determine the influence of heat stress, using the temperature-humidity index (THI), on the production and quality of native sperm of bulls. The effect of heat stress on the quantity of semen (mL), density of ejaculate (number of spermatozoa, 106/mL), gross sperm motility (1-5), number of frozen doses, and motility after freezing was analysed in 1,017 sperm samples taken from 32 Holstein-Friesian bulls, in the 2017-2019 period, at the Centre for Reproduction and [...] ABSTRACT The objective of this research was to determine the influence of heat stress, using the temperature-humidity index (THI), on the production and quality of native sperm of bulls. The effect of heat stress on the quantity of semen (mL), density of ejaculate (number of spermatozoa, 106/mL), gross sperm motility (1-5), number of frozen doses, and motility after freezing was analysed in 1,017 sperm samples taken from 32 Holstein-Friesian bulls, in the 2017-2019 period, at the Centre for Reproduction and