Objectives: This study was conducted to determine the correlation among prolactin gene (PRG), growth differentiation factor 9 (GDF-9), and calpastatin (CAG) genes polymorphism with growth traits in Awassi lambs. Materials and Methods: Records of 779 Awassi lambsfrom 264 dams and 15 sires were used. The sex, type of birth (single versus twins), weight at birth, average daily gain (ADG), and the adjusted weight at 60 days of age were determined for each animal. Blood samples were collected from all lambs to determine PRG, GDF-9, and CAG polymorphism using polymerase chain reaction-Restriction fragment length polymorphism. Results: Three PRG genotypes (AA, AB, and BB) were determined with a frequency of 0.88, 0.05, and 0.07, respectively. The frequency of each allele was 0.84 and 0.16 for A and B alleles, respectively. For GDF-9, there were only two genotypes detected (AB and BB) with a frequency of 0.96 and 0.04, respectively. The frequency of each allele was 0.92 and 0.08 for A and B alleles, respectively. For CAG, two genotypes were also detected (AB and BB) with a frequency of 0.92 and 0.08, respectively. The frequency of each allele was 0.96 and 0.04 for A and B alleles, respectively. A significant (p ≤ 0.04) effect of PRG genotype on birth weight was detected but this effect was not significant on ADG and weight at weaning. There were no associations between any of the pre-weaning growth traits and GDF-9 and CAG variants. Conclusion: The results of this study show that PRG could be used to select dams with a high frequency of dystocia to reduce birth weight of newborn lambs and therefore conserve the dams reproductive functions and improve lamb survivability. [J Adv Vet Anim Res 2019; 6(1.000): 86-91]

The duration of the incubation period for scrapie, a fatal transmissible neurodegenerative disorder of sheep and goats, is mainly determined by the Sip gene, which has 2 alleles (sA-susceptible and pA-resistant). A diagnostic test is not available to detect scrapie in live animals. We analyzed genomic DNA extracted from frozen sheep brains collected from Cheviot sheep of the United States that had been inoculated with the SSBP/1 scrapie inoculum. Digestion of the DNA with EcoRI or HindIII followed by the addition of a scrapie-associated fibril protein (PrP)-specific marker probe, yielded fragments of 6.8 (e1) and 4.0 (e3) kb, or 5.0 (h1) and 3.4 (h2) kb, respectively. Fragments e1 and h2 were associated with the histopathologic diagnosis of scrapie, and fragments e3 and h1 were associated with survival. A valine/alanine polymorphism within the PrP coding region that resulted in a BspHI site was further used to determine the genotype of these Cheviot sheep. Digestion of polymerase chain reaction fragments with BspHI resulted in an undigested fragment b- (0.840 kb), digested fragments b+ (0.460 and 0.380 kb), or both types of fragments. Survival time of b+/b+ homozygous sheep was significantly (P < 0.01) shorter (218 +/- 26.0 days) than survival time for b-/b- sheep (> 700 days after inoculation). Results indicated that b+ and b- are markers for the Sip sA and pA alleles, respectively. The intermediate duration of the incubation period for heterozygous sheep (b+/b-; 342.9 +/- 25.3 days) indicated that the Sip sA allele is expressed codominantly to the Sip pA allele.

In the conditions of the Republic of Belarus there was determined the genetic structure of population of breeding boars, sows, replacement and crossbred stores in accordance with RYR1 gene which was connected with stress resistance. Also, there was analyzed the influence of genetic polymorphism of this gene on meat productivity. In course of the study there was presented a genetic structure of breeds according to gene loci RYR1. There was analyzed the frequency of occurrence of alleles and genotypes in accodance with gene loci RYR1 of breeding boars and replacement stores of different lines. There were showed the indexes of meat productivity and acid capacity of purebred and crossbred stores with different RYR1 gene genotypes. As a result of study there was revealed a rather high level of presence of allele RYR**n in all sex and age specific groups of Belarusian meaty breed (21%) and crossbred stores of Large white x Belarusian meaty breeds (40%). But in the experimental group of three-breed cross breeds (Large white x Belarusian meaty) x Duroc there was not stated the presence of allele of malignant hyperthermia. High level of RYR**n allele presence in populations of meaty breeds and their crossbreeds proved the necessity of obligatory genetic control of pedigree as well as imported animals by means of DNA diagnostic.

Determination of genetic structure of different population lines of Belarusian white-and-black breed in accordance with locus of kappa-casein gene (CSN3) was realized in the conditions of the Republic of Belarus. In course of study there were used DNA samples of Belarusian white-and-black breed cows (380 samples) and bioprobes of servicing bulls (83 samples). With the help of endonuclease Hindill there were revealed two alleles of kappa-casein (A and B) in DNA preparations. As a result of genetic typing of breeding animals by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods there were revealed three genotypes CSN3**AA, CSN3**AB, and CSN3**BB. The frequency of occurrence of desirable genotype CSN3**BB of Belarusian white-and-black breed of cows depending on breed and linear pertain varied from 2,2% up to 7,69%, for servicing bulls – from 0 up to 11,1% . The majority of homozygotic cows with undesirable cow genotype CSN3**AA belonged to the following lines: of Ruties Edward (2,31646 - 92,3%), Niko (86,0%), Vis Ajdal (933122 - 71,9%), Reflection Sovereign (198998 – 63,9%). The desirable CSN3**BB genotype in most of the cases was stated at Annas-Adema (30587) and Hiltes-Adema (37910) lines. Presence of heterozygote genotype predominated in Annas-Adema (46,1%) and Montvik Chiftein (36,3%) lines. Realized analysis of cow population lines of Danish and Holstein breeds showed that the average frequency of occurrence of CSN3**B allel was 17%, but lower concentration (15%) of CSN3**b allel was typical for the Danish breeds. Frequency of occurrence of CSN3**B allel in Holsten lines was 18%. In was revealed that in 86,6% of cases bulls were the genetic carriers of CSN3**A allel and only 11,4% of animals had the desirable allel CSN3**B in their genotype