Abstract. Research to assess the effect of single genes on reproductive traits in bovine species is imperative to elucidate genes' functions and acquire a better perspective of quantitative traits. The present study was undertaken to characterize genetic diversity in the bovine growth hormone (GH) gene in a population of 410 Holstein dairy cows in Tunisia. The analyses were based on single nucleotide polymorphisms, and GH-AluI and GH-MspI detections and genotyping were carried out using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Data were analyzed using a mixed linear model with the MIXED procedure to reveal the possible effect of GH genotypes on reproductive traits. The frequency data of AluI(L//V) and MspI(+//−) alleles were 87.04//12.96 and 70.06//29.94, respectively. The distribution of the frequency of GH genotypes for LL/LV/VV and (−/−)//(+/−)//(+/+) were 77.75//18.59//3.66 and 15.37//29.13//55.50, respectively. The results of the statistical analyses proved that GH-AluI showed a substantial favorable effect on exanimate traits except for the age at first calving; however, only a suggestive effect of GH-MspI on the calving interval (CI) and the days open (DI) was found. The homozygous LL genotype seemed to be advantageous with respect to the CI and the DI compared with LV and VV genotypes. Heterozygous MspI(+/−) cows tended to have a longer CI and DI than MspI(+/+) and MspI(−/−) cows, but the difference was not statistically significant. A significant effect of different GH-AluI–MspI combined genotypes was found on the number of inseminations per conception, the CI and the DI, and the LL/– combined genotype seemed to be associated with better reproductive performance. Based on these results, the LL genotype of the GH locus can be considered to be a favorable genotype for reproductive traits in Holstein dairy cattle, although these findings need to be confirmed by further research before polymorphisms can be used in a marker-assisted selection program.

This study aimed to estimate the nutritional quality of Sander lucioperca fillets and alterations in lipid quality following hot and cold smoking processes. Our results revealed that the total fat content of zander fillets was 1.86 g/100g. Polyunsaturated fatty acids (PUFAs) were higher than saturated and monounsaturated fatty acids in fresh tissue samples. Arachidonic, docosahexaenoic and eicosapentaenoic acids were the most abundant PUFAs. Differences in the fatty acid compositions of the smoked and fresh fillet were significant, with a decrease in (PUFAs) in the proportion of total fatty acids. The fatty acid profile of the neutral lipids was unchanged after the cold smoking process, whereas PUFAs decreased significantly during both smoking processes, especially the hot smoking process. Our findings showed a partial alteration of polar lipids. Both smoking treatments produced lipoperoxidation and lipid oxidation in the fillets. Other investigational smoking conditions should be tested to reduce such oxidation and hydrolysis in fillets, which could be susceptible to off-flavors and off-odors.

Abstract. Multi-trait Bayesian procedure was used to estimate genetic parameters for reproductive traits in Tunisian Holstein cows. A total of 31 348 lactations of the calving years 2005 to 2012 were analyzed. Fertility traits were the calving interval (CI), days open (DO), days to first insemination (DFI), days from first insemination to conception (FIC), and number of inseminations per conception (NI). Posterior means of heritabilities of CI, DO, DFI, FIC, and NI were 0.047, 0.03, 0.025, 0.024, and 0.069, respectively. Posterior means of repeatabilities of the same respective traits were 0.106, 0.094, 0.051, 0.036, and 0.17. Genetic correlations among female fertility traits were also computed. Calving interval and DO had the highest genetic correlation estimate (0.85) because they have overlapping genetic meanings. The lowest genetic correlation estimate ( − 0.25) was found between DFI and NI. Genetic parameter estimates are low and are even lower than those reported in most literature, implying that more focus should be put upon improving the management of reproduction in dairy cattle herds in Tunisia.

Abstract. Lameness is the third most important infection affecting dairy cattle in modern stabling barns. Environmental (food, stables and injuries) and genetic factors are responsible for this pathology. This study aims to investigate the screening of leptin genetic polymorphism and its effect on lameness prevalence. DNA was extracted from 412 blood samples from Holstein cows (lame and healthy). Genotyping was performed by the PCR-RFLP using the Sau3AI restriction enzyme. Prevalence of parity, calving season, age at calving, test-day milk yields, calving year and leptin/Sau3AI genotype was evaluated by the logistics procedure. Results showed that allelic frequencies are 0.68 and 0.32 respectively for the A and B allele. Frequencies for the AA, AB and BB genotypes are 0.52, 032 and 0.16 respectively. All factors included in the logistic regression model significantly affect the prevalence of lameness in Holstein cows (P<0.01). The probability of lameness incidence varied between 37 % and 99 % respectively for the second and the third parity. The lameness incidence recorded in multiparous is higher than primiparous cows. This recorded incidence is greater in winter and autumn than in the summer and spring. The genetic polymorphism affects the prevalence of lameness in Holstein cows. The incidence of lameness in AB genotype is lower than that in BB and AA genotype. These results can be a way to improve length of productive life for cattle breeds in Tunisia.

Abstract. This study aimed at screening genetic diversity and differentiation in four horse breeds raised in Tunisia, the Barb, Arab-Barb, Arabian, and English Thoroughbred breeds. A total of 200 blood samples (50 for each breed) were collected from the jugular veins of animals, and genomic DNA was extracted. The analysis of the genetic structure was carried out using a panel of 16 microsatellite loci. Results showed that all studied microsatellite markers were highly polymorphic in all breeds. Overall, a total of 147 alleles were detected using the 16 microsatellite loci. The average number of alleles per locus was 7.52 (0.49), 7.35 (0.54), 6.3 (0.44), and 6 (0.38) for the Arab-Barb, Barb, Arabian, and English Thoroughbred breeds, respectively. The observed heterozygosities ranged from 0.63 (0.03) in the English Thoroughbred to 0.72 in the Arab-Barb breeds, whereas the expected heterozygosities were between 0.68 (0.02) in the English Thoroughbred and 0.73 in the Barb breeds. All F ST values calculated by pairwise breed combinations were significantly different from zero (p < 0.05) and an important genetic differentiation among breeds was revealed. Genetic distances, the factorial correspondence, and principal coordinate analyses showed that the important amount of genetic variation was within population. These results may facilitate conservation programs for the studied breeds and enhance preserve their genetic diversity.