In this study, beta-lactam and tetracycline antibiotic residues were investigated in cattle liver, kidney and muscle samples. For this purpose, a total of 75 bovine tissue samples (each of 25 from liver, kidney, muscle) taken from 25 cattle slaughtered in a local slaughterhouse in Sivas were used as materials. ELISA method was applied in the analysis and it was studied with commercial test kits. According to the results of the analysis; beta-lactam and tetracycline residues were detected in all bovine tissue samples. Beta-lactam level was determined between 0.75-1.07 ppb (mean 0.94 ± 0.01) in liver samples, 0.67-1.05 ppb (mean 0.81 ± 0.01) in kidney samples and 0.70-2.57 ppb (mean 0.97 ± 0.07) in muscle samples. Tetracycline level was detected in the range of 4.48-8.50 ppb (mean 6.14 ± 0.17) in liver samples, 1.73-6.39 ppb (mean 4.90 ± 0.24) in kidney samples and 3.31-7.45 ppb (mean 5.67 ± 0.25) in muscle samples. The residue levels determined in the examples complied with the legal limits reported in the European Commission and the Turkish Food Codex Communiqué.

Progesterone plays a key role in the establishment and maintenance of pregnancy in mammalian. Increasing levels of circulating progesterone in the post-conception period are associated with conceptus elongation and high pregnancy rates in cattle. Contradictory results are available on the direct role of progesterone in early embryo development. The objective of this study was to evaluate direct effects of progesterone on in vitro development of cattle embryos. Immature oocytes collected from slaughtered animals and cultured in the presence of different concentrations of progesterone (25, 50, 100 ng/mL) following in vitro fertilization. Cleavage rates in 25 and 50 ng/mL concentrations of progesterone were significantly higher than those in controls and 100 ng/mL. Rate of embryos that reached to the morula stage was similar in all groups. Supplementation of 25 and 50 ng/mL progesterone to the culture media significantly increased blastocyst yield while 100 ng/mL progesterone resulted in a decrease. As a conclusion, we can suggest that progesterone supplementation in in vitro culture may support embryo development at low levels.