A new population of Mus musculus domesticus showing Robertsonian translocations (2n = 22) has been identified in Tunisia. Mice carried 9 pairs of 10.17) and Rb(13.15). Five ot the nine translocations are not known to occur elsewhere. In two populations only 2n = 22 mice were present, whereas in a third one a mixture of karyotypes (2n = 22, 38, 39, 40) was found. The slight electrophoretic differentiation observed for other Robertsonian populations as well as the hybrid nature of the karyotypically heterogeneous populations are confirmed. Allele frequency differences between the 2n = 22 and 2n = 40 mice in the latter population show that local electrophoretic differentiation exists and allow to compare chromosome flow and gene flow. The presence of a chromosome-I polymorphism for additional fragments of heterochromatin present in the Robertsonian population provides a convenient marker of recombinational events in the hybrid zone.

Breeding data show that there is no distortion of the transmission ratio of chromosomal types in the progeny of wild mice heterozygous for Rb(16.17) nor was litter size significantly affected by chromosomal heterozygosity. The relevance of these results to those obtained with artificial hybrids and to processes of chromosomal differentiation are discussed.

Bali cattle as one of Indonesia’s native cattle have horns basically, both male and female. However, in its development, Bali cattle without horns have been found and known as polled. Bali polled is cattle whose horns do not grow naturally. The objective of this study was to determine the characteristics of libido and the concentration of testosterone in Bali polled and horned bulls. The samples were 8 individuals (4 polled and 4 horned) with an age between 3-8 years. Libido characteristics were measured by recording the time the bull first fondled the cow until ejaculate and analyzing the testosterone concentration using the enzyme-linked immunosorbent assay (ELISA) method. The collected data were analyzed by an independent sample T-Test. The results of this study indicated that the time required for a polled bull from fondling the female to ejaculation was longer (P<0.05) compared to horned (7.45±2.51 vs 2.42±0.60 minutes). While the testosterone concentration was not significantly different (P>0.05) 6.94±2.43 ng/mL vs 3.74±1.34 ng/mL although showed a higher tendency for the horned bull at 3.2 ng/mL. In conclusion, the polled bull took a longer time from fondling the female to ejaculation compared to horned, while the concentration of the hormone testosterone was equal. However, libido characteristics have a positive correlation with the testosterone concentration with a correlation coefficient of 0.805.

Summary. The ovaries of new born lambs (15 Romanov, 34 ovaries) and of 4-week-old lambs (6 Ile-de-France and 12 Romanov, 18 ovaries) were examined histologically to compare ovarian follicular development in infant lambs of breeds differing in their prolificacy. Breed was the major factor affecting follicular population at birth. Ile-de-France lambs had a higher total number of growing follicles (P < 0\m=.\001), and more preantral (P < 0\m=.\001) and antral (P < 0\m=.\005) follicles than did Romanov lambs. Furthermore, the size of the largest follicles was also reduced in Romanov compared to Ile-de-France lambs. At 4 weeks of age, most of the features of the ovarian follicular population except the mean size of the third largest follicle were similar between the two breeds. However, atresia of antral follicles had appeared only in Ile-de-France and not in Romanov lambs.When a challenge with exogenous gonadotrophins (1000 i.u. PMSG followed by 1500 i.u. hCG) was attempted, ovulation was triggered in 2/6 and 0/12 Ile-de-France and Romanov lambs respectively. Massive follicular development was noted in 3/6Ile-de-France lambs but in none of 12 Romanov lambs.Retardation of follicular development together with retardation in the establishment of ovarian sensitivity to gonadotrophins are therefore features typical of the ovaries of Romanov lambs compared to Ile-de-France lambs during the post-natal period.

This study aims to determine the ability of in vitro embryo cleavage of Bali cattle 48 hours after the fertilization process based on different ovarian reproductive status. Ovaries from abattoirs are grouped into four categories: ovaries without corpus luteum and dominant follicles (-CL and -FD), without corpus luteum and with dominant follicles (-CL and + FD), with corpus luteum and without dominant follicle (+ CL and -FD), and with corpus luteum and dominant follicles (+ CL and + FD). After that, oocytes are collected by slicing and only oocytes with a cytoplasmic are homongent and have compact cumulus cells used in the study. The selected oocytes are then matured in an incubator of 5% CO2, a temperature of 38.5 °C for 24 hours. After maturation, in vitro fertilization was carried out using fertilization media with a final concentration of spermatozoa 1.5 x 106 spermatozoa/ml. Oocytes 5-6 after fertilization were washed 3 times using CR1aa media then cultured in 5% CO2 incubator, temperature 38.5 °C for 48 hours. After 48 hours the culture was evaluated for the ability of embryo cleavage. The results showed that the number of embryos capable of cleave to stage 2 cells were not significantly different (P>0.05) in all treatments (1.64 ± 0.38% vs 8.00 ± 0.90% vs. 4.85 ± 0.96% vs. 8.22 ± 1.86%), while the number of embryos capable of cleave reached stage 4 cells (11.48 ± 0.82% vs 24.00 ± 2.64% vs. 24.27 ± 2.23% vs. 10.96 ± 0.69%), 8 cells (11.48 ± 1.15% vs 8.00 ± 1.07% vs. 26.21 ± 2.79 % vs 15.07 ± 1.40%), 16 cells (0.00 ± 0.00% vs 1.33 ± 0.38% vs. 4.85 ± 0.76% vs. 1.37 ± 0.38%), and the ability of embryos cleavage (24.59 ± 11.60% vs 41.33 ± 24.32% vs. 60.19 ± 22.45 % vs. 35.62 ± 10.83%) was significantly higher (P<0.05) in the ovaries with corpus luteum and without dominant follicles (+ CL and – FD). Conclusion, the ability of embryo division to reach 4 cells, 8 cells, and 16 cells after 48 hours culture was higher in the ovaries with corpus luteum and without dominant follicles (+ CL and – FD).