The objective of the present study was to research the effect of feeding laying hens fish oil-supplemented diets to produce n-3-enriched eggs on their ovarian follicular development, serum lipid peroxidation, antioxidative status and immune response. A total of 105 white Bovens hens at 24 weeks of age were housed in cages in an open-sided building under a 16 h light : 8 h dark lighting schedule. Birds were randomly divided into five treatments and were fed, ad libitum, diets containing 0% (control), 1.25%, 2.5%, 3.5% or 5.0% fish oil from 24 to 36 weeks of age. Egg production and weight were recorded. By weeks 35 and 36 of age 15 eggs were taken at random from each treatment to determine the yolk lipid profile and cholesterol content. At the end of the experimental period, 10 females from each treatment were randomly chosen, anaesthetised and killed by decapitation. Ovary and oviduct samples were immediately weighted and ovarian follicles were classified. Serum thiobarbituric acid-reactive substance (TBARS), hepatic TBARS and hepatic glutathione peroxidase (GSH-Px) activity were measured. No clear trend was observed concerning egg production and egg yolk cholesterol. As dietary fish oil levels increased, n-3-polyunsaturated fatty acids (n-3 PUFA) increased, whereas n-6 PUFA tended to decrease in yolk lipids. No negative effects were detected in ovary and oviduct weights, expressed in both absolute terms and relative to body weight. The numbers and total weights of large yellow follicles (LYF) in the ovary were not significantly affected by fish oil supplementation. Low levels (1.25% to 2.5%) of fish oil reduced both plasma and hepatic TBARS and enhanced GSH-Px activity. It is also interesting to note that inclusion of 2.5% fish oil in laying hen diets enhanced the antibody titre in laying hens. Therefore, it could be concluded that inclusion of fish oil in laying hen diets at moderate levels increased the n-3 fatty acids content in eggs, improved antioxidative status, enhanced the antibody response and did not have a negative influence on the different reproductive morphology parameters in laying hens.

Introduction. En Tunisie, la biologie de la forme hivernale du psylle du poirier a été jusqu'à présent très peu étudiée malgré son importance pour le déclenchement du traitement d'hiver nécessaire au développement d'une protection intégrée en vergers de poiriers. Matériel et méthodes. L'étude de la forme hivernale de C. pyri a eu lieu au cours des années 1998, 1999 et 2000 sur des poiriers de la variété locale Radsi. Des collectes d'adultes ont été effectuées par la méthode du frappage hebdomadaire, sur une toile blanche. Puis, la structure de la population imaginale récoltée a été analysée. Des femelles capturées ont été disséquées afin de déterminer leur état physiologique. Résultats. En Tunisie, la forme d'hiver apparaît à la fin du mois d'octobre et la population devient à 100 % du type hivernal en début décembre. Cette forme passe par une phase migratoire en dehors du verger, au cours de laquelle s'accomplit très lentement une partie du développement ovarien. Le retour des psylles au verger en février coïncide en général avec le début de leur maturation sexuelle qui s'achève fin février avec le début des pontes. Conclusion. Dans les conditions tunisiennes, le traitement d'hiver visant les femelles de C. pyri gravides avant le dépôt des pontes doit être effectué à partir de la mi-février.

Reproductive performance of 714 Holstein Friesian dairy cows was monitored between October 1995 and June 1998 using thrice weekly milk progesterone determinations. Defined endocrine parameters such as interval to post-partum commencement of luteal activity, inter-ovulatory interval and length of luteal and inter-luteal intervals were used with a number of traditional measures of reproductive performance to investigate the current status of fertility in a sample of United Kingdom dairy herds. A comparison of the results of the 1995 to 1998 trial with those of a previous (1975 to 1982) milk progesterone database, which included 2503 lactations in British Friesian cows monitored using a similar milk sampling protocol, revealed a decline infertility between these periods.

Between 1975-1982 and 1995-1998, pregnancy rate to first service declined from 55·6% to 39·7% (P < 0·001), at a derived average rate approaching 1% per year. This decline was associated with an increase (P < 0·001) in the proportion of animals with one or more atypical ovarian hormone patterns from 32% to 44%. There was a significant (P < 0·001) increase in the incidence of delayed luteolysis during the first cycle post partum (delayed luteolysis type I; 7·3% to 18·2%) and during subsequent cycles (delayed luteolysis type II; 6·4% to 16·8%), although the incidence of prolonged anovulation post partům (delayed ovulation type I; 10·9% to 12·9%) and prolonged inter-luteal intervals (delayed ovulation type II; 12·9% to 10·6%) did not alter significantly. These changes resulted in an increase in mean luteal phase length from 12·9 (s.e. 0·09) to 14·8 (s.e. 0·17) days and an increase in inter-ovulatory interval from 20·2 (s.e. 0·1) to 22·3 (s.e. 0·2) days. The decline infertility was also reflected in traditional measures of fertility since although interval to first service remained relatively unchanged (74·0 (s.e. 0·4) to 77·6 (s.e. 1·1) days) calving interval lengthened from 370 (s.e. 2·2) to 390 (s.e. 2·5) days. Collectively these changes may have contributed to the decline in pregnancy rates observed over the last 20 years.

Development of all follicles with antral diameter ≥2 mm during the oestrous cycle was characterized in goats of the Murciana-Granadina dairy breed by daily transrectal ultrasonography. Of nine does initially synchronized in oestrus, six returned to oestrus and three did not. In the first six does, mean cycle length was 21·2 (s.e. 2-3) days. There were mean total numbers of 6·2 (s.e. 0·6) small (2 to 3 mm), 1·9 (s.e. 0·3) medium (4 to 5 mm), and 1·0 (s.e. 0·2) large follicles (≥6 mm) each day but only numbers of large follicles differed with day of cycle (P < 0·01). The diameters of the largest follicle (LF1), the second largest (LF2) and the remaining follicles (RF) varied with day of cycle (P < 0·01). The LF1 and LF2 varied with day in similar patterns but the difference in diameter between them (P < 0·05) was greatest on days 7 and 9 (2·3 mm) and days 19 to 23 (2·2 to 3·8 mm), and least on days 2, 15, 16 and 18 (0·5 to 0·8 mm). The relationship between the LF1 and LF2 to the RF differed only early or late in the cycle when concentrations of progesterone were low (P < 0.05). There was some evidence to support follicular growth in waves. Although the number of apparently new follicles detected (4·8 (s.e. 0·4) per day) did not vary with day of cycle, follicles emerging at 3 mm over a 48-h period that grew to a diameter of ≥6 mm were distributed non-randomly in three of six cyclic does. The three cystic does that did not return to oestrus by day 25 had large follicles (16 to 28 mm), fewer new follicles (3·3 (s.e. 1-1) per day; P < 0·01) than cyclic does (4·8 (s.e. 0·4) per day) and fewer follicles that became largest (4·0 v. 8·8 in cyclic does; P < 0·01).

An investigation was conducted into the effect of buserelin treatment on day 12 post mating on ovarian function and plasma progesterone and oestradiol-17 ji concentration in ewes. Changes in ovarian structures were determined, at laparoscopy or after slaughter, 48 h after treatment in 38 control and 41 ewes given an injection of 4 jig buserelin on day 12 post mating (day 0 = day of oestrus). Ovulation rate was higher in buserelin treated (2·76) than in control (1·87) ewes (P < 0·05). Moreover, 41 of the 113 corpora lutea observed in the buserelin group were the result of ovulations that had occurred within 48 h post treatment, compared with two of 71 in the controls (P < 0·05). Blood samples were collected from 10 ewes in each treatment group for hormone analysis. Mean progesterone concentrations tended to be higher, in samples collected from 2 to 6h post treatment, in the buserelin group (4·31 (s.e. 1·32) p.g/1) compared with the control group (3·71 (s.e. 1·44) fig/l. Furthermore, overall mean oestradiol concentrations were lower, during days 13, 14 and 15 post mating, in buserelin treated (0·72 (s.e. 0·26) ngfl) than in control (0·94 (s.e. 0·50) ng/l) ewes (P < 0·05). The results of this study indicate that buserelin treatment on day 12 post mating changes ovarian function.

Jugular and ovarian venous profiles of progesterone and endometrial progesterone concentrations were measured in pregnant and non-pregnant ewes. Mean jugular concentrations were not significantly different (3·12v.2·39 μg/l). The incidence of progesterone concentrations above a chosen threshold was significantly greater in the ovarian vein than in the jugular vein (P < 0·05) and was greater (P > 0·05) in the ovarian venous plasma of pregnant than of non-pregnant ewes. Mean endometrial progesterone concentrations were significantly higher in pregnant than in non-pregnant ewes (T < 0·05). It is suggested that the lower progesterone concentrations in the ovarian veins of non-pregnant ewes may have a rôle in pregnancy failure and that ovarian venous concentrations may influence endometrial progesterone concentrations.

A protocol for the incubation of Centropristis striata ovarian follicles in vitro from females that spawn repeatedly under laboratory conditions was developed. Isolated follicles underwent maturation after 15–24 h of incubation at 25 °C in 75% Leibovitz L-15 medium, containing relatively low doses of human chorionic gonadotropin (hCG) or homologous pituitary extract (50% response with approximately 2 IU/ml and 0.02 pituitary equivalents/ml, respectively). During maturation in vitro, follicles underwent a remarkable volume increase (about 340%) that was correlated with proteolysis of primarily the largest yolk proteinin the oocyte. The maturation response of follicles to hCG was size-dependent within a range from 400 to 600 m in diameter, with a maximum response displayed by 530–600 m follicles. The response of these follicles to hCG was not inhibited within a range of incubation temperatures from 15 to 28 °C, but the length of time required for the follicles to achieve 50% maturation was negatively correlated with increasing temperatures (r2 = 0.97; p ≤ 0.01). However, the largest follicles (530–600 μm) did not undergo maturation in response to high doses (1 μg/ml) of the major maturation-inducing steroids (MISs) known in teleosts, 17.20-dihydroxy-4-pregnen-3-one (17.20β) and 17.20β.21-trihydroxy-4-pregnen-3-one (20βS), even after a previous incubation period of follicles with 10 IU/ml hCG for 1.3 or 6 h. These observations indicate that C. striata follicles are very sensitive to increasing doses of gonadotropin, and that their responsiveness to this hormone is highly size-dependent within a very narrow range. The preliminary results also suggest that 17.20β and 20βS are not the MIS in this species.

A polytrophic ovariole of the fleshfly, Sarcophaga tibialis Macquart, is composed of two successively maturing egg chambers, each consisting of an oocyte, an interconnected cluster of 15 nurse cells, and an enveloping layer of follicle cells. The oocyte is established at the posterior end of the egg chamber. Nurse cell differentiation is characterized by nucleolar multiplication. At 25°C the first egg generation took approximately 8 days to develop. During this period, the growth rate of the egg chamber increased with time. A dramatic increase occurred during days 4–6, and was associated with the formation of large intercellular spaces between the follicle cells as well as an accumulation of numerous yolk globules. Completion of egg-chamber development was marked by the degeneration of the cluster of nurse cells and that of follicle cells.