The effect of centrally administered losartan, an AT₁ receptor antagonist, on gastric acid secretion and gastric cytoprotection was studied using different models of gastric ulcers, such as acetic acid-induced chronic gastric ulcers, pylorus ligation, ethanol-induced and stress-induced acute gastric ulcers and cysteamine hydrochloride-induced duodenal ulcer. Losartan was administered intracerebroventrically (i.c.v.) at 2 different doses (125 and 250 μg/kg). Both doses of losartan increased the healing of acetic acid-induced chronic gastric ulcers. In pylorus-ligated rats, a significant reduction in free acidity, total acidity and ulcer index was observed with high dose (250 μg/kg, i.c.v.), while low dose (125 μg/kg, i.c.v.) produced reduction only in free acidity and ulcer index. Both doses also produced a significant antiulcer effect in ethanol-induced and stress-induced gastric ulcers. Losartan also reduced ulcer area in cysteamine-induced duodenal ulcer. We conclude that AT₁ receptor antagonism in the brain increases healing of gastric ulcers and reduces gastric acid secretion and increases gastric mucin content.

This study aimed to investigate monthly changes in oestrus and ovulatory activity of Sicilo-Sarde sheep. Experimental animals comprised 25 adult and 10 maiden ewes at the start of the experiment. For 12 consecutive months (September-August), the females were exposed to natural photoperiod and permanently kept in presence of seven aproned rams. Oestrus was checked daily and ovarian activity was monitored by monthly endoscopies during the last week of each month. Ovulation rate for a particular month was assessed as the sum of corpora lutea or corpora albicans present on both ovaries at the time of endoscopy. Proportions of ewes observed in oestrus at least once a month were lowest in March (24.3%) and highest in June and October (100%). They tended (p < 0.06) to be different according to age, dropping during summer from a common value of 100% in June to 85.7% and 90% in July and then to 57.1% and 70% in August for, respectively, the Adults and Maiden females. Overall, the experimental period, 92.5% and 83.8% of Adult and Maiden ewes ovulated at least once per month (p < 0.01) respectively. Least proportions ovulating, attained 60% and 30% in April for, respectively, Adult and Maiden ewes before peaking up at 100% again in May (p < 0.05). Mean (±SD) ovulation rate of Sicilo-Sarde sheep is 1.40 ± 0.503. Adult females had a higher (p < 0.001) ovulation rate than Maiden sheep with respective average values of 1.51 ± 0.516 and 1.16 ± 0.373. It varied little between months and decreased in Adults from a maximum value of 1.95 in October to a minimum value of 1.16 in April. It is concluded that benchmarking seasonal variations of reproductive activity in Sicilo-Sarde breed would be valuable in designing improved management calendars for this breed.

This work aimed to study the sources of variation in productive and reproductive traits of the dairy Sicilo-Sarde ewes and to further investigate the interaction between both classes of traits. After edits, a database containing 5935 lactation records collected during 6 successive years in eight dairy flocks in the North of Tunisia was used. Total milked milk (TMM) in the milking-only period was retained as productive trait. The interval from the start of the mating period to the subsequent lambing (IML) and the lambing status (LS) were designed as reproductive traits. Sicilo-Sarde ewes had an average TMM of 60.93 l (±44.12) during 132.8 days (±46.6) after a suckling period of 100.4 days (±24.9). Average IML was 165.7 days. In a first step, the major factors influencing milk production and reproductive traits were determined. The significant sources of variation identified for TMM were: flock, month of lambing, year of lambing, parity, suckling length, litter size and milking-only length. Flock × month of the start of the mating period, parity, year of mating and litter size were identified as significant factors of variation for IML, while flock × month of the start of the mating period, parity and year of mating were identified as significant sources of variation for LS. In a second step, variance components were estimated using a three traits threshold mixed model, which combined LS as categorical trait and TMM and IML as continuous traits. Repeatability estimates were 0.21 (±0.03) for TMM, 0.09 (±0.02) for IML, and 0.10 (±0.05) for LS. Moreover, TMM and IML were found to be favorably associated for the flock × year of lambing effect (−0.45 ± 0.18) but unfavorably associated for the animal effect (0.20 ± 0.09).

Antagonistic relationship between milk yield and reproduction is reported in several livestock species. This study aimed to investigate whether genetic merit for milk production in dairy sheep affects responses to superovulation, embryo yield and quality. A total of 21 cross-bred Sarda x Lacaune ewes homogeneous for age, parity and stage of lactation were included. The ewes were stratified as high-producing or low-producing based on their genetic merit for milk production estimated by a pentatrait repeatability animal model. Oestrus was synchronized using an intravaginal progesterone pessary inserted on Day 0 and removed on Day 14. Superovulatory treatment consisted of 350 I.U. of porcine FSH administered in eight decreasing intramuscular doses every 12 hr with a total dose of 10 ml of solution starting 12 days after insertion of sponges. Laparoscopic artificial insemination (AI) was performed 48 hr after pessary removal. Surgical embryo recovery was performed at Day 8 after pessary removal. Correlation between breeding value for milk production and the number of corpora lutea (CL) was significantly different from zero (-0.49). High-producing ewes had a lower number of CL than low-producing counterparts (7.6 ± 2.50 vs 12.1 ± 5.16 respectively; p < .02). Furthermore, there was a tendency for high-producing ewes to yield fewer embryos than low-producing females (5.3 ± 3.46 vs 9.18 ± 5.11; p = .09). No differences were observed between ewes in both genetic groups with regard to the number of embryos of grades 1, 2 and 3. To our knowledge, this is the first report highlighting an antagonism between genetic merit for milk production and the ability to produce embryos in sheep. These results deserve to be considered in sheep breeding programmes.