Risk factors associated with bovine tuberculosis and molecular characterization of Mycobacterium bovis strains in urban settings in Niger.

A retrospective and a longitudinal survey were carried out at the abattoir of Niamey. Results showed a highly significant difference in suspected tuberculosis (TB) gross lesions among different animal species (P < 0.0001). The proportion of carcasses with TB-like lesions was 0.19% among cattle, 0.11% among camels, 0.001% among sheep and 0.0006% among goats. In cattle, cows are significantly more affected than the other categories (P < 0.001). Also in cattle, TB-like lesions are mostly localized in the lungs (92.77%) followed by the lymph nodes (50.87%) and the liver (32.40%). The prevalence of gross lesions compatible with bovine TB (BTB) is strongly influenced by the season (P < 0.0001), is closely correlated with the origin of the animals (P < 0.001) and has a negative impact on the weight of affected animals (P < 0.0001). Sixty-two samples of suspected TB gross lesions were subject to microbiological analysis and molecular typing of strains. Mycobacterium bovis was identified in 18 animals showing five different spoligotypes, belonging to type 'African 1' previously identified in Central and West Africa. In addition, a profile (SB1982) not previously reported distinguished by the absence of spacers 3, 4, 9, 16, 22, 30 and 39-43 has been characterized in this study. To assess risk factors for BTB transmission, a questionnaire on animal husbandry practices, food habits, and clinical signs of TB in animals and humans was submitted to the heads of 1131 randomly selected households. The main risk factors identified are consumption of unpasteurized milk (91%) and lack of hygiene within households (32-74%). Clinical signs that could be attributed to TB were also reported both in humans and in animals of the households.

[Annual variations in estrual behavior, rate and possibilities for ovulation in Peulh ewes from Niger]. / Variations annuelles du comportement d'oestrus, du taux et des possibilités d'ovulations chez la brebis Peulh du Niger.

Annual variations in estrous and ovulation behavior were studied in 23 bicolored Peulh ewes for a period of 30 months. The percentages of estrus and ovulation shown over a year of observation were 76 and 86%, respectively. The average rate of ovulation was 1.3 +/- 0.04 (X +/- SEM). Reproductive activity was minimal from January to April, as the percentages of estrus and ovulation varied between 43.8 and 61% and between 53.1 and 86%, respectively. This period was marked by the advent of anestrus, interrupted frequently by silent and irregular ovulations. Anestrus lasted an average of 81.9 +/- 9.8 days (X +/- SEM). Reproductive activity was maximal from May to December, as the percentages of estrus and ovulation varied between 77 and 97% and between 87.5 and 100%, respectively. During this period ovarian activity was interrupted by prolonged diestrus which lasted an average of 24.9 +/- 3.3 days (X +/- SEM). The ovulation rate did not differ significantly (P greater than 0.05) between periods of minimal and maximal sexual activity. These results suggest that the reproductive potentialities of Peulh sheep on a good diet are comparable to those of certain ovine breeds in temperate zones. The results also suggest that anestrus in bicolored Peulh sheep is probably a different physiological process than the one observed in some breeds of sheep in which anestrus is marked by total ovarian inactivity.

Anomalies in ovarian function of peulh ewes.

The ovarian activity of 8 Niger Peulh ewes was followed for 2 1 2 years by assaying the levels of progesterone in blood plasma sampled daily and by endoscopic observation. Although the ewes did not experience seasonal anestrus, their cycles were not regular. Most animals had persistent corpora lutea at some stage, but particularly in June. This resulted in cycles averaging 49.9+/-6.8 days in length instead of the normal 16.9+/-0.1 days. Intervals between successive luteal phases lasted 4-15 days as compared with 2.3+/-0.06 days seen in normal cycles. This occurred in most ewes at least once during the period from December to April. In these cases, the preovulatory discharge of LH was delayed until 7.5+/-1.8 days after the fall in the level of progesterone. The incidence of these anomalies suggests that the ewes had 69% of the ovulations and 56% of the behavioral estrus as compared to ewes that cycled regularly.

[Circannual rhythms in the secretion of prolactin in the Peulh ewe]. / Rythme circannuel de sécrétion de la prolactine chez la Brebis de race peulh.

Plasma prolactin was measured by radioimmunoassay in 6 bicoloured Fulani ewes for 2 consecutive years. The highest concentrations (greater than 200 ng/ml) were observed in April/May when the days were the longest and the average temperature the highest. The lowest concentrations of prolactin (less than 100 ng/ml) occurred concomitantly with the shortest days and lowest temperatures in December/January. Regression coefficients between prolactin levels and photoperiod or temperature, respectively indicated that the correlations were stronger with photoperiod than temperature. These results therefore suggest (1) that the Sahelian climate has little influence on the rhythm of prolactin secretion in the ewe, and that even slight variations in day length can stimulate prolactin secretion; and (2) that there are marked individual variations in prolactin secretion levels in response to the various levels in photoperiod.

[Mathematical model on the development of progesterone in the cow: application and proof of differences between breeds]. / Modèle mathématique de l'évolution de progestérone chez la vache: application et mise en évidence de différence entre races.

Peripheral plasma progesterone levels were compared in "Normandy" (6), "Charolais" (6) and French Friesian (6) heifers. The progesterone curves were fitted to mathematical models for the luteal phase (a logistic function) and for the luteolytic phase (an exponential model). 1. Discriminating and multivariate analyses showed a breed difference in luteal phase duration (17.8 +/- 1.1, 16.8 +/- 2.3, 16.1 +/- 1.06 days, respectively, for Normandy, Charolais and French Friesian heifers) and in the rate of progesterone level increase (1.1 +/- 0.4, 1.09 +/- 0.3, 1.3 +/- 0.3 ng/ml/day, respectively) (chi 2 = 22.5; P less than 0.02). 2. Progressive multiple regression showed the duration of the luteal phase was highly correlated to oestrous cycle duration (20.8 +/- 1.7, 20.5 +/- 2.8, 19.2 +/- 1.5 days, respectively) (r = 0.89). It appears that breed differences in bovine oestrous cycle duration are due to differences in luteal phase duration. 3. The rate of progesterone level increase reached a maximum at 7.2 +/- 0.8, 6.9 +/- 1.1 and 6.4 +/- 0.6 days, respectively, concomitant with maximal corpus luteum secretion. 4. The reproducibility of these parameters, summarizing the progesterone pattern during two consecutive oestrous cycles, showed that each animal had an individual secretion pattern.

[Some reproductive characteristics of the Peulh ewe from Niger]. / Etude de quelques caractéristiques de reproduction chez la brebis Peulh, du Niger.

The duration of the oestrous cycle, oestrous, pregnancy and post-partum anoestrus, as well as the kinetics of plasma progesterone and prolactin levels during each of those periods, were studied in ewes of a tropical breed without wool. The value of the parameters and the profiles of the two hormones were comparable to those of other European and tropical breeds, suggesting that the Sahelian climate has little to do with the sexual endocrinology of the sheep.