Le ranch de la Nyanga (Gabon). Introduction de l'élevage bovin dans un pays d'Afrique Equatoriale

Dans le cadre d'une politique de diversification de ses activités et d'exploitation des potentialités du pays, le gouvernement Gabonais a décidé, il y a une dizaine d'années, d'introduire l'élevage bovin à grande échelle. Les difficultés sont multiples : territoires propices à l'élevage (savanes) restreints, présence d'une pathologie et particulièrement de la trypanosomose, absence de tradition d'élevage dans le pays... Trois ranches ont été créés dans le cadre de ce projet, dont le plus important, le ranch de la Nyanga, situé près de Tchibanga. Trois facteurs ont influencé les choix techniques : contexte écologique, expérience des fondateurs, technique du projet, possibilités financières et cadre économique. Plus de cinq ans après le démarrage effectif du projet, il est dressé un bilan des résultats obtenus et l'avenir technique et économique du projet est considéré. (Résumé d'auteur

Hair cortisol in horses (Equus caballus) in relation to management regimes, personality and breed

Hair cortisol is a promising biomarker to measure long-term stress since cortisol is incorporated into the hair shaft as it grows. However, few studies have previously assessed hair cortisol concentrations (HCC) in horses. In this study, HCC was evaluated in both mane hair from the neck and body hair from the withers in 153 horses of different breeds, from seven different stables with three different management regimes (Free-roaming horses, Riding school horses, Trotter horses). In addition, 4 hours of behavioral observations were performed at each stable, and for 43 of the horses, a personality survey was completed. Mane and withers HCC correlated moderately, but significantly (rs=0.48, p<0.001). Differences between the stables were found for both mane and withers hair (both p<0.01) and the stable with lowest HCC also showed highest occurrences of positive social and resting behaviors (both p<0.01). There were no significant differences in HCC between the management regimes even though Free-roaming horses showed less negative social behavior compared to Riding school horses (p=0.041) and Trotter horses (p=0.055). The personality traits Dominance, Anxiousness, and Excitability revealed weak to moderate correlations with mane HCC (rs=-0.34, p=0.027; rs=-0.46, p=0.002; rs=-0.31, p=0.043 respectively) which might suggest that personality could also be related to long-term stress levels in horses

Evaluation of a field test for trypanotolerance in young N'Dama cattle

Evaluates components of a short term test for trypanotolerance criteria in N'Dama post-weaners exposed to a medium natural trypanosome challenge in Gabon; compares the effectiveness of different measures of control of development of anaemia; and measures the post-test recovery of packed red cell volume (PCV) values following treatment with a trypanocidal drug

Measurement of trypanotolerance criteria and their effect on reproductive performance of N'Dama cattle

Evaluates in detail how environmental and stress factorts affect trypanosome infection in N'Dama cows and their calves, the linkages with curative drug treatment given under the management regime prevailing, the linkages with anaemia control as measured by packed red cell volume (PCV), and the resultant influences on animal performance. Major findings were that over the period from calf birth to weaning, while calves and their dams grazing together had similar numbers of trypanosome infections detected, the Trypanosoma vivax : T. congolense rations were very different: 1:0.7 in calves and 1:2.8 in cows. This indicated that some ability to control the development of parasitaemia following T. vivax infection might be being acquired, from weaning onwards. Table 1 summarizes the data on trypanosome infection, curative drug treatment, PCV value and performance trait levels in the 458 pre-weaner calves, the 458 lactating cows and the 1028 cow-year reproduction records available over the 5-year period. These are the actual overall infection rates recorded, the levels of curative drug treatments required and the PCV values, calf growth and cow calving rates achieved

Aspects of trypanotolerance and associations with growth rate in post-weaner N'Dama cattle under high trypanosomiasis risk

A study conducted to find out the ability of N'Dama cattle to control parasitaemia and anaemia at a ranch in Gabon. Examines the effect of parasitaemia on daily liveweight change

Glossina fusca group tsetse as vectors of cattle trypanosomiasis in Gabon and Zaire

The significance of Glossina fusca group tsetse flies as vectors of cattle trypanosomiasis was examined using biconical traps to survey tsetse populations at one site in Gabon and two sites in Zaire. Mean trypanosome infection rates in G. tabaniformis Westwood over the study period ranged from 8.9 - 17.7 percent at the two sites. The mean infection rate in G. nashi Potts was 6 percent. Up to 49 percent of bloodmeals of G. tabaniformis were from cattle. Trypanosome prevalence in cattle where G. tabaniformis appeared to be the main vector was 9.5 percent and 5.4 percent at the Mushie and OGAPROV ranches respectively. A highly significant positive correlation was found between tsetse challenge and trypanosome prevalence in N'Dama cattle across sites. Tsetse challenge was defined as the product of tsetse relative densities, trypanosome infection rates in the flies and the proportion of feeds taken by them from cattle. Thus G. tabaniformis can be an important vector of pathogenic Trypanosoma species in cattle

Relationships between tsetse challenge and trypanosome prevalence in trypanotolerant and susceptible cattle

Reports results of a study on the relationships between tsetse challenge and trypanosome prevalence in trypanotolerant and susceptible breeds of cattle. Presents data on tsetse challenge and trypanosome prevalence in N'Dama and Zebu cattle in Zaire, Gabon, Ethiopia and Cote d'Ivoire

Tsetse feeding habits and tsetse challenge at sites of the African Trypanotolerant Livestock Network

Reports the feeding preferences of Glossina species at sites of the African Trypanotolerant Livestock Network. Estimates tsetse challenge and relates the results with trypanosome prevalence in cattle. Examines the relationship between tsetse challenge using linear regression analysis. Also examines the difference between the slopes of the regression lines obtained for trypanotolerant and susceptible cattle using a 't-test'