Rapport: conférence électronique sur l'aviculture en Afrique

Cette conférence électronique, du 3 juillet au 11 août 2008, relance la discussion sur les contraintes de l'aviculture et les solutions à y apporter pour en faire un levier important dans les stratégies de réduction de la pauvreté

Aflatoxins in dairy cattle feed in Senegal

Aflatoxins are toxic byproducts from moulds, especially Aspergillus flavus. These moulds grow on crops, and in particular maize and ground nuts are often contaminated. In humans, aflatoxins cause rare, high case fatality outbreaks (acute aflatoxicosis) while long term consumption leads to hepatocellular cancer (globally, around 20,000 deaths annually). Aflatoxins are also associated with childhood stunting, although a causal relation is not yet proven. Humans are exposed through the consumption of contaminated foods, including cereals, legumes and human and animal milk (as aflatoxins are excreted in milk). Similarly in livestock, aflatoxins cause hepatic disease, immunosuppression and reduced productivity. In tropical and sub-tropical developing countries, aflatoxins are common and 4.5 billion people are chronically exposed. In addition to the burden of this exposure, the reduction in livestock productivity impacts food security and trade and hence increases aflatoxins' total burden. Knowledge about aflatoxins in Senegal is scarce, especially in relation to the dairy cattle value chain. In this pilot project we measured aflatoxin B1 levels in dairy cattle feeds. Feed samples were obtained from low-input cattle farms in two regions in Senegal (the Thies and Diourbel regions) in August 2015, with between 16 and 36 samples per feed type. Aflatoxin levels were determined by a commercial competitive ELISA. Feeds with the highest levels of aflatoxin were purchased concentrate (with an average of 50 ppb, and a range of 0 to 305 ppb), ground-nut cake (45ppb, 0 to 187ppb) and millet bran (37ppb, 0 to186 ppb). A number of other feeds tested contained aflatoxins at lower levels, namely cornmeal (18ppb, 0 to 104 ppb), wheat bran (9ppb, 0 to 41 ppb) and rice bran (7ppb, 0 to 58ppb). The percentage of feed samples that were above the World Health Organisation's recommended limit for aflatoxin in animal feed (of 5ppb) was high, for example 96% for ground-nut cake, 80% for millet bran, and 69% for concentrate. Although, the aflatoxin levels reported may not significantly affect herd productivity, their impacts on susceptible livestock and carry-over to animal source food may be problematic. Overall, these results suggest the need for further investigation on aflatoxin in Senegal dairy

Estimation de la variabilité de la digestibilité et des émissions de méthane (CH4) des régimes des ruminants en fonction de la saison sur parcours sahélien

Les ruminants, du fait de leur processus de digestion des aliments, produisent du CH4. Notre objectif dans cette étude, est d’obtenir des données sur la qualité des régimes alimentaires du cheptel sahélien et la relation entre celle-ci et la production de méthane. Pour cela, des données ont été collectées d’octobre 2013 à septembre 2014 sur trois vaches suivies à Niassanté (village d’éleveur) et trois taurillons au centre de recherches zootechnique de Dahra. Les échantillons de fèces et de régimes prélevés ont été ensuite triés par groupes botaniques, pesés, séchés, broyés et analysés par SPIR. La digestibilité de la matière organique (dMO) et la production de méthane ont été calculées à partir des équations de prédiction. La dMO est de 51,26 ± 1,35% à Niassanté et 52,62 ± 3,28% à Dahra. La saison de collecte du régime affecte significativement la dMO (p = 0,000). La production de CH4 est en moyenne de 75 litres/jour/animal et est significativement affectée par la période de l’année (p= 0,000) et la quantité de matière sèche ingérée. Elle est négativement affectée par la dMO des régimes ingérés par les bovins (r = -0,308 ; p = 0,013). Il serait donc intéressant de bien caractériser les ressources fourragères utilisées par nos animaux et de déterminer leurs valeurs alimentaires.© 2016 International Formulae Group. All rights reserved.Mots clés: Digestibilité, régime alimentaire, émission méthane, Zébu GobraEnglish Title:  Estimation of digestibility variability and methane (CH4) emission of ruminants diets depending on the season in Sahelian pastureEnglish AbstractRuminants, due to their food digestion process, produce CH4. Thus, the objective of this study is to obtain data on quality of Sahelian animals’ diets and the relationship between it and the production of CH4. For this, data were collected from October 2013 to September 2014 in three cows followed at Niassanté (a village of farmer) and three bulls at livestock research center of Dahra. Feces samples taken and collected diet were then sorted by botanical groups, weighed, dried, crushed and analyzed by NIRS. The organic matter digestibility (OMD) and methane production were calculated from prediction equations. The OMD is 51.26 ± 1.35% to Niassanté and 52.62 ± 3.28% to Dahra. The collected diet according the season has significant effects on the OMD (p = 0.000). CH4 production is on average of 75 liters/day /animal and is significantly affected by the period of year (p = 0.000) and the amount of ingested dry matter. It is negatively affected by the digestibility of the organic matter ingested by cattle (r = -0.308; p = 0.013). It would be interesting to characterize forage resources used by animals and determine their dietary values.© 2016 International Formulae Group. All rights reservedKeywords: Digestibility, diet, methane emission, Gobra Zeb