Comparaison de l'ingestion et de la digestion de moutons alimentés, à base de fourrage vert, à l'auge et au pâturage

Diffusion du document : INRA Antilles-Guyane, Unité de Recherches zootechniques, Domaine Duclos 97170 Petit-Bourg (Guadeloupe), France Diplôme : Dr. d'UniversitéTHE AIM OF THIS STUDY WAS TO EVALUATE DIFFERENCES IN FEEDING INDOOR OR AT PASTURE AND TO EXPLAIN THE DIFFERENCES. THE STARTING HYPOTHESISES WERE THAT FEEDING DIFFERENCES EXIST BETWEEN ANIMALS FED INDOOR AND AT PASTURE, WHEN THE SAME FORAGE IS OFFERED, THE ORIGIN OF THESE DIFFERENCES IS RELATED TO THE PRESENTATION OF THE FORAGE TO THE ANIMALS. THE METHODOLOGICAL STUDIES SHOWED THAT NEAR INFRARED REFLECTANCE SPECTROSCOPY (NIRS) ALLOW TO PREDICT DIGESTIBILITY (SECV = 2.02 % AND R² = 0.77) AND THE CHEMICAL COMPOSITION OF THE FORAGE REALLY INGESTED. THE INCREASE OF THE NUMBER OF DATA IN THE CALIBRATION DATA SET ALLOWED TO IMPROVE THE PREDICTION OF DIGESTIBILITY (SECV = 1.75 AND R² = 0.85). THE PREDICTION OF DIGESTIBILITY FROM THE FECAL NITROGEN METHOD DID NOT SIGNIFICANTLY AFFECT THE PRECISION AND THE PARAMETERS OF THE EQUATION. THE USE OF THE NIRS AND FECAL NITROGEN EQUATIONS TO PREDICT DIGESTIBILITY OF AN INDEPENDENT DATA SET ALLOWED PRECISE ESTIMATIONS. THE EXPERIMENTAL STUDIES SHOWED THAT DIGESTIBILITY IS GREATER AT PASTURE (65.0 % INDOOR VS 67.0 % AT PASTURE, P < 0.05), 2) DUE TO SELECTION PROCESS IMPLEMENTED AT PASTURE, WHEREAS, INTAKE (77.2 G / 0.75 0.75 KG BWINDOOR AND 64.64 G / KG BW, P < 0.001) AND AMOUNT OF DRY MATTER DIGESTIBLE INTAKE (50.13 G / KG BW0.75 INDOOR AND 43.33 G / KG BW0.75 AT PASTURE, P < 0.001) ARE GREATER INDOOR; DUE TO GREATER PREHENSIBILITY OF FORAGE INDOOR; THAT DIFFERENCES OF INTAKE AND DIGESTIBILITY BETWEEN INDOOR AND PASTURE VARY ACCORDING TO THE QUALITY AND THE QUANTITY OF GRASS OFFERED.L’OBJECTIF DE CE TRAVAIL ÉTAIT DE METTRE EN ÉVIDENCE DES DIFFÉRENCES D’ALIMENTATION ENTRE L’AUGE ET LE PÂTURAGE QUAND LE MÊME FOURRAGE EST PROPOSE, ET DE LES EXPLIQUER. LES HYPOTHÈSES DE DÉPART ÉTAIENT QUE DES DIFFÉRENCES D’ALIMENTATION EXISTENT, ET QUE L’ORIGINE DE CES DIFFÉRENCES SE SITUE DANS LE MODE DE PRÉSENTATION DU FOURRAGE A L’ANIMAL. LES ÉTUDES MÉTHODOLOGIQUES ONT MONTRE QUE LA SPECTROSCOPIE DANS LE PROCHE INFRAROUGE (SPIR) PERMET DE PRÉDIRE LA DIGESTIBILITÉ (SECV=2.02% ET R²=0.77) ET LA COMPOSITION CHIMIQUE DU FOURRAGE RÉELLEMENT INGÉRÉ PAR DES OVINS. L’AUGMENTATION DU NOMBRE DE DONNÉES DE CALIBRATION A PERMIS AMÉLIORER LA PRÉDICTION DE LA DIGESTIBILITÉ (SECV=1.75 ET R²=0.85). LORSQUE LE NOMBRE DE DONNÉES DE CALIBRATION AUGMENTE, LA MÉTHODE AZOTE FÉCAL N’A SIGNIFICATIVEMENT MODIFIE NI LA PRÉCISION, NI LES PARAMÈTRES DE LA RÉGRESSION. L’UTILISATION DES ÉQUATIONS SPIR ET AZOTE FÉCAL POUR PRÉDIRE LA DIGESTIBILITÉ SUR DES DONNÉES INDÉPENDANTES, A PERMIS D’OBTENIR DES ESTIMATIONS PLUS PRÉCISES (RSD=2.53 ET 2.80, POUR LA SPIR ET L’AZOTE FÉCAL, RESPECTIVEMENT). LES ÉTUDES EXPÉRIMENTALES ONT MONTRE QUE LA DIGESTIBILITÉ EST PLUS ÉLEVÉE AU PÂTURAGE (65.0 % A L’AUGE VS 67.0% AU PÂTURAGE, P <0.05) SUITE A LA SÉLECTION DU FOURRAGE AU PÂTURAGE, ALORS QUE L'INGESTION (77.21G/KG PV 0.75 0.75 A L’AUGE VS 64.64G/KGPV AU PÂTURAGE, P<0.001) ET LA QUANTITÉ INGÉRÉE DIGESTIBLE (50.13 G/KGPV0.75 A L’AUGE VS 43.33G/KGPV0.75 AU PÂTURAGE) SONT PLUS ÉLEVÉES A L’AUGE, LIÉES A DES VARIATIONS DE LA PREHENSIBILITE DU FOURRAGE ENTRE AUGE ET PÂTURAGE. LES DIFFÉRENCES ENTRE L’AUGE ET LE PÂTURAGE VARIENT EN FONCTION DE LA QUALITÉ ET DE LA QUANTITÉ DE FOURRAGE OFFERT

Comparison of fecal crude protein and fecal near-infrared reflectance spectroscopy to predict digestibility of fresh grass consumed by sheep

Organic matter digestibility (OMD), an essential criterion for the evaluation of the nutrition of ruminants, cannot be measured easily at pasture. Therefore, the objective of this study was to test and compare 2 methods of OMD prediction based on the fecal CP content (CPf) or near infrared reflectance spectroscopy (NIRS) applied to feces. First, published equations derived from fecal N (Eq. 1CP, n = 40) and from fecal NIRS (Eq. 1NIRS, n = 84) were used to predict OMD of an independent validation data set from which in vivo OMD, ranging from 58 to 74%, was measured for 4 regrowth stages of Digitaria decumbens. Second, to establish equations usable in grazing situations and to improve the efficiency of the predictions, new equations were calculated from a large data set (n = 174) using CPf (Eq. 2CP) or fecal NIRS (Eq. 2NIRS). By applying the CPf method, Eq. 2CPf (OMD, % = 88.4 – 263.9/CPf, % of OM; residual SD = 2.92, r2 = 0.63) showed similar statistical parameters (P < 0.01) when compared with Eq. 1CP (OMD, % = 86.6 – 266.2/CPf, % of OM; residual SD = 2.95, r2 = 0.79). When using fecal NIRS, Eq. 2NIRS showed decreased SE of calibration (SEC = 1.48) and of cross-validation (SECV = 1.75) and greater coefficient of determination of cross-validation (R2CV = 0.85) than the previously published Eq. 1NIRS (SEC = 1.78, SECV = 2.02, R2CV = 0.77). The validation of the 4 equations on the validation data set was satisfactory overall with an average difference between the predicted and the observed OMD ranging from 0.98 to 2.79 percentage units. The Eq. 2NIRS was nevertheless the most precise with a decreased residual SD of 2.53 and also the most accurate, because the SD of the average difference between predicted and observed OMD was the lowest. Therefore, fecal NIRS provided the most reliable estimates of OMD and is thus a useful tool to predict OMD at pasture. However, an adequate number of reference data are required to establish good calibration. Indeed, better calibration statistics were obtained by increasing the data set from 84 (Eq. 1NIRS) to 174 (Eq. 2NIRS). In contrast, using fecal N on a set of 84 or 174 points did not improve the prediction. Both methods are useful for predicting OMD at pasture in certain circumstances, using fecal NIRS when a large data set (n = 84 and n = 174) is available and fecal CP with smaller data sets (n = 40)

Work organization as a barrier to crop–livestock integration practices: a case study in Guadeloupe

International audienceCrop-livestock integration exploits the synergies between cropping and livestock systems, mainly by using animal excreta as an organic crop fertilizer or using crop products as animal feed. From an environmental and economic point of view, crop-livestock integration is thought to increase system autonomy and resilience. However, little research has addressed its social impact and particularly the relationship between crop-livestock integration and work organization although, like most agroecological practices, crop-livestock integration was considered time-and labor-intensive. Here we used quantitative indicators based on the "Qualification and Evaluation of Work" method coupled with qualitative interviews with farmers to understand how implementation of crop-livestock integration practices is affected by work characteristics (perception, organization, duration, and arduousness). This framework was implemented on 14 farms selected from a typology of mixed crop-livestock systems in Guadeloupe (French West Indies), where high labor costs heighten the tension between work organization and agroecological practices. Our results show that three patterns of crop-livestock integration shaped work organization: family farms with strong crop-livestock integration (Pattern 1, n=6 farms), farms with moderate crop-livestock integration (Pattern 2, n=5 farms), and intensive productivity-driven farms (Pattern 3, n=3 farms). We also show for the first time that farmer perceptions of work, especially with animals, influences level of implementation of crop-livestock integration practices. In Pattern 1, work with livestock is done by the farmers themselves or by skilled and trusted persons from their inner circle. In Pattern 3, livestock was considered a source of on-farm income, and work with livestock, including crop-livestock integration practices, is readily delegated to employees or volunteers. Whatever the pattern, the time burden of collecting crop-products and excreta was cited as a primary barrier to further implementation. Actionable opportunities for further implementation of these patterns of croplivestock integration practices are discussed

De l’innovation à l’adoption de nouvelles pratiques de production dans la filière banane

National audienceDans la filière de production de banane aux Antilles, mieux conjuguer performances économiques et environnementales impose un changement de pratiques dans les systèmes de production. Pour contribuer à ce changement, la recherche agronomique développe des solutions techniques innovantes qui ne sont malheureusement pas toujours adoptées par les agriculteurs. Pour faire mieux converger les innovations agronomiques développées par la recherche avec les attentes et contraintes des producteurs, nous avons mis au point une méthode d’évaluation ex ante des conditions d’adoption. Quels systèmes innovants faut-il préconiser dans les différents types d’exploitations ? Quels impacts agro-environnementaux et économiques auront les innovations sur les exploitations et leur fonctionnement ? Quels seront les freins et les motivations à leur adoption ? Quelles politiques mettre en œuvre pour les favoriser ? L’objectif de la méthode que nous avons développée est de répondre à ces questions.La méthode d’évaluation que nous proposons est basée sur la combinaison de modèles agronomiques avec des modèles économiques. D’abord nous identifions par enquête la diversité régionale des exploitations, tant biophysique que socio-économique. Puis l’offre d’innovations agro-écologiques est recensée pour construire un pool de systèmes innovants plus ou moins complexes. Nous utilisons un modèle bio-économique pour prévoir quelles seront les conséquences de l’adoption des systèmes innovants dans les différents types d’exploitations. Les résultats de ces simulations sont alors utilisés pour questionner directement les agriculteurs sur leur consentement à adopter de tels systèmes, sous différents scénarios de prix et d’aides. La modélisation économétrique de ces choix permet enfin de révéler et quantifier les motivations et les freins à l’adoption, et de fonder une politique d’innovation adaptée aux diverses attentes des agriculteurs.En Guadeloupe et en Martinique, nous avons pu identifier une grande diversité de milieux physiques, de structures d’exploitations et de systèmes de culture. Pour renforcer la durabilité de ces divers modes de production, les solutions agro-écologiques candidates sont nombreuses. Celles-ci consistent en l’utilisation de plantes de services cultivées en association ou en rotation avec la banane, à l’intégration avec des systèmes d’élevage et au recours à de nouvelles variétés. Ces innovations ont été assemblées de manière cohérente en une vingtaine de prototypes de systèmes de production permettant de remplacer une gestion de la fertilité et des ravageurs qui est conventionnellement chimique, par une gestion plus durable, basée sur des régulations biologiques au sein de l’agro-écosystème. Nous avons ainsi identifié des options permettant de produire autant voire plus, tout en réduisant l’usage de pesticides de 25 à 50 % par rapport aux systèmes conventionnels. Ces systèmes sont néanmoins généralement plus consommateurs en main d’oeuvre et en savoirs. Notre méthode d’évaluation nous permet d’identifier trois types de recommandations pour concilier performances économiques, respect environnemental et fortes probabilités d’adoption par les agriculteurs : le ciblage des prototypes par type d’exploitation, le soutien à l’innovation via des subventions découplées et la poursuite de l’organisation de filière autour d’une production à haute valeur ajoutée

Work organization as a barrier to crop-livestock integration practices: A case study in Guadeloupe

International audienceCrop-livestock integration is thought to increase system autonomy and resilience by transitioning system components into a circular economy. Like most agroecological practices, crop-livestock integration is considered time-and labor-intensive. We hypothesized that work characteristics (organization, duration, and arduousness) and subjective factors related to work with animals shaped the implementation of crop-livestock integration practices in mixed crop-livestock systems and vice versa. The Qualification and Evaluation of Work method (QuaeWork) was coupled with qualitative interviews. This framework was implemented on 14 farms selected from a typology of mixed crop-livestock systems in Guadeloupe (French West Indies), where the high cost of labor raises tension between work organization and agroecological practices. Three patterns of crop-livestock integration shaped work organization: family farms with strong crop-livestock integration (Pattern 1, 6 farms), farms with moderate crop-livestock integration (Pattern 2, 5 farms), and intensive productivity-oriented farms (Pattern 3, 3 farms). These patterns have different farm characteristics and work organizations. Pattern 2 spent more time using crop by-products as animal feed (on average 253 h/year) than Pattern 1 (on average 222 h/year), whereas Pattern 3 did not use crop-products to feed animals. Farms in Pattern 3 spent more time using crop excreta to fertilize crops (on average 29.8 h/year) than Pattern 2 (on average 19.6 h/year) and Pattern 1 (on average 13.4 h/year). In Patterns 1 and 2, the low availability of family labor, and lack of the presence of skilled employees, may hold back whole-farm crop-livestock integration development and increase in animal units, whereas, in Pattern 3, management of the nutritional value of crop by-products and the cost related to employing additional persons would do so. The subjective link to animals can be more relational (Pattern 1), practical (Pattern 2), or economic (Patterns 2 and 3) regarding farmers' objectives. Adapted mechanization, direct collection of feed and deposition of feces by animals, targeted supportive policies and market governance, and organizational innovation beyond the farm level are discussed as levers that can be operated depending on the pattern

The ability of near infrared reflectance spectroscopy (NIRS) to assess quality and level of tropical grass intake by creole sheep

National audienceNear infrared spectroscopy is increasingly use as an alternative to classical analytical method to evaluate quality and functional properties animal feeds and human food. This method provides a rapid, clean and green, and accurate measure of chemical composition of diet. At the same time, attempts to evaluate these parameters in grazing systems are laborious, time consuming, costly and introduce bias in parameter estimation. The aim of this study is to evaluate the potential of faecal and forage NIRS to assess functional properties of diet ingested by Creole sheep. Derived standard errors of cross validation (SECV) and coefficient of determination using faecal spectra were 2.18% and 0.70 for organic matter digestibility, 9.27g/kgP0.75 and 0.28 for organic matter intake and 6.76 g/kgP0.75 and 0.27 for digestible organic matter intake. Association of faecal and herbage spectra lead to increase of prediction accuracy of 17.4, 7.4 and 7.2 % for organic matter digestibility, organic matter intake and digestible organic matter intake respectively. These results clearly indicate that near infrared reflectance spectroscopy represent a new tool to study and monitor breeding systems

Le bon sens paysan revient au coeur de notre agriculture

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Relations entre pratiques agroécologiques et organisation du travail au sein des systèmes polycultures élevage tropicaux

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