CONVERSION OF A LAMB PRODUCTION SYSTEM TO ORGANIC FARMING: HOW TO MANAGE, FOR WHICH RESULTS?

Two sheep flocks were managed organically (for two years from conversion onwards) under different lambing strategies (1 lambing/year vs. 3 lambings every two years). The second system was tested as there was a producer’s interest in high productivity that is a guarantee of good economic results in conventional. Reproduction, feeding, lamb production, carcass quality, health (particularly internal parasitism), economic return of the flock, grass production, and pasture biodiversity were evaluated. The lambs were bred under low therapeutic input. The economical advantage of increasing lambing frequency was not demonstrated, whereas this strategy complexified management and resulted in higher internal parasitic infection of the lambs, and finally showed a lower stability. There were difficulties in establishing a very high feed self-sufficiency in both systems, especially the more intensive system (4 points lower), due to harsh climatic conditions; following this five-year experiment, we are changing our strategy to provide nitrogen in the systems

CONVERSION OF A LAMB PRODUCTION SYSTEM TO ORGANIC FARMING: HOW TO MANAGE, FOR WHAT RESULTS?

Two sheep flocks were managed organically for two years from conversion under different lambing strategies (1 lambing/year vs. 3 lambings every two years). The second system was tested because pf a producer’s interest in high productivity, which is a guarantee of good economic results in conventional production.. Reproduction, feeding, lamb production, carcass quality, health (particularly internal parasitism), economic return of the flock, grass production, and pasture biodiversity were evaluated. The lambs were bred with low therapeutic inputs. No economic advantage of increasing lambing frequency was demonstrated, whereas this strategy complicated management and resulted in higher internal parasitic infection of the lambs, and finally showed lower stability. There were difficulties in establishing a very high feed self-sufficiency in both systems, especially the more intensive system (4 points lower), due to harsh climatic conditions. Following this five-year experiment, we are changing our strategy to provide nitrogen in the systems

Rethinking agricultural systems and the role of herbivores

Agricultural systems can benefit from the nitrogen (N) and carbon (C) contributed by natural processes, such as photosynthesis and bacteria mediated fixation. Based on their professional experiences and discussions with innovative farmers, M. Journet and J.-P. Dulphy detail their thoughts on the unique role of ruminants in N and C cycles. Whether in the soil or in the rumen, the N cycle depends on C flows and microbial populations; N metabolism and use is optimised when the C/N ratio is about 20. Certain agricultural practices aim for balanced nutrient restitution and thus promote the autonomy and longevity of production systems. Such practices include raising ruminant livestock, using legume cover crops, integrating legume cover crops into commercial crop systems, increasing the surface area dedicated to grasslands, and choosing ruminant livestock based on their ability to recycle C and N.L'agriculture peut bénéficier des disponibilités naturelles d'azote et de carbone via la fixation symbiotique et la photosynthèse. Dans le sol comme dans le rumen, le cycle de l'azote est dépendant des flux de carbone et des populations microbiennes. La réorganisation et valorisation de N est optimale quand le ratio C/N est d'environ 20 dans le rumen comme dans le sol. Les restitutions des herbivores ont un faible ratio C/N, favorable à la minéralisation de N dans le sol et donc à son utilisation par le couvert végétal. Les pratiques agricoles visant des restitutions de composition équilibrée favorisent l'autonomie et la pérennité des systèmes de production : utiliser les couverts avec légumineuses, les intégrer dans les systèmes de grandes cultures, accroître la place des prairies, adapter le type de ruminant pour favoriser son rôle de recycleur de C et N... Plusieurs témoignages d'agriculteurs sont présentés

Intake and digestibility of different forages in Hamas compared to sheep

International audienc

Estimation of the duodenal flow of microbial nitrogen in ruminants based on the chemical composition of forages: a literature review

The objective of this study was to evaluate the estimation of the duodenal flow of microbial nitrogen (N) in ruminants fed forage only, per kilogram of dry matter (DM) intake, which is the yield of microbial protein (YMP). The estimation was based on the chemical composition of forages. A data file of 62 observations was collected from in vivo studies on cattle and sheep fed diets with forage only. A statistical analysis of YMP was conducted with neutral detergent fibre (NDF), crude protein (CP), non structural carbohydrates (NSC), group of forage species (legumes or grasses), method of conservation, physical form of presentation, level of DM intake, animal species, methodology and references as parameters. After a stepwise regression, CP was significant and the most important predictor. NSC or the method of conservation had an extra effect on YMP. On the basis of these three parameters the best fit equations were found and the influence of all parameters on YMP were discussed. Using the data file of this study, the prediction of YMP from the PDI-system was also validated. The statistics of the validation of the PDI prediction were similar to the statistics of the equations from this study. In conclusion, the chemical composition of forages, with or without the method of conservation, is a poor indication for the duodenal flow of microbial N (g$\cdot$kg$^{-1}$ DM intake) in ruminants fed diets with forages only.Estimation du flux d'azote microbien arrivant dans le duodénum à partir de la composition chimique du fourrage chez le ruminant recevant une ration composée uniquement de fourrage. L'objectif de cette revue bibliographique était d'évaluer la prévision du flux duodénal d'azote microbien chez un ruminant recevant une ration composée d'un seul fourrage, par kilogramme de matière sèche (MS) ingérée, c'est-à-dire le rendement en azote microbien (RNM). La prévision a été basée sur la composition chimique des fourrages. Un ensemble de données comprenant 62 observations a été constitué en sélectionnant les études in vivo sur bovins et moutons alimentés avec un seul fourrage. L'analyse statistique a porté sur la relation entre RNM et différents paramètres : teneur en glucides pariétaux (NDF), teneur en Matières Azotées Totales (MAT), teneur en glucides non-pariétaux (GLU), famille botanique (légumineuses ou graminées), méthode de conservation, forme physique de présentation, quantité de MS ingérée, espèce animale, méthode de mesure et références. Après la régression “ stepwise ”, l'effet de la teneur en MAT a été significatif et le plus important. GLU comme la méthode de conservation ont eu un effet supplémentaire sur RNM. À partir de ces 3 paramètres, les équations de prédiction sont proposées. Les paramètres statistiques des équations et l'influence des différents critères de prévision du RNM sont discutés. À partir de cette base de données, la prévision du RNM du système PDI était validée aussi. Les paramètres statistiques de la validation du système PDI étaient similaires aux paramètres statistiques des équations de cette revue bibliographique. En conclusion, la composition chimique d'un fourrage, avec ou sans la méthode de conservation, est une pauvre indication pour le flux duodénal d'azote microbien (en g$\cdot$kg$^{-1}$ MS ingérée) chez le ruminant recevant une ration composée uniquement de fourrage

Is intensification of ewe reproduction rhythm sustainable in an organically managed sheep production system? A 4-year interdisciplinary study

A 4-year interdisciplinary study was performed to compare two organically managed sheep production systems, using 118 ewes and 24 ha each. The systems differed in the ewes’ reproduction rhythm: one lambing per ewe per year (1L/1Y), with the aim of balancing feed self-sufficiency and lamb marketing periods v. three lambings over 2 years (3L/2Y), with the aim of maximising ewes’ productivity. The sustainability was evaluated through ewes’ reproductive performance, lamb growth rate, carcass characteristics and quality, animal health, forage and feed self-sufficiency, soil mineral balance and gross margin. General animal health was assessed by recording ewe and lamb mortality and putative cause of death. Nematode digestive-tract strongyles parasitism was studied using faecal egg counts and necropsies. Carcass quality was assessed by recording carcass weight, conformation and fatness, and colour and firmness of subcutaneous fat. Thirty-three percent of 3L/2Y ewes lambed twice a year against 4% of 1L/1Y. Mean ewe productivity was 161.3% and 151.0% in 3L/2Y and 1L/1Y, respectively, and it was more variable between years in 3L/2Y. Average concentrate feed consumption and the corresponding cost per ewe were higher in 3L/2Y than in 1L/1Y (156 v. 121 kg, and h49.5 v. h39.3, respectively). Finally, average gross margin was lower in 3L/2Y than in 1L/1Y (h59 v. h65 per ewe, respectively). Even in year 2002, when ewe productivity was highest in 3L/2Y (193%), gross margin was not different between systems (h90 v. h86 per ewe in 3L/2Y and 1L/1Y, respectively), because of higher concentrate costs in 3L/2Y. The 3L/2Y animals presented a lower health status, with a higher lamb mortality ( P,0.05) and a higher digestive-tract strongyles and coccidia parasitism level ( P,0.05). Lamb carcass conformation, fatness and fat colour were not different between systems, but carcass weight and subcutaneous dorsal fat firmness were lower in 3L/2Y lambs than in 1L/1Y lambs ( P,0.05 and ,0.001, respectively). Intensification in an organically managed sheep system, through an increased reproduction rhythm, thus did not lead to better economic results and proved riskier, more variable and more difficult to manage, and so less sustainable. The less intensive system (1L/1Y) was both highly efficient from the animal standpoint and highly feed self-sufficient. The technical and economic results of this system were better than those of organic private farms in the same area and matched those of non-organic farms

Study of modes of preparation of fresh and conserved forage samples for measurement of their dry matter and nitrogen degradations in the rumen

International audienc

Les phénomènes de substitution fourrages-concentrés chez la vache laitière

National audienceThe effects of the concentrate supplementation level, the type of roughage and the type of concentrate on the substitution rate (SR) between roughage and concentrates have been studied over a course of 8 trials in three experimental sites. In each trial, the 3 levels of concentrates were compared using a 3x3 Latin square design, repeated with 3 or 4 groups of Holstein-Friesian crossbred cows in mid-lactation, each period lasting 1 month. The 8 trials corresponded to 8 different diets according to the type of roughage and the type of concentrates used. The SRs increase systematically with the concentrate supplementation level, on average 0.47 between L and M and 0.67 between M and H. For a given roughage, the increase in the energy concentration of the concentrate corresponds to an increase in the SR values, mainly between L and M. The average SR values observed when using maize silage (0.7) are higher than those observed with grass silage (0.53) and also for the hay (0.44). These trials show, looking at the 3 variation factors in the study, that in mid-lactation, the higher the energy balance is, the more important the SR values become.Les principaux facteurs de variations des taux de substitution (TS) entre fourrage et aliments concentrés que constituent le niveau d’apport du concentré, la nature du fourrage et la nature de l’aliment concentré ont été étudiés au cours de 8 essais réalisés en 3 lieux différents. Dans chaque essai, 3 niveaux de d’apport de concentrés (bas, moyen et haut) ont été comparés selon un schéma carré latin 3x3, répété 3 ou 4 fois, avec des vaches pie-noires en milieu de lactation et au cours de périodes de 1 mois. Les 8 essais correspondaient à 8 régimes différant par la nature du fourrage (ensilage de maïs, ensilage d’herbe ou foin) et la nature du concentré (riche en amidon, riche en parois très digestibles, ou riche en parois moyennement digestibles). Quels que soient les fourrages et les concentrés, le taux de substitution augmente systématiquement avec le niveau d’apport de concentré : il passe, en moyenne, de 0,47 entre les niveaux bas et moyen à 0,67 entre les niveaux moyens et haut. Pour un fourrage donné, le taux de substitution est plus élevé lorsque la concentration énergétique du concentré est plus forte, mais cet écart n’existe qu’entre les niveaux bas et moyen d’apport. Les taux de substitution moyens observés sur ensilage de maïs (0,70) sont supérieurs à ceux observés sur ensilage d’herbe (0,53) ainsi que sur foin (0,44). Ces essais montrent, à travers les 3 facteurs de variations étudiés, que les taux de substitution observés en milieu de lactation sont d’autant plus importants que le bilan énergétique des animaux est plus élevé

Amélioration de la mesure et de la prévision de l'ingestibilité des fourrages chez le mouton par la prise en compte des variations de la capacité d'ingestion à l'aide d'un fourrage témoin

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