Rangeland grazing to improve farm performance. Example for an extensive meat sheep farming system

Proceedings of the International Seminar Economic, social and environmental sustainability in sheep and goat production systems, Zaragoza, Espagne, 2010/11/10-12The objective of our study was to investigate with bio-technical and economic simulations, whether recognising the diversity of rangeland resources and re-organising reproductive and feeding management in consequence could improve the performance of extensive meat sheep systems. We used data from an experimental farm (INRA La Fage, Larzac plateau, southern France) to build a virtual case study. The farm comprises a flock of 330 ewes with high potential productivity (Romane breed, prolificacy > 240%), reared outdoors in a harsh environment: 280 ha of rangelands of which 18 ha have been long fertilized. We applied changes in flock management (1st lambing at 2 years, lambing date matching grass growth) and grazing management (function of each paddock, adapted paddock size, timing and intensity of utilisation over the year). Based on model predictions, the new system is more sustainable, with a higher net income (+40%) and a lower consumption of non renewable energy (-29%). These changes are explained mainly by a higher proportion of grazed forage (0.73 compared to 0.56 of total dry matter consumption, i.e. +30%), especially on rangelands (+50%), which reduces the energy and money needed to supply the flock with conserved forage and concentrate. The simulation results need to be validated with field data. A better knowledge of rangeland-based system is required to improve model calibration.Notre objectif était de déterminer avec des simulations biotechniques et économiques si prendre en compte la diversité des parcours et réorganiser la conduite de la reproduction et du pâturage en conséquence pouvait améliorer les performances des systèmes d’élevage ovins viande extensifs. Nous nous sommes appuyés sur les données d’une ferme expérimentale (INRA La Fage, Plateau du Larzac) pour construire une ferme virtuelle : 330 brebis avec un potentiel de production élevé (race Romane, prolificité > 240%) conduites en plein air intégral dans un milieu difficile (280 ha de parcours dont 18 ha fertilisés de longue date). Nous avons modifié la conduite du troupeau (1ère mise-bas à 2 ans, mise-bas calée sur la pousse de l’herbe) et la conduite du pâturage (fonctions aux parcs, taille des parcs, périodes et intensités d’utilisation adaptées). Les prévisions des modèles suggèrent que le nouveau système est plus durable, avec un revenu net plus élevé (+40%) et une consommation d’énergie non renouvelable plus faible (-29%). Ces changements sont dus principalement à l’augmentation des fourrages pâturés (0,73 contre 0,56 de la consommation totale de matière sèche, i.e. +30%), en particulier sur les parcours (+50%), ce qui réduit l’énergie et l’argent nécessaires pour fournir au troupeau des fourrages conservés et des concentrés. Les résultats devront être validés avec des observations de terrain. Une meilleure connaissance des systèmes d’élevages à composante pastorale permettrait d’améliorer le calibrage des modèles

Graze rangelands to improve farm performance: Example for an extensive meat sheep farming system

The objective of our study was to investigate with bio-technical and economical simulations, if recognising the diversity of rangeland resources and re-organising reproductive and feeding management in consequence could improve the performance of extensive meat sheep systems. We used data from an experimental farm (INRA La Fage, Larzac plateau, southern France) to build a virtual case study. The farm comprises a flock of 330 ewes with high potential productivity (Romane breed, prolificacy > 240%), reared outdoors in a harsh environment: 280 ha of rangelands of which 18 ha have been long fertilized. We applied changes in flock management (1st lambing at 2 years, lambing date matching grass growth) and grazing management (function to each paddock, adapted paddock size, timing and intensity of utlisation over the year). Based on model predictions, the new system is more sustainable, with a higher net income (+40%) and a lower consumption of non renewable energy (-29%). These changes are explained mainly by a higher proportion of grazed forage (0.73 compared to 0.56 of total dry matter consumption, i.e. +30%), especially on rangelands (+ 50%), which reduces the energy and money needed to supply the flock with conserved forage and concentrate. The simulation results need to be validated with field data. A better knowledge of rangeland-based system is required to improve model calibration.Notre objectif était de déterminer avec des simulations bio-techniques et économiques si prendre en compte la diversité des parcours et ré-organiser la conduite de la reproduction et du pâturage en conséquence pouvait améliorer les performances des systèmes d’élevage ovins viande extensifs. Nous nous sommes appuyés sur les données d’une ferme expérimentale (INRA La Fage, Plateau du Larzac) pour construire une ferme virtuelle : 330 brebis avec un potentiel de production élevé (race Romane, prolificité > 240%) conduites en plein air intégral dans un milieu difficile (280 ha de parcours dont 18 ha fertilisés de longue date). Nous avons modifié la conduite du troupeau (1ère mise-bas à 2 ans, mise-bas calée sur la pousse de l’herbe) et la conduite du pâturage (fonctions aux parcs, taille des parcs, périodes et intensités d’utilisation adaptées). Les prévisions des modèles suggèrent que le nouveau système est plus durable, avec un revenu net plus élevé (+40%) et une consommation d’énergie non renouvelable plus faible (-29%). Ces changements sont dus principalement à l’augmentation des fourrages pâturés (0.73 contre 0.56 de la consommation totale de matière sèche, i.e. +30%), en particulier sur les parcours (+50%), ce qui réduit l’énergie et l’argent nécessaires pour fournir au troupeau des fourrages conservés et des concentrés. Les résultats devront être validés avec des observations de terrain. Une meilleure connaissance des systèmes d’élevages à composante pastorale permettrait d’améliorer le calibrage des modèles

Le parcours, un élément de base du système d’alimentation ? Résultats et perspectives pour l'élevage ovin allaitant au domaine INRA de la Fage

National audienceLe domaine INRA de La Fage a mis en place depuis plus de 30 ans un troupeau de 330 brebis romanes conduit en plein air sur 262 ha de parcours de Causse…Quelle place occupent aujourd’hui les parcours dans l’alimentation de ce troupeau

Polyethylene glycol marker measured with NIRS gives a reliable estimate of the rangeland intake of grazing sheep

Polyethylene glycol (PEG) measured with NIRS is known to be a valuable faecal marker when used in indoor experiments. In order to verify whether it can be used at pasture, an experiment was conducted with two trials. In trial 1, six Romane breed adult dry ewes placed in metabolism cages were fed daily with natural, freshly cut rangeland from a fertilised or unfertilised paddock for 6 weeks. Three ewes did not receive PEG and the three others were dosed with 10 g of PEG in solution form once daily until the end of the experiment to measure in vivo dry matter digestibility and PEG recovery rate for each forage quality. At the same time (trial 2), 15 ewe lambs and 14 lactating adult ewes suckling one or two lambs were allowed to graze together on the same herbage as that cut for indoor ewes. All animals were initially equipped with faecal bags emptied twice daily for collecting total faeces, and eight ewe lambs and seven adults were dosed once daily with 10 g of PEG. Faecal grab samples were collected for 4 to 5 days for each forage quality grazed. Indoor trial 1 showed that PEG had no effect on dry matter intake (DMI) or on digestibility. PEG recovery rates measured on fertilised (77.7%) and unfertilised (82.1%) forage were not different ( P>0.05). PEG recovery rates measured at pasture did not differ( P>0.05) between pasture quality and animal type with an average value of 68.9%. Faecal output measured with bags or estimated with PEG and calculated DMI were not different ( P>0.05) when PEG recovery rate measured at pasture was used. Conversely, using indoor PEG recovery values, significantly ( P<0.05) or tended to overestimate faecal output. In conclusion, PEG could be used as a faecal marker administered at a minimal dose of 1% of DMI with a recovery rate measured under pasture conditions for pasture intake measurements on a group of animals at the same physiological stage but not for individual measurements

Clustering and genetic analysis of body condition score and body weight variations in meat sheep

il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : REPORTClustering and genetic analysis of body condition score and body weight variations in meat shee

Valeur alimentaire des parcours de Causse steppique du Larzac par les ovins viande

National audienc

Growth rates of females from a Romane sheep breed flock reared in rangelands and effects of an early or late first mating regime on their offspring.

International audienceBenefits in lifetime production of the ewe is often determined by the particular characteristics of the growth during the first stages of their life, including the related decision of the age at first mating. The objective of this work was to characterize the growth rates of the young female (from birth to first mating) from the Romane sheep breed, in a flock reared under the Mediterranean rangelands conditions of France. The effects of 2 contrasted first mating regimens (Early; 7 mo vs. Late; 19 mo old) on the individual growth rate of the ewe lamb and their first offspring were also evaluated. A database was built based on historical data that were extracted from the INRA database (GEEDOC). Data from 1359 females born during the period 2002–2012 were collected, processed and interpreted using SAS (9.3). From the total, 762 and 597 females were submitted to the Early or Late regimen, respectively. The effects of the litter size at their birth (singletons; SING vs. multiple; TWIN) and the age of their dams at birth (primiparous, PRIM vs. multiparous, MULT) were considered. The growth curves were built for both population (Early; 39.7 ± 0.07 kg and Late; 50.6 ± 0.04 kg BW at first mating) of ewes lambs. Significant interactions of the litter size at birth and the dam’s parity were found for BW at birth and BW at weaning. Overall, the ewes lambs born from MULT × SING and PRIM × TWIN dams showed the highest (4.7 ± 0.03 and 26.2 ± 0.15 kg) and lowest (3.3 ± 0.01 and 22.5 ± 0.09 kg) BW at birth and weaning, respectively. Even if submitting the ewes lambs from the actual flock to the Late regimen constituted a change on the reproductive management policy of the farm (from 2010), data showed that females submitted to Late corresponded to those having a weaker growth from birth to weaning. When analyzing the growth traits of their first offspring, the first litter size (1.8 ± 0.01 vs. 2.1 ± 0.01 lambs/lambing) and its total weight (6.2 ± 0.03 vs. 7.4 ± 0.02 kg) were different (P < 0.0001) for ewes submitted to the early or late regimen, respectively. Other related carry over effects during the whole productive life of this females’ population and their offspring are currently being analyzed

Genetic determinism of maternal behaviour in sheep and relationship with lamb mortality

Increasing behavioural autonomy of animals ensures their adaptation to various environments and contributesto the sustainability of livestock production. More particularly, maternal behaviour is vital for the offspringsurvival. Breed differences in maternal behaviour are well known but genetic variation within breed has beenpoorly investigated. The aim of the study was to estimate in sheep genetic parameters for maternal reactivityand search QTL associated with the related behavioural traits. Ewes (n=851) reared outside were individuallyphenotyped just after lambing in two behavioural tests based on the reactivity to separation from their lambsand/or to a human. Ewes were tested for one or two lambing. In the first test performed outdoor 2 hours afterlambing, the ewe’s reactivity was assessed by measuring flight distance from lambs, time to restore contactwith lambs and facility to follow transport of lambs. In the second test performed indoor 24 h after lambing,the ewe’s reactivity was assessed by measuring vocalizations, locomotion and proximity to lambs with orwithout human presence. Lamb mortality was recorded until weaning. Heritability estimates were moderate(h2=0.11 to 0.23±0.05) for flight distance from lambs, time to restore contact with lambs and facility to followthe transport of lambs. Genetic correlations between these traits ranged from 0.78 (±0.21) to 0.95 (±0.06). Forthe second test, heritability estimates ranged from 0.11 (±0.05) for proximity to 0.50 (±0.05) for vocalizations.Genetic correlations ranged from 0.13 (±0.06) to 0.44 (±0.07). Lamb mortality was significantly lower in ewesshowing a higher maternal reactivity. A genome wide association study of maternal reactivity is currentlycarried on in ewes genotyped using the Illumina ovineSNP50 beadchip. The moderate to high heritabilities andpotential SNPs polymorphisms for the behavioural traits of ewes may offer opportunities in genetic selectionfor improving maternal behaviour and reducing lamb mortality

Relationships between body reserve dynamics and rearing performances in meat ewes

The main objective of this work was to study the relationships between body reserve (BR) dynamics and rearing performance (PERF) traits in ewes from a Romane meat sheep flock managed extensively on "Causse" rangelands in the south of France. Flock records were used to generate datasets covering 14 lambing years (YR). The dataset included 1,146 ewes with 2 ages of first lambing (AGE), 3 parities (PAR) and 4 litter sizes (LS). Repeated measurements of the BW and BCS were used as indicators of BR. The ewe PERF traits recorded were indirect measurements for maternal abilities and included: prolificacy, litter weight and lamb BW at lambing and weaning, ADG at 1, 2 and 3 months after lambing and litter survival from lambing to weaning. The effects of different BW and BCS trajectories (e.g., changes in BW and BCS across the production cycle), previously been characterized in the same animals, on PERF traits were investigated. Such trajectories reflected different profiles at the intraflock level in the dynamics of BR mobilization-accretion cycles. Genetic relationships between BR and PERF traits were assessed. All the fixed variables considered (i.e., YR, AGE, PAR, LS and SEX ratio of the litter) have significant effects on the PERF traits. Similarly, BW trajectories had an effect on the PERF traits across the three PARs studied, particularly during the first cycle (PAR 1). The BCS trajectories only affected prolificacy, lamb BW at birth and litter survival. Most of the PERF traits considered here showed moderate heritabilities (0.17 to 0.23) except for prolificacy, the lamb growth rate during the third month and litter survival which showed very low heritabilities. With exception of litter survival and prolificacy, ewe PERF traits were genetically, strongly and positively correlated to BW whatever the physiological stage. A few weak genetic correlations were found between BCS and PERF traits. As illustrated by BW and BCS changes over time, favorable genetic correlations were found, even if few and moderate, between BR accretion or mobilization and PERF traits, particularly for prolificacy and litter weight at birth. In conclusion, our results show significant relationships between BR dynamics and PERF traits in ewes, which could be considered in future sheep selection programs aiming to improve robustness