• Energy Research

Some theoretical concepts are discussed, regarding to the systemic and the adaptive capacities approaches of farming systems and their components. They are presented as essential attributes when looking for achieving the goals of overall resilience and farming systems’ sustainability. In the first part, with an applied and context-dynamic perspective, some hierarchical concepts and strategies of integration and adaptation are analyzed, leading to reduce the vulnerability of the systems. In the second part, three successful farming systems’ case studies (two from Mexico and one from Cuba) are described. The last to illustrate with real practical experiences, the integrated application of some of such theoretical concepts, practical strategies of intervention, and mechanisms of regulation that are previously discussed, and that would be orientated to promote the long-term adaptive capacities of the farming systems. The valorization of those mechanisms of regulation (homeostasis, teleophoresis) at all levels would build up the angular stone in the promotion of systems integrated themselves by robust components. Those systems components would be capable of reacting with sound adaptive responses when facing eventual, unpredictable internal and external disturbances, in the time and in the space. Meanwhile, with the application of such effective strategies, we would be in better conditions for helping to create a solid commitment between productivity and the objectives of rational use of natural and local resources. Finally, this change in the philosophy of the farming systems management would help to promote the required sustainability of farming systems, either from the economic, environmental and social standpoints.

In a previous work we demonstrated that efficiency in body reserves (BR) mobilization/accretion was affected by parity [multiparous (MULT) ewes being more flexible than primiparous], litter size and physiological stage (peaks of BR mobilization attained around lambing and 1 mo after mating). The objective of this study was to estimate the dynamic individual energy balance of periparturient MULT Romane grazing ewes, from 15 d before until 15 d after lambing. A group of MULT ewes (n=20), allocated according to litter size (lambing and suckling singletons, SING -n=10-, or twins, TWIN -n=10) was used. Details on management and feeding were reported by González-García et al. (2014). At late pregnancy, ewes were in rotational grazing of native rangeland and supplemented with 0.7, 2.0 and 0.8 kg/d of hay (Dactylus glomerata and alfalfa), silage (Lolium perenne and alfalfa) and barley, respectively. After lambing, ewes were fed on fertilized paddocks without supplementation. Individual progression of BW, BCS, plasma NEFA as well as ADG of lambs was considered for energy balance interpretation. Some estimation is established based on NRC (2007) recommendations. Data were analyzed using the PROC Mixed procedure of SAS (2007) with repeated measures. During the last 4 wk of gestation, one 50 kg ewe from this flock is estimated to display a daily consumption of around 1.6 kg of DM (3.2 % BW) to support around 180 g of BW gain, requiring 3.4 mcal of ME. During the first 6-8 wk lactation, feed intake is affected by litter size (NRC, 2007; 2.1 or 2.4 kg of DM/d for ewes suckling SING or TWIN; 4.2 or 4.8 % BW, respectively) with an increase in energy requirement of 4.9 or 5.6 mcal of ME for SING or TWIN, respectively. At late pregnancy, a positive energy balance of >1.1 mcal/d was observed (4.7 mcal of ME vs. 3.6 of ME requirements) due to the advantageous supplementation regime established in the farm. Paradoxically, at this stage (late pregnancy) NEFA values showed a peak in BR mobilization. After lambing, ewes suckling SING and TWIN were both required to mobilize their BR to meet energy requirement despite the high quality of the fertilized paddocks and the BW increase. More precise and targeted studies are required to better address the combined anabolic and catabolic phases experimented under the conditions of this experiment in periparturient ewes.

AbstractBackgroundIn order to maintain homeostasis, ruminants submitted to alternating shortage and refeeding situations manifest switches in metabolic pathways induced by undernutrition and body reserves (BR) replenishment cycles. The objective of this experiment was to study adaptive regulatory mechanisms present during subsequent feeding transition periods and the inherent lipolytic activity of the adipose tissue in individuals with contrasted BR. Three diets containing different levels of energy were offered to 36 mature, dry, non-pregnant Mérinos d’Arles ewes in an experiment lasting 122 days. Ewes were selected with similar body weight (BW), body condition score (BCS) and were allocated into three equivalent treatments according to the plane of nutrition: normally fed (Control); underfed (Under) or overfed (Over). The BW, BCS and individual energy metabolism were monitored. At the end of the experiment, lipolytic activity of adipose tissue was studied through a ß-adrenergic challenge to the same ewes, with body conditions according to the offered diet (Normal, Leans and Fat, respectively).ResultsAnabolic or catabolic responses to energy dietary manipulation were accompanied by synchronised metabolic regulation, leading to contrasting metabolic and BR profiles. Average BW and BCS were higher and lower in Over and Under ewes, respectively. The higher and lower BR variations were observed for Under and Over ewes. Higher plasma non-esterified fatty acids (NEFA) concentrations were accompanied by lower insulin, leptin and glucose. Differences in leptin were consistent with the dietary energy load (Over > Control > Under). After refeeding, a rebound in BW and BCS was observed for the three groups whereas NEFA was drastically reduced in Under ewes. No differences among treatments were detected in NEFA profiles at the end of the study but lipolytic activity responses to the ß - adrenergic challenge were different and coherent with the adipose tissue mass (Fat > Normal > Lean) and, importantly, was also different between ewes from the same group or BR status, thus evidencing diversity among individual adaptive capacities.ConclusionsThe ability of ewes to quickly overcome undernutrition situations by efficiently using their BR was confirmed. There is potential for a simplified ß-adrenergic challenge protocol helping to identify differences in adaptive capacity among individuals.

There are numerous recent studies highlighting sustainability problems for the development of ruminant production systems (RPS) while facing increasing human food necessities and global climate change. Despite the complexity of the context, in our view the main objectives of the ruminants' physiologist should be convergent for both industrialized (IC) and developing countries (DC) in a common and global strategy of advancing knowledge. In DC, this means improving the efficiency of RPS, taking into account the unique possibility of using rangelands. For IC settings, RPS should be revisited in terms of autonomy and environment- friendly feeding and managing practices. Assuming that competition for feed/food use is still a crucial criterion, future ruminant feeding systems (FeSyst) should preferably focus on lignocellulosic sources. According to biome distributions, and the recent increases in volumes of crop residues and their by-products, the annually renewed volumes of these biomasses are considerable. Therefore, we need to redesign our strategies for their efficient utilization at the local level. For this purpose, digestion processes and rumen functioning need to be better understood. The renewed vision of ruminal digestion through the reduction of greenhouse gas emissions is also a key aspect as it is an environmental demand that cannot be ignored. With regard to other ruminants' physiological functions, accumulated knowledge could be mobilized into an integrative approach that puts forward the adaptive capacities of animals to face variability in quantity and quality of supplied feeds. Basically, the reduction of inputs that were traditionally used to ensure FeSyst will need more flexible animals. In that sense, the concepts of homeostasis and teleophorhesis need to be updated and adapted to domestic species and breeds that were until now largely excluded from the dominant productive systems. In conclusion, a more holistic approach of research targets is required in which physiological functions and farmers' practices must converge and respond to each particular situation in an integral, dynamic and flexible conceptual perspective. From a scientific point of view, both for ICs and DCs, a broader range of experimental scenarios should be explored in order to arrive at innovative practices and solutions that respect environmental, ethical and economical issues. The clear challenge is to in evaluate the sustainability of RPSs. This includes, in our opinion, a strong interaction with other disciplines (multi- and trans-disciplinary conception), thus structuring new relevant indicators for the evaluation sustainability.

Les systèmes d’élevage ovins et les caprins, comme les autres productions animales, sont confrontés aux multiples défis environnementaux : limiter les nuisances et contribuer positivement à l’entretien ou à l’amélioration du milieu. Les travaux de l’INRA, et de ses partenaires, se sont largement impliqués dans ces questions en considérant ces élevages de petits ruminants comme faisant partie d‘agroécosystèmes complexes. Cette synthèse collective rassemble, en privilégiant les niveaux d’approche, les actions dans lesquels l’INRA intervient. Considérant tout d’abord les grandes tendances sur les effectifs d’animaux et leur répartition géographique, les adaptations ou les disparitions de ces élevages se repèrent par les approches technico-économiques. Dans ce contexte, il était important pour l’INRA de s’intéresser surtout aux origines des changements et de déceler les innovations techniques, organisationnelles et opérationnelles qui interviennent. Globalement, les trois leviers de ces évolutions ont été l’accroissement de la taille des troupeaux et des surfaces, la simplification des conduites (travail) et la réduction de l’utilisation des intrants (charges) au profit des ressources fourragères naturelles locales. Dans ce cadre, l’INRA y évalue également l’acceptabilité de certaines de ses inventions. Dans un tel contexte, les aptitudes d’élevage des animaux ne se limitent plus à la seule maximisation de la productivité individuelle. Des travaux spécifiques à ces espèces s’avèrent nécessaires pour identifier les caractères d’élevage qui sont déterminants dans des systèmes capables d’absorber des aléas. L’idée dominante est qu’il faut transférer sur les animaux eux-mêmes des capacités adaptatives qui étaient précédemment sous-utilisées, voire ignorées. La maîtrise de la reproduction pose encore de sérieux problèmes environnementaux chez ces espèces saisonnées et pour lesquelles l’INRA prépare des solutions alternatives à l’interdiction de l’utilisation de traitements hormonaux qui relarguent des résidus et posent des questions éthiques quant à leur utilisation. Pour quantifier les performances environnementales de ces élevages, l’INRA s’est doté de deux plateformes pluridisciplinaires, et mobilise des domaines expérimentaux où des systèmes d’élevages y sont étudiés à long terme. Par une approche pluridisciplinaire, des analyses multicritères permettent d’évaluer les performances environnementales de ces conduites tant sur le plan des GES, de l’énergie fossile que de la biodiversité. Une telle approche permet surtout d’évaluer objectivement les compromis productivité – performances environnementales. Enfin, à des échelles plus vastes de bassins de production et de micro-régions, des démarches de recherche action sur la coordination des acteurs permettent d’évaluer des coordinations d’acteurs qui ménagent des objectifs de production (régularité de la production) avec la valorisation raisonnée d’écosystèmes pâturés. Ces études s’étendent jusqu’à des échelles territoriales où la dimension paysagère est prise en compte, notamment parce que, par exemple, le rôle anti-incendie de l’élevage de petits ruminants est incontestable. Quels que soient les niveaux d’approche, l’évaluation des performances environnementale des élevages ovins et caprins repose largement sur la modélisation des systèmes et/ou sur des simulations.

Shortage and refeeding situations lead to switches in metabolic pathwaysinduced by undernutrition and body reserves (BR) replenishment cycles. In a 122-d experiment, we studied adaptive mechanisms in 36 adult non-pregnant Mérinos d’Arles ewes, selected with similar BW and BCS. Ewes were acclimated to diet ingredients (i.e., wheat straw, pelleted alfalfa and sugar beet pulp) and to the facility environment during 22 d. Then, the “diet challenge” (planes of nutrition; 12 ewes each) was applied during the first 50 d (normally fed, Control; underfed, Under; overfed, Over) and an individual monitoring (twice a week) of BW, BCS and energy metabolism was carried out. Then, a “refeeding challenge” was applied during the last 50 d (i.e., diets were adjusted using the same ingredients). The last day, the lipolytic activity was studied with a “β-adrenergic challenge” (4 nmol/ kg BW of isoproterenol) to the same ewes (BCS according to diet; i.e., Normal, Lean and Fat, respectively). The PROC MIXED with repeated measures of SAS package was used for data analyses. The NEFA response at each time after the β-adrenergic challenge was calculated as well as the area under the concentration curve at 5 min. time intervals during 1 h. Anabolic or catabolic responses were accompanied by synchronized metabolic regulations, leading to contrasting metabolic and BR profiles. Average BW and BCS were higher and lower in Over and Under ewes, respectively, which was proportional to BR dynamics (higher and lower BR mobilization in Under and Over ewes, respectively). Higher plasma NEFA were accompanied by lower insulin, leptin and glucose. Differences in leptin were consistent with energy load (Over > Control >Under). After refeeding, a rebound in BW and BCS was observed and NEFA was drastically reduced in Under ewes. No differences were detected in NEFA profiles at the end of the study but lipolytic activity was different and contrasted with adipose tissue mass (Lean > Normal ≈ Fat). Differences in those responses between ewes with the same BR status evidenced diversity among individual adaptive capacities. There is potential for a simplified β-adrenergic challenge protocol helping to characterize intraflock variability in adaptive capacity.

In a previous work we demonstrated that efficiency in body reserves (BR) mobilization/accretion was affected by parity [multiparous (MULT) ewes being more flexible than primiparous], litter size and physiological stage (peaks of BR mobilization attained around lambing and 1 mo after mating). The objective of this study was to estimate the dynamic individual energy balance of periparturient MULT Romane grazing ewes, from 15 d before until 15 d after lambing. A group of MULT ewes (n= 20), allocated according to litter size (lambing and suckling singletons, SING-n = 10-, or twins, TWIN-n = 10) was used. Details on management and feeding were reported by González-García et al. (2014). At late pregnancy, ewes were in rotational grazing of native rangeland and supplemented with 0.7, 2.0 and 0.8 kg/d of hay (Dactylus glomerata and alfalfa), silage (Lolium perenne and alfalfa) and barley, respectively. After lambing, ewes were fed on fertilized paddocks without supplementation. Individual progression of BW, BCS, plasma NEFA as well as ADG of lambs was considered for energy balance interpretation. Some estimation is established based on NRC (2007) recommendations. Data were analyzed using the PROC MIXED of SAS (2007) with repeated measures. During the last 4 wk of gestation, one 50 kg ewe from this flock is estimated to display a daily consumption of around 1.6 kg of DM (3.2% BW) to support around 180 g of BW gain, requiring 3.4 mcal of ME. During the first 6–8 wk lactation, feed intake is affected by litter size (NRC, 2007; 2.1 or 2.4 kg of DM/d for ewes suckling SING or TWIN; 4.2 or 4.8% BW, respectively) with an increase in energy requirement of 4.9 or 5.6 mcal of ME for SING or TWIN, respectively. At late pregnancy, a positive energy balance of > 1.1 mcal/d was observed (4.7 mcal of ME vs. 3.6 of ME requirements) due to the advantageous supplementation regime established in the farm. Paradoxically, at this stage (late pregnancy) NEFA values showed a peak in BR mobilization. After lambing, ewes suckling SING and TWIN were both required to mobilize their BR to meet energy requirement despite the high quality of the fertilized paddocks and the BW increase. More precise and targeted studies are required to better address the combined anabolic and catabolic phases experimented under the conditions of this experiment in periparturient ewes. Reference: González-García E. et al.(2014). Domestic Animal Endocrinology 46:37–48.