Devenir des jeunes ruminants laitiers : comment concilier élevage et attentes sociétales.

Dans les conditions naturelles, les jeunes ruminants développent un lien privilégié avec leur mère dans les heures qui suivent la naissance, lien qui perdure bien au-delà de l’allaitement. Or, sur les 5,5 millions de jeunes ruminants (veaux, chevreaux et agneaux) qui naissent chaque année en France dans des élevages laitiers, la grande majorité sont séparés de leur mère à la naissance et allaités « artificiellement » au seau. La séparation mère-jeune précoce interpelle les citoyens et certains éleveurs quant au respect du bien-être de l’animal. L’allaitement artificiel des femelles de renouvellement jusqu’au sevrage permet d’assurer, à un coût maîtrisé, un développement mammaire optimal et un bon potentiel laitier. Cependant, l’allaitement par les mères ou par des nourrices se développe, principalement en élevage bovin. Ce type d’allaitement entraîne généralement des quantités de lait commercialisables moindres, mais la croissance, la santé et le bien-être des veaux sont améliorés. Des questions se posent aussi sur le devenir des jeunes, mâles pour l’essentiel, non conservés pour le renouvellement du troupeau. Ceux-ci quittent généralement l’élevage quelques semaines après la naissance pour être engraissés dans des ateliers spécialisés, voire exportés. Là aussi, afin de répondre aux nouvelles attentes des consommateurs et pallier le faible intérêt économique de ces débouchés, éleveurs et filières recherchent des solutions alternatives telles que l’engraissement à la ferme, de nouveaux modes d’élevage ou de nouveaux débouchés. Ces pratiques alternatives – allaitement naturel ou engraissement sur place des jeunes mâles – pourraient se développer grâce à une identification de leurs produits (lait, viande) et au consentement du consommateur à les payer plus cher que des produits standards

M19 Modulates Skeletal Muscle Differentiation and Insulin Secretion in Pancreatic β-Cells through Modulation of Respiratory Chain Activity

Mitochondrial dysfunction due to nuclear or mitochondrial DNA alterations contributes to multiple diseases such as metabolic myopathies, neurodegenerative disorders, diabetes and cancer. Nevertheless, to date, only half of the estimated 1,500 mitochondrial proteins has been identified, and the function of most of these proteins remains to be determined. Here, we characterize the function of M19, a novel mitochondrial nucleoid protein, in muscle and pancreatic β-cells. We have identified a 13-long amino acid sequence located at the N-terminus of M19 that targets the protein to mitochondria. Furthermore, using RNA interference and over-expression strategies, we demonstrate that M19 modulates mitochondrial oxygen consumption and ATP production, and could therefore regulate the respiratory chain activity. In an effort to determine whether M19 could play a role in the regulation of various cell activities, we show that this nucleoid protein, probably through its modulation of mitochondrial ATP production, acts on late muscle differentiation in myogenic C2C12 cells, and plays a permissive role on insulin secretion under basal glucose conditions in INS-1 pancreatic β-cells. Our results are therefore establishing a functional link between a mitochondrial nucleoid protein and the modulation of respiratory chain activities leading to the regulation of major cellular processes such as myogenesis and insulin secretion

Strategies for keeping dairy cows and calves together – a cross-sectional survey study

Although it is still most common to rear dairy calves separately from adult cattle, the interest in prolonged contact between dairy calves and lactating cows during early life is increasing. Previous research has documented positive effects of cow-calf contact (CCC) on for example early calf growth and udder health of suckled cows, but also negative effects such as increased separation distress and reduced weight gains after weaning. The aim of this study was to use information from European farms with prolonged cow-calf contact to identify innovative solutions to common challenges for CCC farms. Commercial dairy farms that kept calves with adult lactating cows for seven days or more after birth were invited to participate, and interviews were performed with 104 farmers from six countries. During interviews, information about farm management, calf rearing, farmers’ perception of animal health on their farm, and farmers’ drivers and barriers for implementing CCC were collected. We found that CCC was practised in a large variety of housing and management systems, and that calves could be reared together with their dam, with foster cows, or using a combination of the two. The contact period varied considerably (7–305 days) between farms and about 25% of the farms manually milk fed the calves during parts of the milk feeding period. Daily contact time varied between farms, from 30 minutes per day to permanent contact except at milking. Behaviours indicative of separation distress, most commonly vocalisation in cows and calves, were reported by 87% of the farmers. Strategies to alleviate separation distress, for example simultaneous gradual weaning and separation, were used on some farms. Building constraints were most often mentioned as a barrier for implementing CCC. Our findings suggest that CCC is practised in a variety of commonly used husbandry systems. Reported challenges were primarily related to weaning and separation, and to building constraints; these aspects should be areas of future research

Effects of high temperature processes on physical properties of silica sand

High temperature processes may alter soil properties, creating potential risks of subsidence, erosion and other hazards. Soils may be exposed to high temperatures during some aggressive contaminant remediation processes as well as natural events such as fires. Characterising the effects of high temperatures on soil properties is essential to understanding the potential hazards that may arise after exposure. Thermal treatment and smouldering remediation were carried out on silica sand used here as a simple soil. Changes observed in physical properties were associated with the treatment type and exposure temperature. Particle, minimum and maximum densities were independent of heat treatment type and temperature. In contrast, particle size distribution, mineralogy, capillary rise, and hydraulic conductivity were linked to treatment type and exposure temperature with the most substantial changes associated with smouldering remediation. Changes in colour and mass loss with increasing temperature suggest changes within the crystal structure of the silica sand beyond loss of moisture content within the pore space and dehydration of iron deposits from goethite to hematite. Based on these observations, exposure to high temperature processes and the complex geo-chemical reactions during smouldering remediation can have significant effects on soil properties. Monitoring after exposure is advisable to determine the severity of exposure and any mitigation measures that may be necessary

Combined effects of once-daily milking and feeding level in the first three weeks of lactation on milk production and enzyme activities, and nutritional status, in Holstein cows

Twenty-four multiparous cows were divided into 4 groups immediately after calving according to a 2 $\times$ 2 factorial design: 2 milking frequencies (1 daily [morning only] milking for the first three weeks of lactation, then 2 daily milkings vs. 2 daily milkings throughout) under two diet energy concentrations (normal or low). The trial lasted 30 weeks, on average, and ended in the pasture on 28 May 2000. During the winter period, the cows were housed together in a free-stall barn, and were given complete rations ad libitum. The cows that were not milked were significantly more vocal than the controls, close to the omitted milking, and in a large number of them, milk leaked from the udder. Once-daily milking gradually reduced the amount of milk secreted in relation to that produced by cows milked twice a day, with differences of 8.5 kg$\cdot$d$^{-1}$ ($P < 0.01$) at week 3. As early as the first week of resumption of twice-daily milking, that difference ceased to be statistically significant but amounted to 1.3 kg$\cdot$d$^{-1}$ ($P > 0.10$) throughout the rest of the trial. Once-daily milking did not affect the contents of milk fat, true protein, serum albumin and lactose contents or somatic cell count, plasmin activity and plasminogen-derived activity. That treatment also increased the G1 immunoglobulin concentration ($P$ = 0.02; measured at week 3) and reduced milk lipoprotein lipase activity. Once-daily milking improved the nutritional status at the beginning of lactation (reduced live weight and body condition losses, and increased the computed energy balance) and had no effect on the ration intake. The normal- energy diet produced expected results, in relation to the low-energy diet: a significant increase in intake (1.2 kg DM$\cdot$d$^{-1}$), milk yield (3.1 kg$\cdot$d$^{-1}$), milk protein content (2.0 g$\cdot$kg$^{-1}$), and nutritional indices, in particular. The decrease in milk yield induced by once-daily milking during the first three weeks of lactation was 5.5 kg$\cdot$d$^{-1}$ in the low-energy group and 8.5 kg$\cdot$d$^{-1}$ for the normal energy group (non- significant interaction; $P > 0.10$).Effets de la traite une fois par jour combinée au niveau d'alimentation pendant les trois premières semaines de la lactation sur la production et les activités enzymatiques du lait, et l'état nutritionnel, chez des vaches Holstein. Vingt-quatre vaches multipares ont été réparties dès le vêlage en 4 lots, selon un schéma factoriel 2 $\times$ 2 : 2 fréquences de traite (1 traite par jour pendant les 3 premières semaines de lactation, puis 2 traites par jour vs. 2 traites par jour en permanence) $\times$ 2 concentrations énergétiques de la ration (normale ou basse). L'essai a duré en moyenne 30 semaines et s'est terminé au pâturage, le 28 mai 2000. Pendant la période hivernale, les vaches étaient logées ensemble dans une stabulation libre à logettes et recevaient à volonté une ration complète. La traite omise était celle du soir. Les vaches non traites ont émis significativement plus de vocalisations que les témoins autour de la traite omise, et elles ont été plus nombreuses à perdre du lait. La traite 1 fois par jour a progressivement réduit la quantité de lait sécrétée par rapport à celle produite par les vaches traites 2 fois par jour, l'écart atteignant 8,5 kg$\cdot$j$^{-1}$ ($P < 0,01$) à la semaine 3. Dès la 1$^{{\rm re}}$ semaine de la reprise de la traite 2 fois par jour, cet écart n'a plus été significatif. Il a été de 1,3 kg$\cdot$j$^{-1}$ ($P > 0,10$) pour l'ensemble de l'essai. La traite 1 fois par jour n'a pas affecté la teneur du lait en matières grasses, en protéines (vraies), en albumine sérique, et en lactose, ni le nombre de cellules somatiques ou l'activité de la plasmine et celle induite par l'activation du plasminogène. Elle a accru la teneur en immunoglobulines G1 ($P$ = 0,02 ; mesure à la semaine 3) et a diminué l'activité de la lipoprotéine lipase, ce qui n'avait pas encore été rapporté. Elle a amélioré l'état nutritionnel en début de lactation (pertes de poids vif et d'état corporel réduites, bilan énergétique calculé accru) et n'a eu aucun effet sur la quantité de ration ingérée. La ration de concentration énergétique normale a entraîné, par rapport à celle de concentration énergétique basse, les effets attendus : accroissement significatif des quantités ingérées (1,2 kg MS$\cdot$j$^{-1}$), de la quantité de lait produite (3,1 kg$\cdot$j$^{-1}$), de son taux protéique (2,0 g$\cdot$kg$^{-1}$) et des index nutritionnels, notamment. La réduction de quantité de lait produite au cours des 3 premières semaines de la lactation entraînée par la traite 1 fois par jour a été de 5,5 kg$\cdot$j$^{-1}$ et 8,5 kg$\cdot$j$^{-1}$ respectivement pour les lots recevant les rations de concentration énergétique faible ou normale (interaction non significative ; $P > 0,10$)