Portail Hal-l'Institut Agro Rennes-Angers
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Performances de croissance différenciées du porc selon la céréale incorporée dans l’aliment granulé
No full textInternational audienceMost feed tables contain nutritional values for feedstuffs in mash form, which are used to formulate diets subjected to technological treatments such as pelleting. The present study aimed to compare the performance of growing pigs fed pelleted diets formulated with reference to mash nutritional values. Growing-finishing diets were formulated with a single starch source (M diets: maize, B diets: barley or W diets: wheat and wheat bran) of a 50:50 blend of B and W (B-W diets), with a net energy (NEMash) content of 9.9 (M diets) or 9.4 (B, B-W, W diets) MJ/kg. The NE content after pelleting (NEPellet) was assessed based on recent results from the literature: 10.3, 9.5, 9.6 and 9.7 MJ/kg for M, B, B-O and W diets, respectively. Sixteen replicates of four pens of seven pigs were studied at a body weight (BW) of 31-117 kg. Although fed ad libitum, B and B-W pigs did not increase their daily feed intake (DFI, 2.70 kg/d on average) above that obtained with M (mean of 2.69 kg/d), which resulted in less intake of NEMash or NEPellet than that with M (P < 0.01). With W diets, DFI tended to be lower (2.62 kg/d, P = 0.06) than that with B or B-W diets, which may have been related to the higher NEPellet content of W diets. Subsequently, a similar intake of NEPellet and energy conversion ratio (MJ NEPellet/kg BW gain) were obtained for these diets. These results were consistent with the similar backfat thickness at slaughter for pigs fed the B, B-W and W diets (mean of 22.3 mm vs 23.9 mm with M diets, P < 0.01). Accounting for the effect of pelleting on the NE content of cereals helps to remove the discrepancy observed between the different performance criteria when flour values are used.Les valeurs nutritionnelles des tables sont obtenues à partir de régimes présentés sous forme de farine, mais utilisées pour formuler des aliments subissant des traitements technologiques. Les performances de croissance de porcs recevant des aliments granulés formulés sur des bases farine, soit à base de maïs (lot MAI), orge (ORG) ou blé et son de blé (BLE) ou un mélange 50:50 blé-orge (B-O), sont comparées. La formulation est réalisée pour une teneur en énergie nette sous forme de farine (ENFarine) de 9,9 (MAI) et 9,4 (ORG, B-O, BLE) MJ/kg. Après granulation, la teneur en ENGranulé est estimée, respectivement, à 10,3, 9,5, 9,6 et 9,7 MJ/kg. Seize blocs de quatre cases de sept porcs sont étudiés entre 31 et 117 kg de poids vif. Bien qu’à volonté, l’ingestion d’aliment ORG ou B-O (2,70 kg/j) reste comparable à celle d’aliment MAI (2,69 kg/j), ce qui conduit à une ingestion plus élevée d’ENFarine ou ENGranulé avec le MAI (P < 0,01). Avec le BLE, la consommation tend à être plus faible (2,62 kg/j, P = 0,06) qu’avec ORG et B-O, ce qui peut être mis en relation avec une teneur en ENGranulé plus élevée. Il en résulte une ingestion d’ENGranulé et un indice de consommation exprimé en MJ ENGranulé comparables entre ces trois aliments, ce qui est cohérent avec l’absence de différence significative entre les épaisseurs de gras mesurées à l’abattoir sur les carcasses ORG, B-O et BLE (22,3 mm en moyenne vs 23,9 mm pour MAI, P < 0,01). La prise en compte de l’effet de la technologie sur la teneur en EN des céréales permet de lever la discordance observée entre les différents critères de performance quand les valeurs farine sont utilisées
Protein–Protein Interactions and Structure of Heat-Set Gels Based on Pea Protein and Egg White Mixtures
No full textInternational audienceThe substitution of animal proteins with plant-based ones to fit environmental and economic demands is a challenge in gel applications. This study examined the thermal elation of mixtures of pea protein isolate (PPI) and egg white proteins (EWPs) at different PPI/EWP weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) at pH 7.5 and 9.0. Viscoelastic and texture properties of the composite gels, along with the microstructure and molecular interactions involved in the gel network, were investigated. Except for PPI-EWP 100/0 at pH 9.0, all systems gelled with increasing gel hardness, springiness, and cohesiveness when EWP content increased. This was explained by the microstructure of the gels, wherein the presence of PPI enhanced the formation of aggregates embedded in the EWP network, thus loosening it. The rheological properties of the mixed gels were primarily influenced by the EWP network, involving disulfide bonds. However, upon the addition of PPI, hydrogen bonds and hydrophobic interactions predominated and the structure of the gel became more sensitive to pH as electrostatic repulsions interfered. Adjusting the ratio of PPI/EWP allows the production of gels with varying textures, and suggests the possibility of partially substituting egg white with pea proteins in food gel formulation
Fisheries performance indicators for assessing the ecological sustainability of wild-caught seafood products in Europe
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Genetic and epigenetic selection signatures from pool sequencing experiment
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How does feeding strategy affect the aromatic volatile compounds profile and sensory properties of organic fresh pork?
No full textInternational audienceThis study aimed to evaluate two feeding strategies on pork quality in organic farming using 77 non-castrated male pigs (Piétrain × Large White) reared in two batches, each including two groups. Male littermates were allocated to either a Control group (C, n = 37), fed following the organic specifications, or to a group receiving an organic test feed mainly based on French raw materials and containing more fibre and omega-3 fatty acids (Bio+, n = 40). Within batch, each group was reared in one pen from the same building on deep straw bedding with free outdoor access, with ad libitum feeding from around 33 kg until slaughter at around 128 kg of live weight. Loin meat samples were analysed by a trained sensory panel and by SPME-GC–MS to identify the main volatile compounds. Meat from Bio+ pigs showed a significantly more intense red colour (P < 0.01), but lower aromatic persistency (P < 0.05) and tended to be less tender (P = 0.08) than meat from C pigs. None of the samples were qualified as boar tainted. A total of 27 volatile compounds were quantified, with more compounds present in Bio+ pigs, probably due to the greater diversity of raw ingredients in the feeds. The multi-dimensional analyses enabled to observe relationships between volatile compounds and sensory traits but did not differentiate the two feeding strategies. Bio+ feeding strategy compared to C influenced some organoleptic characteristics (red colour of raw meat, aromatic persistency) without modifying the texture, odour and flavour of organic cooked pork
Dynamics of the lactose content and other osmotic agents in milk throughout lactation according to the cow's parity
No full textInternational audienceMilk lactose content (LC) is known to vary due to metabolic disorders and udder inflammation. To assess its ability to serve as a marker of these 2 disorders, it is important to first understand its dynamics for healthy cows, particularly its relation with milk osmolarity, because it is the main osmotic agent. To assess the dynamics of LC, we studied relations among contents of lactose and other major osmotic agents in milk throughout lactation in different parities. Cows were fed a constant TMR diet throughout lactation. The profile of osmotic agents in morning milk (lactose, K, Na, Cl, and protein) was measured in the milk of 30 cows (17 primiparous and 13 multiparous). To avoid confounding effects due to udder inflammation, data from cows with unhealthy udders (i.e., 2 or more milk samples with SCC >200,000 cells/mL) were excluded (n = 2 primiparous and 3 multiparous). From 12 to 235 DIM, 8 to 9 samples per cow were first taken 2 wk apart, and then taken monthly. A regression model that included cow parity, DIM, their interaction, and random cow effect was used to illustrate the dynamics of milk osmolarity and each osmotic agent throughout lactation. Milk osmolarity remained stable throughout lactation (279 +/- 0.3 mOsm/L), with no significant difference between primiparous and multiparous cows. The contents of lactose, K, Na, Cl, and protein explained 86.4% of milk osmolarity. Milk LC was lower for multiparous compared with primiparous cows over the entire lactation period, except at 12 DIM, when both parity cows had similar LC. For multiparous cows, the lower LC was compensated by higher Na content. Principal component analysis of all osmotic agents explained 82% and 83% of the cumulative variance throughout lactation for primiparous and multiparous cows, respectively. At 12 DIM, multiparous cows had lower LC and Cl and K contents compared with primiparous cows, which exhibited only lower LC compared with the rest of the lactation period. From 40 to 235 DIM, however, milk from the 2 parities had similar dynamics of osmotic agents: K content decreased and protein content increased. This study revealed that in cows with healthy udders, the dynamics of LC and other osmotic agents contents in milk differed between parities and throughout lactation to maintain a constant milk osmolarity
Characterisation of aged infant formula powder based on ingredients produced by membrane filtration
No full textInternational audienceThe global infant formula (IF) market is expanding rapidly, driven by the increasing working women population, which limits breastfeeding opportunities. Spray-dried powdered IFs are widely used for their enhanced stability and reduced storage and transport. However, physicochemical changes such as the Maillard reaction, lactose crystallization, and fat oxidation during storage can compromise IF quality. Understanding these changes is essential for optimizing production and storage conditions, especially for minimally processed IFs designed to preserve nutritional integrity, for which the literature is scarce. Hence, we aimed at evaluating the physicochemical stability of IFs during storage. Three IF powders were produced at the semi-industrial scale: T-, without heat treatment; T+, with pasteurization of the concentrate alone (75°C, 2 min); T+++, combining milk pasteurization (72°C, 30 s) and heat treatment of the concentrate (85°C, 2 min) before spray-drying. They were then packaged in sealed metal cans under modified atmosphere and stored at room temperature and in a heat chamber at 40°C for periods of up to 11 and 6 months, respectively. Physicochemical properties, including moisture content, water activity, total fat and free fat content, whey protein denaturation were monitored. Maillard reaction was specifically assessed by monitoring lactosylation of whey proteins, and furosine and Nε-carboxymethyl-lysine content and color.All IF powders demonstrated satisfactory microbiological stability after 8 months at room temperature. No significant changes in moisture content or color were observed after 10 months at room temperature. Some variations were observed at room temperature for water activity, but it remained below 0.3. Protein denaturation was negligible, even after 6 months at 40°C. However, higher levels of lactosylation were detected across all IF powders, indicating the early stage of Maillard reaction took place despite low water activity. Thus, minimally processed IFs could achieve stability comparable to classically heat-treated ones, with lactosylation remaining as a challenge
Assessment of Over Four Decades the Status of White Grouper Epinephelus aeneus (Geoffroy Saint-Hilaire, 1817) Population in the Eastern Central Atlantic
No full textInternational audienceSenegalese and Mauritanian fisheries exploit the same species of white grouper but have different exploitation histories. In Senegal, white grouper has been fished for a very long time (since the 1970s), whereas it is relatively recent in Mauritania. In addition, Senegalese small-scale fishermen exploit this species in the Gambia. Nevertheless, mainly for practical reasons, all attempts to assess the status of the stock have, until recently, been conducted at a national level except by the FAO CECAF North working group who assumed it to be a single stock for the three countries. However, their analysis gives very little attention to length frequency data, even though the fisheries have different selectivity that are likely to affect exploitation rates. In addition, management is mainly focused on length, with no TACs or quotas established at national or sub-regional levels. This work is based on a large compilation of available data from the databases of three countries complemented by the collection of length frequencies data within the framework of the European Union Demerstem/PESCAO project. Two approaches were combined (catch and length-based model) to establish a reliable diagnosis of the state of this resource, along with a spatial analysis to identify the areas most affected by fishing. The results obtained for the sub-region show a severe overexploitation of biomass revealed by the Bayesian biomass production surplus model (JABBA). Stock status indicators show overfishing with low biomass (B/Bmsy = 0.34) and high fishing mortality (F/Fmsy = 5.79). Overall, the trajectory of the state of the stock illustrated by the Kobe figure indicates that the white grouper stock has been overexploited since the 1990s. Fishing pressure reached its highest levels during the recent period of 2016–2018 and these results are consistent when considering stock assessment at the national level. However, the length-based model (LBB) indicates a deterioration in average length, particularly in Senegal and the Gambia, especially since 2014. Adults, who migrate, are more abundant in Mauritania. Therefore, due to its high market value, white grouper is increasingly targeted, resulting in an unprecedented rise in fishing mortality over the past decade, particularly among larger individuals, with the most significant pressure observed in Senegal and the Gambia. Given that the stock spans three countries, a coordinated management approach at the stock level is essential. However, management measures must also be adapted to the specific status of the population within each country. Without such a concerted effort, this trend is likely to persist, further endangering the resource
Quantification of the biological control of aphids by their natural enemies in sugar beet crops
No full textInternational audienceConservation biological control system involves a diverse community of natural enemies that significantly regulate pests in crops. However, the relative contribution of these different functional groups of natural enemies to aphid regulation is poorly known in major crop-pest systems. Moreover, there is a need to identify the timing of this contribution, especially when aphids are able to transmit pathogenic viruses to plants, such as in sugar beet crops. In this study, we quantified the effect of ground dwelling predators (carabids, spiders, rove beetles) and parasitoids on aphids’ abundance in sugar beet crops, using two experiments conducted over two successive years (2022 and 2023). Based on physical exclusion devices (pitfall traps, barriers, insect-proof cages), we showed that ground dwelling predators significantly lowered the abundance of aphids (Aphis fabae and Myzuspersicae). Ground dwelling predators made a significant contribution to natural pest control, as they lowered aphids’ populations by up to 80%, especially as they were present early in the season. Around 48% parasitism rate was measured in 2023. Our results suggest that both groups of natural enemies appear to play a particularly important role in aphid regulation, especially ground dwelling predators. This suggests that agricultural practices, as a vegetated field margin, favouring generalist predators overwintering or colonization could lead to fewer damage and losses for farmers