Particle size distribution in commercial pig compound feeds in Switzerland: survey and methodological considerations

Abstracts: English - Deutsch - Français - Italiano English Particle size distribution in commercial pig compound feeds in Switzerland: survey and methodological considerations The grinding intensity of pig feed is considered one potential predisposing factor for gastric ulcers, and a variety of particle size recommendations have been published for pig feeds. We subjected 51 different commercial compound feeds for pigs (38 meals, 13 pellets/granulates) to dry and/or wet sieve analysis. The amount of particles passing the finest sieve (or being soluble) was estimated by the difference to the total dry matter weighed prior to sieving. Mean particle size was calculated based on the weighted average of the material retained on the sieves (MPSsieves), and additionally with accounting for this lost material (MPStotal). Dry sieve analysis of the meals yielded MPSsieves of 0,58–2,90 mm and MPStotal of 0,58–2,89 mm; only 0,02 to 2,71 % of the dry matter passed all sieves. Wet sieve analysis of all meals and pellets yielded similar MPSsieves of 0,63–1,66 mm, but dramatically lower MPStotal of 0,26–1,04 mm; between 35 and 66 % of the dry matter was not retained on the sieves. Pellets had smaller MPS, and a higher proportion of particles passing all sieves than meals. Depending on the reference used, a maximum of 26 % of meals conformed to recommendations for pig feed particle size. None of the pelleted feeds met these criteria, irrespective of the source consulted for the recommendation. Wet sieving should be considered the standard analysis, because in dry sieving, very fine particles adhering to larger particles may not be registered separately but contribute erroneously to larger particle weight. In addition, the MPS calculation should account for material lost through the finest sieve. Reasons why Swiss pig feed does not meet particle size recommendations should be further investigated. Keywords: Diet, ulcer, stomach health, prevention, grinding Deutsch Partikelgrösse in kommerziellen Schweinefuttermischungen in der Schweiz: Erhebung und methodische Überlegungen Das Ausmass der Zerkleinerung von Schweinefutter wird als ein möglicher prädisponierender Faktor für Magengeschwüre angesehen. Für Schweinefutter wurden verschiedene Empfehlungen zur Partikelgrösse veröffentlicht. Wir haben 51 verschiedene handelsübliche Mischfuttermittel für Schweine (38 Mehle, 13 Pellets/Granulate) einer Trocken – und/oder Nass-Siebanalyse unterzogen. Die Menge an Partikeln, die das feinste Sieb passierten (oder löslich waren), wurde durch die Differenz zu der vor dem Sieben gewogenen Gesamttrockenmasse abgeschätzt. Die mittlere Partikelgrösse wurde basierend auf Mittelwert des Gewichtes von dem im Sieb zurückgehaltenen Materials (MPSsieves) unter Berücksichtigung dieses verlorenen Materials (MPStotal) berechnet. Die Trocken-Siebanalyse der Mischungen ergab MPSSiebe von 0,58–2,90 mm und MPStotal von 0,58–2,89 mm; nur 0,02 bis 2,71 % der Trockenmasse passierten alle Siebe. Die Nass-Siebanalyse aller Mehle und Pellets ergab ähnliche MPSSiebe von 0,63–1,66 mm, aber signifikant niedrigere MPStotal von 0,26–1,04 mm; zwischen 35 und 66 % der Trockenmasse wurden nicht auf den Sieben zurückgehalten. Pellets hatten im Vergleich zu den Fütterungsmehlen eine kleinere MPS und einen höheren Anteil an Partikeln, die alle Siebe passierten. Je nach verwendeter Referenz entsprachen maximal 26 % der Fütterungsmehle den Empfehlungen für die Partikelgrösse von Schweinefutter. Unabhängig der konsultierten Referenzliteratur erfüllte keine der pelletierten Futtermittel diese Kriterien. Die Nass-Siebung sollte als Standardanalyse angesehen werden, da bei der Trocken-Siebung sehr feine Partikel, die an grösseren Partikeln anhaften, möglicherweise nicht separat erfasst werden, sondern fälschlicherweise zu einem grösseren Partikelgewicht beitragen. Zusätzlich sollte die MPS-Berechnung den Materialverlust durch das feinste Sieb berücksichtigen. Weiter Untersuchungen sollten die Gründe abklären, warum Schweizer Schweinefutter die Empfehlungen zur Partikelgrösse nicht erfüllen. Schlüsselwörter: Diät, Magengeschwür, Magengesundheit, Vorbeugung, Zerkleinerung Français Taille des particules dans les aliments composés commerciaux pour porcs en Suisse: enquête et considérations méthodologiques L’intensité de broyage des aliments pour porcs est considérée comme un facteur potentiel de prédisposition aux ulcères gastriques et diverses recommandations sur la taille des particules ont été publiées pour les aliments pour porcs. Nous avons soumis 51 différents aliments composés commerciaux pour porcs (38 farines, 13 pellets/granulés) à une analyse par tamisage à sec et/ou humide. La quantité de particules passant le tamis le plus fin (ou étant solubles) a été estimée par la différence avec la matière sèche totale pesée avant le tamisage. La taille moyenne des particules a été calculée sur la base des moyennes pondérées du matériel retenu sur les tamis (MPSsieves) en tenant compte en plus du matériel perdu (MPStotal). L’analyse des mélanges par tamisage à sec a donné des MPSsieves de 0,58–2,90 mm et des MPStotal de 0,58–2,89 mm ; seule 0,02 à 2,71 % de la matière sèche a passé tous les tamis. L’analyse par tamisage humide de toutes les farines et des granulés a donné des MPSsieves similaires de 0,63–1,66 mm, mais des MPStotal nettement inférieurs de 0,26–1,04 mm ; entre 35 et 66 % de la matière sèche n’a pas été retenue sur les tamis. Les granulés présentaient des MPS plus faibles et une proportion plus élevée de particules passant par tous les tamis que les farines. Selon la référence utilisée, un maximum de 26 % des farines étaient conformes aux recommandations relatives à la taille des particules des aliments pour porcs. Aucun des aliments granulés ne répondait à ces critères, quelle que soit la source consultée pour la recommandation. Le tamisage humide devrait être considéré comme l’analyse standard car, dans le tamisage sec, les particules très fines adhérant à des particules plus grosses peuvent ne pas être enregistrées séparément mais contribuer de manière erronée au poids des particules plus grosses. En outre, le calcul du MPS devrait tenir compte de la matière perdue par le tamis le plus fin. Les raisons pour lesquelles les aliments pour porcs suisses ne répondent pas aux recommandations sur la taille des particules devraient être étudiées plus en détail. Mots-clés: Régime alimentaire, ulcère gastrique, santé gastrique, prévention, broyage Italiano Dimensioni granulometriche nelle miscele commerciali di mangimi per suini in Svizzera: indagine e considerazioni metodologiche Il grado di sminuzzamento dei mangimi per suini è considerato un possibile fattore predisponente alle ulcere gastriche e sono state pubblicate diverse raccomandazioni sulla dimensione dei granuli per i mangimi dei suini. Abbiamo sottoposto 51 diverse miscele di mangimi commerciali per suini (38 farine, 13 pellet/granuli) all’analisi del setaccio a secco e/o a umido. La quantità di particelle che hanno superato il setaccio più fine (o che erano solubili) è stata stimata dalla differenza rispetto alla sostanza secca totale pesata prima della setacciatura. La dimensione media delle particelle (DMP) è stata calcolata in base al peso medio del materiale trattenuto nel setaccio (DMPsetacci) tenendo conto del materiale perso (DMPtotale). L’analisi dei setacci a secco delle miscele ha mostrato una DMPsetacci di 0,58-2,90 mm e una DMPtotale di 0,58–2,89 mm; solo lo 0,02–2,71 % della sostanza secca ha superato tutti i setacci. L’analisi al setaccio umido di tutte le farine e dei pellet ha mostrato una DMPsetacci analoghi di 0,63-1,66 mm, ma con una DMPtotale significativamente inferiore di 0,26–1,04 mm; tra il 35 e il 66 % della sostanza secca non è stata trattenuta dai setacci. I pellet presentavano una DMP inferiore e una percentuale maggiore di particelle che passavano tutti i setacci rispetto alle farine. A seconda del riferimento utilizzato, un massimo del 26 % delle farine soddisfaceva le raccomandazioni sulla dimensione delle particelle nei mangimi per suini. Mentre, indipendentemente dalla letteratura di riferimento consultata, nessuno dei mangimi a pellet soddisfaceva le raccomandazioni. La setacciatura a umido deve essere considerata l’analisi standard, poiché la setacciatura a secco potrebbe non rilevare separatamente le particelle molto fini che aderiscono a quelle più grandi, ma che contribuiscono erroneamente a un peso maggiore delle particelle. Inoltre, il calcolo della DMP deve tenere conto della perdita di materiale attraverso il setaccio più fine. Ulteriori indagini dovrebbero chiarire le ragioni per cui i mangimi per suini svizzeri non soddisfano le raccomandazioni sulle dimensioni delle particelle. Parole chiavi: dieta, ulcera, salute dello stomaco, prevenzione, macinazion

Evaluation of the prevalence of stomach ulcers in slaughtered pigs in a Swiss ­abattoir

The development of gastric ulcers in pigs has various reasons. In Switzerland, the last survey on the prevalence of gastric ulcers and possible risk factors was performed in 2005. We aimed to reassess gastric ulcers prevalence today, in 2021. A total of 1005 stomachs from fattening pigs from 136 batches and around 87 herds were evaluated at a Swiss abattoir. The Pars oesophagea of the stomach was scored from 0=healthy to 10=severe ulceration and strictures. Scores were compared between pigs produced under the labels “Integrierte Produktion Schweiz” (IPS, n=242 stomachs, 18 farms) and “Qualitätsmanagement-Schweizerfleisch” (QM, n=649, 58 farms) and others (n=114). The results showed a prevalence of 27.2% mild mucosal changes (Scores 1-3), 14.9% moderate mucosal changes (Scores 4-6) and 19.1% severe mucosal changes (Scores 7-10). Only 38.8% of the stomachs were rated 0 and thus considered healthy. Compared to the results from 2005, there is no difference concerning the lowest scores (0-2) and the highest scores (9-10). However, there was a shift from the medium scores (3-4) to higher scores (5-8). Stomach scores turned out to be herd specific. There were differences (p < 0.01) between labels, indicating that IPS pigs had less affected stomachs. Stomachs that were empty at slaughter showed higher scores (p < 0.001). The mean carcass weight of the pigs in the slaughter groups was negatively correlated (p < 0.05) to their median stomach score. Confiscations were not related to stomach scores. The results suggest that pig stomach health has not improved since 2005. The differences between labels seem to have resulted from different regulations prescribing a minimum particle size of enrichment material in IPS. The reasons for gastric ulcer development, including those on the individual herd within label, still have to be further clarified in order to allow targeted countermeasures. Given apparent farm-specificity, scoring of a limited number of stomachs per farm during the slaughter process could facilitate to establish a feedback scheme

Indications for a lower methane yield from digested fibre in ruminants digesting fibre more efficiently

It is assumed that the absolute amount of methane (CH4) produced on a given diet increases proportionately (i.e., in a linear manner) with the amount of digested fibre. Therefore, the CH4 yield per unit of digested fibre is considered constant for a given diet. This conceptually matches findings of lower digestibility in low-CH4 emitting animals, and of lower CH4 yield at higher intake levels due to shorter digesta passage and hence reduced digestibility. Irrespective of these observations, this general assumption was challenged by findings in one study where CH4 yield per unit of digested fibre had unexpectedly declined in individuals digesting the fibre provided by the same diet more efficiently. To investigate this finding in more detail, we collated a dataset from 16 studies with cattle and sheep with a total of 61 forage-based diet groups consisting of at least five animals each (472 animals in total). We assessed whether there was a linear relationship between the daily CH4 emission and the amount of digested fibre, both within the same and across the different diet groups. Across diets, CH4 emissions did not increase linearly with the amount of digested neutral or acid detergent fibre in either species. Within diet groups, the majority of cases also showed evidence for less-than-linear increase of CH4 emissions with increasing amount of digested neutral or acid detergent fibre, even though the 95 % confidence intervals could not rule out a linear relationship in many cases. Reasons why this phenomenon was not described earlier may include that the great individual variation associated with an accumulation of errors in the variables concerned often prevented statistical significance in individual studies. Although the findings across diets concerning the variation in CH4 yield per unit of digested fibre do not exclude some diet-specific effects, the within-diet assessment clearly points towards individual animal effects in microbial fibre digestion in a way that CH4 production is proportionately lower when fibre is digested more efficiently. Mechanistically, animals with a more efficient fibre digestion might produce volatile fatty acids at a higher rate and have a locally lower ruminal pH, favouring microbiota of propionate-producing pathways. The presence of animal-individual differences in CH4 yield per unit of digested fibre with varying efficiency of fibre fermentation should be confirmed in a specific experiment where also the reasons for such a phenomenon are further investigated

Indications for a lower methane yield from digested fibre in ruminants digesting fibre more efficiently

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Significance of Coprophagy for the Fatty Acid Profile in Body Tissues of Rabbits Fed Different Diets

Four groups of eight New Zealand hybrid rabbits were fattened with ad libitum access to the following pelleted experimental diets: ryegrass meal or alfalfa meal fed either alone or with oats meal in a ratio of 1:1. After 25weeks they were slaughtered and dissected. Fatty acid (FA) profiles of caecotrophs (re-ingested fermentation products of the caecum), perirenal adipose tissue and intramuscular fat in the Musculus quadriceps were determined. With high proportions of branched-chain FA (BFA) and trans FA, and increased proportions of saturated FA relative to the diets, the caecotroph FA profile showed a clear fingerprint of anaerobe microbial lipid metabolism including biohydrogenation. By contrast, the FA profiles of adipose and lean tissue comprised high proportions of polyunsaturated FA (PUFA), whilst BFA and trans FA occurred in much lower proportions compared to the caecotrophs. Thus, coprophagy did not substantially modify the FA composition of the tissues investigated. Use of forage-only diets, compared to the oats supplemented diets, led to extraordinary high proportions of n-3 PUFA (including 18:3 and long-chain n-3) in the fat of adipose (21.3 vs. 6.7%) and lean tissue (15.4 vs. 5.7%). The forage type diet (grass vs. alfalfa) had smaller effects on the FA profiles. Indications of diet effects on endogenous desaturation, chain elongation and differential distribution of functional FA between the two tissues investigated were foun

Polymer-induced swelling of solid-supported lipid membranes

In this paper, we study the interaction of charged polymers with solid-supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes by in-situ neutron reflectivity. We observe an enormous swelling of the oligolamellar lipid bilayer stacks after incubation in solutions of poly(allylamine hydrochloride) (PAH) in DO. The positively charged polyelectrolyte molecules interact with the lipid bilayers and induce a drastic increase in their d-spacing by a factor of ~4. Temperature, time, and pH influence the swollen interfacial lipid linings. From our study, we conclude that electrostatic interactions introduced by the adsorbed PAH are the main cause for the drastic swelling of the lipid coatings. The DMPC membrane stacks do not detach from their solid support at T > T. Steric interactions, also introduced by the PAH molecules, are held responsible for the stabilizing effect. We believe that this novel system offers great potential for fundamental studies of biomembrane properties, keeping the membrane's natural fluidity and freedom, decoupled from a solid support at physiological conditions

Methane Output of Tortoises: Its Contribution to Energy Loss Related to Herbivore Body Mass

An increase in body mass (M) is traditionally considered advantageous for herbivores in terms of digestive efficiency. However, recently increasing methane losses with increasing M were described in mammals. To test this pattern in non-mammal herbivores, we conducted feeding trails with 24 tortoises of various species (M range 0.52–180 kg) fed a diet of grass hay ad libitum and salad. Mean daily dry matter and gross energy intake measured over 30 consecutive days scaled to M0.75 (95%CI 0.64–0.87) and M0.77 (95%CI 0.66–0.88), respectively. Methane production was measured over two consecutive days in respiration chambers and scaled to M1.03 (95%CI 0.84–1.22). When expressed as energy loss per gross energy intake, methane losses scaled to 0.70 (95%CI 0.47–1.05) M0.29 (95%CI 0.14–0.45). This scaling overlaps in its confidence intervals to that calculated for nonruminant mammals 0.79 (95%CI 0.63–0.99) M0.15 (95%CI 0.09–0.20), but is lower than that for ruminants. The similarity between nonruminant mammals and tortoises suggest a common evolution of the gut fauna in ectotherms and endotherms, and that the increase in energetic losses due to methane production with increasing body mass is a general allometric principle in herbivores. These findings add evidence to the view that large body size itself does not necessarily convey a digestive advantage

Raufutter als Alleinfutter für Kaninchen – Auswirkungen auf das Fettsäurenmuster des Fleisches

Four groups of eight New Zealand hybrid rabbits were fed ryegrass meal only, alfalfa meal only, ryegrass and oats 1:1, or alfalfa and oats 1:1. Diets were offered ad libitum in pelleted form from 5-30 weeks of age, when they were slaughtered. Intramuscular fatty acid profiles were determined in the Musculus quadriceps of the left hindleg. Feed intake was not statistically different between the four groups, nor was carcass weight. The main effect of the forage-only diets on the fatty acid profiles was a decrease of monounsaturated and an increase of polyunsaturated fatty acid (PUFA) proportions. Within PUFA, the n-3 fatty acids more than doubled with forage-only compared to forage-oats diets, while the n-6 fatty acids slightly decreased. In general, the proportion of n-3 fatty acids in intramuscular fat of forage-only fed rabbits was extraordinarily high compared to any other meat of agricultural origin. The results demonstrate a specific advantage of roughage-based diets in the nutrition of productive herbivores, which is also known for ruminants

A pilot investigation on the effect of induced saliva flow on digestive parameters in sheep, and a comparison with cattle

Sheep with a relatively low methane yield were observed to have shorter fluid and particle mean retention times (MRT). Because the application of pilocarpine, a saliva stimulant, was successful in reducing retention times in ruminants in previous studies, we applied this substance to sheep, expecting a reduction in MRT and methane yield. Three non‐pregnant sheep (74 ± 10 kg) were fed a hay‐only diet in a 3 × 3 Latin square design with oral doses of 0, 2.5 and 5mg pilocarpine/kg body weight and day. Measurements included feed and water intake, MRT of liquid and particulate phases in the reticulorumen (RR) and total gastrointestinal tract (GIT), ruminal microbial yield (via urinary purine bases and metabolic faecal nitrogen), total tract methane emission, apparent nutrient digestibility and rumen fluid parameters. Data were investigated for linear and quadratic effects using orthogonal polynomial contrasts. The MRT of liquid and small particles in the RR and total GIT, and the short‐chain fatty acid concentration in rumen fluid, linearly declined with increasing pilocarpine dosage, while no quadratic relationship was detected. Intake of feed DM and water, apparent nutrient digestibility, methane yield and microbial yield were not affected by pilocarpine. When combining the sheep data with that of a similar experiment in cattle, we found that the MRT of the liquid phase was positively associated with estimated NDF digestibility and with methane production per digested NDF, but was not associated with microbial yield or the ratio of acetate to propionate. The ratio between MRT of the particulate and the liquid phase was smaller for sheep than that for cattle, and was not affected by treatment. Differences in this ratio might explain why species reacted differently to the saliva‐inducing agent, which might help to explain the discrepancy between species in the effect of induced saliva flow on digestive parameters