Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.

. 1997. The effect of conjugated linoleic acid on fat to lean repartitioning and feed conversion in pigs. Can. J. Anim. Sci. 77: 723-725. The repartioning effect of CLA was evaluated using 108 pigs (54 gilts and 54 barrows) fed from 61.5 to 106 kg liveweight. Pigs were fed a cereal-based basal diet containing either 2% CLA or 2% sunflower oil (a rich source of α-linoleic acid). Irrespective of gender, pigs fed CLA tended to have reduced feed intakes (-5.2%, P = 0.07), improved feed conversion efficiences (-5.9%, P = 0.06) and similar rates of gain relative to sunflower oil fed pigs. In addition, pigs fed CLA deposited less subcutaneous fat (-6.8%, P = 0.01) and gained more lean (+2.3%, P = 0.03) than pigs fed sunflower oil. These data suggest CLA can be used as a repartioning agent in pigs and that further research to optimize the repartitioning effect is warranted. , un meilleur indice de conversion (-5,9 %, P = 0,06) et un GMQ analogue à ceux recevant l'huile de tournesol. En outre, ces porcs déposaient 6,8 % moins de gras sous-cutané (P = 0,01) et produisaient 2,3 % plus de maigre (P = 0,03). Il ressort de ces résultats que ALC peut être utilisé comme répartiteur lipido-protéique chez les porcs, mais qu'il reste des recherches à faire pour optimiser ces effets de répartition.

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. 1999. The effects of feeding conjugated linoleic acid on subsequent pork quality. Can. J. Anim. Sci. 79: 45-51. Feeding conjugated linoleic acid (CLA) has recently been shown to repartition fat to lean in pigs. The present study was undertaken to determine if feeding CLA affects pork quality. Pigs were fed a cereal-based diet containing either 2% CLA or 2% sunflower oil. Fifty-four pigs (27 gilts and 27 barrows) were fed per diet, and diets were fed from 61.5 to 106 kg liveweight. Diet did not affect postmortem longissimus thoracis (LT) glycogen utilization, lactate accumulation, or pH decline. Conjugated linoleic acid fed pigs had slightly higher LT temperatures at 3 h postmortem (+1.15°C; P < 0.05), but subsequent LT shear force, drip loss and soluble protein levels were unaffected. Diet did not affect subjective LT scores for structure or color, but objective color measurements indicated LT from CLA-fed pigs had slightly higher chroma (color saturation) values (+0.84; P < 0.05). Longissimus thoracis from CLA-fed pigs also had increased subjective marbling scores (P < 0.01) and increased petroleum-ether-extractable intramuscular fat (+22%; P < 0.01). Diet did not affect any measured palatability characteristic (initial and overall tenderness, juiciness, flavor desirability, flavor intensity, connective tissue amount, overall palatability; P > 0.05). Feeding 2% dietary CLA to pigs, therefore, shows some potential for improving pork composition by increasing intramuscular fat, while having no detrimental effect on pork quality. On a récemment constaté que l'administration de l'acide linoléique conjugué (ALC) favorise la répartition lipido-protidique chez les porcs. Nos travaux avaient pour objet de vérifier si ALC influe sur la qualité de la viande. Les porcs utilisés recevaient une ration à base de céréales contenant 2 % d'ALC ou 2 % d'huile de tournesol. Cinquatre-quatre porcs, soit 27 cochettes et 27 castrats, étaient affectés à chaque régime, l'expérience durant jusqu'à ce qu'ils atteignent le poids vif de 61,5 à 106 kg. Le régime n'avait pas d'effet sur l'utilisation du glycogène, sur l'accumulation des lactates ou sur la baisse du pH post-mortem dans le longissimus thoracis (LT). Les sujets recevant ALC montraient une température du LT légèrement plus haute 3 h après l'abattage, soit 1,15 °C de plus (P < 0,05) mais, par la suite, la force de cisaillement, les pertes d'égouttage et les concentrations de protéines solubles ne différaient pas de celles obtenues dans le régime à l'huile de tournesol. Le régime n'avait pas non plus d'effet sur les notations subjectives du LT quant à la structure ou à la coloration, mais les mesures colorimétriques objectives révélaient un indice de saturation légèrement plus élevé dans le LT des porcs recevant l'ALC, soit 0,84 de plus (P < 0,05). En outre, chez ces derniers, les notations subjectives du persillé de la viande étaient plus élevées (P < 0,01), de même que les quantités de gras intramusculaire extractible dans l'éther de pét-role, soit 22 % de plus (P < 0,01). Au...

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