Commercial diets high in animal protein and fat are increasingly being developed for pets, however little is understood about the impacts of feeding such diets to domestic cats. The carbohydrate content of these diets is typically low, and dietary fibre is often not included. Dietary fibre is believed to be important in the feline gastrointestinal tract, promoting stool formation and providing a substrate for the hindgut microbiome. Therefore, we aimed to determine the effects of adding plant-based dietary fibre to a high animal protein and fat diet. Twelve domestic short hair cats were fed three complete and balanced diets in a cross-over design for blocks of 21 days: raw meat (Raw), raw meat plus fibre (2%, ‘as is’ inclusion of inulin and cellulose; Raw+Fibre) and a commercially available Kibble diet. A commercially available canned diet was fed for 21 days as a washout phase. Apparent macronutrient digestibility, faecal output, score, pH, organic acid concentrations and bacteriome profiles were determined. Diet significantly affected all faecal parameters measured. The addition of dietary fibre to the raw meat diet was found to reduce apparent macronutrient digestibility, increase faecal output, pH and score. Thirty one bacterial taxa were significantly affected by diet. Prevotella was found to dominate in the Kibble diet, Clostridium and Fusobacterium in the Raw diet, and Prevotella and a group of unclassified Peptostreptococcaceae in the Raw+Fibre diet. Our results show that diets of different macronutrient proportions can strongly influence the faecal microbiome composition and metabolism, as shown by altered organic acid concentrations and faecal pH, in the domestic cat. The addition of 2% of each fibre to the Raw diet shifted faecal parameters closer to those produced by feeding a Kibble diet. These results provide a basis for further research assessing raw red meat diets to domestic cats.

Little is known about how milk proteins affect gastrointestinal (GI) transit, particularly for the elderly, in whom digestion has been observed to be slowed. We tested the hypothesis that GI transit is faster for whey than for casein and that this effect is accentuated with hydrolysates, similar to soy. Adult male rats (18 months old) were fed native whey or casein, hydrolyzed whey (WPH) or casein (CPH), hydrolyzed blend (HB; 60% whey:40% casein), or hydrolyzed soy for 14 days then treated with loperamide, prucalopride, or vehicle-control for 7 days. X-ray imaging tracked bead-transit for: gastric emptying (GE; 4 h), small intestine (SI) transit (9 h), and large intestine (LI) transit (12 h). GE for whey was 33 ± 12% faster than that for either casein or CPH. SI transit was decreased by 37 ± 9% for casein and 24 ± 6% for whey compared with hydrolyzed soy, and persisted for casein at 12 h. Although CPH and WPH did not alter transit compared with their respective intact counterparts, fecal output was increased by WPH. Slowed transit by casein was reversed by prucalopride (9-h), but not loperamide. However, rapid GE and slower SI transit for the HB compared with intact forms were inhibited by loperamide. The expected slower GI transit for casein relative to soy provided a comparative benchmark, and opioid receptor involvement was corroborated. Our findings provide new evidence that whey slowed SI transit compared with soy, independent of GE. Increased GI transit from stomach to colon for the HB compared with casein suggests that including hydrolyzed milk proteins in foods may benefit those with slowed intestinal transit.

Sharpea and Kandleria are associated with rumen samples from low-methane-emitting sheep. Four strains of each genus were studied in culture, and the genomes of nine strains were analysed, to understand the physiology of these bacteria. All eight cultures grew equally well with d-glucose, d-fructose, d-galactose, cellobiose, and sucrose supplementation. d-Lactate was the major end product, with small amounts of the mixed acid fermentation products formate, acetate and ethanol. Genes encoding the enzymes necessary for this fermentation pattern were found in the genomes of four strains of Sharpea and five of Kandleria. Strains of Sharpea produced traces of hydrogen gas in pure culture, but strains of Kandleria did not. This was consistent with finding that Sharpea, but not Kandleria, genomes contained genes coding for hydrogenases. It was speculated that, in co-culture with a methanogen, Sharpea and Kandleria might change their fermentation pattern from a predominately homolactic to a predominately mixed acid fermentation, which would result in a decrease in lactate production and an increase in formation of acetate and perhaps ethanol. However, Sharpea and Kandleria did not change their fermentation products when co-cultured with Methanobrevibacter olleyae, a methanogen that can use both hydrogen and formate, and lactate remained the major end product. The results of this study therefore support a hypothesis that explains the link between lower methane yields and larger populations of Sharpea and Kandleria in the rumens of sheep.

No abstract

Acibenzolar-S-methyl (ASM), the active ingredient in Actigard® (Syngenta), is a plant defence elicitor used for the management of bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) in kiwifruit. We examined changes in gene expression and phytohormone content in two kiwifruit cultivars, ‘Hayward’ (Actinidia chinensis var. deliciosa) and ‘Zesy002’ (A. chinensis var. chinensis), following ASM application. In glasshouse studies, ASM-induced resistance to stem inoculation with Psa was accompanied by upregulation of salicylic acid (SA) defence pathway genes (PR1, PR2, and PR5) in stems and leaves. The expression of PR1 in ASM-treated plants increased by c. 5-fold in ‘Hayward’ and by over 15-fold in ‘Zesy002,’ relative to the untreated controls, whereas PR2 and PR5 increased by up to 4-fold in both cultivars. Orchard studies over three seasons confirmed the utility of PR1, PR2, and PR5 for monitoring ASM-induced responses in mature vines. PR1 and PR5 were more strongly induced by ASM than PR2 and gene upregulation in ‘Hayward,’ was accompanied by a reduction in Psa leaf spotting; no such relationship was measurable for ‘Zesy002’ because leaf spot symptoms are rarely expressed. In the third season, six additional gene candidates, BAD, Gluc2, Class IV Chit, EDS1A, NPR3, and NIMIN2, were responsive to ASM in ‘Hayward’ and ‘Zesy002.’ Gene upregulation was transient, with expression levels increasing by 1 d after ASM application and declining to control levels between 7 and 14 days. Moreover, the amplitude of gene upregulation depended on leaf developmental stage and was greater in the first true leaf and the youngest mature leaves than in immature leaves along the same shoot. Phytohormone content did not show a repeatable response pattern to ASM in potted plants or in vines possibly as a consequence of their wider role in regulating plant growth and mediating environmental responses. In conclusion, this study demonstrates that defence gene expression can be used to monitor responsiveness to ASM in two genetically distinct mature kiwifruit cultivars (‘Hayward’ and ‘Zesy002’) under orchard conditions. The use of defence marker genes could be of broader utility across kiwifruit species and could be used to guide ASM application schedules in the orchard.