Meriel Moore-Colyer

Despite our improved understanding of equid digestive health and accurate rations formulations, obesity in the UK horse population remains high. Study aims: (1) to determine how owners are feeding their horses and what influences their choices, (2) to understand owners’ knowledge of haylage and (3) to identify key areas that require additional education. Data were collected in 2020 from 1338 UK horse owners via two online surveys. Survey 1 was on general feeding practices, and Survey 2 was specifically on the feeding of haylage. Data were processed using chi square analyses + Bonferroni tests, with a significance p < 0.05. Equal numbers of leisure and performance horse owners completed both surveys. For Survey 1, 67% fed hay as the only forage, 30% fed forage (hay/haylage) + balancer, 36% fed haylage and hay to manage energy intake, 84% added a cube or coarse mix, 88% did not do forage analyses, 74% did not see the need for it and 16% did not know analyses could be done. In Survey 2, those who were not feeding haylage, 66% were not sure how to feed it, 68% worried about aerobic spoilage and 79% said the bale size was unsuitable. Body weight measurements (Survey 1 and Survey 2) were rarely performed (11%). Aspects of ration formulations, the value of feed analyses and how to interchange hay and haylage require additional education to owners for improved ration compilation.

Soaking hay fodder to reduce dust and soluble carbohydrate (WSC) contents prior to feeding is common practice among horse owners. Soaking can increase bacteria load in hay but no information exists on how this process alters the bacteria profile, which could pose a health risk or digestive challenge, to horses by introducing foreign bacteria into the gastrointestinal tract and so altering the normal profile. The current objectives were to map the bacterial profile of 3 different hays and determine how soaking alters this with the aim of improving best practice when feeding stabled horses. A Perennial Rye grass hay and two meadow s hays were soaked for 0, 1.5, 9 or 16 hours. Pre and post treatment, hays were analysed for WSC and total aerobic bacteria (CFU/g), and differences in bacteria family profiles were determined using ANOVA with significance set at Pvia genomic DNA extraction and 16S library preparation (V3 and V4 variable region of 16S rRNA) according to the Illumina protocol. Differences in family operational taxonomic units (OTUs) between individual dry hays and different soaking times were identified via paired t-tests on the DESeq2 normalised data and false discovery rates accounted for using Padj (P<0.05). Mean % WSC losses and actual g/kg lost on DM basis (+/- SE) increased with soaking time being 18% = 30 (10.7), 38% = 72 (43.7), and 42% = 80 (38.8) for 1.5, 9 and 16 hours soak respectively. No relationship existed between WSC leaching and bacteria growth or profile. Grass type influenced bacterial profiles and their responses to soaking, but no differences were seen in richness or Shannon diversity indices. PCA analyses showed clustering of bacteria between meadow hays which differed from the perennial rye grass hay and this difference increased post soaking. Soaking hay pre-feeding causes inconsistent WSC leaching, bacteria growth and alterations in bacterial profiles which are unpredictable but may decrease the hygienic quality of the fodder.

Globally hay is the preferred forage for stabled horses. Variable nutritional and hygienic quality stimulates pre-feeding soaking to reduce dust and nutrients to reduce respiratory and metabolic disorders in horses. However, this practice has potential negative impacts on horse health. The objectives of this study were to map the bacterial profile of different hays and determine how soaking alters this with the aim of recommending best practice when feeding fodder to stabled horses. Two meadow and one Perennial Ryegrass hays were soaked for 0, 1.5, 9 or 16 hours. Post treatment, hays were analysed for water-soluble carbohydrate (WSC) and total aerobic bacteria (TVC), with differences determined using ANOVA and least significant difference. Bacteria were identified via genomic DNA extraction (V3 and V4 variable region of the 16S rRNA gene) and 16S library preparation according to the Illumina protocol. Differences in phyla and family operational taxonomic units within hay types were identified via paired t-tests on the DESeq2 normalised data and false discovery rates accounted for using Padj (P<0.05). Mean WSC losses g/kg DM (+/- SE) increased with soaking time being 30 (10.7), 72 (43.7), 80 (38.8) for 1.5, 9 and 16 hours soak respectively. No relationship existed between WSC leaching and bacteria content or profile. Grass type influenced bacterial profiles. Soaking altered the epiphytic bacterial profile across all hays and 9 hours soaking increased richness and Shannon diversity indices. Clustering of bacteria was seen between meadow hays which differed from perennial rye grass and this difference increased post soaking. The normal industry practice of soaking hay for 9 hours pre-feeding cannot be recommended as it increases total bacteria content with noted increases of some potential pathogens. The alterations in bacteria profile and hygienic quality may explain why changing fodder or pre-feeding treatments can frequently precipitate colic in horses.

Five different hays were used to determine the effect of 5 different soaking and steaming treatments on the water soluble carbohydrate and microbial (bacteria and mould) contents of UK hay. Hays were subjected to the following 5 treatments: 1. Dry; 2. Steamed for 50 minutes in the Haygain- 600 steamer; 3. Soaked in water at 16°C for 9 hours; 4. Steamed then soaked and 5. Soaked then steamed. Post treatment hays were tested for water soluble carbohydrates, bacteria and mould contents. Differences between means were determined using ANOVA and least significant difference with hay (5), bale (3) and treatment (5) as fixed factors, thus n = 75. Protein and ash proportions were unaltered in any of the treatments. Soaked, steamed then soaked and soaked then steamed treatments were all equally effective at reducing water soluble carbohydrates, with significantly (P3 and 4.9×10² CFU/g DM) compared with soaked which increased CFU/g DM from 6.0×10⁴ in dry hay up to 3.5×10⁵. Mould contents CFU/g DM were significantly (P<0.05) reduced by steaming (2) and soaking then steaming (1.9) but no difference was seen between dry (1148), soaked (692) or steamed then soaked (501). Soaking for 9 hours followed by steaming for 50 minutes in the Haygain steamer was the most effective method for reducing water soluble carbohydrates and microbial contamination in hay. Soaking or steaming+soaking lowered water soluble carbohydrates but significantly reduced the hygienic quality of the hay which could potentially compromise the health of the horse.