Annette C. Longland

Background: Obesity can negatively impact upon equine welfare and bodyweight (BW) of pastured equines is often difficult to manage. Objectives: To compare the effects of three restricted grazing regimens on changes in pony BW and morphometric measurements. Study design: Randomised study. Methods: Twelve mature ponies were individually grazed in 10m wide, rectangular, electric fenced paddocks. The dry matter (DM) herbage yield of each paddock was determined, and paddock length adjusted on Day 1 to provide 1.5% of individual pony BW as herbage DM daily, for 28 days. There were four ponies per treatment. Treatments were: total paddock area (TA) and strip grazing treatments, SG1 and SG2. SG1 had a ‘lead’ fence spanning the paddock width being moved a set distance along the paddock length daily to provide 1.5% of pony BW as fresh pasture DM (as determined on Day ‐1). SG2 also had a ‘back fence’ 7–12m behind the ‘lead’ fence which was moved the same distance as the lead fence daily. Calculated dry matter intakes, changes in cresty neck score (CNS), body condition score (BCS) and percentage changes in BW, heart girth (HG), belly girth (BG) and rump width (RW) were compared between treatments. Results: Mean (±SD) calculated pasture DM intakes (as % BW/d) by TA ponies were 2.33 ± 0.50, being significantly higher (P < 0.05) than 1.82 ± 0.43 (SG1) and 1.59 ± 0.42 (SG2). Mean percentage BW changes were higher (P < 0.05) for TA ponies at 4.82 ± 1.36 vs. 1.16 ± 0.39 (SG1) and 1.54 ± 1.35 (SG2). SG1 and SG2 pony BW changes were not significantly different. TA, but not SG1 or SG2 animals showed significant (P < 0.05) increases in BCS1/9 (+0.94 ± 0.32), CNS1/5 (+0.5 ± 0), RW (+2.11 ± 3.6) and BG (+4.15 ± 2.29). SG1 and SG2 ponies showed significant (P < 0.05) decreases in HG (−0.05 ± 2.12) and BG (−5.53 ± 4.89) respectively. Main limitations: Small sample size. Conclusions: Strip grazing limited pony bodyweight gains and upward changes in morphometric parameters.

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.

The effects of different water‐soaking treatments on removal of water‐soluble carbohydrates (WSC), WSC constituents and protein from four UK hays were determined. Hays were soaked in water for up to 16 hours at mean temperatures of 8°C, 16°C, in hot tap water (initially 49°C) or agitated and rinsed in clean water at 16°C. Initial hay WSC contents ranged from 154 to 216 g/kg dry matter. Losses of WSC from hays after 16 hours soaking at 8°C, 16°C, 16°C plus agitation and 49°C averaged 28, 46, 49 and 44 per cent, respectively. Corresponding percentage losses of fructan were 16, 37, 39 and 33. Percentage losses of sucrose averaged 55 (8°C), 86 (16°C), 91 (16°C+agitation) and 82 (initial temperature 49°C), those of glucose were 60, 85, 75 and 75, and of fructose were 41, 52, 54 and 46. Hay crude protein contents were not significantly changed by any of the soaking treatments. Soaking at 8°C generally resulted in reduced losses of WSC compared to when soaked at the higher temperatures. Thus, in cold weather using warmer water to soak hays may effect greater WSC loss, although very prolonged soaking at warm temperatures might encourage the proliferation of unwanted micro‐organisms in the soak liquor.

Laminitis is a debilitating disease of the equid foot and appears to result from altered metabolism due to insulin resistance (IR) or hindgut acidosis. These disorders may be elicited by high intakes of simple sugars or fructans in pasture grasses. The aim was to determinein vitro(i) whether grass fructan is degraded in the equid foregut and (ii) the fermentation kinetics and organic acid production in cultures containing grasses differing in fructan content incubated with an equid hindgut microbial inoculum. When grass fructan was incubated with equid gastric and small intestinal digesta, polymeric fructan was partially degraded to oligo‐fructan. When incubated with small intestinal digesta, but not gastric digesta, there was limited net loss of total fructan (oligomeric + polymeric fructan). WhenLolium perenneof elevated (PRGH) or moderate (PRGL) fructan content was incubated with an equine hindgut microbial inoculum, the rate of fermentation and accumulation of lactate 6 and 9 h post‐inoculation were significantly greater forPRGHthan forPRGL(P < 0·05). This may suggest that grass fructan ingested by grazing horses is incompletely digested in the foregut and passes into the hindgut, resulting in elevated production of lactate, which may indirectly lead to metabolic disorders such as laminitis.

Intakes were determined in four mature ponies, grazing spring, summer and autumn pastures on four, 3 hour occasions per pony per season when fitted with or without a grazing muzzle. Pasture intakes were determined by change in liveweight (LW) over the 3 hour grazing period, after accounting for insensible weight loss (ISWL) and weight of excreta. Ponies were prevented from drinking during the 3 hour grazing period. Pastures were sampled daily mid-way through the grazing period for determination of DM. Wearing grazing muzzles reduced pasture dry matter intake (DMI) relative to when grazing muzzles were not fitted by 78, 77 and 83% for spring, summer and autumn pastures respectively.

The term ‘forage quality’ encompasses the nutritive value, hygienic status and intake of the forage. The concept of ‘forage quality’, however, should be regarded in terms of meeting the specific requirements of individual animal, rather than solely as a descriptor of nutrient content and/or intake potential. Methods of assessing quality include chemical analysis of main nutrients, in vitro methods and in vivo studies. The nutrient content of fresh forage changes radically throughout the growing season, and such changes are reflected in forages conserved at different times of the year. Grazed forage alone can support the energy and protein requirements of all classes of horse for at least part of the year. Depending on the forage type and time of harvest, well conserved forages of moderate-high nutritive value may meet the energy and crude protein requirements of horses in moderate work and pregnant mares. Hygienic quality should always be considered in conjunction with nutritive value, and contaminated forages should not be fed. As forages should form the basis of all equid diets, and as their nutrient content is so highly variable, forages need to be analysed if they are to be incorporated into specifically tailored rations for horses.

The degradation of grass fructan in vitro under conditions simulating the equine foregut was investigated. An extract enriched for fructan obtained from timothy grass (Phleum pratense) was incubated with digesta from the equid stomach and small intestine. In all incubations with gastric and small intestinal digesta, there was evidence of partial depolymerisation of fructan polymers to oligomeric fructan. There was no net loss of total fructan (polymeric plus oligomeric fructan) when the timothy grass fructan was incubated with gastric digesta. However, there was limited loss of total fructan when incubated with small-intestinal digesta. This may suggest that grass fructan is not substantially degraded in the equid foregut, and therefore would pass into the hindgut where it may be fermented.