Studies on the degradation kinetics of botanically diverse fibrous feeds and their apparent digestibility and rate of passage when fed to ponies

The horse evolved to obtain most of its dietary energy from the hindgut fermentation of fibrous feeds and so in the interests of health and welfare, the domestic horse should be fed forage-based diets. However, little information exists on the nutritive value of different forages that are potentially valuable feeds for horses. The aim of this thesis was to measure the in vivo apparent digestibility of a range of botanically diverse fibrous-feeds and to investigate the suitability of ruminant in sacco and in vitro techniques as routine methods for estimating, degradation kinetics and rates of passage of fibrous feeds through the gastrointestinal tract of ponies. In the first study, the in vivo apparent digestibility (AD) of hay (H), haylage (HY), big bale silage (BB) and clamp silage (CS) were determined in 4 ponies. Dry matter intake was significantly (P H > CS (2.95 kg/d). For all parameters measured AD of CS and BB were significantly (P<0.05) greater than for H, with HY being intermediate. The theoretical digestible energy and crude protein requirements of the ponies were met or exceeded by all diets except hay. Secondly, the in vivo AD, intra-caecal fermentation parameters and rates of passage of hay cubes (HC), an oat hulls:naked oats mix (OH:NO), plain sugar beet pulp (SBF), soya hulls (SH) and a hay cubes:sugar beet mix (HC:SB) were determined in 3 caecally-fistulated ponies. Total collection and mobile bag studies produced similar AD values, with SBF being greater (P<0.05) for all parameters measured than OH:NO and HC, with intermediate values for SB:HC and SH. All feeds maintained the intra-caecal pH and acetate molar proportions above 6.5 and 700 mmol/mol respectively. Higher levels of propionate and lactate and lower levels of butyrate were recorded for ponies fed the OH:NO compared with those on diets SBF and HC (P<0.05). Pre-caecal losses of total non-starch polysaccharides (TNSP) from feeds in sacco were highest for SBF (133g/kg) >SH > OH:NO > HC (51g/kg). In contrast, the highest crude protein (CP) losses were from OH:NO (771 g/kg) which were greater than SH = HC > SBF (296g/kg) (P<0.05). Of the 7 ruminant models fitted to faecal excretion data, the G3 and G4 time-dependent models of Pond et al. (1988) best described the passage of both chromium (Cr) and ytterbium (Yb) marked feeds in the three diets. Mean caecal to faecal passage rates measured using Crmordanted feed, were ca. 36 h for OH:NO, which was greater than that of HC at ca. 26 h (P<0.05). Total tract mean retention time (MRT) was measured using orally administered Yb-marked feeds and averaged 43 h for OH:NO which was greater than the 30 h noted for the HC (P<0.05). Finally, the in vitro fermentation by pony faecal inoculum of hay (H) and plain sugar beet pulp (SB) in ratios of 100% H, 75:25 H:SB 1, 50:50 H:SB2, 25:75 H:SB3 and 100%SB, in the presence (+N) or absence (-N) of added nitrogen was assessed by the manual pressure transducer technique of Theodorou et al. (1994). DM loss was significantly (P H:SB3 > H:SB2 > HSB1 > H. Addition of N reduced the time to reach 50% of gas production (tso), indicating a positive influence of N on degradation rate (P<0.05). Maximum DM loss {ca. 850 mg/g) from SB occurred within 49 h post-incubation whereas maximum degradation from the other feeds was attained at ca. 135 h incubation. A positive associative effect was noted on both the rate and extent of degradation of H when incubated with HSB3 (-N), indicating an increase in microbial activity associated with the addition of SB. Results from the experiments described in this thesis indicate that a range of botanically diverse fibrous feeds are suitable for incorporating into equid diets, and offer a valuable relatively energy-dense alternative to hay as the basal forage for stabled horses. Ruminant techniques for measuring in sacco AD and the use of markers for determining rate of passage of digesta offer rapid and reliable methods for measuring digestion of a range of fibrous feeds in ponies. In vitro gas production showed considerable potential as a routine method for determining DM loss and degradation rate of fibre feeds for horse

The Effect of Management Regime on Airborne Respirable Dust Concentrations in Two Different Types of Horse Stable Design

Airborne respirable dust (ARD) (<5 mm) in the stable environment is strongly implicated in equine asthma. Bedding, forage, ventilation rate, and stable management activities all contribute to ARD. This study investigated the relationship between ARD in the breathing zone (BZ) and the stable zone (SZ) in eight American barns (ABs) and eight stable complexes with individual stables under four different management regimes. Airborne respirable dust was measured in eight replicate stables per regime in ABs (n ¼ 32) and eight per regime in single stables (n ¼ 32). Regimes were as follows: (1) steamed hay and shavings; (2) dry hay and shavings; (3) haylage and straw; and (4) dry hay and straw. Samples were taken in quite periods between 3 PM and 4 PM hours. Airborne respirable dust levels were analyzed using Split-Plot analysis of variance and Wilcoxon matched-pairs test (Genstat 15) with P <.05 as significant. The lowest ARD (<360 RP/L air) was found for shavings and steamed hay in AB and single stables in both BZ and SZ. Straw and dry hay in ABs produced ARD of 6,250 (SZ), 5,079 RP/L air (BZ) which was greater (P < .05) than the 2,901 (SZ) and 942 (BZ) RP/L air in single stables. Straw and haylage produced more ARD across both zones in single stables compared with ABs. Shavings and dry hay ¼ more dust in the BZ than in the SZ, whereas straw and haylage ¼ higher ARD in the SZ versus the BZ across both stable designs. Using dry hay and/or straw cannot be recommended as a suitable management regime for stabled horses

Development of a comprehensive protein microarray for immunoglobulin E profiling in horses with severe asthma

Background: Severe asthma in horses, known as severe equine asthma (SEA), is a prevalent, performance-limiting disease associated with increased allergen-specific immunoglobulin E (IgE) against a range of environmental aeroallergens. Objective: To develop a protein microarray platform to profile IgE against a range of proven and novel environmental proteins in SEA-affected horses. Animals: Six SEA-affected and 6 clinically healthy Warmblood performance horses. Methods: Developed a protein microarray (n = 384) using protein extracts and purified proteins from a large number of families including pollen, bacteria, fungi, and arthropods associated with the horses, environment. Conditions were optimized and assessed for printing, incubation, immunolabeling, biological fluid source, concentration techniques, reproducibility, and specificity. Results: This method identified a number of novel allergens, while also identifying an association between SEA and pollen sensitization. Immunolabeling methods confirmed the accuracy of a commercially available mouse anti-horse IgE 3H10 source (R2 = 0.91). Biological fluid source evaluation indicated that sera and bronchoalveolar lavage fluid (BALF) yielded the same specific IgE profile (average R2 = 0.75). Amicon centrifugal filters were found to be the most efficient technique for concentrating BALF for IgE analysis at 40-fold. Overnight incubation maintained the same sensitization profile while increasing sensitivity. Reproducibility was demonstrated (R2 = 0.97), as was specificity using protein inhibition assays. Arthropods, fungi, and pollens showed the greatest discrimination for SEA. Conclusions and clinical importance: We have established that protein microarrays can be used for large-scale IgE mapping of allergens associated with the environment of horses. This technology provides a sound platform for specific diagnosis, management, and treatment of SEA

An Anti-Urban Education? Work camps and ideals of the land in Interwar Britain

The article examines the role of work camp movements in developing rural critiques of urban living in interwar Britain. A variety of work camp movements flourished in Europe during the interwar years, often partly as a reaction against urbanisation, and this paper explores the ways in which three such movements developed the work camp as a means of countering the socialising influences of city life. Yet while all of the interwar British work camps were located in the countryside, they varied in the extent to which they tried to promote rural values and orientations among their trainees.We can see the work camp as a liminal pedagogic space, designed to lead trainees to particular educational outcomes, using techniques and methods that focused on bodily change as well as cognitive development

The Effect of Moxidectin Treatment on the Equine Hind Gut Microbiome, Metabonome and Feed Fermentation Kinetics in Horses with Very Low Parasite Burdens

Seventeen horses, mean 12 ± 3.5 years, kept at pasture, with haylage provided and no concentrates. Faecal Egg Counts were conducted September 2015‐March 2016, no eggs seen, no anthelmintic given. Sampling commenced March 2016, points were 0 (prior), 16, 48 and 168 hours post anthelmintic. Treatments were randomized, nine animals dosed orally with Moxidectin 18.92 mg/g at 0.4 mg/kg bw and eight controls. Three horses from each group were randomly assigned for fermentation kinetics. Sequencing of the 16S rRNA gene was conducted on extracted faecal bacterial DNA, bioinformatics using QIIME assigning operational taxonomic units (OTUs). LEfSe (Segata et al., 2011) was used to identify differentially abundant OTUs. Bacterial metabolic profiles were characterized by 1H NMR spectroscopy (Escalona et al., 2015), from urine, analysed by Principal Components Analysis. Fermentation of hay and oats, separately, were measured by in vitro gas production (Murray et al., 2006), data were analysed by repeated measures ANOVA

Neural modulators of temperament:A multivariate approach to personality trait identification in the horse

A relationship between dopamine and temperament has previously been described in human cases of dopaminergic dysfunction. Adjustment in temperament prior to disease manifestation can enable the early identification of individuals at risk of such 20 conditions, and scope exists to extend this application of temperament alterations to cases of dopaminergic dysfunction in horses. A multivariate and mixed-methods approach utilising a questionnaire along with two inferred measurements of dopamine activity (Spontaneous Blink Rate [SBR] and Behavioral Initiation Rate [BIR]) were recorded from direct observation of animals (n=99) to identify the potential relationship between dopamine and temperament in horses. Principal components analysis (PCA) of 36 temperament variables revealed nine Principal Components, including ‘Anxiety’ and ‘Docility’, which accounted for 72.4% of the total variance. Component scores were calculated and correlated with SBR and BIR utilising Spearman Rank Correlation Coefficient analysis. The component ‘Anxiety’ was found to have a significant positive relationship with SBR, whereas ‘Docility’ was observed to have a significant negative relationship with SBR. These results indicate a relationship between dopamine and temperament within the horse that is certainly worthy of further study. Potential mechanisms involving neural dopaminergic and GABAergic systems are presented, in addition to how such alterations could be utilised to probe for equine dopamine dysfunction pending future research. Highlights: A significant positive correlation was observed between ‘Anxiety’ and dopamine levels A significant negative correlation was found between ‘Docility’ and dopamine levels Chronic dopamine adaptations may initially manifest as temperament alterations Potential exists to identify horses at risk of dopamine dysfunction development through analysis of temperament Key words: Temperament; Dopamine; Equine; Behavior; Anxiety; Docilit

The influence of hay steaming on clinical signs and airway immune response in severe asthmatic horses

ackground Avoidance of antigenic stimuli was found to significantly reverse airway obstruction of horses with severe equine asthma (sEA). To date, no published study investigated the influence of steaming hay on lower airway condition of sEA-affected horses. The objectives were to determine the clinical, cytological and cytokine respiratory responses of both sEA and control (CTL) horses experimentally exposed to steamed or dry hay. Results A cohort of 6 sEA horses and 6 CTL horses was involved in this field study. On day 0, both groups were fed with steamed hay for 5 consecutive days, followed by a wash-out period of 26 days prior to be fed with dry hay for 5 consecutive days. Investigations performed 2 days prior to and 5 days after each challenge included clinical score, tracheal mucus accumulation, and bronchoalveolar lavage fluid (BALF) cytology and cytokine mRNA expression. Feeding steamed hay significantly decreased its mould content (P < 0.001). Mucus score significantly increased when feeding dry hay (P = 0.01). No significant influence of challenge type was found on clinical score. Percentages of neutrophils (P < 0.001) as well as mRNA expression of IL-1β (P = 0.024), IL-6R (P = 0.021), IL-18 (P = 0.009) and IL-23 (P = 0.036) in BALF of sEA affected horses were significantly increased after both (steamed and dry hay) challenges. Relative mRNA expression of IL-1β, IL-6R and IL-23 in BALF were also significantly correlated to neutrophil percentages and both clinical and tracheal mucus score. Conclusions Steaming significantly decreased mould content but inconsistently influenced the respiratory response of sEA affected horses when fed hay. Based on BALF cytology and cytokine profiles, its relevance might be controversial as a non-medicinal therapy for sEA-affected horses

Antigen array for serological diagnosis and novel allergen identification in severe equine asthma

Severe equine asthma (sEA), which closely resembles human asthma, is a debilitating and performance-limiting allergic respiratory disorder which affects 14% of horses in the Northern Hemisphere and is associated with increased allergen-specific immunoglobulin E (IgE) against a range of environmental proteins. A comprehensive microarray platform was developed to enable the simultaneous detection of allergen-specific equine IgE in serum against a wide range of putative allergenic proteins. The microarray revealed a plethora of novel pollen, bacteria, mould and arthropod proteins significant in the aetiology of sEA. Moreover, the analyses revealed an association between sEA-affected horses and IgE antibodies specific for proteins derived from latex, which has traditionally been ubiquitous to the horse’s environment in the form of riding surfaces and race tracks. Further work is required to establish the involvement of latex proteins in sEA as a potential risk factor. This work demonstrates a novel and rapid approach to sEA diagnosis, providing a platform for tailored management and the development of allergen-specific immunotherapy