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

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

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

Growth rates of Thoroughbred foals and in vitro gut health parameters when fed a cereal or an all fibre creep feed.

Abstract Traditions and the economic advantage when producing big athletic TB yearlings for sale, encourages owners to feed high levels of cereals. Such diets can predispose gastric ulceration and developmental orthopaedic diseases, impacting negatively on future careers. Study aims: 1. Determine if an all fibre creep feed (TMFR) would sustain equal growth rates in TB foals versus a cereal based stud cube (SC); 2. Compare pH and lactate produced by SC and TMFR in in vitro foregut and hind gut conditions. Eight TB foals in matched-pairs were fed SC or TMFR for 18 weeks. Weight gain (ADG), height at wither and hip, heart girth and body length were recorded weekly. Similar growth rates were recorded for all measurements. ADG of 1 and 1.1kg/head/d for TMFR and SC respectively. In vitro foregut incubation of SC and TMFR at 37oC in pepsin HCl solution for 6 hours, produced higher pH 5.84 (TMFR) compared with 5.33 (SC) (P<0.05). Gas production measured fermentation rate, acidity and lactate from TMFR and SC, incubated with faecal inoculum from the foals on the same diet. Fermentation rates and lag times were equal for both feeds; total gas produced, t 50 and Y50 were greater (P<0.05) for SC. Lactate and pH levels were lower and higher respectively for the TMFR. This study showed that similar growth in TB foals was achieved on the TMFR feed and that potentially better gut health, denoted by higher pH and lower lactate levels could be maintained by fibre compared with cereal feed

Where Are We Now? Feeds, Feeding Systems and Current Knowledge of UK Horse Owners When Feeding Haylage to Their Horses

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

In vitro fermentation of different ratios of high-temperature dried lucerne and sugar beet pulp incubated with an equine faecal inoculum

An in vitro gas production technique, where equine faeces was the source of microbial inoculum, was used to determine the fermentation kinetics of high-temperature dried lucerne (A) and molassed sugar beet pulp (SB) mixed in the following ratios; 100:0 (A), 80:20 (ASB1), 60:40 (ASB2), 40:60 (ASB3), 20:80 (ASB4) and 0:100 (SB). Total gas pool size increased linearly (P&#60;0.05) with increasing level of SB substitution of lucerne, with values ranging from 148 to 281 ml. Mathematical analysis of the cumulative gas production curves showed significant differences in the fermentation patterns of these feeds (P&#60;0.001). Rate parameter values; fractional rate of degradation (FRGP) and time taken to produce 50 or 95% of the total gas production (T50 and T95, respectively) were all improved by SB addition, which was particularly notable at lower levels of SB substitution (ASB1 and ASB2). Moreover, ASB1 and ASB2 produced rate parameters similar to those observed in bottles containing SB alone. In conclusion, the addition of SB to lucerne at levels of up to 400 mg g−1 dry matter (DM) inclusion appears to significantly increase the rate at which Lucerne is degraded, which has important implications for the overall energy balance in the horse. Furthermore, the gas production technique appears to be a valuable tool for evaluating fibrous feedstuffs and feedstuff combinations, such as lucerne and SB, for equids in vitro, allowing the kinetics of degradation to be studied as opposed to end-point data