Validation of the AC2 Codes ATHLET and ATHLET-CD

Verification and validation are basic quality assurance elements in code development and essential for code release. Therefore, the codes of AC2 (ATHLET – ATHLET-CD – COCOSYS) are tested on separate effect tests, integral tests as well as plant scenarios to verify and validate the models after new implementation or updates. The verification assures that the models are implemented and working correctly while the validation checks if the models predict the right phenomena and combined with other models and modules. The selected experiments are summarized in GRS's validation matrices, which in turn are based on the CSNI validation matrices derived from OECD/WGAMA task groups as well as current activities on experimental test campaigns. For ATHLET several test series are used to cover a wide range of phenomena which can occur in PWR, BWR and VVER. Additionally, plant transients are considered for German LWR. The ATHLET-CD validation matrix contains experiments covering most phenomena which can occur during a severe accident. But due to the interaction of several effects even in small scale experiments mainly integral experimental campaigns are used for the validation. Over the last decades the validation of the AC2 codeds ATHLET and ATHLET-CD has reached a high degree of fulfilment of GRS's validation matrices over all code versions. Innovative and advanced reactor concepts come with new or newly relevant phenomena, which AC2 needs to provide models for. Extending the validation base of AC2 for these models is one challenge for further code validation efforts besides the on-going update of the validation basis to recent code versions.

Contracting for care - the construction of the farrier role in supporting horse owners to prevent laminitis

BACKGROUND

Emerging research highlights how, due to demographic changes in horse owner populations in Western societies, complex owner-horse relationships are leading to inappropriate horse care, including overnutrition, which in turn can lead to laminitis. Farriers, due to their regular visits, may be in a position to support owners in dealing with this problem.

OBJECTIVES

This study explored whether UK farriers have a role in working with horse owners to support horse welfare and prevent laminitis.

STUDY DESIGN

Grounded theory analysis, a qualitative methodology.

METHODS

Semi-structured interviews were conducted with 12 farriers and 11 horse owners. The interviews were transcribed verbatim and systematically analysed, using an inductive coding approach.

RESULTS

The analysis of the farrier and horse owner interview data revealed farriers and horse owners undertake a contracting process leading to either a task-focussed or holistic care-focussed approach. Either approach can be satisfactory, but the evidence from this study suggests that when horses are at risk of laminitis, a task-focussed approach misses important opportunities to prevent it.

MAIN LIMITATIONS

This analysis, based on a small sample of participants, was not able to identify the frequency of farriers or horse owners orientating towards different approaches in a way that can be generalised to a wider population. However, the power of grounded theory lies in its inductive design to develop new theory, which can be subsequently tested.

CONCLUSIONS

Farriers are in a perfect position to support horse owners to prevent laminitis through providing feedback, guidance and advice. However, not all farriers adopt this role and it is not necessary in all contexts. The evidence presented in this study has implications for equine veterinarians and welfare officers in educating horse owners about the value of holistic care-focussed farriery.

The use of nutritional supplements in dressage and eventing horses

The aim of the study was to determine which types of nutritional supplements were used in dressage and eventing horses, and the reasons that owners used supplements. An online questionnaire was distributed through British Eventing and Dressage websites, to collect data on demographics of owners and their horses, supplements used and their opinion on health and performance problems. Data were evaluated using descriptive analysis, Sign and Fisher's exact tests for quantitative data, and categorisation of qualitative data. In total, 599 responses met the inclusion criteria (441 dressage and 158 eventing horse owners). Participants had 26.4 (3-60) (mean (range)) years of riding experience, owned 1.2 (0-10) horses and used 2 (0-12) supplements in their highest performing horse. The main health and performance issues identified for dressage were 'energy/behaviour', 'lameness' and 'back and muscle problems'. The main issues for eventing were 'stamina and fitness levels',' lameness' and 'energy/behaviour'. The main reasons for using supplements in their highest performing horse were 'joints and mobility', and 'behaviour' for dressage, and 'electrolytes', and 'joints and mobility' for eventing. Lameness and behavioural problems were significant concerns within both disciplines. There was incongruence between owners' opinions of problems within their discipline and their reasons for using supplements.

Effects of processing barley on its digestion by horses

Four horses were randomly fed a diet containing rolled, micronised or extruded barley; the barley intake was adjusted to supply 2 g starch/kg bodyweight per day. During a 10-day acclimatisation period the horses were also fed 1 kg grass hay/100 kg bodyweight per day. Samples of blood and breath were collected at the end of each period after the test meal of barley had been fed after a 12-hour overnight fast. The glycaemic and insulinaemic responses of the horses were measured as an indication of the pre-caecal digestibility of starch, and postprandial breath hydrogen and methane were measured to detect microbial fermentation of starch. The highest peak serum glucose and serum insulin concentrations were observed after feeding the extruded barley, lower concentrations were observed after feeding the micronised barley and the lowest concentrations were observed after feeding the rolled barley. Breath hydrogen increased within four hours of feeding all the barley diets, and the mean (sd) peak hydrogen concentrations were 98.3 (55.2) ppm for rolled barley, 59.3 (31.5) ppm for micronised barley and 96.1 (51.9) ppm for extruded barley. There were wide variations within individual horses but these concentrations were not significantly different. Breath methane concentrations were very variable and, although there were no significant differences, there was a trend for higher methane concentrations after the feeding of rolled barley.

Effect of forage intake on bodyweight and performance

The horse evolved to survive on rations high in forage. Many performance horses are fed rations containing reduced levels of forage, with a corresponding increase in concentrate supply. Such reductions in forage intake are widely established to be associated with a corresponding number of physiological and psychological adaptations. Therefore, the influence of forage intake on bodyweight (bwt) and performance was investigated. Four Thoroughbred-type geldings in light to moderate work received 4 diets (100% forage [100H]; 80% forage:20% concentrate [80H]; 60% forage:40% concentrate [60H] and 50% forage:50% concentrate [50H]) in a 4 x 4 Latin-square design. A submaximal standardised exercise test (SET) was performed for each diet. Rate of passage, bwt and water intakes were measured throughout the trial and maximum, recovery heart rates and postexercise rectal temperatures recorded for each SET. Mean +/- s.e. bwt was significantly (P<0.001) higher for the 100H compared to the 50H ration (556.89 and 546.28 kg, respectively). Rate of passage of digesta was significantly (P<0.01) slower for the 100H compared to the 50H ration. Water intakes and SET maximum and 1 min recovery heart rates were significantly (P<0.05) higher (mean +/- s.e. 44.72 and 39.07 l/day, 186 and 165 beats/min, and 105 and 96 beats/min, respectively) for 100H compared to the 50H diet. Post-SET rectal temperatures tended to increase with increasing forage intakes, although these effects were not significant (mean 39.85 and 38.65 degrees C for the 100H and 50H diets, respectively). In conclusion, forage intake has significant effects on equine bwt and submaximal performance and a compromise needs to be made between the potential detrimental effects of high forage intake on performance and the potential detrimental effects of low forage intake on equine welfare.

Use of height-specific weigh tapes to estimate the bodyweight of horses

Two thousand horses of different ages, heights and breeds were divided into two height groups of up to 14.2 hands high (hh) and more than 14.2 hh, and weighed on a weighbridge; each horse then had its weight estimated by three weigh tapes, one height specific (tape 1 or 2, depending on the animal's height) and two for general use (tapes 3 and 4). For horses up to 14.2 hh, weigh tape 1 provided the most accurate estimate of mean (sd) bodyweight (100.5 [6.2] per cent), and weigh tapes 3 and 4 were 112 (6.8) and 97-0 (6.1) per cent accurate, respectively. For horses more than 14.2 hh, weigh tape 2 provided the most accurate estimate of bodyweight (98.6 [18.4] per cent), with weigh tapes 3 and 4 being 102.6 (17.4) and 90.8 (15.2) per cent accurate, respectively.

Accuracy of different methods of estimating the weight of horses

Six hundred horses of different ages, heights and breeds were weighed on a weighbridge and had their weights estimated by two weigh tapes, 1 and 2, by a formula, and by a visual estimate. For the population as a whole, the most accurate method was the formula (mean [sd] 98.6 [10.6] per cent) closely followed by weigh tape 2 (98.1 [8.1] per cent). Tape 1 and the visual estimate were the least accurate (112.0 [9.3] and 88.3 [20.1] per cent respectively). When the population was divided into two height groups, the formula and weigh tape 2 were the most accurate for horses < 15 hh (99.6 [5.2] per cent and 99.0 [5.6] per cent respectively), and weigh tape 1 and the visual estimate were 113.5 (6.5) per cent and 88.4 (16.3) per cent accurate respectively. For horses > or = 15 hh weigh tape 1 was most accurate (103.5 [9.1] per cent) and the formula, tape 2 and the visual estimate were 95.5 (13.1) per cent, 91.8 (9.2) per cent, and 89.3 (22.2) per cent accurate respectively. Overall the formula appeared to be the most accurate estimator of a horse's weight. However, owing to individual variation, it is recommended that the weights of horses < 15 hh are estimated by the formula or weigh tape 2, and that the weights of those > or = 15 hh are estimated with weigh tape 1.