Thesis (M. A.)--University of Canterbury, 2007. / Typescript (photocopy). Includes 2 maps. Includes bibliographical references (leaves 255-270). Also available via the World Wide Web.

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Two groups of three horses each were fed either a control diet of ground hay and concentrates or a similar diet with 10.5% added fat. The horses were trotted at 2.9 m/sec to a heart rate (HR) of 160 beats per minute (BPM) 5 d/wk on an equine treadmill set at go for a training period of 12 wk. A standard exercise test (SET) was performed at wk 0, 6, and 12. Blood samples were taken before, during, and after exercise and analyzed for lactate, glucose, cholesterol, total serum protein, and free fatty acids (FFA). Muscle biopsies were taken before and after exercise during the SETs on wk 1 and wk 12. Differences between wk 0, 6, and 12 in blood levels were found: lactate (P < .01) and glucose (P < .001) decreased, while cholesterol (P < .01) and FFA (P < .05) for both groups, indicating a conditioning response. However, no differences were found in any of the blood factors between groups. In the final SET, pre-exercise muscle glycogen levels in the fat-fed horses were lower (13.61 vs 25.44 mg/g wet tissue). Post-exercise glycogen levels, however, were higher in the fat- fed horses (10.95 vs 8.27 mg/g wet tissue), indicating that there may have been a glycogen-sparing effect. The fat-fed horses avg .3 kg/d less in daily consumption, and avg .03 kg/d more in ADG (.36 kg/d for control vs .33 kg/d for fatfed). Differences in trotting times (time to HR 160 BPM) between groups were seen at the end of four (P < .05) and eight (P < .05) Wki control horses improved 39% while fatfed horses only 25% from wk 1 to wk 8. No differences were seen between groups from wk 9 to 12. Improvement over the 12 wk period was similar for both groups (control 61%, fatfed 67%). These results seem to suggest that although fat appears to be a reasonable source of energy for the horse, there may be a long adaptation period for horses fed higher levels of fat. / Master of Science

Lecithins may improve the digestibility of high fat diets and the tractability of horses. Experiments were conducted to determine the acceptability, digestibility and effects on behavior of lecithin-containing diets. Seven young horses of light breeds were used for the studies. The four concentrates consisted of corn, oats, beet pulp, trace mineralized salt, dried sugar cane molasses plus 10% added fat: corn oil (CO);soy lecithin-corn oil (SL\CO); soy lecithin-soybean oil (SL\SO); or soy lecithin-corn oil-soybean oil (SL\CO\SO). Half the ration was provided by chopped hay. The CO concentrate was the most palatable (P=.OOOl). The remaining three concentrates were palatable in the following order: SL\CO, SL\CO\SO, and SL\SO, with SL\CO diet preferred (P=.OOl) to SL\SO. In the digestibility experiment, a complete mixed diet was fed containing chromic oxide as a marker. The control diet had no added fat: the others contained CO, SL\CO, or SL\SO at 10% by weight. Apparent digestibility was higher in the control diet than in the others for dry matter (P=.OOOl). Apparent digestibilities of crude protein (P=.0002) and acid detergent fiber (P=.08) decreased with any of the three fats. In contrast, apparent digestibility of ether extract was increased (P=.OOOl) in the fat containing diets. In the activity experiments, horses on the SL\CO diet were less spontaneously active (P=.0125) than horses on the control diet. Horses on the CO and SL \SO diet also had slightly lower activity levels (P=.125). Horses fed the SL\SO diet reacted less (P=.0625) than control horses to the opening umbrella. Horses fed CO and SL\CO diets showed trends towards less reactivity (P=.125 and P=.25, respectively), compared to the control horses. These studies support the practical feasibility of using lecithins in diets for horses. Especially interesting would be studies of interactivity with trainers and riders. / Master of Science

Two experiments were conducted to investigate the effect of conditioning on the ability of the equine to digest and utilize nutrients and to determine the effect of dietary fat as an energy source on the physiological parameters associated with fitness using a standard exercise test. Conditioning horses increased apparent digestibilities of crude protein (CP) (P<.05), dry matter(DM), and acid detergent fiber (ADF) (P<.1). Conditioning also tended to increase the apparent digestibility of neutral detergent fiber (NDF), cellulose, cell contents, and energy. Heart rates and blood lactate levels indicated that the conditioned horses were fitter than their unconditioned controls. In the second experiment, horses were fed isocaloric diets, one containing added fat and the other a standard hay/corn diet. Adding fat while maintaining equal available energy concentration depressed apparent digestibility of dry matter (56.7 vs 67.3 % P<.05), cell contents (75.6 vs 82 %, P<.05), energy (61.2 vs 71.8 %, P<.05) and NDF (29.2 vs 51.3 %, P<.05), in unconditioned horses. There was a trend towards decreased apparent digestibility of CP and ADF. Addition of fat increased apparent digestibility of ether extract (89.2 vs 65.6 %, P<.05). Conditioning increased apparent digestibility of CP (64.8 vs 73.7 %, P<.05) and energy (61.2 vs 65.6 %, P<.05) and tended to increase apparent digestibility of DM (56.7 vs 60.8 % ) and ADF (26.8 vs 17.8 %) for horses fed a fat supplemented diet. Conditioning did not cause a change in apparent digestibility of ADF, CP, and DM in horses fed the control diet, or apparent digestibilities of NDF, ether extract, cell contents, or energy for either diet. There were no differences in physiological parameters used for assessing fitness (heart rate, blood lactate, and respiration rate), between horses fed a diet containing 14% added fat and no added fat. There was no difference in body temperature, blood glucose levels, blood urea-N (BUN), or creatine phosphokinase (CPK) between horses fed the two diets. / Ph. D.

published_or_final_version / Botany / Master / Master of Philosophy

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Genetic evaluations for sport horses are performed by many Northern European studbooks, and estimated breeding values - which aid the selection of horses for breeding progeny with good competing ability - are routinely published. Either competition data or young horse evaluation data, or frequently a combination of both is used. Genetic evaluations are not yet performed in GB, and to date the only research conducted has been for the sport of eventing. The aims of this thesis were to: i) perform genetic evaluations for performance in dressage, including considering the effect of breed, ii) perform genetic evaluations for eventing, extending previous work, by using and comparing different methods of producing large (co)variance matrices and using a larger dataset, iii) characterise for the first time data recorded in the recently established young horse evaluation scheme, and if possible perform genetic evaluations and iv) investigate the suitability of international performance data for genetic evaluations for showjumping. Competition data was obtained from the national competition bodies and young horse evaluation data from the British Equestrian Federation. Pedigree was sourced from both. Appropriate mixed effects models were developed; animal models were used where pedigree data was sufficient, and sire models otherwise. Variance components were estimated using residual maximum likelihood and estimated breeding values were predicted using best linear unbiased prediction. Eventing comprises 3 disciplines, each with 4 grades i.e. 12 traits. For the evaluation, multivariate variance component analysis was performed, using and comparing three different methods of estimating the large 12 by 12 (co)variance matrices required for breeding value prediction. Significant, but low, heritabilities were found for dressage (0.07 – 0.09) and showjumping (0.09 – 0.16), and in the lower grades of cross-country (0.01), indicating that genetic progress for competition performance can be made by selection, particularly in showjumping. Genetic correlations within dressage and showjumping were high whereas those across disciplines were generally low and only significant for some of the lower grades, particularly between dressage and showjumping. Twelve breeding values were predicted for each horse. The methods based on combining covariance matrices from bivariate analyses were found to be the most reliable. In the dressage evaluations, significant heritabilites of 0.15 without accounting for breed effects and 0.11 when accounting for breed were found. Breed had a significant effect on competition performance, with warmbloods performing better than other breed groups. The model including breed was found to be the most appropriate for genetic evaluations in GB, although not currently implementable in practice due to limited recording of the breed identifier. In the young horse scheme, owners select which discipline (dressage, showjumping or eventing) their horse will enter. Traits are then recorded within the intended discipline. For the analyses, a genetic correlation of 1.0 was assumed between the same trait recorded in different disciplines. Significant, moderate, heritabilites were found for all five traits – veterinary (0.25), type and temperament (0.42), athleticism (0.20), conformation (0.29) and correctness of paces (0.30). The young horse scheme appears to be successful in establishment and uptake. Evaluations were performed for showjumping using international competition data. The small size of the dataset (approximately 6239 records on 479 horses) and large degree of selection limited the study. A larger dataset, including national data, needs to be made available to perform more accurate evaluations. However, an upper limit on the heritability was estimated to be 0.09 (standard error 0.012). This study explored the use of competition and young horse data for genetic evaluations. The eventing evaluations were the most reliable, and breeding values have been estimated which are ready for publication. However, there are certain limitations to all the competition data sources; there was selection in the data available for dressage and showjumping that biases the analyses. In addition, there were general limitations in the recording of competing horses, and in pedigree recording that limit the accuracy of the analysis. The young horse data represents a very valuable data source for genetic evaluations, although the scheme is still in its early stages. Ultimately, the most appropriate genetic evaluations will likely use a combination of young horse data and adult competition data. Further work can now perform multi-trait genetic evaluations using multiple data sources, such as combining young horse and competition data, or multiple competition disciplines.

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