No abstract

No abstract

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.

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.

The estimation of dry matter intake (DMI) using the alkane pair technique has been validated in ruminants, but not in equids. The current paper reports the finding of three comparative validation studies carried out using a total of 12 cattle, 29 donkeys and 10 horses during which directly measured intake was compared to estimated intake using the alkane pair technique. Two methods were developed to dose the even chain alkanes that were used as external markers. Study I, carried out in Zimbabwe, compared the accuracy of estimated intake with measured intake in cattle and donkeys using hexatriacontane (C36) as the external marker. Studies II and III were carried out in the UK with horses and donkeys and compared the accuracy of estimated intake with measured intake using dotriacontane (C32) as the external marker. Study III also tested the effect on the accuracy of intake estimates of two marker dosing levels (mean daily dose of 224 mg per animal and 448 mg per animal) and two dosing frequencies (2× and 3× daily). Twice daily dosing of even-chain alkane at the lower dose level provided an estimate of DMI similar to that obtained by thrice daily dosing at this low level. The higher dose level given twice daily tended to produce large variation in faecal concentrations of dosed even-chain alkanes, this variation was reduced when dosing frequency was increased to thrice daily. The accuracy of estimated intake improved progressively as the number of faecal sampling days was increased from one to six with no significant difference between estimated intake based on day 5 or 6 of faecal sampling. The results of all three studies indicate that the alkane pair technique provides a robust method of estimating intake in equids with no significant difference between measured and estimated values in all but one case. Using C31 as an internal marker provided a more accurate estimated intake than using C33 as the internal marker in all cases. Faecal recoveries of alkanes in equids do not appear to show the same influence of carbon chain length that has been observed in ruminant studies. © 2007 Cambridge University Press