Determining the composition of herbivore diets in the trans-Himalayan rangelands: A comparison of field methods (2006)

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In late summer, in a semi-arid mountain range in Nepal, three field methods for determining the botanical composition of herbivore diets were compared. Data were collected from the same animals belonging to one herd of domestic yak (Bos grunniens) and two herds of mixed smallstock, consisting of domestic goats (Capra hircus) and sheep (Ovis aries). Bite count, feeding site examination, and microhistological analysis of feces gave different estimates of forage categories and plant species in both animal groups. Because yaks grazed in other vegetation communities when not observed for bite-counts and feeding signs, the results from the latter methods could not be compared directly with that from fecal analysis. In smallstock, feeding site examination gave higher estimates of graminoids and lower estimates of shrubs than the other two methods, probably because all feeding signs on shrubs were not detected. Bite-counts and fecal analysis gave comparable results, except that forbs were underestimated by fecal analysis, presumably due to their more complete digestion. Owing to the difficulty in collecting samples that are representative of the entire grazing period and the problem of recording feeding signs correctly, both feeding site examination and bite-counts are unsuitable methods for studying the food habits of free ranging domestic and wild herbivores. Microhistological analysis of feces appears to be the most appropriate method, but correction factors are needed to adjust for differential digestion. The systematic use of photomicrographs improves the speed and accuracy of the fecal analysis. A fines del verano, en un pastizal semia´rido motan˜ oso de Nepal, comparamos 3 me´todos de campo para determinar la omposicio´n bota´nica de la dieta de herbi´voros. Los datos fueron colectados de los mismos animales pertenecienntes a un hato e yaks (Bos grunniens) dome´sticos y dos hatos de rumiantes menores combinados de cabras dome´sticas (Capra hircus) y ovinos Ovis aries). El conteo de bocados, la examinacio´n del sitio de alimentacio´n y el ana´ lisis microhistolo´ gico de heces dieron iferentes estimaciones de las categori´as de forraje y especies de plantas en ambos grupos de animales. Debido a que los yaks
apacentaron otras comunidades vegetales, cuando no se observaron para el conteo de bocados y signos de alimentacio´ n, los esultados de este me´todo no pudieron ser comparados directamente con los del ana´ lisis fecal. El examen del sitio de limentacion de los ruminates menores produjo estimaciones ma´ s altas de las graminoides y ma´ s bajas de los arbustos que los tros dos me´todos, probablemente porque todos los signos de alimentacio´n en los arbustos no fueron detectados. El conteo de bocados y el ana´ lisis fecal produjeron resultados comparables, excepto para las hierbas que fueron subestimadas por el ana´ lisis ecal, presumiblemente debido a su ma´ s completa digestio´ n. Debido a la dificultad en colectar las muestra que son representatives el periodo completo de apacentamiento y el problema de registrar correctamente los signos de alimentacio´ n, tanto l examen del sitio de alimentacio´n como el conteo de bocados son me´todos inadecuados para estudiar los ha´bitos alimenticios e los animales dome´sticos en libre pastoreo y la fauna silvestre. El ana´ lisis microhistolo´ gico de las heces parece se el me´todo
ma´ s apropiado, pero se necesitan factores de correcio´n para ajustar el diferencial de digestio´ n. El uso sistema´tico de otomicrogra´ fi´cas mejora la velocidad y certeza del ana´ lisis fecal.
Year: 2006
Language: English
In: Rangeland Ecology Management 59:512?518 September 2006,

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