Influência da raça na seleção da dieta por caprinos e ovinos em caatinga nativa e raleada no sertão central cearense.

Abstract

The experiment was carried out at Fazenda Iracema, in Quixadá county, Sertão Central of Ceará, Brazil, with the objective of evaluating the differences on diet's profiles of different breeds of sheep and goats grazing under native and thinned caatinga conditions. A total of 24 adult females was used. The goats belonged to the Moxotó and Anglo Nubian breeds, while sheeps belonged to Morada Nova and Rabo Largo breeds. The animaIs grazed two different types of pastures, native and thinned caatinga. The experiment extended for a period of one year, with five colletion dates, being three in the 1983/84 dry season and two in the 1984 wet season. In each date the animaIs were subjected to three consecutive days of faeces colection with a frequency of two collections in the first two days, totalling five collections per period, per animal. Microhistological analysis technique, that consists on identification of vegetal tissue fragments in the faeces, was used to determine the diet botanic composition. Of the 39 plant species found in the pasture, 32 were present in the animal diet, consisting of six grasses, 19 forbs and 14 ligneous species. Grasses predominated in the dry season and forbs in the wet season, both in the pasture and in the diet. The high percentage of panasco grass (Aristida setifolia) in the diet suggests the possible importance of this forage plant in the Ceará sertão. Catingueira (Caesalpinia bracteosa) was consumed mostly in the dry season, while pau branco (Auxemma oncocalyx) was mostly selected during the wet season. The preference by group for species by goats was: grasses, 39,01%; forbs,37,07%; and shrubs and trees, 23,97%. On the other hand, sheep consumed 47,76% of grasses, 36,34% of forbs, and 15,80% of ligneous species. No differences in diet composition was shown by goat breeds. However, Morada Nova sheep presented a diet richer in ligneous species than Rabo Largo sheep. Generally, the similarity between sheep and goat diets reached 82%, with substantial differences when different variables were considered. The similarity coeficient in native caatinga was 85%, while in thinned caatinga was 78%. The lowest value was 39%, obtained when comparing the diets in terms of brush and tree species in thinned caatinga.