Date of Award:

5-1983

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Wildland Resources

Department name when degree awarded

Range Science

Committee Chair(s)

John C. Malechek

Committee

John C. Malechek

Committee

Don Dwyer

Committee

Dave Balph

Committee

John Butcher

Abstract

Production of sheep and goats in the Brazilian Northeast is important for the livelihood of both subsistence and market-oriented producers. Seasonal nutritional stress on animals in the caatinga vegetational zone of this region causes periodic high mortality and chronically low productivity. Under such conditions, the survivability of goats has been higher than for other domestic livestock. Possible reasons for this include unique aspects of dietary selection and goat feeding behavior. The objectives of this research were to seasonally determine the botanical and nutritive content of goat and sheep diets, to determine forage intake by grazing goats and sheep, and to compare their feeding behavior.

Dietary selections by sheep and goats were similar during the dry season, but diverged markedly during the wet season. Leaf litter from the deciduous trees was the major dietary component for both species during the dry season, and provided the bulk of dry season forage.

Current hypotheses predict that goats select diets of higher nutritional quality and have a greater forage intake than do sheep. Goats selected diets significantly (P < .05) in cell wall content, and lower (P > .05) in cell wall content, and lower (P < .05) in digestibility than did sheep. Voluntary intake was significantly (P < .05) greater for sheep than for goats. This study did not support such hypotheses.

Goats and sheep used feeding stations similarly during the dry season. Feeding stations are grazing sites where animals pause to eat (measured in seconds of duration). However, differences emerged during the wet season. Goats increased (P < .05) their time spent grazing per feeding station as the forage grew in stature and matured, while sheep showed no increase.

This study confirmed the vertical stratification of foraging by goats and sheep. Sheep foraged more in lower vertical strata than did goats. Goats spent about 4% of their grazing time in a bipedal stance, while sheep virtually never used a bipedal stance to feed. In addition, no nutritional advantage was found for goats over sheep through use of a bipedal stance. This latter finding is constrained by the deciduous nature of the caatinga woodland during the dry season.

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