Comparing the browsing behavior of inexperienced kids versus adult goats on heterogeneous vegetation

Abstract

The present study compared the feeding behavior of inexperienced kids on heterogeneous vegetation with that of adult goats with browsing experience. Twelve non-pregnant, non-lactating adult Criollo goats (35 ± 5 kg live weight (LW)) with >3 years of browsing experience and ten weaned kids (19 ± 3 kg LW) without previous browsing experience were used. The two groups of animals browsed simultaneously on 10.2 ha of tropical heterogeneous vegetation (4 h daily) in the rainy season. Mouth dimensions (width and length) were determined from contemporary animals in the same herd (14 kids and 79 adult goats). The proportion of dry matter intake (DMI) was estimated for the following categories: (i) life forms: shrubs, dicot-herbaceous plants, vines and grasses; (ii) height of strata: low (<25 cm), medium (25−50 cm) and high (>50 cm of height); and (iii) bite size: small (<5 cm) and large (>6 cm). The proportions of materials consumed in each category were compared between kids and adult goats via Chi-squared tests. Kids consumed fewer plant species than adult goats, but total DMI was similar between kids and adult goats (52.5 ± 5.1 and 51 ± 5 g DM/Kg LW0.75; P > 0.05). The proportion of the DMI obtained from different life forms was also similar between kids and adult goats (35.3 % and 40.4 % from shrubs, 1.6 % and 2.1 % from dicot-herbaceous plants, 0.3 %, and 0.6 % from vines, and 62.8 % and 57.0 % from grasses, respectively). However, kids had less DMI from high strata than adult goats (14.6 % and 58.0 %) and more DMI from low strata (66.8 % and 24.5 %, P < 0.05), possibly due to their smaller height. Although inexperienced kids consumed fewer plant species than adult goats, the two groups of animals consumed similar proportions of shrubs and grass in their diets. In addition, kids consumed a smaller proportion of large bites than adult goats, most likely due to the smaller size of their mouths (P < 0.0001). Overall, the differences in feeding behavior between kids and adult goats seem related to zoometric differences, but the browsing experience of adult goats should also be considered.