Seasonal effects of Rhus lancea and Celtis africana on intake preference and physiological responses in South African indigenous goats

Abstract

This study investigated the seasonal effects of Rhus lancea and Celtis africana leaves on preference, intake, weight, and serum metabolites in South African indigenous, mature, male goats. Twelve mature, male goats weighing 34 ± 5.9 kg (mean ± SD) were randomly allocated to two groups of six and kept in metabolic crates for periods of 21 days in October 2015 and March, May, and August of 2016. A browser diet of R. lancea and C. africana and a control diet (lucerne and concentrates) were randomly allocated to each group. Measurements taken included nutritional composition of browse per season, and browse preference, intake, weight changes, and serum metabolites in the goats. The acid detergent fibre (24–36%) and neutral detergent fibre (26.9–70.4 %) in R. lancea over the months were greater than in C. africana (50.3–53.2% and 49.4–55.4%, respectively). In the preference study, the goats preferred C. africana more in October (51.2 vs 48.8%), March (51.4 vs 48.6%), and May (54.3 vs 45.7%). Goats on the browser diet lost weight in March, May, and in August whereas those on the control diet gained weight. The serum urea concentration of goats consuming browser diets in May and August (1.8–3.3 mmol/l) was lower than the normal range, consistent with animals failing to derive their protein requirements from the diet. Goats prefer to browse C. africana more than R. lancea. The study also indicated the need for supplementation to meet maintenance requirements in animals fed R. lancea and C. africana.