Growth Performance of Boer and Savanna Goat Doelings at Lobu Small Stock Ranch Under Natural Rangeland Conditions During the Late Wet and Early Dry Seasons In Kgalagadi Region (Botswana).

Abstract

Goats have the most integral socio-economic role in many African countries, hence, the ministry of Agricultural Development and Food Security, the Government of Botswana has taken a step in supporting Lobu ranch since its inception in 1978 to turn it into a small stock hub. However, there is lack of knowledge on the vegetation, nutritional status and growth performance of different types of goats in Lobu Ranch. Therefore, the objectives of the study was to determine abundance and diversity of woody plants (trees and shrubs) within the ranch, the nutritional composition of common woody plants that are consumed by the goats and also to measure growth performance of the goats. This study was performed at Lobu small stock ranch in Kgalagadi region, Botswana during the late wet and early dry seasons. The first study used a systematic sampling approach to survey woody plants along the grazing gradient (from water point). In the second study, proximate analysis of the dried and milled composite samples (herbaceous and woody species) was performed for DM, OM, Ash, CP, NDF, ADF, ADL, Fat and Gross Energy as well as IVDMD and nutritional analysis for both Macro and Micro nutrients, after abserving which plants species were commonly eaten by goats. In the third study, goats body weights were measured using a weighing scale and all body parts measurements using a measuring tape in the morning on an empty stomach for 4-5months starting from late wet to end of early dry seasons. The most dominant woody plants species in the ranch were Asparugus asparagus, Rhigozum trichotomum and Senegelia mellifera across the distances (near, mid and far from the kraals). Woody plants with the hihest density are those <20m (P<0.05). However, the above three species showed high distribution in the catergory of >2m (P < 0.05), with increasing distance from the kraals. There was significant difference in percentage level of chemical content within the forage species (P<0.05) with DM, OM, and ADF increasing as the dry season increases while CP was decreasing as the dry season increases. On the other hand, Ash, NDF, ADL and fat were high during the late wet season and decreased at the beginning of the early dry season but eventually increased at the end of the dry season. In macro nutrients only the K and N showed significant difference (P<0.05), K content was low during the late wet season recording 0.99% but later increased at the end of the dry season to 1.06% while N was high during the late wet season recording 1.42% and slightly decreased at the end of the dry season to 1.32% . In terms of micro nutrients, only Fe was noticed to be significantly different (P<0.05) increasing from 104.53-235.64ppm. Generally, the obtained results were too high ranging from 235.64ppm -104.53ppm as compared to the acceptable quantities required for growth of goats (30-50ppm) and this compromised the optimal weight gain of the animals during the seasons of study. The body weight gain of the breeds was considered similar throughout the seasons (P > 0.05). Though there was homogeneity in body weight gain among the breeds, the Savanna goats gained more daily weight (0.035kg/day), than the Boer goat (0.030kg/day). It should be noted that there was positive growth of the goats which was mainly influenced by the positive development of the hip height, shoulder height and body length. It should be appreciated that during the dry season the nutritional value of the range is minimal hence growth of the animals being compromised.