Evaluation of local feed resources, their response on intake, growth, milk yield and composition and product properties of Namibian indigenous goats

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The study evaluated alternative local feed resources as potential protein supplements for dairy goats. Four linked-experiments were carried out in this research. The first experiment, a survey was conducted to investigate farmer’s indigenous knowledge on woody plants available in Omatako, Guinas, Tsandi, Daurês, Gibeon and Kongola constituencies of Namibia. Structured questionnaire was randomly administered through face to face interviews with farmers. Sixty (60) households were selected using purposive sampling strategy and GPS-point reading to evenly-space the points in the villages. Information on gender, age, level of education of farmers, type of livestock species reared and predominant woody plant species in the constituencies and their multiple uses were captured. The results from the survey revealed that farmers had profound knowledge on native woody plant species in their constituencies. Most households interviewed were male-headed (73 %), aged between 41- 60 years (43 %) and had at least primary (53.3 %), secondary (35.0 %), and very few with no education (3.3 %) background. The highest number of cattle (39 %) and goats (31 %) were recorded in Guinas, sheep (77.7 %) in Gibeon and chicken (34.1 %) in Kongola. A. erioloba and C. apiculatum were predominantly listed across all the constituencies, and A. hereroensis, C. collinum and R. trichotomum were the least common species listed as they were confined to certain constituencies. About 47 % of famers indicated to harvests pods and leaves for animal feeding, whereas 53.3 % do not harvest. C. mopane, Z, mucronata, G. bicolor, A. erioloba and T. sericea were used in the treatment diarrhoea in cattle and goats, whereas, B. albitrunca was used to improve fertility in breeding bulls. The second experiment (Feed evaluation) determines the chemical composition and in-vitro gas production of 17 woody plant species collected during the survey from 6 constituencies. Woody plant pods (3) and leaves (16) were randomly collected by hand during wet {January}, early dry vii {May} and late dry {September} season. Chemical analysis of each sample was performed in duplicates and in vitro gas fermentation was replicated in 5 runs of 48 hours with 77 units in each run. Gas production readings were recorded at 3, 6, 9, 12, 24, 36 and 48 hours of incubation. Mean values for NDF were highest noted in P. nelsii leaves (499.9 g/kg DM) and lowest in Z. mucronata leaves (317.9 g/kg DM). ST concentrations were detected highest(15.5 g/100g DM) in D. cinerea pods and lowest in A. karoo leaves (1.9 g/100g DM).DM, OM, NDF and ST were significantly higher in dry season than in wet season (P>0.005) whereas, CP, Ash and ADF were not affected by season and location of study (P>0.05). Ca, P and Se concentrations were high in wet season than in dry season. P concentration differed by location with Kongola (3.6 g/kg) having highest value than others. There was a significant positive correlation between NDF and ADF (r=0.62), ST and ADF (r=0.46) but all these were negatively correlated to gas production parameters (P<0.05). CP had a weak relationship with cell-wall constituents and gas production parameters. Among the 17 woody plant species, AE and DC pods were selected for further animal feeding based on chemical composition and in vitro gas production. An on-station feeding trial was conducted to determine the effect of AE and DC pod supplementation on intake, doe weight changes, growth of kids and estimate milk yield consumed by the kids on metabolic body weight basis. Forty eight (48) indigenous lactating does with average weight of 35 kg from parity 2 and 3 were allocated in a 2x3 factorial arrangement of treatments as a CRD with 6 does per treatment. The main factors were 2 pod types {AE; DC} at 3 different feeding levels {20; 40; 60 %}, benchmarked against positive {Commercial feed} and negative control {non-supplemented} resulting in 8 treatment diets. Phosphate-salt lick and water were available at ad libutum. The result showed that daily intake of does on Comm (430.9 gDM/day) were higher and lowest in AE (289.3 gDM/day) however, does on DC had the highest gain (38.9g) and lowest on Nosupp group (28.1 g), whereas does on AE had viii slightly higher final weight (35.6 kg). Kids from does on Comm had the highest ADG (114.4g) and lowest in AE (98.6g). When AE and DC were compared without the treatment controls, does on DC40 had highest intake (316.6 g DM/day), ADG (106.9 g) of kids and better weaning weights (15.6 kg). On average, milk consumption of kids per metabolic body weight was between 1.34 and 2.75 kg DM/M 0.75 /day. Does supplemented with AE60 and DC60 indicated reduced intake, growth and lower milk consumption of kids. In the last experiment, milk obtained from the animal feeding trial was collected every second week to determine the effect of AE and DC pod supplementation on milk composition. Milk composition data was analysed in a 2x3 factorial arrangements of treatments as a CRD. In the 10 th week of the feeding trial, 16 litres (2 litres per treatment) of milk was collected for the processing of fresh milk, fermented-sour milk and yoghurt for sensory evaluation. Sensory evaluation was assessed in a 3x8 factorial arrangements of treatments resulting in 24 products samples offered for testing by 20 panelists. Sensory evaluation using trained team was done to confirm the descriptive characteristics of the products mainly; the color, aroma, flavour, texture, consistency and overall productivity. A 5-point Hedonic scale ranging from 1 to 5 was used to rate the products, where; 1= like very much, 3= neither like nor dislike and 5= dislike very much. The results indicated that AE and DC pod supplementation had no effect on total solids, fat, protein, solid-non-fat and ash; however, Ca and P concentrations in milk increased with DC rate and declined with AE rate. Fermented-sour milk and yoghurt were significantly rated highest for colour, aroma and overall palatability (P<0.05), whereas fresh milk mean scores were not significantly different (P>0.05).Panellist did not detect any unpleasant odours or off-flavours in the dairy products. The study concluded that supplementation with AE and DC pods improved performance (intake, growth, milk yield) in goats. Supplementing with 40 % DC was recorded to be superior in improving milk in lactating does and growth of kids.
A thesis submitted to the Department of Animal Science, Faculty of Agriculture, College of Agriculture and Natural Resources Kwame Nkrumah University of Science and Technology, in fulfilment of the requirements for the degree of Doctor of Philosophy (Animal Nutrition),