International Journal of Agricultural Research and Review

ISSN 2360-7971

Quantification and characterization of nutrients in Senegalia mellifera milled biomass, feed intake and nitrogen balance in female Boer goats fed with Senegalia mellifera bush-based feeds

Abstract: The objectives of this study were to quantify and characterise the nutritional content of milled Senegalia mellifera milled biomass obtained from nine blocks at Neudamm Farm and to determine the dry matter intake (DMI), apparent digestibility and nitrogen retention in female Boer goats fed with Senegalia mellifera bush based feeds. Wood ash (WA), polyethylene glycol (PEG, 6 000) and biochar were evaluated as tannin deactivation methods. The milled biomass of S. mellifera was mixed using a clean concrete mixer with the following ingredients: yellow maize meal, liquid molasses; Marula oil press cake and coarse salt to formulate a complete diet with 14% CP and 11MJ ME/kg. Detannification treatment methods were added at a level of 5 g per day during feeding time. We used eight (8) female Boer goats weighing an average of 31.5 kg (± 2.5 kg) for the feeding experiment. We penned the goats individually in metabolic cages. Clean water was available ad libitum to the goats during the entire feeding experiment. The goats were fed in a 4x4 cross over Latin square design with four periods of experimental feeding. Each period lasted for 17 days, resulting in 68 days of experimental feeding. The goats were fed twice daily at 09:00h and 16:00h. The level of dry matter (DM) of feed offered was 4% of body weight.  The results obtained in this study showed that there was a significant difference (p <0.05) in the chemical composition of Senegalia mellifera milled biomass harvested from the nine blocks at Neudamm Farm. The CP content of Senegalia mellifera milled biomass ranged from 9.39 to 9.68 %DM while the NDF and ADF ranged from 59.17 to 64.33%DM and 43.77 to 48.01%DM, respectively. The condensed tannins (CT) content from all blocks did not differ (p >0.05) and had a mean of 0.02 to 0.03%DM as leucocyanidin equivalent (LE Absorbance at 550 nm). The apparent digestibility coefficients of DM, OM and NDF were not significantly different among treatments and the control diet (p >0.05). Goats fed biochar treated diet had the highest nitrogen intake of 13.74g/d (p <0.05), faecal nitrogen of 8.43g/d (p <0.05) and nitrogen retention of 5.11g/d (p <0.05), while goats fed the control feed (CNT), PEG and WA were similar (p >0.05). All treatments resulted in a positive nitrogen retention (p >0.05) with mean values ranging from 3.79 to 5.11 g/d.  The study concluded that, there was a significant difference (p <0.05) in the chemical composition of S. mellifera milled biomass collected from nine blocks at Neudamm Farm.  Given the high CP content of the S. mellifera, this fodder resource can be considered a suitable supplement for poor quality (low N content) natural pastures and crop residues such as grass hay, straw and stover. The study also concluded that, there was a significant difference (p <0.05) in the DMI, and nitrogen balance in Boer goats fed with A. mellifera feeds treated with Wood ash (WA), Polyethylene glycol (PEG, 6 000) and Biochar (BIO). The study therefore recommends that each detannification method should be tested at different rates of inclusion in S. mellifera bush based feed resources.


Keywords: Wood ash, Biochar, PEG, condensed tannins, DMI, apparent digestibility coefficient and Nitrogen