Rumen fermentation and microbial profile of Red Sokoto goats fed threshed sorghum top supplemented with browse foliages

Abstract

Most of the ruminants in Nigeria are found in the Guinea savanna and Sahel zones where crop residues constitute an important feed for ruminants during the long dry season. Threshed sorghum top is the outer coverage of the sorghum grain after the grains have been removed through various threshing methods. The experiment was carried out to evaluate the rumen fermentation and microbial profile of Red Sokoto goats fed threshed sorghum top (TST) supplemented with five indigenous browse foliages (Piliostigma thonnigii, Daniellia oliveri, Afzelia africana, Pterocarpus erinaceus and Annona senegalensis). Twenty growing Red Sokoto bucks of 7 - 9 months old with average weight of 9.00±0.25 kg were used for this study. They were randomly allocated to the five dietary treatments in a completely randomized design. Each treatment was replicated with four animals. Data collected include feed intake, rumen pH, temperature, ammonia nitrogen, volatile fatty acids, microbial count and identification of microbial isolate. Goats fed various browse plants as supplement had higher (p<0.05) bacterial population than goats on TST only. Also those fed A. aficana had higher (p<0.05) total rumen bacterial count (10.2 × 10⁵CFU/mL), while those on TST had the lowest value (7.2×10⁵ CFU/mL). Total coliform count ranged from 0.3×10⁵ in D. oliveri supplemented diet to 0.5×10⁵ CFU/mL in animals fed TST alone. There was increase in the population of total fungi count from 0.35× 10⁵ in goats fed TST alone to 0.53×10⁵ CFU/mL in those supplemented with P. thonnigii. Protozoa count ranged from 0.33×10⁵ CFU/mL in the rumen content of goats on D. oliveri and A. aficana  to 0.6×10⁵ CFU/mL in rumen content of those fed TST only. The rumen ammonia nitrogen concentration of goats on A. Africana (199.33mg/L) and P. thonnigii (191.33mg/L) were superior (P<0.05) to those of goats on other diets.  Goats on TST alone had the lowest ammonia nitrogen concentration (104.66 mg/L). The effect of supplementation of TST with browse foliage on total volatile fatty acids (VFA) ranged from 72.33 – 168.67mmol/L. Mean rumen ethanoic acid concentration ranged from 65.33 mol/100mL in animals on TST to 128.33 mol/100mL in animals on A. africana. In conclusion, supplementation of low quality roughages such as Threshed sorghum top with browse foliage led to improvement in rumen fermentation efficiency of rumen microbes, this led to increased production of microbial protein and VFA production (energy supply) which resulted to improved productivity of the goats.