EVALUATION OF Parquetina nigrescens LEAF MEAL AS ADDITIVE IN CASSAVA RESIDUE-BASED DIET FOR WEST AFRICAN DWARF SHEEP

Abstract

ABSTRACT Crop residues serve as alternative feeds to forage resources which are less available during dry season. However, the fibrous nature of these residues increases methane emission, arising from rumen fermentation thereby limiting growth performance. Phytogenic additives have been identified to improve animal growth performance, hence the use of Parquetina nigrescens leaf meal as an additive. This study evaluated the potentials of Parquetina nigrescens leaf meal (PNLM) as phytogenic additive in cassava residue-based diet for West African Dwarf (WAD) sheep. Two experiments were conducted; experiment 1 investigated the in vitro total gas, methane production, fermentation and post-incubation parameters of diets containing PNLM. The experimental substrate for the in vitro experiment included cassava peels, cassava leaves, Megathyrsus maximus and a formulated concentrate diet which contained 0, 1, 2, 3, 4 and 5% DM PNLM to form six different treatments. Substrates were incubated for 48 hours and in vitro total gas, methane production and fermentation parameters were evaluated. In experiment 2 was an in vivo study which involved eighteen (18) WAD sheep (12-16 kg body weight), which were divided on weight equalization basis into six groups of three animals each. Each group was randomly allotted to one of the dietary treatments in a completely randomized design. The animals were fed for 90 days during which growth performance characteristics, nutrient digestibility, nitrogen utilization, rumen fermentation parameters and blood profile of animals were determined. Data obtained were analyzed. Results showed that inclusion of 2 - 5% PNLM in the substrate degraded caused a reduction (p<0.05) in in vitro total gas (16.80 – 10.80ml), methane (6.21-3.53%) and ammonia nitrogen (20.14 -15.15 mg/100ml) production, reduced (p<0.05) in vitro dry matter degradation (66.37 – 54.14%) and an increased (p<0.05) total volatile fatty acids (36.70 – 54.90 mM/ 100 ml) were observed at 3 - 5% PNLM inclusion. The growth performance parameters were not influenced (p>0.05) by the inclusion of PNLM in the diets. Nitrogen retention was higher (p<0.05) in sheep fed diet containing PNLM up to 5% (50.86 – 55.40%) inclusion. Sheep fed diets with 3 - 5% PNLM recorded the lowest protozoa (400count/g) population compared to the control (2100count/g). Inclusion of PNLM in the diets of WAD sheep increased (p< 0.05) the packed cell volume (25.00 – 42.00%), haemoglobin concentration (9.5 – 14.7 g/dl), total protein (5.2 – 8.2 g/dl), albumin (3.2 – 4.9 g/dl), globulin (2.0 – 3.3 g/dl) and glucose (48.3 – 67.5 mg/dl) levels in sheep within acceptable range. The study concluded that 3 - 5% PNLM levels could be included as phytogenic additive in the diet of West African Dwarf sheep to reduce methane production and ammonia production in the rumen (in vitro), while under the in vivo condition up to 5% PNLM inclusion enhanced efficient nitrogen retention and improved the health status of the animals.