Nitrogen Balance of Pregnant West African Dwarf (WAD) Ewe fed Mexican Sunflower Leaf Meal (MSLM) based Diets

Fifteen days prior to parturition, a study was conducted using sixteen West African Dwarf (WAD) ewes (Initial BW 24.415±1.615kg) were used in a completely randomized design to study the effects of increasing level of mexican sunflower leaf meal (MSLM) on nitrogen balance. The experimental animals were assigned to 4 treatment groups A,B,C and D of 4 replicates each and were fed with grass (Panicum maximum)plus concentrate diet mixture of MSLM and wheat bran (WB) such that 0%,15%,30% and 45% of wheat bran was replaced by weight with MSLM gravimetrically. The experiment lasted for one week. Digestibility was determined using a 6-d total urine and fecal collection. Ewes were given adlibitum access to feed and water and routine vaccination and medication followed standard procedures. The 16 ewes were previously brought to heat (Oestrus) by synchronization and served by two rams (1:8). Parameters measured were nitrogen intake, nitrogen balance, nitrogen apparent digestibility and nitrogen retention. Data were analyzed using descriptive statistics and ANOVA. Animals on treatment B had the highest N-intake (17.4g/d), N faecal (1.5g/d), N absorbed (15.9g/d) and N balance (15.9g/d) and this was significant (P < 0.05). Urinary nitrogen (g/d) was significantly greater (P < 0.05) with increasing inclusion of MSLM in the ration while protein retention increased from treatment A (0%MSLM) to treatment B (15%MSLM) (90.7 – 91.2%) and subsequently decreased from treatment B(15%MSLM) to D (45%MSLM) (91.2 - 85.5%). Ewes on treatment B was distinctly superior (P < 0.05) in nitrogen balance than animals on treatment D and this might have been due to a better balance of nutrients particularly N from MSLM and soluble carbohydrates from wheat bran. Nitrogen balance was positively related to DM intake and N intake. The overall regression were NB=2.48+0.068DMI; R2 = 0.9379, (P=0.3874) and NB= 0.74+0.207NI; R2 = 0.9959, (P=0.1326). Mexican sunflower has astringent taste and this could be a possible reason for the reduction in DM intake of animals on treatment D which probably resulted in reduced nitrogen balance. The high nitrogen retained across the treatments may be due to high nitrogen content of the diets, less incident of endogenous addition of nitrogen and low concentration of anti-nutritional factors like alkaloids, tannins that could bind enzymes responsible for protein digestion. The values obtained in this study compared favorably with values in literature. The present results, therefore suggest that it is uneconomical to feed 45% Mexican Sunflower Leaf as replacement for wheat bran to pregnant ewes.