Effect of Cowpea (Vigna unguiculata) Pasture Grazing on Growth, Gastrointestinal Parasite Infection and Immune Response Biomarkers of Goat

The objective of this study was to evaluate the effect of grazing cowpea pastures on growth, parasite egg count and biomarkers of immune response in goats. Spanish and Savannah goats (n = 48) stratified by initial body weight (42.0±7.0 kg) and fecal egg count (FEC), were randomly assigned to three pasture forages (Cowpea varieties: Mississippi silver (MS), or Iron and Clay (IC) or Pearl millet (PM) as control with 4 replicates, for a 28-day feeding trial. Forage samples collected at the start of the study were analyzed for nutrients, chemical and polyphenols content. Body weight, body condition score, and fecal egg count were measured weekly. Blood was collected from goats on days 0 and 28 for PCV and white blood cell differential counts. The concentration of total proteins, prostaglandin E2 (PGE2) and total antioxidant capacity (TAC) were evaluated in blood serum. Concentration of DNA isolated from fecal samples was used as a measure of gut health. Goats grazed on cowpea forage (MS and IC) had higher body weight (p = 0.01) compared to goats grazed on PM. Percent lymphocyte (p = 0.008) and neutrophil (p = 0.013) increased in MS fed goats. Goats grazed on MS pasture had decreased FEC (p = 0.03) also. Cowpea pasture grazing had no effect on serum protein concentration, PCV and BCS (p > 0.05), but decreased PGE2 concentration in serum. The concentration of TAC in serum, increased at day 28 (p < 0.05). The concentration of fecal microbial DNA decreased in all the treatment groups at day 28. Cowpea forage grazing had an impact on body weight, FEC, and blood serum parameters (PGE2, TAC) in goats. These results demonstrate that freshly grazed cowpea forage has potential impact and benefits on growth and health of goats. Integrating cowpea diet in goat feeding system may enhance growth performance, stimulate and prime the immune system for defense against gastrointestinal parasites.