Health and production benefits of feeding cowpeas to goats

The effect of grazing on cowpea forage on growth, parasite egg counts and markers of immunity was evaluated in goats. Spanish (n = 24) and Savannah goats (n = 24) were stratified by initial body weight (BW) (42.0 ± 7.0 kg) and fecal egg counts (FEC), and randomly assigned to 1 of 12 grazing plots (4 animals/plot) for 4 wks. Plots contained either of two varieties of cowpea commonly used in the Southern U.S., Mississippi silver (MS) and Iron and Clay (IC) or pearl millet (PM) grass as control. Body condition scores (BCS), BW, FAMACHA scores, and FEC were measured weekly. Initial and end of study blood samples were collected and analyzed for PCV, total and viable cells, and white blood cell differential counts. The concentration of total proteins, pro-inflammatory cytokines, prostaglandin E2 (PGE2) and total antioxidant capacity (TAC) were evaluated in serum. Body weight, BCS and FAMACHA score data were analyzed by repeated measures analysis using the PROC MIXED model procedure of SAS. The model included treatment, time (sampling day), breed, and the treatment x time x breed interaction. The FEC data were log-transformed before statistical analysis. Two-way ANOVA was performed on all other data. Goats fed cowpea forage, BW (P = 0.01), percent lymphocyte (P = 0.008), and percent neutrophils (P = 0.013) increased, and FEC decreased (P = 0.03) compared with goats fed control PM forage. A significant interaction (P = 0.01) was observed between goat breeds, cowpea varieties and measured parameters such as BW, percent lymphocyte, percent neutrophil and percent viable cells. The MS cowpea forage was associated with greater BW and neutrophil counts in the Savannah breed and with increased lymphocyte counts in Spanish goats. Although feed did not affect serum protein concentration (P > 0.05), a decrease in PGE2, TNF-α, IL-8, and IP10, and an increase in TAC, G-CSF, Rantes and IFNγ was observed over time (P < 0.05). Results from the study suggest potential benefits and impact of cowpea forage grazing, particularly MS variety on growth, internal parasites burden, and markers of immunity in goats. Feeding a cowpea diet to goats may stimulate and prime innate immune responses for defense against gastrointestinal parasites and warrants further study under different management conditions.