Mesquite pods contain cytotoxic alkaloids that may cause symptoms of intoxication in cattle, horses, sheep and goats when diets contain high levels of pods (more than 50%). Problems have been reported in the USA, Peru and Brazil (Silva et al., 2007; Tabosa et al., 2006; Camara et al., 2009; Assis et al., 2010). Poisoning was also recorded from pods eaten after exposure to rain (Göhl, 1982).
In two studies, goats and cattle fed with diets containing 60-90% and 50-75% mesquite pods suffered mandibular tremors during chewing, due to a toxicity to neurons of certain cranial nerve nuclei (Tabosa et al., 2000; Tabosa et al., 2006). In another series of outbreaks in Brazil, the main clinical signs were progressive weight loss, atrophy of the masseter muscles, dropped jaw, tongue protrusion, difficulties in prehending food, tilting the head during mastication or rumination, salivation, impaired swallowing, and decreased tone of the tongue (Camara et al., 2009). Neuronal lesions resulted in difficulties in prehending and chewing; it subsequently caused feed wastage and death of the animal (Tabosa et al., 2006). In India, goats offered dry mesquite pods as the sole feed over 4 days suffered from partial anorexia, depression, salivation, twitching, dehydration and bloody diarrhoea. Mesquite had deleterious effects on haemoglobin, rumen pH, rumen bacteria count and caused total disappearance of rumen protozoa. There was a significant decline in blood pH and increase in blood urea nitrogen. Histopathological studies revealed necrotic lesions in the liver, degenerative changes in renal tubules and rarefaction of lymphoid tissue (Misri et al., 2003).