Effect of high forage oxalate and calcium consumption on goat urine characteristics

Abstract

Goat production in Hawaii has grown steadily in the past decade and this growth necessitated a more 
controlled diet to sustain production. Local goat pastures on the Big Island, Hawaii, are dominated by 
Napier grass (Pennisetum purpureum Schumach.), yellow foxtail (Seteria glauca L.), and guava trees 
(Psidium guajava L.). These plants contain compounds such as calcium and oxalates that could have 
detrimental effects on growth and development of goats when consumed in large quantities. This 
experiment was designed to evaluate the effect of grazing Napier grass and yellow foxtail with and 
without added guava tree parts using two groups of 14 female goats (Capra hircus L.) crossbred 
between Boer, Spanish, and Kiko breeds by analysis of some urine characteristics such as color, 
turbidity, specific gravity, pH, presence of bacteria, fungi, casts, as well as concentrations of nitrite, 
blood, urobilinogen, protein, glucose, ketones, bilirubin, red blood cells, and white blood cells. 
Urinalyses were performed on four sampling periods over three months. All variables were subjected to 
Repeated Measures in General Linear Models and correlation analysis using SAS. Urinalysis results 
were similar for both the groups. Urine protein levels of the (-) guava group, however, were higher, but 
not statistically different than those of the (+) guava group; significant interactions existed with some of 
the variables with time. The increased concentrations of calcium or oxalates in guava tree bark, Napier 
grass, and yellow foxtail may cause calculogenic minerals to accumulate, over longer periods of 
grazing, causing uroliths with a calcium and (or) oxalate base in male goats. This could result in penile 
obstruction in male goats.