Macromineral status, water balance and kidney function of goats fed two cactus cladodes species

Abstract

The aim of this research was to evaluate the impact of diets with two cactus cladodes species on macrominerals metabolism, water balance, and kidney function markers of feedlot goats. Thirty-six castrated male undefined breed goats (19.0 ± 2.81kg initial body weight) were distributed in a completely randomized design, in three dietary treatments: diet containing Tifton-85 hay as exclusive roughage (control), diet with partial replacement (75%) of Tifton-85 hay by Miúda cactus cladodes (Nopalea) or Orelha de Elefante Mexicana cactus cladodes (OEM) (Opuntia), with twelve replicates per treatment. The feedlot lasted 100 days. Dietary and total Ca and Mg intakes were higher (P = 0.001) in goats fed cactus cladodes, regardless of species. The faeces of animals fed the control diet had twice (P = 0.049) as much K compared to the diet containing OEM cactus cladodes. Only OEM cactus cladodes caused increase (P = 0.001) in urinary Ca concentration, in relation to animals fed control diet. Goats fed cactus cladodes showed, on average, 45.8% more (P = 0.001) serum Mg. Diets containing cactus cladodes induced lower (P = 0.001) voluntary water intake and higher (P = 0.001) body water retention. The values of creatinine (P = 0.006) and total protein (P = 0.008) in the urine were affected by diets. For the given duration of the experiment, the partial replacement (75%) of Tifton-85 hay by cactus cladodes in diets for goats is recommended because it improves intake of macrominerals calcium and magnesium, and increase body water retention, without impairing kidney function.