Substituting grass hay and ground corn with forage cactus genotypes on mineral status of lambs.

Limited information exists on how different forage cactus genotypes affect mineral metabolism in lambs. This study evaluated the effects of partially replacing elephant grass hay and fully replacing ground corn with three forage cactus genotypes on mineral intake, absorption, and tissue deposition in lambs. Forty uncastrated Santa Inês crossbred lambs (21.0 ± 2.0 kg; 6 months) were randomly assigned to four treatments (10 lambs/treatment), including a control and three experimental diets in which part of the elephant grass hay and all ground corn were replaced by forage cactus genotypes (530 g/kg): “Miúda”, “IPA-Sertânia”, or “Orelha de Elefante Mexicana”. Over a 93-day feeding period, samples of water, feed, leftovers, and feces were collected. Moreover, on the 60th day after the introduction of the tested diets, blood samples were collected, and after the feedlot period, the animals were slaughtered for liver and rib sampling. Diets with forage cactus resulted in significantly higher (P = 0.01) levels of absorption of calcium (Ca), phosphorus, magnesium (Mg), sodium and potassium (g/day) compared to control diet. Lambs fed forage cactus diets exhibited elevated serum concentrations of Ca and Mg (P = 0.01) compared to control diet. Additionally, the diet containing “Miúda” genotype promoted greater Mg deposition in bone (P = 0.01) and, regardless of the forage cactus genotype, increased rib weight was observed (P = 0.01). In conclusion, the evaluated forage cactus genotypes (530 g/kg) can be incorporated into lamb diets without adversely affecting macromineral metabolism; however, all tested diets led to excessive hepatic accumulation of trace minerals.