Effects of increasing levels of cactus pear (Opuntia ficus-indica L. Miller) in the diet of dairy goats and its contribution as a source of water

This study evaluated the effect of substituting corn meal with cactus pear (Opuntia ficus-indica L. Miller) on water intake of dairy goats during lactation. Ten goats (Saanen, n = 5; Alpine, n = 5) were distributed in two 5 × 5 Latin squares according to breed. Ration consisted of 50% hay and 50% concentrate in which corn meal was replaced by increasing levels of cactus pear (0, 7, 14, 21 and 28% DM). Milk production, feed intake, dry matter (DM) intake, weight gain, water intake and water intake from cactus pear were evaluated. There were no differences (P > 0.05) between breeds or interaction breed × treatment for the evaluated variables. Cactus pear levels had no effect on milk production; however, there was a linear reduction of milk fat with increasing cactus pear levels (P < 0.01). Increasing levels of cactus pear in the diet increased dry matter intake according to an exponential equation (P < 0.001; R2 = 0.81) and fresh matter intake increased linearly (P < 0.01; R2 = 0.99); mean values ranged from 1.95 to 2.31 kg/d and 2.03 to 13.48 kg/d, respectively. On the other hand, water intake was markedly reduced in a linear manner due to cactus pear addition to the diet (P < 0.01). Cactus pear may substitute corn meal in the diet of lactating goats without affecting milk production negatively, and may be an important resource to reduce water intake in dairy goats.