Inclusion of Opuntia stricta (Haw.) in sheep diets affects nutrition and the physicochemical characteristics of the rumen content

ABSTRACT The aim of this study was to evaluate the effects of the inclusion of the cactus Opuntia stricta (Haw.) in sheep diets on the feed intake, digestibility, fermentation, and physicochemical characteristics of the ruminal digesta. Five sheep cannulated in the rumen (61.5±9.5 kg body weight) were assigned in a Latin square design (5×5), with five diets and five experimental periods of 21 days each. The first 14 days were the adaptation period, and data were collected over the following seven days, making the total duration of the experiment 105 days. The diets included a control diet and four diets containing cactus at 121, 245, 371, and 500 g/kg of dry matter (DM). The diets had a forage:concentrate ratio of 65:35. The inclusion of cactus increased the DM intake and non-fiber carbohydrates, but reduced the neutral detergent fiber intake. It also increased the apparent digestibility of the DM, reduced the digesta density 4 h after feeding, and increased the production of ruminal fluid foam. The inclusion of cactus quadratically affected the DM rumen turnover, with the lowest value observed in the 336.5 g/kg cactus diet. The DM ruminal disappearance rate increased with the inclusion of cactus to the diets and quadratically affected the ruminal pH, with the highest value found in the 150 g/kg cactus diet. The concentrations of short-chain fatty acids (SCFA) increased, but the acetate:propionate ratio decreased with the inclusion of cactus at 500 g/kg DM. Taken together, our findings indicate that the evaluated spineless cactus can be added to sheep diets up to the level of 500 g/kg DM. The inclusion of O. stricta (Haw.) improves feed intake, DM digestibility, and SCFA and modifies the physicochemical characteristics of the ruminal digesta.