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.

RESUMO Objetivou-se com este estudo avaliar se a produção de gases e a degradabilidade in vitro de dietas para ovinos podem ser influenciadas pelo uso do extrato etanólico de propólis.Foram avaliados cinco níveis de inclusão do extrato etanólico de própolis (EEP) nas dietas, sendo: sem adição de EEP; 6 mL de EEP; 12 mL de EEP; 24 mL EEP e 36 mL de EEP/kg de concentrado, sendo a dieta experimental constituída de 50% de capim elefante triturado (Pennisetum purpureum) como volumoso e 50% de concentrado (milho, farelo de soja e núcleo mineral e vitamínico). Houve efeito quadrático (P<0,05) para os volumes de produção de gases total (Vt),gases produzidos pelas frações de degradação rápida (Vf1) e para a degradabilidade in vitro em 120 horas (Deg120), onde os menores valores de Vt, Vf1 e Deg120, foram encontrados para a inclusão aproximada de 9 mL de EEP/Kg de concentrado, representando, 79,85 (Vt) e 55,08 (Vf1) mL/g de MS, e 79,14% de degradabilidade. Já produção de gás pela fermentação da fração de degradação lenta (Vf2) não foi significativo (P<0,05), com média de 25 mL/g MS. O tempo de colonização das partículas do alimento (λ) reduziu significativamente (P<0,05) com o aumento dos níveis de inclusão do EEP. Sendo assim, é possível concluir que o extrato etanólico de própolis até a inclusão de 9,4 mL/Kg de concentrado foi eficiente em inibir in vitro a produção de gases total (Vt) e a partir das frações de degradação rápida (Vf1)em 9,9 e 15,3%, respectivamente, além de promover uma redução de 5,3% na degradabilidade após 120 h de incubação (Deg120h), em dietas com proporção concentrado:volumoso de 50:50. Assim, a inibição na produção de gases foi proporcionalmente superior a redução da degradabilidade.

SUMMARY This study evaluated the influence of the propolis ethanolic extract (PEE) on gas production and in vitro degradability of sheep diets. Five experimental diets (treatments) were evaluated: without addition of PEE; 6 mL PEE; 12 mL PEE; 24 mL PEE and 36 mL PEE/kg concentrate. The experimental diet consisted of 50% elephant grass (Pennisetum purpureum) and 50% concentrate. There was a quadratic effect (P <0.05) for the volumes of total gas production (Vt), gases produced by the rapid degradation fractions (Vf1), and for in vitro degradability at 120 hours (Deg120), where the lowest values of Vt, Vf1 and Deg120, were found for the inclusion of 9.4 mL PEE/kg concentrate. Gas production by fermentation of the slow degradation fraction (Vf2) presented a mean of 25 mL/g DM (P <0.05). The colonization time of food particles (λ) significantly reduced (P<0.05) with increasing inclusion of PEE. Thus, it can be concluded that the PEE up to the inclusion of 9.4 mL/kg concentrate was efficient in inhibiting in vitro total gas production and from the fractions of rapid degradation by 9.9 and 15.3%, respectively, in addition to promoting a reduction of 5.3% in degradability after 120 h incubation in diets with a concentrate: forage ratio of 50:50. Thus, the inhibition in gas production was proportionally greater than the reduction of degradability.