Digestive effects and intestinal health of ponies fed a complete single diet, thermally processed and containing long fiber

Abstract

This paper describes the digestible and fermentative effects of total replacement of a traditional diet (it supplies hay and concentrate separately) for a thermally processed complete feed (it supplies both concentrate and forage) in ponies. Acetate, butyrate, propionate and lactate concentrations in feces, relative population of bacteria in feces, serum tumor necrosis factor alpha (TNF-α) activity and apparent digestibility coefficients (ADC) of nutrients were determined in eight adult ponies in maintenance. Three different sources of fiber (dehydrated whole corn plant, dehydrated elephant grass and Tifton 85 hay) and two thermal processing (pelleting or extrusion) were tested. Ponies were randomized in two simultaneous Latin square (4 × 4). First, we compared the means of processed diets versus control group by contrasts, to identify changes caused by the processing. For this, the analysis of variance considered a factorial scheme 2 × 4. Second, to compare the effects among processed diets only, statistical analysis disregarded the control group and used a 2 × 3 factorial scheme. The means were compared by the Tukey test with P < 0.05. The experimental chronogram considered 4 periods with 20 days each (15 for adaptation to diet and 5 for data collection) with 21-day intervals among periods. The control group had higher (P < 0.05) dry matter, neutral detergent fiber (NDF) and acid (ADF) digestibility coefficients when compared to the thermally processing complete feed group. The Tukey test (processed feeds only), showed that dehydrated elephant grass had higher fecal pH values, lower digestibility coefficients of dry and organic matter, while the diets containing Tifton 85 hay presented better results for NDF and ADF. There was higher lactate concentration in feces for pelletized group, while extrusion improved the ADF's digestibility coefficients. In summary, when processed complete feed replaces the traditional diet, the apparent digestibility coefficients of some nutrients reduces. Dehydrated elephant grass had the lowest ADC's and it presented higher fecal pH. The pelleted diet resulted in a higher lactic acid feces concentration, but it did not alter the results of fecal pH. No gastrointestinal or clinical problems were observed in the ponies.