PSI-4 The effects of Total Equinegrain containing Ascophyllum nodosum seaweed extract and chelated minerals on cecal digestibility during the recovery period of recovering, malnourished horses

From April to June 2023, we conducted a study to evaluate the effects of Total Equine containing Ascophyllum nodosum seaweed extract and chelated minerals on cecal digestibility in 10 recovering malnourished horses. Horses were used on a preceding 8-wk study and given a 21-d washout period with 24 h turnout and ad libitum access to Bermuda hay between trials. Once the washout was complete horses were randomly assigned to one of three diets: Control (Ctrl), a commercial grain product and Bermuda hay (n = 3); Treatment (Trt), Total Equine and Bermuda hay (n = 4); and Grain only (Grn), Total Equine without Bermuda hay (n = 3) for 8 wk with ad libitum access to water. For Ctrl and Trt diets, hay was offered hay twice a day in port-a-grazer tubs to control waste. Orts were collected 2x/d and hay offered was adjusted daily to maintain a 3 % refusal rate. Horses were weighed weekly with an electronic equine scale and BCS was evaluated at wk 0, 4, and 8. Grain was offered at a rate of 0.005% BW + 227 kg and divided into 2 equal feedings for Ctrl and Trt diets, while Grn diet horses were offered up to 9.07 kg of grain per day divided into 3 feedings. Grain offered was adjusted weekly based on BW. For physical reconditioning, horses were exercised 5 d/wk with a Priefert hot walker with an increase in duration and intensity from wk 1-8. Samples were collected of grain, hay, and orts for DM, NDF, ADF, EE, CP, and ash analysis. Cecal digestibility (dNDF and dADF) of Bermuda was measured using the Ankom Daisy system at wk 4 8 for 48 and 72 h. Jars were inoculated with a fresh composite fecal sample. Fecal samples were equally composited by diet. Data were analyzed using Proc Mixed procedures in SAS. No effect was observed on dNDF by diet (P = 0.21), yet diet*week (P = 0.0005) and diet* hour (P = 0.04) differed. dADF was improved by diet*week (P ≤ 0.0004) for diets containing Total Equine grain versus the Ctrl diet. Results indicate dNDF and dADF improved for wk 8 versus wk 4, which may indicate recovery of microbial efficiency as horses recovered. The improvement in dADF for Trt and Grn diets versus Ctrl is noteworthy, particularly the increase in dADF (Grn) because of the lack of hay in this diet. Improvement in fiber digestibility may help explain the improved body weight gain of horses on Trt and Grn diets in comparison to the Ctrl. Further research is needed to fully evaluate the impact of Total Equine on cecal digestibility especially in recovering, malnourished horses.