Interpretive Summary: Efficacy of sheep as a digestibility model for cattle when fed concentrate-based or forage-based diets
By: Jackie Walling
A recent article published in Translational Animal Science investigated using sheep as a model for digestibility in cattle while feeding two different total mixed ration diets (forage based-and concentrate-based). Often small ruminants are used as models for the ruminant system; however, there is a lack of research in comparing diets between sheep and cattle.
This study divided 12 Suffolk wethers, and six Angus steers into two groups that fed half a forage- or concentrate-based diet. Feed intake, feed refusals, and feces were collected to analyze dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and starch.
Under a concentrate-based diet, cattle had similar OM and DM digestibility compared to wethers. Fiber digestibility was several times greater in cattle, while the digestibility of starch was lower. Under a forage-based diet, the digestibility for OM, DM, and fiber were all greater in cattle. Starch, however, was similar between the species.
Rumen retention of grass is greater in cattle, who are thought to have superior digestibility. Under a forage based-diet, the degree of difference for DM and OM between cattle and sheep was more substantial than previous studies. This could be due to genetics or differing collection methods. Cattle were limit fed to reduce ruminal upset while wethers were fed ad libitum. Despite differences in feed management, DM intake as a percent of BW between the species was similar.
Overall, fiber digestibility in cattle is greater than sheep regardless of feed type. Digestion between species is more similar when feeding a concentrate-based diet than a forage-based. This study suggests using sheep as a model when feeding a concentrate-based diet; however, sheep are not as useful when feeding a forage-based diet.
To read the full article, visit Translation Animal Science.