AUTHOR=Jiao Ting , Wu Jianping , Casper David P. , Davis Delmer I. , Brown Michael A. , Zhao Shengguo , Liang Jianyong , Lei Zhaomin , Holloway Bill 

TITLE=Feeding Sheep Cobalt and Oregano Essential Oil Alone or in Combination on Ruminal Nutrient Digestibility, Fermentation, and Fiber Digestion Combined With Scanning Electron Microscopy

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.639432

DOI=10.3389/fvets.2021.639432

ISSN=2297-1769

ABSTRACT=The feeding of Co lactate (Co), an essential oil blend (EO; Oregano), or a combination of Co and EO (EOC) may improve nutrient digestion of corn silage-based rations. In 3 separate studies, each treatment was fed at 0, 4, and 7 g/d to 9 rumen fistulated rams arranged in a replicated 3 x 3 Latin square design. In each ram, fresh ensiled corn silage, leaf and husk were placed in nylon bags inserted through the ruminal cannula and removed after 48 h. Rams fed increasing carrier rates demonstrated similar (P > 0.10) nutrient digestibilities and ruminal pH and volatile fatty acid concentrations. Feeding Co at 4 and 7 g/d increased (P < 0.05) digestibility of DM (59.4, 63.9, and 62.4% for 0, 4, and 7 g/d, respectively), NDF (59.4, 63.9, and 62.4%), and hemicellulose (HC: 56.2, 63.6, and 65.9%) compared with rams fed 0 g/d, while CP digestibility (46.4,  49.9, and 57.8%) was improved (P < 0.05) in rams fed 7 g/d compared with those fed 0 and 4 g/d. Rams fed 7 g/d EO digested greater (P < 0.05) HC (64.1, 71.4, and 69.1%) than rams fed 0 g/d, while rams fed 4 g/d were intermediate and similar (P > 0.10). Rams fed the EOC combination at 4 and 7 g/d demonstrated greater (P < 0.05) digestibilities of DM (57.7, 60.0, and 60.0%), NDF (21.4, 28.8, and 27.7%), and ADF (24.3, 33.3, and 34.4%) than rams fed 0 g/d. The SEM and SM techniques visually demonstrated minor evidence of husk and leaf digestibility in rams across the 3 experiments when fed 0 g/d of Co, EO, or EOC, while rams fed 4 g/d of Co, EO, or EOC exhibited varying visual signs of leaf digestion of the surface wax and epidermis, with some of the palisade tissue, spongy tissue and whole vein structure remaining, while rams fed 7 g/d only the vein structure remained. Results demonstrated feeding Co, EO, or EOC at 4 or 7 g/d enhanced ruminal nutrient digestion and fermentation parameters which was visually confirmed via SEM and SM.