|CEROSIMO, LAURA - Oak Ridge Institute For Science And Education (ORISE)|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 5/31/2018
Publication Date: 6/11/2018
Citation: Cerosimo, L.M., Radloff, W.J., Zanton, G.I. 2018. Microbial inocula alter the ruminal environment and animal performance of post-weaned dairy calves. J.Dairy Sci. 101(Suppl. 2): i.
Technical Abstract: The purpose of the experiment was to determine if the composition of microbial inoculum affects the ruminal environment and performance of post-weaned dairy calves. Holstein bull calves (n=20) were housed individually with sand bedding and provided texturized calf starter (19.1±0.8% CP, 19.5±3.9% aNDF, 39.0%±2.3% starch). Calves were randomly assigned to one of four treatments administered by stomach intubation at 3-6 weeks of age with responses analyzed at 9 weeks of age as a randomized complete block design. Treatments included: Control: 50 mL cell-free rumen fluid (RF), bacterial-enriched RF (BE), ciliate protozoa-enriched RF (PE), or 50 mL each of BE and PE (BE+PE). A rumen contents composite from four cannulated Holstein cows was used to prepare the inocula either by differential centrifugation (BE) or by gravimetric sedimentation (PE; 5.0 x 105 protozoa/mL). Calves were sacrificed at 9 weeks of age. BE treated calves had greater gains in heart (28 vs 24±1.0 cm, P=0.02) and paunch girths (51 vs 44±1.7 cm, P<0.01) between 1 and 9 weeks of age. Bodyweight gain (56.6±2.7 kg), DMI (3.2±0.1 kg/d), total ruminal DM (0.98±0.12 kg), reticulorumen (7.9±0.6 kg), and abomasum (1.3±0.1 kg) weights did not differ by treatment. Mean ruminal protozoa densities determined by real-time PCR for control, BE, PE, and BE+PE treated calves were 1.1, 13.5, 8.9, and 24.1 cells/mL RF, respectively. Calves dosed with PE (5.6 vs 8.0±0.7%, P=0.02) had lower butyrate molar proportions and tended to have greater total VFA (73.7 vs 58.8±5.0 mM, P=0.05). Ruminal ammonia and total amino acids did not differ by treatment. Based on next-generation sequencing, relative abundance of Firmicutes tended to be greater in calves treated with BE and PE (30.1 vs 22.4±2.7%, P=0.06), while Proteobacteria from were less abundant in calves dosed with BE (13.7 vs 27.9±4.1%). Calves dosed with BE or PE had greater Shannon diversities (3.3 vs 2.9±0.1, P=0.02) and operational taxonomic units (189 vs 155±7.7, P<0.01). These findings show that prior microbial inoculation and inocula type altered the ruminal environment and animal performance of post-weaned dairy calves.