Reduce Reuse ReRumen: Preservation method of rumen fluid collected from slaughtered cattle changes in vitro true digestibility
Abstract: Microbes and chemical constituents in the rumen fluid play an important role in re-establishing the rumen microbial population. Samples (n = 12) were collected from slaughtered cattle at the Tarleton State University Meat Laboratory, Stephenville, TX. Rumen content was collected from different locations within the rumen, pooled, and strained through eight layers of cheesecloth. Strained liquid divided into five 500-mL aliquots. Aliquots were randomly allocated to one of five treatment combinations. Treatment factors included preservation method (freezing or lyophilisation) and preservative (glycerol; yes or no). A fresh control was maintained from each sample. Three reference feeds and two roughage sources were used in the batch culture procedure. Reference feeds were dried to a constant weight at 55 ?C. Samples were ground to pass through a 2-mm screen and subjected to batch culture in vitro digestibility (IVTD) assays using each of the four ruminal fluids (plus the control). Original samples and incubated residues were assayed for DM, CP, NDF, and ADF. Data were analyzed in a 2 x 2 + 1 augmented factorial design using GLIMMIX procedure of SAS v. 9.4. Orthogonal contrasts were written to test the effect of preservation of rumen fluid with or without a preservative in comparison with a fresh sample. There were no differences (P > 0.05) in IVTD for soybean meal and cracked corn among any of the treatments compared to fresh; however, there were differences (P < 0.05) in IVTD for all treatments for rice bran and grass hay. All treatments except frozen (without glycerol) were different for alfalfa hay IVTD compared to fresh (P < 0.05). Despite lower degradation of feeds when frozen or lyophilized rumen fluid is used, differences in IVTD suggest that, in the absent of fresh inoculum, preserved rumen fluid may be a viable option.
T.J. Garcia*, J.P. Muir, K.A. Guay, J.A. Brady, and W.B. Smith
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