Rumen liquor from slaughtered cattle as inoculum for feed evaluation

Abstract

Use of nonlinear mathematical models has been majorly based on in vitro gas production (GP) data generated when substrates are incubated with rumen liquor from fistulated steers. However, existing evidence suggests that rumen liquor from slaughtered cattle of unknown dietary history also generates quantifiable in vitro GP data. Fitting and description of GP data obtained from 4 diets incubated with rumen liquor from slaughtered cattle was evaluated using single-pool exponential model with discrete lag time (EXPL), logistic (LOG), Groot's (GRTS) and Gompertz (GOMP) models. Diets were formulated by varying proportions of Rhodes grass (Chloris gayana) hay and a concentrate mixed on dry matter basis to be: 1,000 g/kg Rhodes grass hay (RGH) and 0 of the concentrate (D1), 900 g/kg RGH and 100 g/kg concentrate (D2), 800 g/kg RGH and 200 g/kg concentrate (D3), 700 g/kg RGH and 300 g/kg concentrate (D4). Dietary kinetics for the models were determined by measuring GP at 2, 4, 8, 10, 18, 24, 36, 48, 72, 96 and 120 h. Model comparison was based on derived GP kinetics, graphical analysis of observed versus predicted GP profiles plus residual distribution and goodness-of-fit from analysis of root mean square error (RMSE), adjusted coefficient of determination (Adj-R2) and Akaike's information criterion (AIC). Asymptotic GP, half-life and fractional rate of GP differed (P < 0.001) among the 4 models. The RMSE, Adj-R2 and AIC ranged from 1.555 to 4.429, 0.906 to 0.984 and 2.452 to 15.874, respectively, for all diets compared across the 4 models. Based on the goodness-of-fit statistical criterion, GP profiles of D1 were more appropriately fitted and described by GRTS and GOMP than the EXPL and LOG models. The GRTS model had the lowest AIC value for D2 (2.452). Although GRTS model had the most homogenous residual dispersion for the 4 diets, all the 4 models exhibited a sigmoidal behavior. Therefore, rumen liquor from slaughtered cattle of unknown dietary history can be used to derive nutritionally important feed parameters, but choice of the most appropriate model should be made based on fitting criteria and dietary substrates incubated.

Effects of Chestnut Tannin Extract, Vescalagin and Gallic Acid on the Dimethyl Acetals Profile and Microbial Community Composition in Rumen Liquor: An In Vitro Study

“…The whole rumen content was collected from one ewe sacrificed at the slaughterhouse and used as inoculum for the fermentation, according to Denek et al [21] and Lutakome et al [22]. The animal was fed for one month before the slaughtering with the diet C used in the in vitro trial.…”

Effect of amino acid supplementation and choline chloride for low protein diet on nitrogen efficiency and methane emission of dairy cows

“…Synthetic saliva was prepared according to McDougall (1948). Ruminal contents of at least three slaughtered dairy cattle obtained from slaughter house were strained through 3-layer cheese cloth to the pre-warmed flasks leaving no headspace, rumen liquor flasks were taken to the laboratory (Lutakome et al, 2017). To form a uniform aliquot, all liquors were blended in 39ºC under the flush of CO 2 and mixed with the artificial saliva (1:2 v/v) and loaded (20 ml) to the glass vials.…”

Effect of Slow-Release Non-Protein Nitrogen Produced from Agro-Industrial Byproducts on Bio Gas Production, Feed Digestibility and Inoculum Parameters

“…Buffer solution (synthetic saliva) was prepared as proposed by McDougall (1948). Ruminal uid of at least three freshly slaughtered beef (Lutakome et al, 2017) were percolated through a 4-layer cheese cloth to a ask which had been warmed at 39C, and promptly taken to the laboratory. Strained ruminal inoculums were mixed thoroughly at 39 • C together with the synthetic saliva (1:2 v/v) to have a homogeneous digestion medium.…”