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Buffers are an essential component in various biochemical and biophysical assays, enabling the control of pH shifts in the environment. The Tilley and Terry (1963) and Goering Van Soest (1970) methods dominate in vitro forage digestibility research with equally viable results. However, the methods utilize distinct buffer solutions to control the in vitro environment. Given this divergence, it is of interest whether differences in estimates are a factor of the methodology, or the buffer solutions employed in the method. The objective of this study was to determine the effects of in vitro DM digestibility (IVDMD) methodology and buffer solution on digestibility estimates of four bermudagrass cultivars. We conducted our experiment as a randomized complete block design with a 2 × 2 × 4 factorial treatment structure. Approximately 1,000 mL of rumen content (solid and liquid fractions) were collected from two ruminally fistulated heifers in each of two periods (blocks). The samples were separated into two 500-mL aliquots; the first aliquot was subjected to the procedures of Tilley and Terry (1963), and the second aliquot was subjected to the Goering and Van Soest (1970) procedure. Duplicate samples of four bermudagrass cultivars (Coastal, Russell, Tifton 44, Tifton 85) were placed in 125-mL Erlenmeyer flasks and incubated according to the assigned in vitro method. One-half of the samples in each method received the methodologically prescribed buffer solution, and the other one-half in each method received the opposite buffer. There was no effect of in vitro method (P = 0.78), buffer solution (P = 0.53), or bermudagrass cultivar (P = 0.46), or their interactions (P = 0.23) on IVDMD estimates in this experiment. Results are interpreted to mean that buffer type is not pivotal to methodological success, and both methods will yield similar estimates of digestibility. [ABSTRACT FROM AUTHOR]

While much effort has been devoted to both the characterization of ruminal fermentation dynamics and the evaluation of bermudagrass production, independently, there is a lack of information regarding ruminal digestive kinetics using beef cattle in southern forage systems. Thus, the objective of our study was to evaluate in situ digestive kinetics of four bermudagrass (Cynodon dactylon [L.] Pers.) cultivars in heifers consuming typical southern forages. (Coastal, Tifton 44, Tifton 85, and Russell). Ruminally fistulated heifers (n = 4) were assigned randomly to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods (21-d adaptation and 9-d collection). On d 31 of periods 2 and 3, an in-situ experiment was conducted as a randomized complete block design with a 3-factor factorial treatment structure. The first factor (n = 4) was diet consumed by the animal (described above). The second factor (n = 4) was the incubated forage (same cultivars as the in vivo experiment). The third factor was incubation timepoint (n = 19; 0, 0.25, 0.50, 0.75, 1, 2, 3, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144, and 168 h). Four in situ bags were incubated in each animal at each timepoint; two were used for NDF, ADF, and ADL, and two were used for CP determination. Data were analyzed using SAS v. 9.4. There was a decreased (P < 0.05) potentially degradable fraction from COS (30.0%) compared with T85 (55.1%), T44 (48.1%), or RUS (47.1%). Similarly, COS presented the greatest (P < 0.05) undegradable fraction (37.0%) and T85 the least (15.9%), with RUS and T44 intermediate (25.0 and 21.9%, respectively). There was no effect of bermudagrass cultivar, however, on the rate constant of digestion (0.94%/h; P = 0.26) or lag time (3.2 h; P = 0.38). A visual appraisal of the degradation curve suggests that the asymptote of digestion was not reached at the measured 168 h. Results are interpreted to mean that T44 is the preferable bermudagrass cultivar, followed by T85 and RUS, while COS is the least favorable. Further, given the lack of visible asymptote, we speculate that bermudagrass likely passes the rumen before full digestion is realized. [ABSTRACT FROM AUTHOR]

Dried distillers grains with solubles (DDGS) is commonly used as supplemental feed in cattle rations. However, the systemic effects of overfeeding DDGS, especially to potential fertilizer benefits of passthrough nitrogen, are widely unknown. Therefore, our objective was to evaluate plant and soil response to fertilization with manure from steers supplemented with titrated levels of DDGS. Manure utilized was collected from steers supplemented with DDGS (0%, 0.25%, 0.5%, and 1% BW) during a 2-yr experiment. The experimental design was a randomized complete block design with an augmented factorial treatment structure wherein benches represented blocks. The factorial was made up of manure treatment (0, 0.25, 0.5, or 1% BW DDGS, chemical fertilizer, or none) soil type (Windthorst or Purves), and plant species (none, crimson clover, or rye). Pots were sown (5 seeds/pot) and grown in a greenhouse for 35 d. Water was applied daily at 90% evapotranspiration. After harvest, soils were sifted, dried for 72 h at 55°C, then assayed for C, N, NO3-N, P, K, Ca, Mg, Na, and S. There was an interaction of manure and soil type for soil C (P < 0.01). Purves soils amended with any manure had a greater (P < 0.05) concentration of C (1.8%) than did the negative control (1.3%). From Windthorst, soil C was greatest from 1% BW DDGS manure (1.9%), and least from 0% DDGS manure (1.5%), with 0.25 and 0.5% manures and the negative control intermediate. There was an interaction of manure, soil type, and forage for soil N (P < 0.01). Manures with higher levels of supplementation had greater (P < 0.05) soil N than lower levels of supplementation or the negative control. Legumes had greater soil N than grasses. Results are interpreted to mean that moderate supplementation of steers with DDGS may yield soil nutrient benefits through nutrient deposition. [ABSTRACT FROM AUTHOR]