9 research outputs found
Effects of Static or Oscillating Dietary Crude Protein Levels on Fermentation Dynamics of Beef Cattle Diets Using a Dual-Flow Continuous Culture System
<div><p>The objective of this study was to evaluate the effects of increasing dietary crude protein (CP) levels and also comparing the effects of static versus oscillating dietary CP on ruminal nutrient digestibility, ruminal fermentation, nitrogen (N) metabolism, and microbial efficiency in beef cattle diets using a dual-flow continuous culture system. Eight fermenters (1,223 ± 21 mL) were used in a replicated 4 x 4 Latin square design with periods lasting 12 d each (8 d for adaptation and 4 d for sampling). Dietary treatments were: 1) 10% CP, 2) 12% CP, 3) 14% CP, and 4) 10 and 14% CP diets oscillating at 48-h intervals. Experimental diets consisted of 50% orchard hay and 50% concentrate. Fermenters were fed 72 g/d and solid and liquid dilution rates were adjusted to 5.5 and 11%/h, respectively. Data were analyzed using the MIXED procedure in SAS with α = 0.05. Apparent and true ruminal digestibilities of dry matter and organic matter were not affected (P > 0.05) by increasing dietary CP, nor by oscillating dietary CP. Total volatile fatty acids concentration and molar proportions of acetate, propionate, butyrate, valerate, iso-butyrate and iso-valerate were not affected (P > 0.05) by increasing or oscillating dietary CP. Ruminal NH<sub>3</sub>-N concentration increased linearly (<i>P</i> < 0.01) in response to increasing dietary CP. Total N, non-ammonia N, and rumen undegraded protein flows did not differ among treatments or between oscillating dietary CP and static 12% CP. Microbial N and NH<sub>3</sub>-N flows and microbial efficiency did not differ when comparing oscillating versus static CP (P > 0.05). However, there was a quadratic effect (<i>P</i> < 0.05) for these variables when dietary CP was increased. These results indicate that either ruminal microorganisms do not respond to oscillating CP levels or are capable of coping with 48-h periods of undernourishment.</p></div
Effects of dietary CP levels or oscillating dietary CP on ruminal nitrogen metabolism in dual-flow continuous culture system.
<p>Effects of dietary CP levels or oscillating dietary CP on ruminal nitrogen metabolism in dual-flow continuous culture system.</p
Effects of dietary CP levels or oscillating dietary CP on ruminal pH at different times after feeding in dual-flow continuous culture system.
<p>Effects of dietary CP levels or oscillating dietary CP on ruminal pH at different times after feeding in dual-flow continuous culture system.</p
Dual-flow continuous culture system frontal view.
<p>Dual-flow continuous culture system frontal view.</p
Ingredient and chemical composition of experimental diets.
<p>Ingredient and chemical composition of experimental diets.</p
Dual-flow continuous culture system right view.
<p>Dual-flow continuous culture system right view.</p
Dual-flow continuous culture system left view.
<p>Dual-flow continuous culture system left view.</p
Effects of dietary CP levels or oscillating dietary CP on ruminal pH, total VFA concentration and individual VFA proportions in dual-flow continuous culture system.
<p>Effects of dietary CP levels or oscillating dietary CP on ruminal pH, total VFA concentration and individual VFA proportions in dual-flow continuous culture system.</p
Effects of dietary CP levels or oscillating dietary CP on apparent and true ruminal digestibilities of dietary nutrients in dual-flow continuous culture system.
<p>Effects of dietary CP levels or oscillating dietary CP on apparent and true ruminal digestibilities of dietary nutrients in dual-flow continuous culture system.</p