Influence of Roughage Level and Corn Processing Method on Microbial Protein Synthesis by Beef Steers

106

Four Suffolk wethers (avg wt 65 kg) with ruminal and duodenal cannulae were fed diets containing 75% (75F) or 25% (25F) alfalfa hay at two levels of intake, 1,700 (high intake, HI) or 1,100 (low intake, LI) g dry matter (DM)/d, in a 4 • 4 Latin-square design. When fed 75F diets, wethers had higher (P<.05) ruminal pH and molar proportion of acetate in ruminal fluid than when fed 25F. Ruminal fluid dilution rates were not affected by type of diet, but ruminal particulate dilution rates increased (P<.05) when wethers were fed 75F as compared with 25F. When fed 2$F-HI, wethers had higher (P<.O5) molar proportion of propionate and lower (P<.05) molar proportion of butyrate in ruminal fluid than when fed 25F-LI or 75F at either level of intake. A lower (P<.OS) proportion of total apparent organic matter (OM) digestion occurred in the stomach when wether* were fed at HI. When fed 25F, wethers had a greater (P<.05) quantity of OM and a greater (P<.05) percentage of OM intake truly digested in the stomach than when fed 75F. When fed 75F, wethers tended (P<.IO) to have a greater proportion of digestible neutral detergent fiber (NDF) disappearing in the stomach and a lower proportion digested postruminally than when fed 25F. When fed at HI, wethers had increased (P<.05) flows of nonammonia N (NAN) to the small intestine due to increases (P<.05) in flow of both bacterial and nonbacterial NAN. When fed 25F-Hi, wethers had greater (P<.05) quantities of bacterial N reaching the duodenum than when fed 75F-HI or either diet at LI. Efficiency of bacterial protein synthesis was increased (P<.05) when wethers were fed at HI relative to LI. Duodenal flows of total, essential, nonessential and all individual amino acids were increased (P<.05) when wethers were fed at HI, but were not affected (P>.05) by type of diet. Amino acid profiles of duodenal digesta were similar, regardless of diet. It is concluded that effects due to dietary variables such as intake and forage level must be considered in attempts to predict responses in protein utilization by animals fed diets of differing composition at different levels of intake. (Key Words: Wethers, Forage, Intake, Rumen, Bacterial Protein, Amino Acids.) 216Animals (avg wt 65 Materials and Methodsand Diets. Four Suffolk wethers kg) fitted with permanent t-type J. Anim. ScL 1986.62:216-225

Section: Resultssupporting

confidence: 69%

Effect of Intake and Forage Level on Ruminal Turnover Rates, Bacterial Protein Synthesis and Duodenal Amino Acid Flows in Sheep

Merchen

Firkins

Berger

1986

106

“…Diet effects may have caused differences in Ac and Pr shifts upon FDR alteration. Increased molar proportion of propionate has been associated with elevated proportion of dietary concentrates Rumsey et al, 1970) and reduced FDR (Cole et al, 1976;Huntington et al, 1981). Trials in which high concentrate diets were fed generally showed slower FDR, higher Pr and lower Ac proportion (table 2), which may have been responsible for depressed (P<.05) Pr and a trend for elevated (P>.10) Ac with increased FDR in the combined analysis.…”

Section: Resultsmentioning

confidence: 85%

“…Moreover, few data are available regarding effects of dietary constituents on FDR. Slower FDR has been associated with increased dietary concentrate level (Cole et al, 1976;Prins and Clarke, 1980;Huntington et al, 1981;Goetsch and Galyean, 1982) and decreased dry matter intake (Grovum and Williams, 1973;Kennedy and Milligan, 1978;Galyean et al, 1979;Evans, 1981;Adams and Kartchner, 1984). Both elevated roughage percentage and increased dry matter intake should increase FDR (Owens and Isaacson, 1977).…”

Section: Introductionmentioning

confidence: 99%

Relationship of Rumen Fluid Dilution Rate to Rumen Fermentation and Dietary Characteristics of Beef Steers

Estell

Galyean

1985

Data from seven beef steer trials were compiled and regression analyses used to evaluate relationships among molar proportions of acetate (Ac), propionate (Pr) and butyrate (Bu), total concentration of volatile fatty acids (VFA), rumen ammonia (NH3), rumen pH, rumen fluid dilution rate (FDR), rumen fluid volume (FVOL), body weight (WT), dry matter intake (DMI) and dietary concentration and intake of crude protein (CP and CPI), acid detergent fiber (ADF and ADFI), ash (ASH and ASHI) and metabolizable energy (ME and MEI). Of the six fermentation variables, Pr (negative regression coefficient, beta) and pH (positive beta) were related (P less than .05) to FDR, but only 3 and 12% of the variation in these two variables, respectively, was explained by FDR. When FDR was described by dietary characteristics, ASHI was positively related to FDR (R2 = .16). The best two-variable model for FDR contained DMI (positive beta) and WT (negative beta) and increased R2 to .36. Fluid volume was best described by ME (positive beta; R2 = .20). The two-variable model for FVOL added ASH with a positive partial beta (R2 = .23). When fermentation variables were regressed on dietary characteristics, Ac was best described by ADF (positive beta; R2 = .71). The variable that best described Pr proportion was ADF (negative beta; R2 = .50), and addition of CP (negative beta) and MEI (positive beta) into the Pr model improved R2 to .70. Molar proportion of butyrate was related to CP (positive beta; R2 = .23), and addition of ME (positive beta) to the model improved the R2 to .31. Total VFA concentration was best described by ADFI (positive beta; R2 = .14). An R2 of .29 resulted when ME (positive beta) and CPI (negative beta) were included in the total VFA model. Rumen pH was related to ADF (positive beta; R2 = .45), and addition of CP (positive beta) to the rumen pH model increased R2 to .55. Crude protein concentration was related to ruminal NH3 level (positive beta; R2 = .42), and inclusion of ADFI (positive beta) into the model improved the R2 to .47.

“…Oldham et al (1979), using total collection to measure digesta flow and either RNA or DAP as microbial markers, reported values of microbial N yield 20 and 25% greater than feed N degraded in the rumen of cows fed a 90% barley diet. Calculations from data presented in several studies (Cole et at., 1976;Prigge et al, 1978;Muntifering et al, 1981;Stern et al, 1983;Zinn and Owens, 1983a;Spicer et al, 1986) based on various bacterial and flow markers, indicate that yields of microbial N could be greater than accounted for by feed N degraded in the rumen of cattle fed high grain diets (ratios of microbial N to feed N degraded ranged from .6 to 2.6).…”

Section: Resultsmentioning

confidence: 99%

“…; forage or grain processing methods (Tamminga, 1975;Prigge et al, 1978) and forage-to-concentrate ratios (Cole et al, 1976;Tamminga, 1979;Oldham and Tamminga, 1980;Wanderley and Theurer, 1983;Zinn and Owens, 1983b). However, accurrate in vivo measurement of bacterial and feed protein reaching the small intestine is difficult and, according to Theurer (1979Theurer ( , 1982, part of the difficulty is caused by the methods used to quantitate bacterial and feed protein in digesta samples, as well as digesta flow rates throughout the gastrointestinal tract.…”

Section: )mentioning

confidence: 99%

Duodenal Bacterial and Nonbacterial Protein Supply in Steers Fed Forage and Grain Diets

Wanderley

Theurer

Poore

1987

Four beef steers (avg wt 300 kg) fitted with duodenal re-entrant cannulae were used to study the effect of dietary concentrate to forage ratio on bacterial and nonbacterial N flow in the duodenum. According to a change-over design, the steers were designated to receive an all forage (83% alfalfa hay and 17% wheat straw) and an 80% sorghum grain diet. Lignin (ADL) and chromium oxide (Cr2O3) ratio techniques were compared with automated total collection (ATC) of digesta for quantitating duodenal protein flow and efficiency of bacterial N yield in the rumen. Estimates of bacterial protein synthesis and ruminal escape of feed protein based on Cr2O3 and lignin tended to be higher by 8 to 16% than those obtained by ATC. Efficiency of ruminal bacterial protein yield estimated by these two markers tended to be greater than that based on ATC (16 vs 12 g of bacterial protein/100 g ruminal true digestion of dry matter corrected for bacterial cell synthesis). Efficiency values did not differ between diets. Crude protein flow into the duodenum was about 33% greater (P less than .01) for the grain than the forage diet, although protein intake was about 10% less on the grain diet. Duodenal bacterial protein, rather than feed protein escaping ruminal degradation, accounted for most of this difference. Average duodenal flow of N, expressed as g/Mcal metabolizable energy (ME) intake, was 11.9 for the forage diet and 10.3 for the grain diet.(ABSTRACT TRUNCATED AT 250 WORDS)