Biomedical subjects

D O Erickson

Publications and source records attributed to D O Erickson.

10 recordsLinked to original sources

PubMed1992

Effects of nitrogen fertilization and maturity of bromegrass on nitrogen and amino acid utilization by cows.

Four nonlactating Holstein cows (593 kg) with ruminal cannulas were fed bromegrass hay that was fertilized with 0 or 89 kg of N/ha and harvested in the late-boot or full-head stage of maturity. Total tract apparent digestibility of N was less for full-head than for late-boot bromegrass (48 vs 64%; P less than .01) and was greater for N-fertilized than for unfertilized bromegrass (60 vs 52%, P less than .01). True N digestibility was greater (P less than .01) by cows fed late-boot hay than by those fed full-head bromegrass (85 vs 81%). Maturity did not affect N retention. Nitrogen fertilization increased N retained, both grams per day (70 vs 20; P less than .01) and as a percentage of N intake (P less than .01). Nitrogen and amino acid disappearance kinetics were determined in situ. Rate constants for N disappearance within rapidly and slowly degraded pools were not different among treatments, but because late-boot had a larger proportion of N in the rapidly degraded pool, overall disappearance rate for N was faster (P less than .05) for late-boot than for full-head bromegrass (12.0 vs 7.1 %/h). Treatment effects observed for individual amino acids were similar to those found for N. Both composition and kinetic data were needed to explain differences in N digestion and balance. Distribution of N within the forage had profound effects on the N economy of the cows.

Amino Acids↗

PubMed1991

Effects of nitrogen fertilization and maturity of bromegrass on in situ ruminal digestion kinetics of fiber.

Four ruminally cannulated, nonlactating Holstein cows (593 kg) were fed bromegrass hay diets within a 4 X 4 Latin square. Treatments were arranged factorially and consisted of bromegrass fertilized with 0 or 89 kg N/ha and harvested in the late-boot or full-head stage of maturity. Total tract digestibility of DM (57.6 vs 51.1%), NDF (68.8 vs 63.0%), ADF (51.1 vs 46.0%) and cellulose (63.4 vs 53.5%) decreased with increasing maturity (P less than .05). These forages also were placed in dacron bags for determination of in situ digestion kinetics. Rate, extent of digestion, and lag times were determined for DM and fiber components using linear regression of log-transformed data or a nonlinear fitting procedure. Treatment effects generally were consistent between methods of calculating kinetic data; however, numerical results often differed greatly. Extents of in situ ruminal digestion (72 h residue) for NDF, hemicellulose and cellulose were lower (P less than .05) for full-head than for late-boot-stage bromegrass. Extent of digestion calculated using the nonlinear method followed similar trends. Nitrogen fertilization had no effect on extent or total tract digestibilities of fiber components of DM. In situ disappearance rates (calculated using both methods) for fiber fractions and DM generally were almost always affected less by maturity than by fertilization. Particles of N-fertilized bromegrass had more (P less than .05) bacterial N associated with them during the first 12 h in situ than did particles of unfertilized brome. Surface area equations based on lignification of NDF accurately estimated fiber digestion and suggested that lignification was the primary reason DM and NDF digestibilities decreased with advanced maturity. Due to the relatively low DM intakes of these diets (11 kg/d), rate of passage, not rate of digestion, was of principle importance in determining extent of digestion of these diets.

Animal Feed↗

PubMed1989

Barley distillers grains as a protein supplement for dairy cows.

Dried distillers grains produced from a mix of 65% barley and 35% corn were evaluated in digestion and lactation experiments. Dried barley distillers grains had 56% NDF, 29% CP, 3% amino acid N, 2.5% NDIN (55% of total N), and 1.8% ADIN (39% of total N). Wet barley distillers grains had 38% NDF, 27% CP, 2.7% amino acid N, .5% NDIN (12% of total N), and .8% ADIN (19% of total N). Digestibility of DM and N was similar among lactating dairy cows fed diets containing approximately 25% corn silage DM, 15% alfalfa silage DM, 15% alfalfa hay DM, plus varying amounts of a corn-barley concentrate mix and supplemental CP from soybean meal, barley distillers grains, or from 1:1 mixture of soybean meal and barley distillers grains. Digestibility of ADIN, NDF, and ADF increased with increasing amounts of barley distillers grains in the diet. Similar diets were fed to 60 Holstein cows for 84 d in a lactation experiment. Source of supplemental protein did not affect milk production (22.5 kg/d), FCM (20.4 kg/d), milk fat percent (3.6%), or DM intake (19.0 kg/d). Milk protein percent was decreased by feeding barley distillers grains. It was concluded that barley distillers grains were an acceptable protein source for dairy cows and that ADIN and NDF might not be appropriate measures of the nutritional value of this product.

Amino Acids↗

PubMed1982

Nitrogen metabolism in sheep fed protein sources of various solubilities with low quality roughages.

Four rumen-cannulated, mature crossbred wethers were used in a 4 x 4 latin square experiment designed to examine the effects on protein metabolism of protein sources with various solubilities fed with low quality roughages. Four diets were used: (1) grass hay plus oat straw (control), (2) control plus urea, (3) control plus soybean oil meal (SBOM) and (4) control plus sunflower oil mean (SFOM). The diets were isocaloric, isofibrous and isonitrogenous (1.60% except for the control, which contained 1.09% N). The protein solubility means determined by three solvents (Burroughs' mineral mixture, McDougal's artificial saliva and sodium chloride) were 23.7, 50.5, 18.2 and 24.2% for the respective diets. The average protein solubilities of SBOM and SFOM were 20.5 and 35.4%, respectively. Apparent crude protein digestibilites were higher (P less than .05) for diets with higher protein solubility. The Urea diet (highest protein solubility) resulted in higher urinary N excretion (P less than .05) and lower N retention than the SBOM and SFOM diets. N retention was similar for the animals fed the SBOM and SFOM diets. Ruminal NH3-N and plasma urea N levels were higher (P less than .05) in animals fed the urea diet. The protein source altered VFA concentrations but not C2 to C3 ratios of VFA. The SBOM and SFOM produced more branched chain fatty acids. These data illustrate that protein sources of higher solubility result in higher crude protein digestion and higher N loss in the urine. N balance was similar with SFOM and SBOM. SFOM and SBOM can be used interchangeably on an equal protein basis for sheep fed high roughage diets.

Ammonia↗

PubMed1970