Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

1984

Plant Sciences

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Articles 1 - 11 of 11

Full-Text Articles in Life Sciences

Soil Physical Characteristics Of Reduced Tillage In A Wheat-Fallow System, L. N. Mielke, Wallace Wilhelm, K. A. Richards, C.R. Fenster Dec 1984

Soil Physical Characteristics Of Reduced Tillage In A Wheat-Fallow System, L. N. Mielke, Wallace Wilhelm, K. A. Richards, C.R. Fenster

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Soil physical characteristics of reduced tillage for fallow-wheat (Triticum aestivum L.) were compared for two soils in western Nebraska. The soil physical environment influences the amount of water that enters soil, the availability of water for plants, and the microenvironment important to soil biological processes. Fallow tillage (plow, subtill, no till) did not affect bulk density in Alliance silt loam (fine silty, mixed mesic, Aridic Argiustolls). For Duroc loam (fine silty, mixed mesic Pachic Haplustolls), in which native sod was compared to the above three wheat-fallow tillage methods, numerous effects on soil physical properties were found. Reduced tillage reduced …

Go to article

Crop Residue Removal And Soil Productivity With No-Till Corn, Sorghum, And Soybean, J. W. Doran, Wallace Wilhelm, J. F. Power Nov 1984

Crop Residue Removal And Soil Productivity With No-Till Corn, Sorghum, And Soybean, J. W. Doran, Wallace Wilhelm, J. F. Power

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Crop residues have been considered during the past decade as alternate energy sources to supplement dwindling fossil fuel sources and enhance energy independence in the United States. Agricultural scientists have demonstrated the importance of crop residues in reducing soil erosion, enhancing the soil physical environment for plant growth, and as a reserve for major crop nutrients. In eastern Nebraska, we evaluated the effects of various amounts of surface crop residues (aboveground dry matter remaining after harvest) on dryland production of no-till corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merrill] over …

Go to article

Effects Of Water Flow Restriction And Environmental Factors On Performance Of Nursery-Age Pigs, John A. Neinaber, G. Leroy Hahn Jan 1984

Effects Of Water Flow Restriction And Environmental Factors On Performance Of Nursery-Age Pigs, John A. Neinaber, G. Leroy Hahn

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A series of three feeding trials was conducted to determine if nipple waterer flow rate affects the performance of nursery-age pigs and if there are any interaction effects with environmental factors. In the first trial, 42 barrows, 10 wk of age, were fed during a period of 4 wk at 5 or 35 C and given water ad libitum with flow rates of 100, 600 and 1,100 ml/min and a control treatment of 20 C and 600 ml/min.

Go to article

Growth Analysis Based On Degree Days, M. P. Russelle, Wallace Wilhelm, R. A. Olson, James F. Power Jan 1984

Growth Analysis Based On Degree Days, M. P. Russelle, Wallace Wilhelm, R. A. Olson, James F. Power

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Comparisons of growth analysis functions within and among experiments are often confounded by sources of variation other than those imposed by treatment. we suggest use of a temperature index, such as modified growing degree days, as the divisor in growth functions to facilitate treatment comparisons within certain experiments and to reduce the effects of differing temperature regimes among experiments on these comparisons. Three experiments were identified to provide data to analyze this new approach. Mean absolute growth rate (GR) and mean relative growth rate (RGR) were compared in two experiments with maize (Zea mays L.) conducted in eastern Nebraska. …

Go to article

Endocrine Mechanisms Of Puberty In Heifers: Estradiol Negative Feedback Regulation Of Luteinizing Hormone Secretion, M. L. Day, K. Imakawa, M. Garcia-Winder, D. D. Zalesky, B. D. Schanbacher, Roger J. Kittok, J. E. Kinder Jan 1984

Endocrine Mechanisms Of Puberty In Heifers: Estradiol Negative Feedback Regulation Of Luteinizing Hormone Secretion, M. L. Day, K. Imakawa, M. Garcia-Winder, D. D. Zalesky, B. D. Schanbacher, Roger J. Kittok, J. E. Kinder

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The hypothesis that luteinizing hormone (LH) secretion in prepubertal females is responsive to estradiol negative feedback and that decreased feedback occurs as puberty approaches was tested in heifers. In the first experiment, seven heifers were maintained prepubertal by dietary energy restriction until 508 days of age (Day 0). All heifers were placed on a high-energy diet on Day 0 at which time they received no additional treatment (CONT), were ovariectomized (OVX) or were ovariectomized and subcutaneously implanted with estradiol-17β (OVX-E2). This feeding regimen was used to synchronize reproductive state in all heifers. A second experiment was performed with …

Go to article

Manipulation Of Endogenous And Exogenous Hormones For Red Meat Production, Bruce D. Schanbacher Jan 1984

Manipulation Of Endogenous And Exogenous Hormones For Red Meat Production, Bruce D. Schanbacher

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Growth and development of domestic livestock for red meat production are often discussed in the context of environmental factors, nutritional requirements, genetic potential and the anabolic agents affecting production efficiency. In this minireview, the effects of endogenous and exogenous hormones on animal growth are reviewed. The pituitary, pancreatic and gonadal hormones known to affect growth and(or) carcass composition are cited to illustrate and place into perspective the important contributions that the endocrine system makes to animal production. Manipulation of endogenous hormones through 1) administration of synthetic releasing and inhibiting peptides and 2) immunoneutralization techniques, will likely provide the livestock producer …

Go to article

Thermal Shrinkage Temperature Of Intramuscular Collagen Of Bulls And Steers, M. D. Judge, E. D. Aberle, H. R. Cross, B. D. Schanbacher Jan 1984

Thermal Shrinkage Temperature Of Intramuscular Collagen Of Bulls And Steers, M. D. Judge, E. D. Aberle, H. R. Cross, B. D. Schanbacher

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The thermal shrinkage temperature (Ts) of bull muscle collagen was higher (Ps from bull muscles increased from 12 to 15 mo and decreased from 15 to 18 mo of age, whereas that of steer muscles did not change with age (age × sex interaction, Ps. Carcass electrical stimulation did not affect collagen Ts in steer muscle, but there was a trend toward reduction of Ts in collagen of bull muscle.

Go to article

In Vitro Testosterone Secretion By Testicular Tissue From Young Bulls And The Effects Of Chronic And Acute Exposure To Estradiol- 17Β, M. J. D'Occhio, B. D. Schanbacher, J. E. Kinder Jan 1984

In Vitro Testosterone Secretion By Testicular Tissue From Young Bulls And The Effects Of Chronic And Acute Exposure To Estradiol- 17Β, M. J. D'Occhio, B. D. Schanbacher, J. E. Kinder

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The possibility that estradiol-17/3 may directly influence testicular steroidogenesis in bulls was investigated in vitro. Testicular tissues were incubated for 4 h and regression coefficients (b, ng·ml-1·h-1) based on the increase in testosterone in the medium were used to describe testosterone secretion rates. In the first experiment, testicular tissues from control bulls and bulls chronically implanted with estradiol were incubated in the absence (basal conditions) or presence of 10 mlU/ml human chorionic gonadotropin (hCG). Under basal conditions, testosterone secretion rates were similar for tissues from control (b = 24.1 ± 6.0) and implanted (b = 34.7 …

Go to article

Pituitary-Testicular Responses Of Estradiol-17Β-Implanted Bull Calves To Continuous Versus Pulsatile Infusion Of Luteinizing Hormone Releasing Hormone, Bruce D. Schanbacher Jan 1984

Pituitary-Testicular Responses Of Estradiol-17Β-Implanted Bull Calves To Continuous Versus Pulsatile Infusion Of Luteinizing Hormone Releasing Hormone, Bruce D. Schanbacher

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The luteinizing hormone (LH), folliclestimulating hormone (FSH) and testosterone response of bull calves implanted with estradiol-17β to continuous and pulsatile infusion of luteinizing hormone releasing hormone (LHRH) has been examined. Estradiol-17β reduced serum LH and FSH concentrations and suppressed testosterone secretion and testicular growth when compared with sham-implanted bulls. Putsatile iv infusion of LHRH [500 ng every 2 h (6 μg/d)] for a 4-wk period to estradiol-17β- implanted bulls resulted in elevated mean serum LH and testosterone concentrations that were characterized by discrete secretory episodes. Mean serum FSH was also increased by LHRH pulse infusion, but LHRH-coup!ed secretory episodes were …

Go to article

Effects Of Castration And Electrical Stimulation On Beef Carcass Quality And Palatability Characteristics, S. Kalstrup, H. R. Cross, B. D. Schanbacher, R. W. Mandigo Jan 1984

Effects Of Castration And Electrical Stimulation On Beef Carcass Quality And Palatability Characteristics, S. Kalstrup, H. R. Cross, B. D. Schanbacher, R. W. Mandigo

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Thirty bull and 30 heifer Hereford x Simmental calves were weaned at approximately 5 mo of age and assigned randomly to one of the following treatments: intact, conventionally castrated or luteinizing hormone-releasing hormone-immunized (LHRH). All animals were slaughtered at 16 mo of age and the right side of each carcass was electrically stimulated (ES) or restimulated (RES). Yield and quality grades were determined on both right and left sides after 24 h chilling. Longissimus muscles (LD) were obtained at 7 d postmortem for objective color measurements, chemical analysis, shear force and trained sensory panel evaluation. Semitendinosus muscles (ST) were also …

Go to article

Hypothalamic Control Of The Post-Castration Rise In Serum Lh Concentration In Rams, B. D. Schanbacher, M. J. D'Occhio Jan 1984

Hypothalamic Control Of The Post-Castration Rise In Serum Lh Concentration In Rams, B. D. Schanbacher, M. J. D'Occhio

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Sexually mature rams were left intact, castrated (wethers), castrated and implanted with testosterone, or castrated, implanted with testosterone and pulse-infused every hour with LHRH. Serum concentrations of LH increased rapidly during the first week after castration and at 14 days had reached values of 13·1 ± 2·2ng/ml (mean ± s.e.m.) and were characterized by a rhythmic, pulsatile pattern of secretion (1·6 ± 0·1pulses/h). Testosterone prevented the post-castration rise in serum LH in wethers (1·0 ± 0·5ng/ml; 0 pulses/h), but a castrate-type secretory pattern of LH was obtained when LHRH and testosterone were administered concurrently (10·7 ± 0·8 ng/ml; 1·0 pulse/h). …

Go to article