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Full-Text Articles in Life Sciences
Ratoon Stunting Disease Of Sugarcane: Isolation Of The Causal Bacterium, Michael J. Davis, A. Graves Gillaspie, Russell W. Harris, Roger H. Lawson
Ratoon Stunting Disease Of Sugarcane: Isolation Of The Causal Bacterium, Michael J. Davis, A. Graves Gillaspie, Russell W. Harris, Roger H. Lawson
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
A small coryneform bacterium was consistently isolated from sugarcane with ratoon stunting disease and shown to be the causal agent. A similar bacterium was isolated from Bermuda grass. Both strains multiplied in sugarcane and Bermuda grass, but the Bermuda grass strain did not incite the symptoms of ratoon stunting disease in sugarcane. Shoot growth in Bermuda grass was retarded by both strains.
Dryland Corn Development Under Various Tillage Systems, Wallace Wilhelm
Dryland Corn Development Under Various Tillage Systems, Wallace Wilhelm
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Corn (Zea mays L.) was grown under dryland conditions in eastern Nebraska to study the influence of tillage practice on plant development and leaf growth characteristics during 1977, 1978, and 1979. Tillage practices used in these experiments were plow, disk, chisel, and no-till. All tillage operations were applied during the spring of each cropping season. Green leaf area increased from emergence through tasseling and then decreased slowly until physiological maturity for all treatments. The maximum green leaf area indices (LAI) averaged 2.14, 2.56, and 1.89 for 1977, 1978, and 1979, respectively. There was no significant tillage treatment effect on …
Relationship Of Daylength And Prolactin To Resumption Of Reproductive Activity In Anestrous Ewes, Bruce Schanbacher
Relationship Of Daylength And Prolactin To Resumption Of Reproductive Activity In Anestrous Ewes, Bruce Schanbacher
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Concentrations of prolactin were measured in serum from three groups of Rambouillet ewes for 8 weeks to determine whether changes in prolactin concentrations were important during the transition from anestrus to seasonal breeding. Group I (control ewes) was maintained under conditions of natural daylength;group II (short-day ewes) was exposed abruptly on the longest day of the year to artificially shortened daylengths (8 hr light and 16 hr darkness); group III (CB 154 ewes) was maintained similar to control ewes except each ewe received twice daily im injections of 2-bromo-α-ergocryptine (CB 154). A fertile ram was kept with each group of …
Testosterone Influences On Growth, Performance, Carcass Characteristics And Composition Of Young Market Lambs, B. D. Schanbacher, J. D. Crouse, C. L. Ferrell
Testosterone Influences On Growth, Performance, Carcass Characteristics And Composition Of Young Market Lambs, B. D. Schanbacher, J. D. Crouse, C. L. Ferrell
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Ram lambs, wethers and wethers implanted with Silastic capsules containing crystalline testerone were placed on test at 14.9 ± 1.1 kg and evaluated for differences in growth, performance, carcass characteristics and composition. Silastic implants that were able to maintain physiological concentrations of serum testosterone provided appropriate replacement therapy in wethers. Growth rate, efficiency of feed utilization and carcass yield of intact ram lambs and testosterone-implanted wethers were superior to the corresponding traits of wethers. Wethers had greater backfat thickness and percentage kidney and pelvic fat, and their carcasses graded higher than those of ram lambs or wethers implanted with a …
Androgen Secretion And Characteristics Of Testicular Hcg Binding In Cryptorchid Rats, B. D. Schanbacher
Androgen Secretion And Characteristics Of Testicular Hcg Binding In Cryptorchid Rats, B. D. Schanbacher
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Response of the cryptorchid testis to gonadotrophic stimulation was assessed by comparison of the androgen production capability in vivo and in vitro with that of the normal scrotal testis. Serum androgen concentrations in cryptorchid rats were similar to those in normal rats, and the incremental increase 60 min after 50 i.u. hCG (i.v.) was about 7-fold for both groups. Basal and hCG-stimulated androgen production in vitro was higher for abdominal testes (557 and 3286 ng/pair) than for scrotal tests (157 and 504 ng/pair). Specific binding of hCG by testicular homogenates was slightly higher (P < 0·05)for cryptorchid testes when expressed per unit weight, but Scatchard analysis indicated that although hCG binding affinities did not differ (Ka = 2×1010 M-1), hCG binding …
Testosterone Regulation Of Luteinizing Hormone And Follicle Stimulating Hormone Secretion In Young Male Lambs, B. D. Schanbacher
Testosterone Regulation Of Luteinizing Hormone And Follicle Stimulating Hormone Secretion In Young Male Lambs, B. D. Schanbacher
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Polydimethylsiloxane (Silastic) capsules containing crystalline testosterone were implanted subcutaneously in castrate lambs and evaluated for their ability to (1) provide stable, physiological concentrations of serum testosterone and (2) regulate secretion of LH and FSH. Testosterone was nondectable (<.2 ng/ml) between 12 and 24 weeks of age in the serum of castrate lambs implanted with empty capsules but was increased at those ages in Iambs implanted with 20 cm (1.2 ± .1 and .5 ± .1 ng/ml), 60 cm (2.8 ± .1 and .9 ± .1 ng/ml) and 180 cm (6.6 ± .3 and 1.9 ± .2 ng/ml) of testosterone-filled Silastic tubing. Serum concentrations of LH and FSH were suppressed by exogenous testosterone and did not exceed concentrations in intact control rams as long as serum testosterone concentrations were greater than 1 ng/ml. In conclusion, simultaneous suppression of serum LH and FSH by concentrations of testosterone that cause a dose-dependent stimulatory effect on accessory sex gland weights indicates that testosterone is a physiological regulator of gonadotropin secretion in ram lambs. Although testosterone per se may not be directly responsible for negative feedback on LH and FSH secretion, the results presented herein question the need for a nonsteroidal "inhibin-like" testicular hormone to regulate FSH in lambs.
Fertilizing Capacity And Morphology Of Fowl And Turkey Spermatozoa In Hypotonic Extender, M. R. Bakst
Fertilizing Capacity And Morphology Of Fowl And Turkey Spermatozoa In Hypotonic Extender, M. R. Bakst
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The effects of graduated increments of hypotonic Beltsville Poultry Semen Extender (BPSE) on fowl and turkey sperm morphology, motility, percentage dead
and fertility were examined. The morphology of fowl and turkey spermatozoa was
adversely affected by decreases in BPSE osmolarity; a reduction of osmolarity of
BPSE to below 200 and 140 mosmol adversely affected the fertility of fowl and
turkey spermatozoa, respectively. The addition of Ficoll to the extender allowed
direct observation of the effects of hypotonic BPSE on the sperm plasmalemma.
Plasmalemmal swelling, due to the uptake of water, was noted initially at the
midpiece. Such plasmalemmal swelling may …
Growth And Performance Of Growing-Finishing Lambs Exposed To Long Or Short Photoperiods, B. D. Schanbacher, J. D. Crouse
Growth And Performance Of Growing-Finishing Lambs Exposed To Long Or Short Photoperiods, B. D. Schanbacher, J. D. Crouse
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The effects of photoperiod (8 hr light: 16 hr dark [8L:16D] or 16L:8D) on performance of growing-finishing lambs were evaluated in an experiment with 24 rams and 24 wethers. All lambs were caged in groups of two in a controlled environment and fed a pelleted diet ad libitum for the duration of the study (10 to 22 weeks of age). Performance and carcass data showed that both photoperiod and sex of lamb affected growth rate (P<.01) and feed efficiency (P<.05) but that only sex of lamb affected carcass quality (P<.05) and yield (P<.10). A sex by photoperiod interaction was not observed for any of the traits measured. Average daily gain (grams/per day) and feed efficiency (feed/gain) for lambs in the four treatment groups tested were: rams (16L:8D), 410 and 4.3; rams (8L:16D), 340 and 4.5; wethers (16L:8D), 345 and 4.6, and wethers (8L:16D), 300 and 4.8, respectively. Carcass weight, like slaughter weight, was affected by photoperiod (P<.01) and sex of lamb (P<.05); both rams and wethers exposed to long photoperiods had the heaviest carcasses. Ram carcasses were leaner, had better yield grades and were heavier than wether carcasses, yet both ram and wether carcasses graded Choice. Testosterone concentrations in serum were undetectable (<.2 ng/ml) at 22 weeks of age in wethers but were elevated (P<.O1) in ram lambs exposed to short (3.4 ± 1.4 ng/ml) or long (.8 ± .2 ng/ml) photoperiods. Prolactin concentrations, on the other hand, were not influenced by sex of lamb but were influenced (P<.01) by photoperiod; i.e., prolactin concentrations were high in rams (190 ± 34 ng/ml) and wethers (178 ± 28 ng/ml) exposed to long photoperiods and low in rams (43 ± 9 ng/ml) and wethers (27 ± 11 ng/ml) exposed to short photoperiods. These results suggest that testosterone and prolactin may independently affect growth and performance of growing-finishing lambs.
Androgen Response Of Cryptorchid And Intact Rams To Ovine Lh, B. D. Schanbacher
Androgen Response Of Cryptorchid And Intact Rams To Ovine Lh, B. D. Schanbacher
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Surgically induced cryptorchidism in rams resulted in elevated serum concentrations of LH but near-normal concentrations of androgen (testosterone and 5α-DHT).Injections of ovine LH (2 × 50μg;2 × 500 μg)resulted in maximal androgen secretion in the intact rams and similar but lower concentrations in cryptorchid rams. Peak concentrations were 14·9and 8·5ng/ml in the intact and cryptorchid rams respectively (P < 0·05).