Life Sciences Commons^™

Developmental And Reproductive Characteristics Of Beef Heifers Classified By Number Of Estrous Cycles Experienced By Start Of First Breeding, Andy Roberts, Jaclyn N. Ketchum, Richard N. Funston

West Central Research and Extension Center, North Platte

A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or >3 (n = 249). Heifers (P …

Reproductive Characteristics Of Landlocked Fall Chinook Salmon From Lake Oahe, South Dakota, Kelsen L. Young, Michael E. Barnes, Jeremy L. Kientz

The Prairie Naturalist

Lake Oahe, South Dakota, USA, landlocked fall Chinook salmon (Oncorhynchus tshawytscha) reproductive characteristics were examined over a 27 year period, from 1988 to 2015. Mean total lengths of spawning females ranged from 665 mm (1995) to 812 mm (2015) with considerable year-to-year variation. Post-spawn female weights varied, ranging from 2.02 kg (2000) to 5.55 kg (2015), with an overall mean of 3.04 kg. Fecundity peaked at 4,555 eggs per female in 2003, which was just 3 years after a low of 2,011 eggs per female in 2000. Relative fecundity based on female weight was greatest at 1,211 eggs/kg …

Asymmetrical Gene Flow In A Hybrid Zone Of Hawaiian Schiedea (Caryophyllaceae) Species With Contrasting Mating Systems., Lisa E. Wallace, Theresa M. Culley, Stephen G. Weller, Ann K. Sakai, Ashley Kuenzi, Tilottama Roy, Warren L. Wagner, Molly Nepokroeff

College of Arts and Sciences Publications and Scholarship

Asymmetrical gene flow, which has frequently been documented in naturally occurring hybrid zones, can result from various genetic and demographic factors. Understanding these factors is important for determining the ecological conditions that permitted hybridization and the evolutionary potential inherent in hybrids. Here, we characterized morphological, nuclear, and chloroplast variation in a putative hybrid zone between Schiedea menziesii and S. salicaria, endemic Hawaiian species with contrasting breeding systems. Schiedea menziesii is hermaphroditic with moderate selfing; S. salicaria is gynodioecious and wind-pollinated, with partially selfing hermaphrodites and largely outcrossed females. We tested three hypotheses: 1) putative hybrids were derived from natural crosses …

Life History Of An Exotic Soft Scale Insect Phalacrococcus Howertoni (Hemiptera: Coccidae) Found In Florida, Kaushalya G. Amarasekare, Catharine M. Mannion

Agricultural and Environmental Sciences Faculty Research

We investigated the life history of an exotic soft scale insect, Phalacrococcus howertoni Hodges and Hodgson that damages croton and several other economically important ornamental and fruit plants in Florida. There was no difference in the development, survival, and reproduction of this scale insect species when reared either on croton or on buttonwood at 27 ± 1°C, 12:12 (L:D) h and 65% R. H. The scale insect practiced ovoviviparity. We observed that eggs that came out from vulva hatched to first instars immediately. Newly hatched nymphs had a tendency stay underneath the female body for somewhat less than approximately 24 …

Effects Of Xenobiotics And Phytotoxins On Reproduction In Food Animals, Kip E. Panter, Bryan L. Stegelmeier

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

The influence of natural toxicants and anthropogenic compounds on reproduction in food animals is significant in its economic impact, and the subject requires more research and further experimental substantiation. Confounding factors such as stress, nutritional status, season of the year, animal species involved, genetic variability, disease conditions, management factors, and so forth exacerbate the difficulty of making an accurate diagnosis and thereby may impede progress to improve reproductive performance on an individual operation. The interaction between the reproductive system and xenobiotics (reproductive toxicology) is a relatively new area of study and a subject of increasing interest, especially in the area …

Reproductive Status Of Holstein And Jersey Cows In The United States, H. D. Norman, J. R. Wright, S. M. Hubbard, R. H. Miller, J. L. Hutchison

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

Reproductive information since 1995 from the USDA national dairy database was used to calculate yearly Holstein and Jersey means for days to first breeding after calving (DFB), 70-d nonreturn rate, conception rate (CR), number of breedings per lactation (NB), interval between first and last breedings during the lactation, days to last breeding after calving (DLB), pregnancy rate (PR), calving interval (CI), and interval between consecutive breedings. Data were from nearly 20 million breedings during >8 million lactations of >5 million cows in >23,000 herds. Means were also calculated for some traits by parity and breeding number for both breeds and …

Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler

Dartmouth Scholarship

Pollen movement within and among plants affects inbreeding, plant fitness, and the spatial scale of genetic differentiation. Although a number of studies have assessed how plant and floral traits influence pollen movement via changes in pollinator behavior, few have explored how nectar chemical composition affects pollen transfer. As many as 55% of plants produce secondary compounds in their nectar, which is surprising given that nectar is typically thought to attract pollinators. We tested the hypothesis that nectar with secondary compounds may benefit plants by encouraging pollinators to leave plants after visiting only a few flowers, thus reducing self-pollen transfer. We …

Paddlefish Egg Deposition In The Lower Yellowstone River, Montana And North Dakota, Shannon E. Miller, Dennis L. Scarnecchia, Steven R. Fain

The Prairie Naturalist

We used passive egg collectors during May, June, and July of2003 and 2004 in the lower 50 river kiiometers (rkm) of the Yellowstone River, eastern Montana and western North Dakota, to detect egg deposition by spawning paddle fish (Polyodon spathula). Sampling yielded 292 eggs (46 in 2003 and 246 in 2004). All egg collections in 2003 occurred on the descending limb of the spring hydrograph but 99% of egg collections in 2004 occurred before the spring hydrograph began to descend. Catch-per-unit-effort (CPUE) in 2004 was about four times that of 2003. A combination of river conditions, in addition …

Sheep Updates 2007 - Part 4, Dean Thomas, Dominique Blache, Dean Revell, Hayley Norman, Phil Vercoe, Zoey Durmic, Serina Digby, Di Mayberry, Megan Chadwick, Martin Sillence, David Masters, R. Silberstein, F. Byrne, P. G. H. Nichols, J. Young, L. Aitkins, M. G. Wilmot, A. J. Rintoul, T. Lambert, D. R. Mcclements, P. Raper, P. Ward, C. Walton, T. York, David Pethick, David Hopkins, Malcolm Mcphee, D. B. Savage, J. V. Nolan, I. R. Godwin, A. Aoetpah, T. Nguyen, N. Baillie, C. Lawler, Ken Geenty, John Smith, Darryl Smith, Tim Dyall, Grant Uphill, John Young, Michael Paton, John Dorrian

Sheep Updates

This session covers eight papers from different authors:

GRAZING

1. The impact of high dietary salt and its implications for the management of livestock grazing saline land, Dean Thomas, Dominique Blache, Dean Revell, Hayley Norman, Phil Vercoe, Zoey Durmic, Serina Digby, Di Mayberry, Megan Chadwick, Martin Sillence and David Masters, CRC for Plant-based Management of Dryland Salinity, Faculty of Natural & Agricultural Sciences, The University of Western Australia, WA.

2. Sustainable Grazing on Saline Lands - outcomes from the WA1 research project, H.C. Norman^1,2, D.G. Masters^1,2, R. Silberstein^1,2, F. Byrne^2,3, P.G.H. Nichols …

Reproductive Development In The Sicklefin Chub In The Missouri And Lower Yellowstone Rivers, Douglas J. Dieterman, Eric Roberts, Patrick J. Braaten, David L. Galat

The Prairie Naturalist

We describe aspects of sicklefin chub (Macrhybopsis meeki) reproductive development from three study areas encompassing greater than 2,700 km of the Missouri and Lower Yellowstone rivers. The sicklefin chub was collected between late July and early October in 1996 and 1997. A total of 193 sicklefin chub was collected and examined for reproductive characteristics. Twenty-nine sicklefin chub were found to be reproductively mature females. Some sicklefin chub matured at age 2, but most matured at age 3 and all matured by age 4. Females first became mature at 70 to 79 mm total length (TL) in the Upper …

Herbivory Alters Resource Allocation And Compensation In The Invasive Tree Melaleuca Quinquenervia, P. D. Pratt, M. B. Rayamajhi, T. K. Van, T. D. Center, P. W. Tipping

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

The Australian native Melaleuca quinquenervia is highly invasive in the Florida Everglades, U.S.A., where it experiences limited competition or herbivory from native species, making it a likely candidate for compensation. The introduced biological control agent Oxyops vitiosa feeds exclusively on the seasonal flushes of developing foliage at branch apices, which represents ~ 15% of the total foliar biomass.

Reproductive Ecology Of Two Common Woody Species, Juniperus Sabina And Artemisia Santolinifolia, In Mountain Steppes Of Southern Mongolia, Katrin Ronnenberg

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

The present study describes the reproductive ecology of the prostrate shrub Juniperus sabina and the dwarf shrub Artemisia santolinifolia in dry mountain steppes of southern Mongolia. Whereas stands of the juniper are located at the drought limit of the genus’ distributional range, the genus Artemisia is typical of central Asian drylands. Both species produce large numbers of reproductive organs. For Juniperus sabina, however, only 2.5% of the morphologically intact seeds were found to be viable. Correspondingly, neither seedlings nor saplings were found in the field, and recruitment by reseeding happens at most rarely under the present climatic conditions.

Instead, …

Identification Of Quantitative Trait Loci Affecting Female Reproductive Traits In A Multigeneration Meishan-White Composite Swine Population, G. A. Rohrer, J. J. Ford, T. H. Wise, J. L. Vallet, R. K. Christenson

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

A multigeneration crossbred Meishan- White composite resource population was used to identify quantitative trait loci (QTL) for age at first estrus (AP) and the components of litter size: ovulation rate (OR; number of ova released in an estrous period) and uterine capacity (UC). The population was established by reciprocally mating Meishan (ME) and White composite (WC) pigs. Resultant F1 females were mated to either ME or WC boars to produce backcross progeny (BC) of either ¾ WC ¼ ME or ¼ WC ¾ ME. To produce the next generation (F₃) , ¾ WC ¼ ME animals were mated …

The Association Of Seed And Cone Predator Populations And Cone Crop Production In Engelmann Spruce, Dawn E. Cameron

T.W. "Doc" Daniel Experimental Forest

Engelmann spruce (Picea engelmannii Parry ex Engelm.) exhibits cone crop periodicity, producing seed in a cyclic pattern. Variation in seed production has been noted between individuals of a population, but synchronization on a large scale is common. The theory that ultimately these periodic large cone crops have resulted from the selective pressures of seed and cone predators, referred to as the predator satiation hypothesis, is considered. Assuming predator pressures have operated over evolutionary time to select for periodic synchrony, associations between seed and cone predators and cone crop production levels were anticipated. These potential consequences of predator satiation were examined. …

Increased Lamb Production With Rams Exposed To Short Daylengths During The Nonbreeding Season, B. D. Schanbacher

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

Exposure of rams during the nonbreeding season (anestrous period) to short daylengths will initiate a new sexual cycle characterized by testicular growth, increased mating activity and improved semen quality. Lambing results accumulated from 300 potential matings indicate that rams exposed to artificial photoperiods of 8 hr light and 16 hr darkness for 10 weeks (referred to as rams on short-days) are more fertile than control rams maintained under the relatively long days of spring. When five control rams were penned individually with 30 ewes synchronized with progestogen and PMSG, 67% of the ewes were mated. Eighty-nine percent of the ewes …

Acute And Chronic Effects Of Gonadotropin Releasing Hormone On Reproductive Characteristics Of Rams During The Nonbreeding Season, B. D. Schanbacher, D. D. Lunstra

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

Acute and chronic effects of gonadotropin releasing hormone (GnRH) administration on reproductive characteristics of 32 rams have been assessed during the nonbreeding season. Rams injected intramuscularly with 50 µg of GnRH had elevated (P<.01)concentrations of serum testosterone and noticeably higher (60%) mating activities when compared to control animals injected with saline. Daily injections of GnRH resulted not only in higher testosterone concentrations and mating activity, but also in increased testes size (P<.05). The apparent change in testicular function may account for the improvement in semen quality which was observed in these animals. Although benefits were only slight for percentages of live sperm, normal sperm and sperm with normal acrosomes, sperm motility was markedly increased (P<.05).

These data suggest that reproductive performance in rams is related to testicular androgen secretion and that a spring decline in those characteristics normally associated with high fertility in the male can be lessened by chronic treatment with GnRH.

Influence Of Size Of Cone Crop On Diameter Growth Of Engelmann Spruce (Picea Engelmannii Parry), Herbert Hager

T.W. "Doc" Daniel Experimental Forest

The influence of the average annual cone crop of 170 Engelmann spruce trees on the average basal area increments over a period of 23 years was tested in climatically compensated and uncompensated multiple regression models. In addition, three outstanding cone producing trees were analyzed with the climate compensating model. The cone production of the individual trees were analyzed for the effect on each basal area increment without climatic compensation. A multiple regression model with bimonthly climatic parameters for the growing season, yielded the best prediction (R2 = 98%) of annual basal area increment from the independent parameters among which was …

The Structure And Reproduction Of Corn, T. A. Kiesselbach

Historical Research Bulletins of the Nebraska Agricultural Experiment Station

The primary purpose of this paper is to summarize investigations concerning the structure and reproduction of the corn plant (Zea mays L.). Because of wide interest in the reproductive process in connection with breeding and genetic studies the floral development, fertilization, and embryology are especially stressed. The morphology and development of the vegetative organs is also included. The botanical relationship, origin, genetics and breeding of corn are briefly considered.