Life Sciences Commons^™

Prediction Of Breeding Values For Unmeasured Traits From Measured Traits, Kristin L. Barkhouse, L. Dale Van Vleck

Conference on Applied Statistics in Agriculture

Henderson (1977, 1984) described a method for prediction of breeding values for traits not in the model for records. This method may be practical for animal or sire models for the case when no measurements can be obtained on any animals for some traits to be evaluated. The least squares equations are augmented with A^-1⊗G_N^-1 rather than with A^-1⊗G₀^-1 where A is the numerator relationship and G₀and G_N are the genetic covariance matrices for measured and for all traits. This method can be used for each unmeasured trait or …

Applications Of Estimable Functions In Agricultural Research With Special Emphasis On The Glm Procedure Of Sas., L. Munyakazi, R. L. Hintz, B. D. Selby

Conference on Applied Statistics in Agriculture

An understanding of estimable functions is essential when using an overparameterized linear model. The most attractive features of these functions are their invariance property to the solution vector and their wide range of practical applications in agricultural research. This study reviews some of the ways that estimable functions can be used by the agricultural scientist.

Extrapolating Intra-Cluster Correlation To Optimize The Size Of Segments In An Area Frame., E. Carfagna, F. J. Gallego

Conference on Applied Statistics in Agriculture

In the frame of the "Rapid Crop Area Estimates in the European Community" we use a sample of squared segments (pieces of land) of 49 ha. each; estimates are made for difference of crop areas between years. The optimum size seems to be larger than the current one, and much larger if ground survey data are obtained by photo-interpretation. The main purpose of this paper is to assess a method, based on splitting the segments into pieces of 1/4 ha., to forecast the precision of estimates with larger segments. The tests made for France confirm the belief that better estimates …

Modelling Within-Plant Spatial Dependencies Of Cotton Yield, E. B. Moser, R. E. Macchiavelli, D. J. Boquet

Conference on Applied Statistics in Agriculture

In field experiments during 1987-1990, cotton plants were grown under 8 different levels of nitrogen application to assess the impact of nitrogen fertilization on the fruiting and yield distribution of cotton within the plant (Boquet et al. 1993).lr.dividual boll weights and average seedcotton yield were determined at each fruiting site fur each main-stem node along the plant. Various models of dependence and independence are possible to explain and account for the dependencies of the yields among the sites and nodes of the plant. Here we investigate models of total yield per node and yield per node adjusted for the number …

Fitting Bole-Volume Equations To Spatially Correlated Within-Tree Data, Timothy G. Gregoire, Oliver Schabenberger

Conference on Applied Statistics in Agriculture

Equations to predict the volume of an individual tree bole between stump height and the height at which its diameter has tapered to a specified minimum are common in forestry. When fitting such a regression equation, a sample of trees which span the range of sizes needed for eventual application of the equation is selected. Bole diameter is measured at ascending heights on the bole. Each tree, therefore, contributes multiple measurements to the data fitted to the equation. In contrast to past practice, we model these data in a manner which accounts for the likely spatial correlation among measurements within …

A Bootstrap Analysis Of Temperature Effects On Bean Leaf Beetle Egg Hatch Times, Kenneth J. Koehler

Conference on Applied Statistics in Agriculture

The bean leaf beetle (Cerotoma trifurcata) is a significant soybean pest in the Midwest. The possibility of reducing crop damage by disrupting the synchrony between emergence of F2 adults and the availability of young green pods requires an increased understanding of bean leaf beetle (BLB) phenology. An important consideration in predicting emergence of F2 adults is the influence of temperature on the rates of egg and larval development. In this article we concentrate on the analysis of data from a controlled study of the effects of temperature on both the hatch time distribution and the viability of BLB …

Nonlinear Regression Functions For Forage Nutrient Disappearance From Bags Incubated In The Rumen, W. J. E. Potts, B. P. Glenn, J. B. Reeves, R. A. Erdman

Conference on Applied Statistics in Agriculture

Seven nonlinear regression functions are compared for fitting rumen in situ disappearance data. The standard function is based on a simple one-compartment model. In addition, we consider a time lag modification, a two-compartment model, and functions based on underlying probability models for degradation time. The empirical suitability of the seven regression functions are assessed using two in situ experiments involving forages fed to dairy cows. A function based on the loglogistic distribution is shown to have empirical and theoretical advantages.

Obtaining Models For Alfalfa, Sorghum, And Wheat Residue Decomposition, H. H. Schomberg, T. W. Popham

Conference on Applied Statistics in Agriculture

Crop residues provide an economical means for controlling wind and water erosion in addition to being a valuable source of plant nutrients. As residues decompose they lose nutrients, mass and the ability to protect the soil surface from erosive forces. The research was designed to evaluate rates of residue decomposition of sorghum, wheat and alfalfa on the soil surface and buried, in five soil moisture regimes. Moisture was applied to soil by line source irrigation and bags containing crop residues were retrieved and analyzed across time. Thus, observations were repeated in both space and time .

Wieder and Lang (1982) …

Determination Of The Inoculation Frequency, Timing Of Inoculation And Dose Of A Bacterial Ruminal Inoculant For Acidosis Prevention In Feedlot Cattle, J. F. Boucher, W. J. Smolenski, J. A. Robinson

Conference on Applied Statistics in Agriculture

We are evaluating the efficacy of a ruminal bacterial inoculant (Megasphaera elsdenii 407 A) for prevention of acute acidosis in grain-fed cattle. As a part of this process, we examined the effects of inoculation frequency, timing of inoculation and dose of 407 A for prevention of acute acidosis in ruminally fistulated cattle. Three levels of frequency, two levels of timing and three doses were considered, however, a complete 3x2x3 factorial study was not run because of resource constraints. The study was conducted in two separate trials. The first was designed as a 3x2 factorial experiment with inoculation frequency and timing …

Design For The Experimenter, O. B. Allen, D. A.J. Ryan

Conference on Applied Statistics in Agriculture

Three research problems, for which there was no obvious textbook design available, are presented. Each of the three involve constructing incomplete block designs for factorial treatment arrangements. While the designs are not likely optimal by any of the classical criteria, they meet the objectives of the research projects. The constructions involved confounding, with incomplete blocks, those effects which were of least interest. However, effects of interest were also allowed to be slightly non-orthogonal to blocks in order to be able to examine a larger number of effects of interest.

Experimental Error In Agronomic Field Trials, Thomas M. Loughin, D. F. Cox, Paul N. Hinz, William T. Schapaugh Jr., Lora Kilgore-Norquest

Conference on Applied Statistics in Agriculture

Agronomic experiments often summarize work carried out in trials run in several locations over several years, referred to generically as environments. The appropriate statistical analyses for these experiments depend on definitions used for experimental error. The results of one such experiment, in which identical designs were used in each environment, illustrate the commonalities and differences in analyses that can result from using different definitions of experimental error.

Markov-Recapture Population Estimates, E. Paul Wileyto

Conference on Applied Statistics in Agriculture

This paper reviews recent development of a method for estimating insect populations. It is like mark-recapture methods, except that marking is done passively at bait stations by the insects themselves, and capture probabilities are generated using a simple Markov process model. Assumptions about rates of marking and capture are made from the sampling scheme, and the estimate is based upon the resulting multinomial probability distribution and maximum likelihood methods. The paper continues to review the sampling distributions for the population estimate, revealed by simulation, and explores correction of the bias. Relative likelihood based confidence intervals are compared with two standard …

Predicting Common Crupina Habitat With Geographic And Remote Sensing Data, Timothy S. Prather, Bahman Shafii, Robert H. Callihan

Conference on Applied Statistics in Agriculture

Field surveys for common crupina, as part of an eradication program, are time intensive and could be made more efficient if common crupina habitat could be predicted. Slope, aspect, and vegetation data were used as generalized plant community variables to predict common crupina habitat using a transformed logistic regression. Models were constructed using either aspect or slope as an explanatory variable such that one model predicted the overall effect of either slope or aspect and a set of models predicted the effect of slope or aspect at each of three vegetation classes. A second data set was used to validate …

Stratification And Cluster Estimator On An Area Frame By Squared Segments With An Aligned Sample, M. Fuentes, F J. Gallego

Conference on Applied Statistics in Agriculture

Several European countries (Portugal, Spain, Greece, Rumania, and the Czech Republic) make crop surveys on area frame with an aligned systematic sampling of squared segments. So far crop area estimates are obtained with standard formulae for random sampling, without using the spatial structure of the sample. This is in general conservative, the estimated standard error is larger than the error actually made. Taking as clusters the set of segments with the same relative position in a block, gives often lower but very unstable variances. A more stable variance estimate is computed by repeated random permutations of the sample segments in …

Generalized Linear Mixed Models: An Application, Stephen D. Kachman, Walter W. Stroup

Conference on Applied Statistics in Agriculture

The purpose of this paper is to present a specific application of the generalized linear mixed model. Often of interest to animal-breeders is the estimation of genetic parameters associated with certain traits. When the trait is measured in terms of a normally distributed response variable, standard variance-component estimation and mixed-model procedures can be used. Increasingly, breeders are interested in categorical traits (degree of calving difficulty, number born, etc.). An application of the generalized linear mixed to an animal breeding study of the number of lambs born alive will be presented. We will show how the model is determined, how the …

Generalized Linear Mixed Models - An Overview, W. W. Stroup, S. D. Kachman

Conference on Applied Statistics in Agriculture

Generalized linear models provide a methodology for doing regression and ANOV A-type analysis with data whose errors are not necessarily normally-distributed. Common applications in agriculture include categorical data, survival analysis, bioassay, etc. Most of the literature and most of the available computing software for generalized linear models applies to cases in which all model effects are fixed. However, many agricultural research applications lead to mixed or random effects models: split-plot experiments, animal- and plant-breeding studies, multi-location studies, etc. Recently, through a variety of efforts in a number of contexts, a general framework for generalized linear models with random effects, the …

Autologistic Model Of Spatial Pattern Of Phytophthora Epidemic In Bell Pepper: Effects Of Soil Variables On Disease Presence, M. L. Gumpertz, J. Graham, J. B. Ristaino

Conference on Applied Statistics in Agriculture

The pathogen Phytophthora capsici causes lesions on the crown, stem, and leaves of bell pepper, and rapidly causes the plant to die. The spatial patterns of disease in an agricultural field contain information about pathogen dispersal mechanisms and can be useful for developing methods of control of disease. Soil water content, soil pathogen population density, and disease incidence data were collected on a 20 x 20 grid in two naturally infested commercial bell pepper fields. In one field the initial pattern of disease closely matched the soil water content pattern and disease developed in areas where the pathogen population levels …

Determining Sample Size To Bound The Probability Of Classifying A Sample Into The Wrong One Of Two Multinomially Distributed Populations, C. Philip Cox

Conference on Applied Statistics in Agriculture

The problem considered is that of choosing between the two specifications . . . of known multinomial probabilities on the basis of sample values x _j, the observed counts in the j = 1,... ,k, classes, with . . . The particular question examined is 'how large should N be to achieve reliable differentiation?'. It is shown how to find N such that the probability of misc1assification does not exceed a prescribable value. The method is exemplified in a genetic context.

Vertical Integration In The Chicken Broiler Industry, Juana Sanchez

Conference on Applied Statistics in Agriculture

This paper analyzes three hypotheses concerning supply in the U.S. chicken broiler industry: (a) there has been a cycle in the industry of approximately 27-36 months length; (b) the seasonal and other periodic components, as well as relations between variables, have changed as a result of vertical integration in the industry; (c) the effects of vertical integration in the industry were counteracted in the early seventies by such forces external to the industry as domestic and international economic conditions .

The hypotheses are analyzed using new monthly, non-seasonally adjusted time series data for chick placement, wholesale broiler prices, chicks hatched …

A Study Of The Statistical Properties Of Two Measures Of Competition, Ann L. Oberg, Linda J. Young, Leon G. Higley

Conference on Applied Statistics in Agriculture

In competition studies, two species are studied, generally in ratios of 1:0, 3:1, 1:1, 1:3,and 0: 1. The standard measure of competition is the Relative Crowding Coefficient (RCC)...

An Individual-Plant Growth Simulation Model For Quantifying Plant Competition, William J. Price, Bahman Shafii, Donald C. Thill

Conference on Applied Statistics in Agriculture

Plant competition models traditionally have used population or stand level parameters as a basis for modeling. While such models may be valid with regard to average responses, they fail to account for important factors such as within stand variability and spatial relationships. This translates to an assumption of uniformity in growth characteristics among individual plant,S as well as an equidistant spacing arrangement which are unlikely in real populations. One alternative is to model the growth characteristics of individual plants separately which, when combined as a system, will inherently have popUlation attributes related to competition. Competition models of this type allow …

Editor's Preface, Table Of Contents, And List Of Attendees, James R. Schwenke

Conference on Applied Statistics in Agriculture

These proceedings contain papers presented in the sixth annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 24 through 26, 1994..

Marketing Quality Alfalfa Hay, Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

Alfalfa hay is a potentially marketable-profitable product if--if quality is satisfactory to meet buyer's needs, if it is packaged such that it meets buyer's feeding program and can be transported efficiently, if in sufficient quantity, if storage site is accessible by truck or trailer, and if it is competitively priced. Meeting these minimum criteria only means the hay is potentially marketable; only after it has been sold does it become potentially profitable.

Producing Quality Alfalfa Hay, Jimmy C. Henning, Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

Hay is one of the most versatile of stored forages in that (1) it can be kept for long periods of time with little loss of nutrients if protected from weather; (2) a large number of crops can be successfully used for hay production; (3) it can be produced and fed in small or large amounts; (4) it can be harvested, stored and fed by hand or the production and feeding can be completely mechanized; and (5) hay can supply most nutrients needed by many classes of livestock. Hay is, therefore, the most commonly used stored feed on most farms. …

Harvesting Hay For High Yield And Quality — More On Bale Ventilators And Other Harvest Aids, Michael Collins

Kentucky Alfalfa and Stored Forage Conference

In some areas of the country, producers store a substantial portion of their forage for winter feeding as silage or haylage. However, hay remains the most popular storage method for forage. Hay stores well for long periods and is better suited to cash sale and transportation than silage. Mechanical conditioning, which gained acceptance during the 1950's is probably still the greatest single change in hay harvesting and storage technology during this century. However, a number of other noteworthy changes and innovations have occurred in recent years which have helped to reduce the extent of losses during hay harvesting and storage. …

Role In Alfalfa In Livestock Feeding Programs In Kentucky, Donna M. Amaral-Phillips

Kentucky Alfalfa and Stored Forage Conference

Alfalfa, the "Queen of the Forage Crops", is a highly versatile forage crop which can be grazed directly by livestock or harvested as hay or silage. With the development of new alfalfa varieties, increased pest and weed control, and increased demand from livestock owners, the amount of alfalfa fed to livestock will increase. As with any forage crop, proper harvest and feeding management is necessary to reap the benefits.

Fencing For Optimum Grazing, Larry W. Turner

Kentucky Alfalfa and Stored Forage Conference

Controlled or rotational grazing can result in better utilization of forage resources. By better forage management through controlled grazing, producers may increase profitability of cattle/forage systems. To effectively develop a controlled grazing system, however, fencing must be used to subdivide the pasture into sub-fields or paddocks. The animals may then be rotated among the paddocks to optimize forage and beef or dairy production from the system. Alfalfa grazing can play an important part in such a system.

Planning the "best", or optimum, fencing strategy should be done with the overall goal in mind of improving profitability. Key factors that describe …

Grazing Alfalfa — Momentum Continues, Garry D. Lacefield

Kentucky Alfalfa and Stored Forage Conference

In my presentation at our XIII Kentucky Alfalfa Conference held here last year, I stated. that interest in grazing alfalfa was at an all time high. Five other speakers followed me on the program with presentations about alfalfa grazing. Steve Osborne discussed alfalfa grazing trials in Monroe County. Ken Johnson talked about the Do's and Dont's in Alfalfa Grazing. Dr. Roy Burris talked about alfalfa grazing from a state perspective and Mr. Warren Thompson discussed the topic from a national perspective. Professor Joe Bums concluded the grazing portion of the program with grazing alfalfa experiences in Tennessee.

Despite a rather …

Alfalfa Weed Control — Strategies For Success, James R. Martin

Kentucky Alfalfa and Stored Forage Conference

Field evaluation, cultural and chemical practices are key ingredients of a successful weed control program in alfalfa. A weak link in any of these components could lead to reduced profits and possibly shorten the life of an alfalfa stand.

Managing Alfalfa Diseases, Paul C. Vincelli

Kentucky Alfalfa and Stored Forage Conference

Diseases of alfalfa can limit productivity of this valuable forage crop. Alfalfa diseases can reduce forage yield, reduce forage quality, and decrease stand persistence. The effects of diseases can be dramatic, such as sudden stand loss due to Sclerotinia crown and stem rot. Often, the effects of alfalfa diseases are more subtle but are no less important. For example, alfalfa plants with Phytophthora root rot sometimes regrow slowly after cutting, resulting in a stunted stand showing no other obvious symptoms of disease.

Like most crop diseases, alfalfa diseases are most effectively managed by integrating as many control measures as practical. …