eChapters

What is dispersion?

In statistics, dispersion (also called variability, scatter, or spread) is the extent to which a distribution is stretched or squeezed. Common examples of measures of statistical dispersion are the variance, standard deviation, and interquartile range. For instance, when the variance of data in a set is large, the data is widely scattered. On the other hand, when the variance is small, the data in the set is clustered.

Dispersion is contrasted with location or central tendency, and together they are the most used properties of distributions.

Measure of dispersion

(a) Range

The range is defined as the difference between the largest and smallest observations. Range(X)= Max(X)- Min (X)

Example

The range in statistics for a given data set is the difference between the highest and lowest values. For example, if the given data set is {2,5,8,10,3}, then the range will be 10 – 2 = 8. Thus, the range could also be defined as the difference between the highest observation and lowest observation.

Introduction

E lectronic-resources is an umbrella term which refers to provision of digital instruction courseware over the public Internet, private distance learning networks or in-house via an intranet. E-resources most often means an approach to facilitate and enhance access through the use of devices based on information and communications technologies (ICT) like personal computers, digital television, PDAs (Personal Digital Assistant) and mobile phones. The electronic resources might include notes, PowerPoint presentations, video clips or Internet sites.

Online library resources aim at providing materials, information and services by different types of libraries to the end users. These libraries may be in different jurisdictions, but agree to serve one another on the same basis as each service to its own users through the use of ICT. With the rapid growth of information on veterinary science, there are frequent delays in providing service to the end users when traditional library systems are adopted. The cost of providing service is also rising, mainly because of manual methods and duplication of investments in library holdings. ICT enables the use of the Internet, email, discussion forums, and collaborative software to support students and veterinarians through the use of WANs (Wide Area Networks), and may also be considered where greater flexibility and just-in-time access is desired.

Computer Purchase

With so many factors to consider, deciding which omputer to buy can be a real challenge. From components to software to accessories, new PCs offer a bewildering array of choices. Sifting through the large number of options can be a daunting task. Almost any PC on the market today can more than adequately handle such standard office chores as word processing and spreadsheets, as well as basic Internet functions like e-mail and general browsing. If you want to edit digital video or manage a large database, however, you may need more than the basics.

The best way to pay only for what you need is to carefully consider what you want to do with your system now, and try to anticipate what might interest you next 2-3 years. Specific applications call for certain types of hardware, whether at home or in the office. When you’re ready to buy a computer, here are some recommendations for the average user’s basic requirements:

We can categorize statistical theory into two general parts.

1. Firstly, there is descriptive statistics which uses the appropriate tools, typically tables, diagrams and/or numerical measures, to describe a data set and provide a summary of its distribution.

2. In addition, there is inferential statistics which is concerned with drawing conclusions about a population using information obtained from a representative sample selected from it.

(a) One aspect of statistical inference is the estimation of a population parameter by the appropriate sample statistic (e.g. the population mean by the sample mean).

(b) The second aspect of inferential statistics is hypothesis testing. In this case, we examine a hypothesis, framed in terms of the parameters in one or more populations.

Estimation is concerned with description whereas hypothesis testing is ultimately concerned with decision.

Basic concepts of hypothesis testing

Hypothesis testing is a process that is concerned with making conclusions about the population using the information obtained from its sample.

MOMENTS

The term moment in mechanics refers to the measure of a force with reference to its tendency to produce rotation. The strength of this tendency is depen- dent upon the amount of the force and the distance from the origin at which the force is applied. If on both the sides of the origin the force are equal than there will be a balance, at a balanced position the positive product equals the negative product.

Moment is used in Statistics in a quite analogous sense. The class frequencies are looked upon as the forces and the deviations of the different values from the mean are taken as the distances. In other words, moment is the mean of the first, second, third, fourth, etc. powers of deviations of the different values from the arithmetic mean. The first moment about the mean is always zero and second moment about the mean is variance.

If the moment calculated from arithmetic mean are called central moments and denoted by μ with a subscript which indicate the order of the moment. Moments are the mean values of powers of the deviations in any frequency distribution taken about three points

9.1 Introduction

The tests used to ascertain whether the differences between estimator and the parameter or between two estimators are real or due to chance are called tests of hypothesis or tests of significance. In other words, the procedures, which enable us to decide whether to accept or reject hypothesis, are called tests of hypothesis or tests of significance. The following terms are commonly used in testing of hypothesis

SKEWNESS

Skewness means lack of symmetry. Skewness denotes the tendency of a distri- bution to depart from symmetry. A frequency distribution is said to be skewed if the frequencies decrease with markedly greater rapidity on one side of the central maximum than on the other side. This characteristic of a frequency distribution is known as skewness and the measures of asymmetry are usually called measures of skewness.

The main object of measuring skewness is to know the direction of the varia- tion from an average and to compare the frequency distribution and the shape of their curves.

There are two types of skewness

(i) Positive Skewness (ii) Negative Skewness

KURTOSIS

Kurtosis refers to the extent to which unimodal frequency curve is peaked. Kurtosis is a measure that refers to the peakedness of the top of the curve. Kurtosis gives the degree of flatness in the region about the mode of a frequency distribution.

Types of Kurtosis

There are three categories of kurtosis that can be displayed by a set of data. All measures of kurtosis are compared against a standard normal distribution, or bell curve.

The first category of kurtosis is a mesokurtic distribution. This type of kurtosis is the most similar to a standard normal distribution in that it also resembles a bell curve. However, a graph that is mesokurtic has fatter tails than a standard normal distribution and has a slightly lower peak. This type of kurtosis is considered normally distributed but is not a standard normal distribution.

The second category is a leptokurtic distribution. Any distribution that is leptokurtic displays greater kurtosis than a mesokurtic distribution. Characteristic of this type of distribution is one with extremely thick tails and a very thin and tall peak. The prefix of “lepto-” means “skinny,” making the shape of a leptokurtic distribution easier to remember. T-distributions are leptokurtic.

The final type of distribution is a platykurtic distribution. These types of distributions have slender tails and a peak that’s smaller than a mesokurtic distribution. The prefix of “platy-” means “broad,” and it is meant to describe a short and broad-looking peak. Uniform distributions are platykurtic.

• In statistics, best linear unbiased prediction (BLUP) is used in linear mixed models for the estimation of random effects. BLUP was derived by Charles Roy Henderson in 1950 but the term “best linear unbiased predictor” (or “prediction”) seems not to have been used until 1962 (Henderson, 1975, 1985).

• “Best linear unbiased predictions” (BLUPs) of random effects are similar to best linear unbiased estimates (BLUEs) of fixed effects. The distinction arises because it is conventional to talk not about estimating fixed effects but rather about predicting random effects, but the two terms are otherwise equivalent.

BLUE and BLUP are both acronyms used in statistics

• BLUE stands for Best Linear Unbiased Estimates and refers to the solutions (or estimates) associated with the fixed effects of a model.

• BLUP stands for Best Linear Unbiased Predictions and refers to the solutions (but identified as predictions) associated with the random effects of a model.

• Both BLUEs and BLUPs are linear functions of the data and have the lowest variance.

• The expected value of a mean estimate for an individual equals its true value for BLUEs.

• BLUPs are similar to BLUEs, but it is conventional to talk about estimating fixed effects but predicting random effects.

• BLUP is the standard selection method in animal breeding where the breeding values of sires are estimated based on progeny performance to select superior genotypes and to breed superior families.

India is very rich in biodiversity especially in animal genetic resources and animals have been part and parcel of agricultural heritage. There are about 30 well defined breeds of cattle found in different parts of the country. To name a few are Sahiwal, Red Sindhi, Gir, Kankrej, Deoni, Tharparkar, Hariana, Ongle, Nagori, Amritmahal and Hallikar. The cattle breeds are classified into three types i.e. dairy, dual purpose and draft/drought animals. The number of the animals of majority of indigenous breeds has declined over the years. Further, their number is very low and majority of cattle population (80%) in India is non-descript. The introduction of systematic crossbreeding program of our native cattle with exotic breeds in seventies have further led to the depletion of prized germplasm of all the indigenous breeds under farm and field conditions. However, considering the importance of indigenous cattle, some of the breed improvement programs have been initiated to conserve and multiply these breeds. The associated herd progeny testing program has been going on at NDRI Karnal for the genetic improvement of Sahiwal cattle. All India Coordinated Research Project on Hariana and Ongole cattle has been undertaken at different centres by Project Directorate on Cattle, Meerut. Lately, three more breeds namely Sahiwal, Gir and Kankarej have been included in the indigenous breed improvement program (IBP) and different centres have been identified as germplasm units and data recording units for different breeds under the program.

The state of Uttaranchal was carved out of Uttar Pradesh on 9^th November 2000 as the 27th state of the union of India and renamed as Uttarakhand. The state is located in western Himalayan region and is one of the geographically smallest states of the country. However, the state is enriched with livestock biodiversity represented by cattle, buffaloes, goats, pigs, horses, mules and poultry.  The climate of the state varies from subtropical in the valleys to temperate on higher slopes with a summer monsoon. The temperature ranges from -5.4ºC (Muketshwar, higher hills) to 40.2ºC (Pantnagar, plains) but it drops below freezing point in many parts of high mountainous areas of the region during winter. Preponderance of hilly terrains and forestland restricts the size of the agricultural land/ holding. The average rainfall recorded in the year 2008 was 1605 mm.  Higher rainfall, abundance of natural pastureland and suitable climatic conditions makes the state favorable for livestock development. The human population was 84.89 lacs with a density of 159 people per sq km during the year, 2001.

Genetic Transfer and Mapping in Bacteria a

Bacteria can transfer genetic material during conjugation

Hfr strains contain an F factor integrated into the bacterial chromosome

Hfr strains can transfer a portion of the bacterial chromosome to recipient cells

Conjugation experiments can map genes along the E. coli chromosome

A genetic map of the E. coli chromosome has been obtained from many conjugation studies

Bacteria may contain different types of plasmids

Bacteriophages transfer genetic material from one bacterial cell to another via transduction

Cotransduction can be used to map genes that are within 2 minutes of each other

Bacteria can also transfer genetic material by transformation

Bacteria may acquire new genes by horizontal gene transfer

Sex Chromosomes

Sex can be considered at chromosomal, gonadal, phenotypic, and gender identity levels.

Human females are homogametic (XX) and males are heterogametic (XY).

The Y chromosome contains few identified genes, while the larger X chromosome contains several thousand genes. Pseudoautosomal regions at both tips of the Y chromosome contain genes that have counterparts on the X chromosome.

The male determining gene, SRY, has been found on the Y chromosome.

Introduction
 
Livestock sector plays an important role in Indian economy and is an important sub sector of India agriculture the contribution of livestock to gross domestic product was 4.7% in 2004-05 with 27% share in agriculture and allied sector. Milk production in India reaching a level of 91 million tones in 2004-05. It is estimated that in milk production 58% of milk was contributed by buffaloes with average lactation milk about 1300 kg. Some of the buffaloes produce as high as 4000 kg but their number is limited. India with 185 million cattle and approximately 98 million buffaloes possesses 20% of the world bovine and 14% of the cattle population. Buffalo population in the country has been increasing at a steady wait with slight increase in productivity. Highest increase in the past five years was observed in Haryana (25.1% ), followed by Uttar Pradesh (20.6%), Madhaya Pradesh (13.9%), Gujrat (13.6%), Uttaranchal (12.2%), Andhra Pradesh (10%) and Rajasthan (6.6%). Productivity per animal is very low mainly due to low genetic potential for milk production, near absence of the genetic improvement programmes, poor plan of nutrition and health measures. 

Overview of Transcription

Gene expression requires base sequences that perform different functional roles

The three stages of transcription are initiation, elongation, and termination

RNA transcripts have different functions Transcription in Bacteria

A promoter is a short sequence of DNA that is necessary to initiate transcription

Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a promoter sequence

The RNA transcript is synthesized during the elongation stage

Transcription is terminated by either an RNA-binding protein or an intrinsic terminator

Abstract

Buffaloes are considered to be the principle milk producing livestock species in India and Surti is one of the well-defined buffalo breeds of India. The study on lactation curve and persistency is very much helpful to know the sustainability of the lactation. The present study is based on daily milk production records for 298 lactations from 130 buffaloes belonging to 15 sires. Lactation curve was prepared through Statistical Packages for Social Sciences programme. Two functions, i.e. gamma function and inverse polynomial functions were fitted to the daily milk yield records. Persistency was calculated through simple analysis in Microsoft Excel 2000 on the weekly records of the milk yield. Gamma function was found to be more effective as compared to inverse polynomial function with higher R2 value for all the four lactations, which indicated that gamma function can be effectively used to establish lactation curve and predict milk yield of animals on any day of lactation. The value of persistency ranged from 97.94% in fourth lactation to 98.56 % in first lactation, indicating Surti buffaloes as fairly persistent in milk production throughout the lactation.

The Genetic Basis for Protein Synthesis

Archibald Garrod proposed that some genes code for the production of a single enzyme

Beadle and Tatum’s experiments with Neurospora led them to propose the one gene-one enzyme hypothesis

During translation, the genetic code within mRNA is used to make a polypeptide with a specific amino acid sequence

Exceptions to the genetic code are known to occur, which include the incorporation of selenocysteine and pyrrolysine into polypeptides

Synthetic RNA helped to decipher the genetic code

The use of RNA copolymers and the triplet binding assay also helped to crack the genetic code

A polypeptide chain has directionality from its amino terminal to its carboxyl terminal end

The amino acid sequences of polypeptides determine the structure and function of proteins

Cellular proteins are primarily responsible for the characteristics of living cells and an organism’s traits

Gujarat state blessed with rich goat genetic resources. Recognized goat breeds in the state are Kutchi, Surti, Zalawadi, Mehsanba and Gohilwadi which have been the integral component of small, marginal farmers, landless labourers and significantly contribute rural livelihood. These breeds excel in drought capacity, disease resistance and better adapted to harsh local climatic conditions under extensive production system. The population status and breeding tract of goat breeds are given in Table 1.

The goat genetic resources (AnGR) of state may be important assets for having the valuable adaptive traits that they have developed over long periods of time, such as:

Genome Sequencing: A Continuation of Genetics

• The human genome project involves the assembly of a DNA sequence map for the 3 billion base pairs present in all 23 human chromosomes.
• Two groups, the International Consortium and Celera Genomics, used two opposite strategies to obtain a draft sequence of the human genome.
• The use of bacterial artificial chromosomes (BACs), shotgun clones, and positional cloning has yielded a detailed look at the human genome and is facilitating the identification of disease causing genes.

The Sanger Method of DNA Sequencing

The Sanger method of DNA sequencing involves an enzymatic extension reaction to generate complementary copies of an unknown DNA sequence.

Incorporation of “dideoxy” base causes chain termination and separation of extension products on polyacrylamide gels reveals the sequence bases in the unknown DNA.

DNA sequencing occurs on a vast scale today through the use of automated DNA sequencing machines.

Introduction

From the very early days human beings depend on animals and animal products for food and other requirements. In dairy and poultry farms high yielding animals are reared. These high yielding animals are produced by hybridization experiments. Previously the animals were developed basing on unscientific methods. Before the discovery of principles of heredity human beings have selected the animals with required characters and learned to develop the plants having the selected characters. This phenomenon is called Artificial selection. However, an increased knowledge of biology, especially genetics, has helped in improving the quality of animals and animal products as per the human requirements.