Crossbred sheep production. III. Selection for growth rate and carcass attributes in the second-cross lamb

1964 ◽  
Vol 6 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Maurice Bichard ◽  
B. C. Yalçin
Keyword(s):  
Growth Rate ◽  
Individual Performance ◽  
Small Scale ◽  
Progeny Testing ◽  
Genetic Merit ◽  
Ram Lambs ◽  
Selection For ◽  
Sheep Production ◽  
The Individual ◽  
Selection Of

Results have been presented from a small scale investigation into operational and theoretical aspects of progeny testing Down rams as sires of crossbred fat lambs. Twenty-six Suffolk rams were evaluated from the growth records of 922 lambs out of Border Leicester × Cheviot ewes. In addition measurements were recorded on 260 carcasses. Significant differences were found between corrected progeny means, which were equivalent t o heritabilities of between 0·03 and 0·13 for live-weights up to 15 weeks, and o t higher values for skeletal measurements.A scheme for the selection of Down rams was considered which involved measuring the individual performance of all ram lambs and then progeny testing the best of these by measuring a fixed total number of crossbred lambs. It was concluded that the proportion to be progeny tested could be varied within quite wide limits without seriously changing the genetic merit of the selected group.

scholarly journals Selection for plasmid post–segregational killing depends on multiple infection: evidence for the selection of more virulent parasites through parasite–level competition

2005 ◽  
Vol 272 (1561) ◽  
pp. 403-410 ◽  
Author(s):  
T. F. Cooper ◽  
J. A. Heinemann
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Multiple Infection ◽  
Virulence Determinant ◽  
New Hosts ◽  
Parasite Reproduction ◽  
Selection For ◽  
The Cost ◽  
Selection Of

Is the virulence of parasites an outcome of optimized infection? Virulence has often been considered an inevitable consequence of parasite reproduction when the cost incurred by the parasite in reducing the fitness of its current host is offset by increased infection of new hosts. More recent models have focused on how competition occurring between parasites during co–infection might effect selection of virulence. For example, if co–infection was common, parasites with higher intrinsic growth rates might be selected, even at the expense of being optimally adapted to infect new hosts. If growth rate is positively correlated with virulence, then competition would select increased virulence. We tested these models using a plasmid–encoded virulence determinant. The virulence determinant did not contribute to the plasmid's reproduction within or between hosts. Despite this, virulent plasmids were more successful than avirulent derivatives during selection in an environment allowing within–host competition. To explain these findings we propose and test a model in which virulent parasites are selected by reducing the reproduction of competitors.

scholarly journals An Analysis of Cepheid Distances Using Bayesian Statistics

2000 ◽  
Vol 176 ◽  
pp. 228-228
Author(s):  
Thomas G. Barnes ◽  
William H. Jefferys
Keyword(s):  
Bayesian Analysis ◽  
Surface Brightness ◽  
Radial Velocity Curve ◽  
Objective Model ◽  
Likelihood Approach ◽  
Selection For ◽  
Absolute Magnitudes ◽  
The Individual ◽  
Fully Bayesian ◽  
Selection Of

We have applied an approximately Bayesian and a fully Bayesian analysis to the calculation of Cepheid distances, radii and absolute magnitudes using the surface brightness (Baade–Wesselink) method. Both methods successfully account for errors in the data, provide unbiased distance estimates, and provide objective model selection for the radial velocity curve. In addition, the fully Bayesian analysis objectively selects a model for the magnitude curve; averages over models of various Fourier orders, properly weighted by the posterior probabilities of the individual models; and includes a Lutz–Kelker correction.The approximately Bayesian method is that described by Jefferys & Barnes (1999) and Barnes & Jefferys (1999). It is a maximum likelihood approach with objective selection of the order of the Fourier series model of the radial velocities.

The effect of correction factors on response to selection in beef cattle

1980 ◽  
Vol 30 (2) ◽  
pp. 211-216 ◽  
Author(s):  
L. P. Jones ◽  
I. R. Hopkins
Keyword(s):  
Growth Rate ◽  
Age Groups ◽  
Correction Factors ◽  
Response To Selection ◽  
Weaning Weight ◽  
Selection For ◽  
Rate Selection ◽  
Genetic Responses ◽  
Selection Differentials ◽  
Selection Of

ABSTRACTProgeny of younger dams grow more slowly than those of older dams. When the environmental effects of dam age are not allowed for in selection for growth rate, selection differentials and genetic responses to selection are reduced.In a model herd, with cows aged 2 to 8 years, it was found that neglecting the dam age effects reduced genetic gains by about 15% when selection is for weaning weight, and by 11 to 7 % when selection is at an age of 12 to 20 months. Much of the reduction occurs because of the selection of higher proportions from genetically inferior groups.If genetic differences among dam age groups are small the reduction is only 7% at weaning and less at older ages. The effect of ignoring calf age was also estimated. It was found that if calves born within a period of 33 days were compared and calf age was neglected, the response to selection for weaning weight would be reduced by about 6%.

A study of factors affecting the efficiency of feed conversion in Red Danish heifers

1968 ◽  
Vol 70 (3) ◽  
pp. 245-252 ◽  
Author(s):  
J. B. Owen ◽  
E. Nielsen
Keyword(s):  
Dairy Cows ◽  
Body Weight Gain ◽  
Feed Utilization ◽  
Winter Period ◽  
Progeny Testing ◽  
Feeding System ◽  
Feed Conversion ◽  
Factors Affecting ◽  
Selection For ◽  
Selection Of

SUMMARYData from 692 daughters of 38 Red Danish bulls, tested as heifers in the Danish cattle progeny testing stations 1963–64, were analysed to provide information on the efficiency of feed utilization by dairy cows. The results showed that because of, the feeding system adopted, efficiency measured as FCM per food unit was automatically closely related to FCM yield.Analysis based on pooled, within-bull, values showed that (a) both efficiency and FCM were negatively associated with body-weight gain during lactation, suggesting that feed allowances per unit FCM were low in relation to those for maintenance, (b) weight measured after calving was positively associated with efficiency and FCM yield whereas the association of these latter variables with weight at the end of the winter period was negative, and (c) the gain in weight during lactation was much lower in cows heavy at calving and higher in those heavy at the end of the winter.The between-bull correlations, although less reliable than the within-bull values, clearly indicated that the selection for FCM yield would result in increased cow weight.It is suggested that the selection of dairy cattle should not be based solely on milk yield but that suitable adjustments should be made so that selection for efficiency is safeguarded. Quantitative assessment of such adjustments would necessitate changing feeding procedures at central testing stations.

The relationship of plasma somatomedin (IGF-1) to lamb growth rate

1995 ◽  
Vol 75 (3) ◽  
pp. 327-331 ◽  
Author(s):  
G. J. Mears
Keyword(s):  
Growth Rate ◽  
Plasma Concentrations ◽  
Growth Potential ◽  
Free Access ◽  
Total Weight Gain ◽  
Weight Gains ◽  
Ram Lambs ◽  
Relationship Of ◽  
The Relationship ◽  
Selection Of

Somatomedin (IGF-1) was measured in plasma samples obtained from lambs undergoing SRIF immunization to improve their rate of growth. Weight gains and blood samples were obtained at predetermined intervals between weaning and slaughter for a total of 78 crossbred ewe, ram and wether lambs in three experiments. Plasma IGF-1 concentrations were not altered by SRIF-immunization despite improved rates of gain in wether and ram lambs. Ewe, wether and ram lambs had similar plasma IGF-1 concentrations until 12 wk old. After 12 wk of age, ram lamb IGF-1 plasma concentrations were significantly higher than those of ewe and wether lambs. Fasting lambs for 24 h reduced plasma IGF-1 concentrations, having the greatest effect on heavier lambs. When lambs were allowed free access to feed, plasma IGF-1 concentrations obtained between 7 and 18 wk of age were positively correlated, both with weight gains prior to sampling, and with total weight gain from weaning to slaughter. Thus, at each age examined, lambs with higher than average plasma IGF-1 concentrations weighed considerably more than average at slaughter. This indicates that plasma IGF-1 concentrations obtained at an early age may be useful indicators of growth potential and aid in the selection of fast growing animals. Key words: Somatomedin, IGF-1, lambs, growth rate, somatostatin immunization

Selection of dairy cattle for growth rate and milk production

1966 ◽  
Vol 8 (1) ◽  
pp. 109-119 ◽  
Author(s):  
M. Soller ◽  
R. Bar-Anan ◽  
H. Pasternak
Keyword(s):  
Growth Rate ◽  
Milk Production ◽  
Economic Value ◽  
Performance Testing ◽  
Live Weight ◽  
Economic Conditions ◽  
Progeny Testing ◽  
Genetic Progress ◽  
Weight For Age ◽  
Selection Of

The genetic progress in live-weight-for-age (LFA), milk production, and in overall economic value expected as a result of performance and progeny testing of young bulls with respect to milk production and LFA was computed. It was shown that performance testing can contribute considerably to overall progress in economic value, while under certain circumstances progeny testing for LFA can also contribute to genetic progress in overall economic value, but to a lesser degree than performance testing. The relative economic value of LFA and milk production was derived and found to be relatively stable under differing economic conditions.

Starters and Bacteriophages in Lactic Acid Casein Manufacture

1975 ◽  
Vol 38 (5) ◽  
pp. 275-278 ◽  
Author(s):  
T. D. THOMAS ◽  
R. J. LOWRIE
Keyword(s):  
Lactic Acid ◽  
New Zealand ◽  
Acid Production ◽  
Continuous Selection ◽  
Streptococcus Cremoris ◽  
Selection For ◽  
The Individual ◽  
First Time ◽  
Selection Of

A controlled starter system was used for the first time in commercial lactic acid casein manufacture in New Zealand. Multiple starters of up to four components were constructed from 18 recently derived Streptococcus cremoris isolates which were not lysed by any of the phages in the collection of the New Zealand Dairy Research Institute. During the first season of casein manufacture, phages attacking 17 isolates were detected in the casein whey. Of these, 12 prevented adequate acid production by the appropriate host even at levels below 1 phage per 10 to 1000 ml in the milk before starter addition. In contrast, the first detected phages attacking the other five isolates did not significantly influence the rate of acid development; use of these starters continued until phages which eliminated acid production appeared. An alternative starter system based on the continuous selection of “phage-tolerant” cultures was investigated. Regular addition of whey, from previous manufacture, to the individual mother cultures of each component permitted long-term use of the multiple starter. This procedure of continued selection for phage-tolerant organisms has been used successfully for a complete season in a major casein factory.

scholarly journals Piano cycles by Roman Tsis: stylistic and expressive aspects

2019 ◽  
pp. 103-114
Author(s):  
Mariia Gerega
Keyword(s):  
Small Scale ◽  
Structural System ◽  
Small Cycle ◽  
The Aesthetic ◽  
The Individual ◽  
First Time ◽  
Selection Of

The task of this article is to consider the genre specifics of the cycle of preludes and a small cycle of program pieces, the interconnection of traditions and innovative searches in the field of creating an executive- didactic repertoire for pianists on the example of the author's collection of Roman Tsis. The methodology of the research is to use theoretical and structural-system methods in the analysis of sources and samples of the didactic repertoire of different authors; comparative - in the study of the features of the individual author's style as the basis for mastering technical and sound creation tasks. The scientific novelty lies in the fact that for the first time the author analyzes the interconnection of traditions and innovative searches in the field of creating an executive-didactic repertoire for pianists in the class of general and specialized piano in the genre system of a cycle of programmatic preludes and small cycles with the help of contemporary composer creativity. R. Tsis's piano cycles have a significant didactic potential from the standpoint of understanding interpretative tasks in terms of different stylistics, genre varieties, principles of texture organization, composing techniques and sounding aspects. With a rather modest technical arsenal and small scale compositions, they reproduce a variety of formative techniques and principles of melodic development. Due to the presence of small cycles and the monogamous suite of preludes, it is possible to simulate the selection of the repertoire depending on the tastes, preferences and interpretive-didactic needs of a particular representative of the class of general and specialized piano. This approach allows individually to form the most appropriate set of works that would gradually build and develop the aesthetic and performing-interpretive potential of the student, his ability to solve artistic tasks and overcome technical difficulties. The key to success is to engage in a multi-role and multi-genre repertoire with the ability to separate individual thumbnails or, conversely, simulate suites-cyclic structures.

scholarly journals Characteristics of Technical and Physical Fitness of Young Athletes in the Selection for Classes in the Basketball Section

2021 ◽  
Vol 2 (2 (340)) ◽  
pp. 252-259
Author(s):  
Serhii Shynkarov ◽  
Keyword(s):  
Biological Age ◽  
Small Scale ◽  
Sports Training ◽  
Social Psychological ◽  
Young Athletes ◽  
Basketball Players ◽  
Selection For ◽  
The Relationship ◽  
Initial Selection ◽  
Selection Of

The article reveals the essence of the content and basic theoretical principles of selection and sports training of young basketball players based on biological age, substantiates the need to take into account the biological age of young basketball players in sports training. The main features of the initial selection of young basketball players are identified, systematized and characterized. It is shown that the problem of selection of athletes is very multifaceted. It affects many aspects: social, psychological, pedagogical, philosophical and others. On some issues of selection there are more or less clear ideas from the theory, on others – they are still in the process of formation. The idea of the relationship between physical and technical fitness of young athletes in the selection for classes in the basketball section, their sports training in the training of young basketball players, taking into account the biological age, was expanded. A small-scale and quantitatively selective experiment was conducted, which provided an opportunity to solve the objectives of the study. The importance of using different methods and means of selection, the importance of this process to achieve high results in basketball give grounds for further scientifically sound search for a solution to this problem.

Features of professional psychological selection, as an integral part of the system of primary prevention of occupational deformity

2020 ◽  
Author(s):  
N. V. Martirosova ◽  
◽  
A. M. Ksenofontov
Keyword(s):  
Russian Federation ◽  
Individual Characteristics ◽  
Practical Implementation ◽  
The Russian Federation ◽  
Selection For ◽  
Internal Affairs ◽  
The Government ◽  
The Individual ◽  
Selection Of

The article deals with the issues of professional psychological selection in the internal Affairs bodies as an integral part of the system of measures to prevent professional deformation in service collectives. The implementation of the measures organized on the basis of monitoring of data received by psychologists of internal Affairs bodies is aimed at maintaining and improving the efficiency of the police. The purpose of this area of work of psychologists is to equip police service teams with reliable employees who meet the requirements of the modern legal state. The presented materials consider the practice of implementing by police psychologists the decree Of the Government of the Russian Federation dated December 06, 2012 No. 1259 «on approval of the Rules of professional psychological selection for service in the internal Affairs bodies of the Russian Federation». The materials are consistent with the results of research conducted by Russian and foreign researchers. The conclusions are based on a comparative analysis of the results of the work of the Commission on psychological selection of the regional Department of the Ministry of internal Affairs. Describes some of the individual characteristics of the persons who were refused admission to the service. Individual factors that hinder the process of effective adaptation in service teams are listed, as well as the role of early maladaptive schemes in the process of adaptation. Individual and environmental factors of influence on the formation and development of deforming influence on employees in the course of performance of official activities are presented, based on the analysis of incidents that occurred in collectives in the period 2018–2020. The article deals with the actual difficulties of practical implementation of psychological selection for service as the basis for early prevention of professional deformation in the service collectives of internal Affairs bodies.

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