Genetic parameters for breech cover, wrinkle and wool coverage scores and their implications for Merino sheep breeding programs and flock management

2015 ◽  
Vol 130 ◽  
pp. 36-46 ◽  
Author(s):  
S. Hatcher ◽  
J.W.V Preston
Keyword(s):  
Genetic Parameters ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Merino Sheep

Genetic relationships between internal parasite resistance and production traits in Merino sheep

2017 ◽  
Vol 57 (2) ◽  
pp. 209 ◽  
Author(s):  
D. J. Brown ◽  
N. M. Fogarty
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Production Traits ◽  
Parasite Resistance ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Breeding Values ◽  
Merino Sheep ◽  
Internal Parasite ◽  
Australian Sheep

Breeding Merino sheep that are resistant to internal parasites alleviates the high costs associated with treatment of worm infestation and loss of production, as well as mitigating the development of anthelmintic resistance among the major worm species. Faecal worm egg count ((cube root transformation), wec) can be used in sheep as a measure of internal parasite resistance. Accurate estimates of genetic parameters for wec are required for calculation of Australian Sheep Breeding Values and inclusion of worm resistance in sheep breeding programs. This study provides updated estimates of heritability for wec and its genetic correlations with production traits. Data were analysed from a wide range of Australian and New Zealand Merino sheep in the MERINOSELECT database, which included 141 flocks with 801 flock years and up to 217 137 animals with wec recorded in at least one of four ages (W = weaning, P = post weaning, Y = yearling, H = hogget). The heritability estimates ranged from 0.16 ± 0.01 for Ywec to 0.29 ± 0.01 for Wwec, with generally high genetic correlations between the ages. Bivariate analyses estimated genetic correlations between wec at the various ages and growth, carcass quality, reproduction and wool production traits at various ages. These genetic correlations were generally small or close to zero, albeit with some significantly different from zero. The moderate heritability for wec (0.2–0.3) and its high phenotypic variation (coefficient of variation >30%) shows that relatively rapid selection response for worm resistance could be achieved. Inclusion of wec in sheep breeding programs to increase worm resistance would be expected to have little if any impact on other important production traits. These genetic parameters have been incorporated into MERINOSELECT by Sheep Genetics to provide Australian Sheep Breeding Values for wec and appropriate indices for wool and meat production. There is evidence that genotype × environment interactions may be important in some environments by reducing the accuracy of Australian Sheep Breeding Values for wec. Hence it may be prudent for breeders to implement strategies that manage the risk of any impact of genotype × environment on their breeding program.

scholarly journals Analysis of Ewe Longevity and Lamb Survival in Teleorman Black Head Sheep

2020 ◽  
Author(s):  
Rodica Stefania Pelmus ◽  
Horia Grosu ◽  
Mircea Cãtãlin Rotar ◽  
Mihail Alexandru Gras ◽  
Cristina Lazãr ◽  
...  
Keyword(s):  
Survival Analysis ◽  
Genetic Parameters ◽  
Breeding Value ◽  
Careful Monitoring ◽  
Breeding Programs ◽  
Sheep Population ◽  
Sheep Breeding ◽  
Productive Life ◽  
Black Head ◽  
Lamb Survival

Background: The aim of this paper was to estimate the genetic parameters for the longevity of ewes and lamb survival at 30 days in a Teleorman Black Head Sheep population. Methods: Data was analysed with survival model. Result: Mean length of productive life of ewes was 673.16 days. The heritability for longevity was 0.097 and for lambs’ survival at 30 days was 0.098. The breeding value of the best sheep for longevity as productive life ranged from 0.081 months to 0.129 months and for the best lambs for survival at 30 days ranged from 0.041 days to 0.127 days. The results obtained in survival analysis are showing that the improvement of environmental conditions will increase longevity of ewes and survivability of lambs. Daily and careful monitoring of the health of sheep was performed. It was ensured administration of feed and water in a proper state of hygiene, a suckling and milking hygienic and a proper microclimate. Regarding the utility, longevity is a trait that is recommended to be used in local sheep breeding programs in Romania.

scholarly journals Genetic Variability, Correlation among Agronomic Traits, and Genetic Progress in a Sugarcane Diversity Panel

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 533
Author(s):  
Fernanda Zatti Barreto ◽  
Thiago Willian Almeida Balsalobre ◽  
Roberto Giacomini Chapola ◽  
Antonio Augusto Franco Garcia ◽  
Anete Pereira Souza ◽  
...  
Keyword(s):  
Genetic Parameters ◽  
Mixed Model ◽  
Agronomic Traits ◽  
Average Increase ◽  
Genetic Progress ◽  
Breeding Programs ◽  
Future Studies ◽  
Diversity Panel ◽  
Adjusted Means ◽  
Historical Series

Sugarcane breeding programs require 15 years of experimentation to create more productive cultivars, and estimates of genetic progress can indicate the efficiency of breeding programs. In this study, we used a diversity panel, the Brazilian Panel of Sugarcane Genotypes (BPSG), with the following objectives: (i) to estimate, through a mixed model, the adjusted means and genetic parameters of ten traits evaluated over three harvest years; (ii) to estimate genotypic correlation among those traits; and (iii) to estimate genetic progress over six decades of breeding. The heritabilities ranged from 0.43 to 0.88, and we detected 42 significant correlations, 9 negative and 33 positive. Over six decades, the sucrose-related traits BRIX, POL%C, and POL%J showed an average increase per decade of 0.27 °Brix (0.26% and 0.31%, respectively). Stalk number, height, and weight of the plot, and cane and sucrose yields revealed average increases per decade of 3.27 stalks, 0.06 m, 9.42 kg, 11.22 t/ha, and 2.08 t/ha, respectively. The genetic progress of the main agronomic traits is discussed through a historical series of sugarcane genotypes present in the BPSG. The findings of this study could contribute to the management of new breeding strategies and allow for future studies of associative mapping.

scholarly journals Review: Genetic diversity studies using microsatellite markers and their contribution in supporting sustainable sheep breeding programs

2017 ◽  
Vol 1 (01) ◽  
pp. 46-51
Author(s):  
OUMER SHERIFF ◽  
KEFYALEW ALEMAYEHU
Keyword(s):  
Genetic Diversity ◽  
Microsatellite Markers ◽  
Polymorphic Information Content ◽  
Domestic Sheep ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Population Structures ◽  
The Mean ◽  
Tree Building ◽  
Diversity Studies

Sheriff O, Alemayehu K. 2017. Review: Genetic diversity studies using microsatellite markers and their contribution in supporting sustainable sheep breeding programs. Asian J Agric 1: 46-51. Microsatellites have been widely accepted and employed as useful molecular markers for measuring genetic diversity and divergence within and among populations. The various parameters developed so far to measure genetic diversity within and among populations are observed and expected heterozygosities (Ho and He), the mean number of alleles per locus (MNA),polymorphic information content (PIC), genetic distance and phylogenetic or tree building approach.The objective of thisreview was therefore to quantifythe genetic diversity studies of domestic sheep populations using microsatellite markersand their contribution in supporting sustainable sheep breeding programs. From the review, it is possible to see that there was high within population genetic variations in all the studied sheep populations, poor level of population differentiations and high levels of inbreeding. On the other hand, low estimates of hetrozygosities and mean number of alleles and employing only few and weak markers were observed in some of the studies. The gaps observed in the previous genetic diversity studies of the sheep populations may demand further works to reveal more information on the population structures andto start appropriate and sustainable breeding programs.

scholarly journals Molecular Characterization and Expression Profiles of the Ovine LHβ Gene and Its Association with Litter Size in Chinese Indigenous Small-Tailed Han Sheep

Animals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 460 ◽  
Author(s):  
Weimin Wang ◽  
Yongfu La ◽  
Fadi Li ◽  
Shijia Liu ◽  
Xiangyu Pan ◽  
...  
Keyword(s):  
Litter Size ◽  
Cdna Sequence ◽  
Expression Profiles ◽  
Follicular Development ◽  
Reproductive Traits ◽  
Granular Cells ◽  
Glycoprotein Hormone ◽  
Breeding Programs ◽  
Sheep Breeding ◽  
Qpcr Analysis

The luteinizing hormone beta polypeptide (LHβ) is a glycoprotein hormone secreted by basophilic granular cells of the adenohypophysis, and plays an important role in mammalian follicular development. In this study, we cloned and analyzed the cDNA sequence of the ovine LHβ gene. RT-qPCR analysis showed that ovine LHβ was widely expressed in tissues, with significantly higher expression in the hypophysis than that in other tissues (heart, liver, spleen, lung, kidney, rumen, duodenum, muscle, fat, hypothalamus, and sex glands) (p < 0.01). Hypophyseal expression of LHβ mRNA in lamb increased with age and reached a peak at 70 days, although a slight decrease was observed at 84 days of age. In addition, the synonymous mutation g.727C > T detected in the LHβ gene was confirmed to be significantly associated with the litter size (p < 0.01). Ewes carrying the TT genotype produced more lambs than those carrying the TC and CC genotypes (0.42 and 0.39 per delivery, respectively; p < 0.05). Our results confirm the association of ovine LHβ with litter size in Small-Tailed Han Sheep and implicate LHβ as a candidate for improving reproductive traits in agricultural sheep breeding programs.

scholarly journals Morpho-agronomic characterization and estimates of genetic parameters in annatto plant

2017 ◽  
Vol 35 (2) ◽  
pp. 242-246 ◽  
Author(s):  
Nilma O Dias ◽  
Tiyoko NH Rebouças ◽  
Abel R São José ◽  
Cláudio LF Amaral
Keyword(s):  
Genetic Parameters ◽  
Environmental Influence ◽  
Genotypic Variation ◽  
Morphological Characterization ◽  
Breeding Programs ◽  
Tropical America ◽  
Self Fertilization ◽  
Superior Genotypes ◽  
Increasing Demand

ABSTRACT Originally from tropical America, annatto is an important source of natural dyes for food, pharmaceutical and textile industries, especially for the increasing demand of this pigment substituting artificial dyes. The aim of this study was to evaluate genotypic variation of annatto cultivar Embrapa 37, aiming to generate subsidies for breeding programs as well as to help out the producers using vegetative propagation of superior genotypes. Therefore, the morphological characterization was carried out and estimates of genetic and phenotypic parameters, for production and quality of the fruits, were obtained. The results showed wide rate of genetic variability among the plants with low environmental influence on the phenotype for traits bixin content, fruit width, number of fruits per bunch and mass of 100 seeds. The authors concluded that superior genotypes can be selected through the parental performance and propagated vegetatively to form more profitable crops, as well as used in breeding programs through self-fertilization with analysis of resulting progeny.

Response to selection in Australian Merino sheep. VII. Phenotypic and genetic parameters for some wool follicle characteristics and their correlation with wool and body traits

1975 ◽  
Vol 26 (5) ◽  
pp. 937 ◽  
Author(s):  
N Jackson ◽  
T Nay ◽  
HN Turner ◽  
Turner H Newton
Keyword(s):  
Control Systems ◽  
Genetic Control ◽  
Genetic Parameters ◽  
Unit Area ◽  
Fibre Diameter ◽  
Environmental Correlations ◽  
Merino Sheep ◽  
Wool Follicle ◽  
Australian Merino

Four numerical characteristics-follicle depth, follicle curvature, number of follicles per unit area of skin, and ratio of number of secondary to number of primary follicles-describing the size, shape, and arrangement of wool follicles have been measured in Peppin Merino sheep at 4-5 months (weaning), 15-16 months (two-tooth shearing) and at later ages ranging from 2 1/2 to 7 1/2 years. Estimates of their repeatability, heritability and phenotypic, genetic, and environmental correlations with 10 wool and body characteristics are reported. All four follicle characteristics were found to be highly inherited and sufficiently correlated with wool characteristics to be of interest to both the wool biologist and the sheep breeder. Fixed environmental effects influenced the expression of some follicle characteristics, while others, notably follicle curvature at any age, were unaffected, and therefore potentially more useful as practical selection aids. Groups of sheep selected for clean wool weight with control of (i) fibre diameter and wrinkle score, and (li) crimp frequency and wrinkle score, exhibited changes in the four follicle characteristics, which agreed with what the genetic correlation estimates would predict. The role of follicle characteristics in the biology of genetic control of wool growth is portrayed by fitting causal models invoking follicle characteristics as intermediates between the gene and the wool character. The analysis separates three independent genetic control systems, the identity of which corresponds closely to factors postulated in previous theoretical studies.

Can we breed Merino sheep with softer, whiter, more photostable wool?

2010 ◽  
Vol 50 (12) ◽  
pp. 1089 ◽  
Author(s):  
S. Hatcher ◽  
P. I. Hynd ◽  
K. J. Thornberry ◽  
S. Gabb
Keyword(s):  
Genetic Parameters ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Phenotypic Selection ◽  
Quality Traits ◽  
Current Generation ◽  
Merino Sheep ◽  
Initial Cohort ◽  
Selection For

Genetic parameters (heritability, phenotypic and genetic correlations) were estimated for a range of visual and measured wool traits recorded from the 2008 shearing of the initial cohort of Merino progeny born into the Sheep CRC’s Information Nucleus Flock. The aim of this initial analysis was to determine the feasibility of selectively breeding Merino sheep for softer, whiter, more photostable wool and to quantify the likely impact on other wool production and quality traits. The estimates of heritability were high for handle and clean colour (0.86 and 0.70, respectively) and moderate for photostability (0.18), with some evidence of maternal effects for both handle and photostability. The phenotypic correlations between handle and clean colour and between handle and photostability were close to zero, indicating that achieving the ‘triple’ objective of softer, whiter, more photostable wool in the current generation through phenotypic selection alone would be difficult. There was evidence of an antagonistic relationship between handle and photostability (–0.36), such that genetic selection for softer wool will produce less photostable wool that will yellow on exposure to UV irradiation. However genetic selection for whiter wool is complementary to photostability and will result in whiter wool that is less likely to yellow. Genetic selection to improve handle, colour and photostability can be achieved with few detrimental effects on other visual and measured wool traits, particularly if they are included in an appropriate selection index.

The genetic foundation of fitness and reproduction traits in Australian pig populations. 2. Relationships between weaning to conception interval, farrowing interval, stayability, and other common reproduction and production traits.

1996 ◽  
Vol 47 (8) ◽  
pp. 1275 ◽  
Author(s):  
E Tholen ◽  
KL Bunter ◽  
S Hermesch ◽  
HU Graser
Keyword(s):  
Genetic Parameters ◽  
Performance Test ◽  
Genetic Relationships ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Data Sets ◽  
Production Traits ◽  
Breeding Programs ◽  
Reproduction Traits ◽  
Daily Gain

Data sets from 2 large Australian piggeries were used to estimate genetic parameters for the traits weaning to conception interval (WCIi-l,i) and farrowing interval (FIi-l,i), number born alive (NBAI), average piglet birthweight (BWi), 21-day litter weight (W21i), and sow stayability (STAYli) recorded for each ith parity, as well as sow average daily gain (ADG) and backfat (BF) recorded at the end of performance test. Over parities and herds, heritabilities for each trait were in the ranges: WCI/FI, 0.0-0.10; NBA, 0.09-0.16; BW, 0.11-0.35; W21, 0.12-0.23; STAYli, 0.02-0.09; ADG, 0.35-0.37; BF, 0.36-0.45. Genetic correlations between NBAl and NBA from later parities were significantly different from 1. In addition, in 1 herd negative genetic correlations (rg = -0.04 to -0.25) were found between sow stayability traits and NBA1, but not NBA recorded in later parities. Stayability was Unfavourably correlated with ADG and BF, and favourably correlated with WCI12. However, WCI12 was unfavourably correlated genetically with BF (rg = -0.24) but uncorrelated with ADG. Antagonistic relationships also existed between NBA and BW, NBA and W21, and BW and STAY. In addition to the traditional traits currently included in pig-breeding programs (e.g. ADG, BF, and NBA), traits such as WCI, BW, and STAY should also be considered as selection criteria to minimise the detrimental effects of antagonistic genetic relationships between traits.

Genetic parameters for nematode resistance in periparturient ewes and post-weaning lambs in Uruguayan Merino sheep

2012 ◽  
Vol 147 (1-3) ◽  
pp. 181-187 ◽  
Author(s):  
Virginia Goldberg ◽  
Gabriel Ciappesoni ◽  
Ignacio Aguilar
Keyword(s):  
Genetic Parameters ◽  
Nematode Resistance ◽  
Merino Sheep
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