A preliminary genetic analysis of breech and tail traits with the aim of improving the welfare of sheep

2007 ◽  
Vol 58 (2) ◽  
pp. 161 ◽  
Author(s):  
D. R. Scobie ◽  
D. O'Connell ◽  
C. A. Morris ◽  
S. M. Hickey
Keyword(s):  
New Zealand ◽  
Genetic Analysis ◽  
Genetic Correlation ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Linear Scale ◽  
Bare Area ◽  
Phenotypic Correlations ◽  
Tail Docking

The area of naturally bare skin around the perineum was scored at weaning in lambs (n = 2152) from a composite flock of New Zealand crossbred sheep. Breech bareness was scored on a range from 1, where wool was growing right to the edges of the anus, to 5, where a large bare area surrounded the perineum. Bareness on the under surface of the tail was measured on a linear scale at tail docking. Dag score (degree of breech soiling) was recorded at weaning, on a scale of 0–5, where an increasing score indicated more dags. Dag score was taken as a measure of the risk of flystrike in the breech. Female lambs tended to have slightly greater (P < 0.001) breech bareness score (mean score 2.7) than males (mean score 2.6), whereas mean dag score of females was lower than that of males (0.45 v. 0.53; P < 0.05). Breech bareness score had a heritability of 0.33 ± 0.06, and the length of bare skin under the tail had a heritability of 0.59 ± 0.06. The genetic correlation between breech bareness score at weaning and length of bare skin under the tail at docking was positive (0.35 ± 0.10). These 2 traits had phenotypic correlations with dag score of –0.17 ± 0.02 and –0.03 ± 0.03, respectively, and genetic correlations with dag score of –0.30 ± 0.13 and 0.03 ± 0.12, respectively; negative values indicated a favourable relationship. Tails were removed at docking, so the phenotypic correlation of about zero between tail data and dag score at weaning was of little utility. Our results suggest that selecting for these 2 bareness traits could reduce dag formation and the associated risk of breech strike.

scholarly journals Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1409-1416 ◽  
Author(s):  
Kenneth R Koots ◽  
John P Gibson
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Parameter Estimates ◽  
Sampling Variance ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

HERITABILITY OF TEAT NUMBER IN SWINE

1990 ◽  
Vol 70 (2) ◽  
pp. 425-430 ◽  
Author(s):  
R. M. McKAY ◽  
G. W. RAHNEFELD
Keyword(s):  
Key Words ◽  
Genetic Correlation ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Data Set ◽  
Phenotypic Correlations ◽  
Teat Number ◽  
Genetic And Phenotypic Correlations ◽  
Time Periods ◽  
Selection For

Heritabilities were estimated for teat number in nine populations of swine over two time periods. From 1962 to 1974 the populations included Lacombe, Yorkshire, and Lacombe × Yorkshire. In this data set, only total teat number was recorded. From 1982 to 1988 three purebred populations (Landrace, Yorkshire, and Hampshire) and three crossbred populations (Landrace-Yorkshire rotation, Landrace × Yorkshire, and Landrace × Hampshire) were represented and total teat number and the number of teats anterior and posterior to the navel were recorded. Heritabilities for total teat number were greater in the 1982–1988 data (ranging from 0.27 to 0.47) than in the 1962–1974 data (ranging from 0.20 to 0.32). The heritability of posterior teat numbers (ranging from 0.08 to 0.39) was generally larger than the heritability of anterior teat numbers (ranging from 0.03 to 0.21) and both were considerably less than the heritability of total teat number. Genetic and phenotypic correlations were calculated for the relationships between anterior and posterior teat numbers (AP), anterior and total teat numbers (AT), and posterior and total teat numbers (PT). The relative magnitudes of the genetic and phenotypic correlations with respect to AP, AT, and PT revealed that selection for increased total teat number would increase the number of anterior and posterior teats. However, the larger genetic correlations for PT relative to AT would lead to a greater increase in posterior teat number than anterior teat number. Key words: Pigs, teat number, heritability, genetic correlation, phenotypic correlation

Evaluation of repeatability and pre-structured repeatability models for genetic analyses of repeated records of fat and protein contents of milk in Iranian Holstein cows

2018 ◽  
Vol 58 (11) ◽  
pp. 1983
Author(s):  
M. Asadi Fozi
Keyword(s):  
Genetic Analysis ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Holstein Cows ◽  
Phenotypic Correlation ◽  
Genetic Covariance ◽  
Future Studies ◽  
Phenotypic Correlations ◽  
Variance Structure

Fat and protein content of milk measurements from first to fifth lactations of Iranian Holstein cows were analysed using repeatability and several pre-structured repeatability models that varied in additive genetic variance structure and fitted heterogeneous residual co (variance). For this research, a total of 257 197 fat and 218 688 protein records were used. The records were measured on 116 531 cows born between 2010 and 2014. The animals originated from 2355 sires and 91 212 dams. Pre-structured repeatability models with heterogeneous residual co (variance) and the respective genetic variance structure were the best models for genetic analysis of the fat and protein data. The results derived from these models showed that heritability of both fat and protein are decreased from first to fifth lactations. Heritability of fat measured at first, second, third, fourth and fifth locations were between 0.10 and 0.19 and those for protein were between 0.07 and 0.24. Moderate to high phenotypic correlations were estimated between the repeated records of the fat and protein. Values of 0.13 and 0.16 were estimated for heritability of fat and protein using repeatability model. Phenotypic correlations among the repeated records of fat and protein were estimated to be 0.30 and 0.33, respectively when this model was applied. The results showed the genetic variance, heritability and phenotypic correlation of the fat and protein are changed over the lactations but the genetic parameters derived from the repeatability model are homogenous whereas in both models unity genetic correlations are assumed among the repeated records. The results of this study show that the repeatability model is not an appropriate model for genetic analysis of the repeated records of fat and protein in the population investigated and can be improved when pre-structured repeatability model is used. In the present study homogenous genetic covariance was assumed among the fat and protein taken at the different lactations which can be modelled in future studies for more improving the models.

HERITABILITIES AND GENETIC CORRELATIONS FOR ULTRASONIC BACKFAT MEASUREMENTS, GROWTH AND CARCASS TRAITS IN SWINE

1982 ◽  
Vol 62 (3) ◽  
pp. 665-670 ◽  
Author(s):  
D. C. JEFFRIES ◽  
R. G. PETERSON
Keyword(s):  
Key Words ◽  
Genetic Correlation ◽  
Genetic Parameters ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Ultrasonic Measurements ◽  
Yorkshire Pigs ◽  
Daily Gain ◽  
Season Interaction

Genetic parameters were estimated for 2403 purebred Yorkshire pigs over a 2-yr period, representing 21 sires. The traits studied included average daily gain, age adjusted to 90 kg, ultrasonic measurements of backfat at the mid-back and loin positions, total and adjusted total ultrasonic backfat and corresponding carcass backfat measurements. Least squares analyses were used to estimate and adjust for the effects of sex, year-season and sex by year-season interaction. Heritabilities and genetic correlations were calculated for all traits using both half- and full-sib estimates. Adjusted age and adjusted total ultrasonic backfat measurements were found to have the highest heritabilities of the live traits in this study. Estimates of heritability for adjusted age and adjusted total ultrasonic backfat were 0.24 ± 0.10 and 0.26 ± 0.10 based on half-sib and 0.56 ± 0.07 and 0.41 ± 0.06 from full-sib analyses. The genetic correlation between these two traits was −0.07 ± 0.28 based on the half-sib method. The total phenotypic correlation was −0.01 ± 0.02. Key words: Swine, ultrasonic backfat, heritabilities, genetic correlations

scholarly journals Genetic correlations and path-coefficient analysis of yield and quality components in wheat, Triticum aestivum L.

Genetika ◽  
2004 ◽  
Vol 36 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Veselinka Zecevic ◽  
Desimir Knezevic ◽  
Danica Micanovic
Keyword(s):  
Genetic Correlation ◽  
Harvest Index ◽  
Genetic Correlations ◽  
Grain Weight ◽  
Spike Length ◽  
Phenotypic Correlation ◽  
Path Coefficient ◽  
Thousand Grain Weight ◽  
Path Coefficient Analysis ◽  
Bread Making

The genetic and phenotypic correlations between yield components (productive tillering, plant height, spike length, number of spikelets per spike, number of grains per spike, grain weight per spike, grain weight per plant, harvest index, thousand grain weight) and quality components (grain protein content and sedimentation value) were investigated. The plant material was comprised of 50 genotypes of winter wheat grown during two years. Path- coefficient analysis of genetic correlation coefficients for grain mass/plant and other traits determined interrelationships among grain mass per plant and other yield and bread making quality components. The strongest positive genetic correlation was found between grain weight per spike and thousand grain weight and between spike length and number of spikelets per spike. Phenotypic correlation analysis indicated that grain weight per spike correlated positively and significantly with harvest index and thousand kernel weight. The strongest direct effect on grain weight per plant had harvest index and number of spikelets per spike. The spike length through number of spikelets per spike had the strongest indirect effect on grain weight per plant.

DEVELOPMENT OF DLS BREED OF SHEEP: GENETIC AND PHENOTYPIC PARAMETERS OF DATE OF LAMBING AND LITTER SIZE

1990 ◽  
Vol 70 (3) ◽  
pp. 771-778 ◽  
Author(s):  
MOHAMED H. FAHMY
Keyword(s):  
Key Words ◽  
Genetic Correlation ◽  
Breeding Season ◽  
Litter Size ◽  
Least Square ◽  
Phenotypic Correlation ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations

Least square means, heritabilities, repeatabilities, genetic and phenotypic correlations of date of lambing and litter size in a population of DLS sheep selected for extended breeding season were estimated by different methods. Mean date of lambing for first, second and third parities was 20 Jan., 6 Jan., 31 Dec. and mean litter size was 1.20, 1.25 and 1.41 lambs, respectively. Heritabilities for date of lambing were 0.37 (sire component, 0.25 (sire and dam component), 0.52 (correlation between full sisters) and 0.17 (regression of daughter on dam). For litter size these methods gave the following estimates: 0.17, 0.14, 0.22 and 0.04, respectively. Repeatability estimates averaged 0.21 for date of lambing and 0.24 for litter size. Genetic correlation between the two traits was calculated at −0.38 (sire component), −0.25 (full sisters) and −0.07 (regression of daughter on dam) while the phenotypic correlation was estimated at −0.19 (P < 0.01). Key words: DLS sheep, heritability, repeatability, genetic correlation, phenotypic correlation, date of lambing, litter size

Estimating the association between wool and skin characters and fleece rot

1983 ◽  
Vol 34 (1) ◽  
pp. 47 ◽  
Author(s):  
R Evans ◽  
BJ McGuirk
Keyword(s):  
Correlation Coefficient ◽  
Selection Criteria ◽  
Genetic Correlations ◽  
Indirect Selection ◽  
Phenotypic Correlation ◽  
Phenotypic Correlations ◽  
Standard Deviations

To assess the value of skin and fleece characters as potential indirect selection criteria for increased resistance to fleece rot, estimates of the genetic correlations between the skin and fleece characters and fleece rot are needed. The characters most likely to be useful can be identified relatively cheaply and quickly by estimating the phenotypic correlation with fleece rot. This paper illustrates how phenotypic correlations with fleece rot, scored as an all-or-none character, can be estimated retrospectively from published estimates of means and standard deviations of fleece and skin characters measured in groups of sheep affected by or free from fleece rot. The paper emphasizes the incidence-dependent nature of the correlation coefficient so obtained, and points out that this must be allowed for when comparisons of correlations are made between flocks in which the incidence of fleece rot differs. This problem can be avoided by using the concept of liability to fleece rot. Data from three recently published papers are used to illustrate the main points.

Dag score is negatively correlated with breech bareness score of sheep

2008 ◽  
Vol 48 (7) ◽  
pp. 999 ◽  
Author(s):  
D. R. Scobie ◽  
D. O'Connell ◽  
C. A. Morris ◽  
S. M. Hickey
Keyword(s):  
New Zealand ◽  
Genetic Correlation ◽  
Bare Area ◽  
Organic Farm ◽  
Ewe Lambs ◽  
Combining Data ◽  
Ram Lambs ◽  
And Performance ◽  
Breeding Farms ◽  
Conventional Farm

At weaning in two consecutive years, traditional Romney and composite lambs (crosses with East Friesian and Texel; n = 3254) were observed on a conventional farm and Perendale and composite lambs (crosses with Texel, Wiltshire and small numbers of Finnish Landrace; n = 2095) were observed on an organic farm. Both were ram breeding farms recording pedigree and performance, and the composite breeds were developed from, and run with, the original flock on each farm. Breech bareness was scored on the lambs between 80 and 120 days of age on a scale from 1, with wool right to the edge of the anus, to 5, where a large bare area surrounded the perineum. Dag score was recorded on a 0–5 scale where an increasing score indicated more dags. Within farms, mean dag score was more pronounced in traditional Romney (1.2) than in composite lambs (0.4), and Perendales were more daggy (1.3) than composite lambs (0.7) across both years (P < 0.001). Dag score was phenotypically correlated with breech bareness score on the Romney farm (−0.18 ± 0.02) and Perendale farm (−0.27 ± 0.03). Combining data from both flocks, heritabilities of breech bareness score (0.55 ± 0.04) and dag score (0.41 ± 0.05) were high, and a strong genetic correlation was observed between the two traits (−0.59 ± 0.07). Mean dag score of ram lambs was greater than ewe lambs (0.8 v. 0.7, P < 0.001) and lambs reared as twins were more daggy than singles (0.8 v. 0.7, P = 0.008). Composite sheep have been adopted throughout New Zealand for the advantages they deliver in lamb production, but through breech bareness they also provide an opportunity to limit dag production and thereby improve both welfare and profitability. Genetically increased breech bareness and decreased dagginess could be used in Australia as alternatives to mulesing.

PSXII-30 Genetic and phenotypic correlations for growth and resistance to gastrointestinal parasitism in meat goats and hair sheep

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 491-492
Author(s):  
Yoko Tsukahara ◽  
Terry A Gipson ◽  
Steven P Hart ◽  
Lionel J Dawson ◽  
Zaisen Wang ◽  
...  
Keyword(s):  
Genetic Correlation ◽  
Average Daily Gain ◽  
Phenotypic Correlation ◽  
Hair Sheep ◽  
Phenotypic Correlations ◽  
Fecal Egg Count ◽  
Meat Goats ◽  
Genetic And Phenotypic Correlations ◽  
Moderately Resistant ◽  
On Farm

Abstract Genetic and phenotypic correlations for growth and response to parasite infection traits were estimated for growing male meat goats and hair sheep from different farms in the southcentral United States during three consecutive central performance tests (CPT). Data were collected for 7–10 wk after artificial infection with Haemonchus contortus, which included average daily gain (ADG), fecal egg count (FEC), packed cell volume (PCV), and immunoglobin (Ig) levels. Animals evaluated were selected randomly in year 1 and in years 2 and 3 progeny of CPT sires classified as highly or moderately resistant and included 46, 50, and 51 Boer, Kiko, and Spanish goats and 59, 61, 34, and 46 Dorper, Katahdin-farm A, Katahdin-farm B, and St. Croix sheep, respectively. Females were classified accordingly on-farm based on FEC and FAMACHA. Pedigree records included 4 and 10 full-sibs and 97 and 149 half-sibs for goats and sheep, respectively. Variance components and correlations were estimated by AIREML using WOMBAT with a multivariate animal model. The additive genetic correlation between FEC and PCV was negative for goats (r=-041, P &lt; 0.001) but positive for sheep (r=0.21, P = 0.004), whereas the phenotypic correlation between FEC and PCV was nonsignificant for goats but negative for sheep (r=-0.252, P &lt; 0.001). The genetic correlation between FEC and IgA was positive (r=0.39, P &lt; 0.001) for goats but nonsignificant (P = 0.439) for sheep, whereas those of FEC with IgM and IgG were both negative (r=-0.369 and -0.732 with IgM and r=-0.284 and -0.702 for goats and sheep, respectively; P &lt; 0.001). Genetic and phenotypic correlations between ADG and FEC were nonsignificant for both species. In conclusion, different relationships of FEC and PCV between species require careful attention during selection and the lack of relationship between ADG and FEC suggests that selection of growing male meat goats and hair sheep for resistance to internal parasitism will not adversely affect growth performance.

Genetic analysis of growth traits in Mecheri sheep

2015 ◽  
Author(s):  
V. Jeichitra ◽  
R. Rajendran ◽  
K. Karunanithi ◽  
P. S. Rahumathulla
Keyword(s):  
Genetic Analysis ◽  
Genetic Correlation ◽  
Genetic Control ◽  
South India ◽  
Growth Traits ◽  
Genetic Correlations ◽  
Research Station ◽  
Body Weights ◽  
Weight Gains

Data on 1763 Mecheri sheep, maintained at the Mecheri Sheep Research Station, Pottaneri, Salem, south India, and recorded between 1991 and 2006, were analysed to study the growth related traits and their genetic control. The average weights at birth and at 12 months of age were 2.25 ± 0.01 and 17.48 ± 0.14 kg, respectively. The pre- and post-weaning (3-6, 3-9 and 3-12) average daily weight gains were 63.40 ± 0.58, 39.57 ± 0.57, 37.48 ± 0.44 and 34.31 ± 0.42 g respectively. The heritabilities of body weights and weight gains were in general moderate to high. The phenotypic and genetic correlations among body weights were positive and moderate to high. The phenotypic and genetic correlations among average daily gains were positive and low to high. The estimates of genetic correlation among average daily gains and body weights were positive and high with few exceptions.

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