Genetic aspects of cold resistance and related characters in newborn Merino lambs

1991 ◽  
Vol 31 (2) ◽  
pp. 175 ◽  
Author(s):  
J Slee ◽  
G Alexander ◽  
LR Bradley ◽  
N Jackson ◽  
D Stevens
Keyword(s):  
Fixed Effects ◽  
Cold Resistance ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Skin Thickness ◽  
Significant Other ◽  
Manual Palpation ◽  
Rate Of Recovery ◽  
Body Cooling

Resistance to body cooling and rate of recovery from induced hypothermia were measured in 287 single, newborn Merino lambs from 24 different sire families, using a water bath test in which partly immersed lambs were progressively cooled. Birth weight, birthcoat type (fine-hairy) and skin thickness were recorded at the time of test. There was an unexpected occurrence of congenital goitre, the incidence and severity of which was estimated by manual palpation of the thyroid gland. Heritability (� s.e.) of cold resistance (CR), estimated by paternal half-sib analysis, was 0.70 � 0.25. Sex of lamb, type of weather, time of test, Fecundin treatment and age of ewe were fitted in the model as fixed effects but none were significant. Other heritable traits (h2 � s.e.) included birthweight (0.50 � 0.22), birthcoat grade (0.61 � 0.24), coat depth (0.62 � 0.24), skin thickness (0.35 � 0.19) and the severity of goitre (0.21 � 0.16). Significant genetic correlations (r �s.e.) between cold resistance and other traits were: birthweight, +0.76 � 0.18; birthcoat grade, +0.56 � 0.24; birthcoat depth, +0.56 � 0.24; skin thickness, +0.51 � 0.27; goitre, -0.58 � 0.40. Most of the corresponding phenotypic correlations were small. Goitre did not affect CR significantly, despite the genetic correlation between them. Heritability of CR, further adjusted for the effects of birthweight, birthcoat grade and depth, and skin thickness as covariates, was 0.55 � 0.23. About 40% of the variation in CR was accounted for by fitting fixed effects and covariates, but significant sire effects remained. Rate of recovery from hypothermia was not heritable and it was unrelated to any other variable except goitre, which tended to be associated with slower recovery (rp = 0.18). It was concluded that genetic selection for increased CR would succeed but would promote birthcoat hairiness unless a corrective selection index was used. The relationship between birthcoat type and CR was considered to be mediated by genes affecting both coat type and CR, not primarily by a direct effect of coat insulation.

Genetic selection for cold resistance in Scottish Blackface lambs

1986 ◽  
Vol 43 (3) ◽  
pp. 397-404 ◽  
Author(s):  
J. Slee ◽  
A. W. Stott
Keyword(s):  
Cold Resistance ◽  
Selection Process ◽  
Genetic Selection ◽  
Resistance Rate ◽  
Realized Heritability ◽  
Resistance Response ◽  
Rate Of Recovery ◽  
Ram Lambs ◽  
Selection For ◽  
Time Required

ABSTRACTHypothermia with starvation is a major cause of neonatal mortality among lambs born outdoors. The results of selection for resistance to hypothermia (cold resistance) in newborn Scottish Blackface lambs are described. Cold resistance was defined as the time required to induce a decline in body temperature of about 4·5°C by means of tests involving part-immersion in a cooled water bath. From about 200 tested lambs (half males) four ram lambs with the lowest cold resistance and four with the highest resistance were selected and each mated randomly at 7 months of age to about 30 ewes to establish upward and downward selection lines. The progeny were subsequently tested for cold resistance and the selection process was repeated for four male generations. Tested females were allocated at 18 months of age to high or low lines according to their performance as lambs.Preliminary half-sib analysis and sire-offspring regression gave estimates of 0·3 for the heritability of cold resistance. Response to selection was rapid but asymmetrical with a realized heritability for cold resistance of 0·27 (s.e. 0·13) for upward selection, 0·01 (s.e. 0·16) for downward selection and 0·17 (s.e. 0·09) for the line divergence.Body weight at test was phenotypically, but not genetically, correlated with cold resistance. Rate of recovery from induced hypothermia was not significantly correlated with cold resistance. The results are discussed in relation to lamb mortality in the field.

The effects of litter size, sex, age, body weight, dam age and genetic selection for cold resistance on the physiological responses to cold exposure of scottish blackface lambs in a progressively cooled water bath

1987 ◽  
Vol 45 (3) ◽  
pp. 477-491 ◽  
Author(s):  
A. W. Stott ◽  
J. Slee
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Cold Exposure ◽  
Cold Resistance ◽  
Genetic Selection ◽  
Water Bath ◽  
Skin Thickness ◽  
Selection Line ◽  
Unit Body Weight ◽  
Total Body

ABSTRACTThe resistance to body cooling of 594 newborn Scottish Blackface lambs was measured in a water bath during a programme of upwards and downwards genetic selection. Cold resistance was defined as the time taken for rectal temperature to fall to 35°C in the water bath.Upwards selection produced increased cold resistance which was genetically associated with increased skin thickness, increased total body insulation and greater persistence of high metabolic rate during cold exposure. The first two correlated responses to selection were more pronounced in twins than in singles.High cold resistance was phenotypically, but not genetically, associated with greater body weight, increased coat depth and higher levels of cold-induced metabolic rate (heat production). Single lambs showed higher weight-adjusted metabolic rates and higher cold resistance than twins. Singles recovered from hypothermia faster than twins in the low selection line only.Female lambs showed higher metabolic rate (whether weight-adjusted or not) and greater total body insulation than males. Their greater cold resistance was not quite significant. Increasing age (range 0·3 to 36 h) was associated with a small but significant decline in cold resistance.Thermoneutral metabolic rate was proportional to body surface area, whereas peak metabolic rate was proportional to body weight such that peak metabolic rate per unit body weight was independent of changes in body weight. These findings are discussed in relation to lamb survival.

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.

scholarly journals Genomic Prediction for Twin Pregnancies

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 843
Author(s):  
Shaileen P. McGovern ◽  
Daniel J. Weigel ◽  
Brenda C. Fessenden ◽  
Dianelys Gonzalez-Peña ◽  
Natascha Vukasinovic ◽  
...  
Keyword(s):  
Genomic Prediction ◽  
Management Practices ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Genetic And Environmental Factors ◽  
Effective Inclusion ◽  
Sound Management ◽  
Multitrait Selection ◽  
Twin Pregnancies

Twinning is a multifactorial trait influenced by both genetic and environmental factors that can negatively impact animal welfare and economic sustainability on commercial dairy operations. To date, using genetic selection as a tool for reducing twinning rates on commercial dairies has been proposed, but not yet implemented. In response to this market need, Zoetis (Kalamazoo, MI, USA) has developed a genomic prediction for twin pregnancies, and included it in a comprehensive multitrait selection index. The objectives of this study were to (1) describe a genetic evaluation for twinning in Holstein cattle, (2) demonstrate the efficacy of the predictions, (3) propose strategies to reduce twin pregnancies using this information. Data were retrieved from commercial dairies and provided directly by producers upon obtaining their permission. The twin pregnancies trait (TWIN) was defined as a pregnancy resulting in birth or abortion of twin calves, classified as a binary (0,1) event, and analysed using a threshold animal model. Predictions for a subset of cows were compared to their on-farm twin records. The heritability for twin pregnancies was 0.088, and genomic predicted transmitting abilities ((g)PTAs) ranged from −7.45–20.79. Genetic correlations between TWIN and other traits were low, meaning that improvement for TWIN will not negatively impact improvement for other traits. TWIN was effectively demonstrated to identify cows most and least likely to experience a twin pregnancy in a given lactation, regardless of reproductive protocol used. Effective inclusion of the prediction in a multitrait selection index offers producers a comprehensive tool to inform selection and management decisions. When combined with sound management practices, this presents a compelling opportunity for dairy producers to proactively reduce the incidence of twin pregnancies on commercial dairy operations.

scholarly journals 179 Breeding for enhancing feed efficiency in dairy cattle

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 183-184
Author(s):  
Flavio Schenkel ◽  
Luiz Brito ◽  
Hinayah Oliveira ◽  
Tatiane Chud ◽  
David Seymour ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Feed Efficiency ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Methane Emissions ◽  
Genome Project ◽  
Nutrient Loss ◽  
Breeding Value ◽  
Selection For

Abstract Genetically selecting for improved feed efficiency has been recognized by the dairy cattle industry as an important economic and environmental goal. Improved feed efficiency has the potential to significantly reduce costs, improving dairy farmers’ profitability and, at the same time, minimize environmental impact, for example by reducing nutrient loss in manure and methane emissions. Feed efficiency is recognized as a complex trait that may be define in different ways, but it generally describes units of product output per unit of feed required. An overview of genetic selection for improved feed efficiency and international initiatives to implement genomic selection for feed efficiency in dairy cattle is presented. In general, studies have indicated that feed efficiency, defined and assessed in alternative ways, is moderately heritable and genetic selection could be successfully implemented. Various initiatives around the world have worked collaboratively to carried out research and create reference datasets for joint genomic evaluations. An example is the large international Efficient Dairy Genome Project (EDGP) led by Canada. The EDGP database was developed in 2017 to allow data sharing among the international collaborators. Currently, the database contains genotypes and records on feed intake of 5,289 cows and on methane emissions of 1,337 cows from eight research herds in six countries (Australia, Canada, Denmark, Switzerland, United Kingdom and United States). Genetic parameters (heritability and genetic correlations) were estimated for dry matter intake, metabolic body weight and energy corrected milk at two time-periods: a) 5–60 DIM and b) 60–150 DIM. These parameters provide a basis for development of breeding value estimation procedures and subsequent selection index for feed efficiency, which will incorporate genomic information.

Factors affecting resistance to induced body cooling in newborn lambs of 10 breeds

1981 ◽  
Vol 33 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Deborah E. Samson ◽  
J. Slee
Keyword(s):  
Birth Weight ◽  
Cold Resistance ◽  
Cooling Water ◽  
Skinfold Thickness ◽  
Water Bath ◽  
Factors Affecting ◽  
Highest Weight ◽  
Rate Of Recovery ◽  
Body Cooling

ABSTRACT1. The ability to resist hypothermia was measured in 265 lambs of 10 breeds immersed in a progressively cooling water bath.2. Cold resistance varied significantly between breeds, with hill lambs showing the highest resistance. Hill breeds and feral breeds together had the highest weight-specific cold resistance.3. Cold resistance was positively correlated with birth weight and skinfold thickness.4. Age at test varying from 1 to 60 h did not significantly affect cold resistance.5. Rate of recovery from hypothermia varied slightly between breeds. The feral lambs tended to recover fastest.

Metabolic rate responses to cold and to exogenous noradrenaline in newborn Scottish Blackface lambs genetically selected for high or low resistance to cold

1987 ◽  
Vol 45 (1) ◽  
pp. 69-74 ◽  
Author(s):  
J. Slee ◽  
S. P. Simpson ◽  
J. A. Woolliams
Keyword(s):  
Genetic Variation ◽  
Metabolic Rate ◽  
Cold Exposure ◽  
Cold Resistance ◽  
Metabolic Response ◽  
Genetic Selection ◽  
Subcutaneous Injections ◽  
The Difference ◽  
Body Cooling ◽  
Shivering Thermogenesis

AbstractNewborn Scottish Blackface lambs from lines previously selected for high (H) or low (L) resistance to body cooling were tested for their metabolic response (O2 consumption) to cold exposure in a water bath or to subcutaneous injections of exogenous noradrenaline as a measure of non-shivering thermogenesis (NST). Six rams from the H line and six rams from the L line were used to produce lambs such that each sire had both cold-tested (no. = 48) and noradrenaline-tested (no. = 86) progeny.The mean elevations in metabolic rate produced by cold exposure and by noradrenaline were, respectively, 3·4 times and 2·4 times resting (thermoneutral) metabolic rate. H lambs showed significantly greater cold resistance and metabolic response to cold than L lambs. H lambs showed greater NST than L lambs but the difference was not significant. There were significant sire effects on NST, indicating genetic variation. There was a significant correlation between the metabolic responses to cold and those o t noradrenaline among the sire progeny groups. NST capability appears to be a phenotypic component of neonatal cold resistance which would respond to genetic selection, but this genetic variation is not a major component of that determining cold resistance.

Genetic and phenotypic parameters for Aleutian disease tests and their correlations with pelt quality, reproductive performance, packed-cell volume, and harvest length in mink

2021 ◽  
Author(s):  
Guoyu Hu ◽  
Duy Ngoc Do ◽  
Karim Karimi ◽  
Younes Miar
Keyword(s):  
Cell Volume ◽  
Reproductive Performance ◽  
Packed Cell Volume ◽  
Fixed Effects ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Study Data ◽  
Health Concern ◽  
Economic Losses ◽  
Enzyme Linked Immunosorbent Assay

Abstract Aleutian disease (AD), caused by the Aleutian mink disease virus (AMDV), is a major health concern that results in global economic losses to the mink industry. The unsatisfactory outcome of the culling strategy, immunoprophylaxis, and medical treatment in controlling AD have urged mink farmers to select AD resilient mink based on several detection tests, including enzyme-linked immunosorbent assay (ELISA), counterimmunoelectrophoresis (CIEP), and iodine agglutination test (IAT). However, the genetic analysis of these AD tests and their correlations with pelt quality, reproductive performance, packed-cell volume (PCV), and harvest length (HL) have not been investigated. In this study, data on 5,824 mink were used to estimate the genetic and phenotypic parameters of four AD tests, including two systems of ELISA, CIEP, and IAT, and their genetic and phenotypic correlations with two pelt quality, five female reproductive performance, PCV, and HL traits. Significances (P<0.05) of fixed effects (sex, year, dam age, and color type), covariates (age at harvest and blood sampling ), and random effects (additive genetic, permanent environmental, and maternal effects) were determined under univariate models using ASReml 4.1 software. The genetic and phenotypic parameters for all traits were estimated under bivariate models using ASReml 4.1 software. Estimated heritabilities (±SE) were 0.39±0.06, 0.61±0.07, 0.11±0.07, and 0.26±0.05 for AMDV antigen-based ELISA (ELISA-G), AMDV capsid protein-based ELISA, CIEP, and IAT, respectively. The ELISA-G also showed a moderate repeatability (0.58±0.04) and had significant negative genetic correlations (±SE) with reproductive performance traits (from -0.41±0.16 to -0.49±0.12), PCV (-0.53±0.09), and HL (-0.45±0.16). These results indicated that ELISA-G had the potential to be applied as an indicator trait for genetic selection of AD resilient mink in AD endemic ranches, and therefore help mink farmers to reduce the adverse effects caused by AD.

scholarly journals Genetic Parameters of Honey Bee Colonies Traits in a Canadian Selection Program

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 587 ◽  
Author(s):  
Ségolène Maucourt ◽  
Frédéric Fortin ◽  
Claude Robert ◽  
Pierre Giovenazzo
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Genetic Parameters ◽  
Selection Index ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Hygienic Behavior ◽  
Domestic Species ◽  
Honey Production ◽  
High Heritability

Genetic selection has led to spectacular advances in animal production in many domestic species. However, it is still little applied to honey bees (Apis mellifera), whose complex genetic and reproductive characteristics are a challenge to model statistically. Advances in informatics now enable creation of a statistical model consistent with honey bee genetics, and, consequently, genetic selection for this species. The aim of this project was to determine the genetic parameters of several traits important for Canadian beekeepers with a view to establishing a breeding program in a northern context. Our results show that the five traits measured (Varroa destructor infestation, spring development, honey production, winter consumption, and hygienic behavior) are heritable. Thus, the rate of V. destructor infestation has a high heritability (h2 = 0.44 ± 0.56), spring development and honey production have a medium heritability (respectively, h2 = 0.30 ± 0.14 and h2 = 0.20 ± 0.13), and winter consumption and hygienic behavior have a low heritability (respectively, h2 = 0.11 ± 0.09 and h2 = 0.18 ± 0.13). Furthermore, the genetic correlations between these traits are all positive or null, except between hygienic behavior and V. destructor infestation level. These genetic parameters will be instrumental to the development of a selection index that will be used to improve the capacity of honey bees to thrive in northern conditions.

scholarly journals Prediction of meat quality traits in the abattoir using portable near-infrared spectrometers: heritability of predicted traits and genetic correlations with laboratory-measured traits

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Simone Savoia ◽  
Andrea Albera ◽  
Alberto Brugiapaglia ◽  
Liliana Di Stasio ◽  
Alessio Cecchinato ◽  
...  
Keyword(s):  
Meat Quality ◽  
Near Infrared ◽  
External Validation ◽  
Genetic Correlations ◽  
Genetic Selection ◽  
Quality Traits ◽  
Eye Muscle ◽  
Meat Quality Traits ◽  
Color Traits ◽  
Selection Of

Abstract Background The possibility of assessing meat quality traits over the meat chain is strongly limited, especially in the context of selective breeding which requires a large number of phenotypes. The main objective of this study was to investigate the suitability of portable infrared spectrometers for phenotyping beef cattle aiming to genetically improving the quality of their meat. Meat quality traits (pH, color, water holding capacity, tenderness) were appraised on rib eye muscle samples of 1,327 Piemontese young bulls using traditional (i.e., reference/gold standard) laboratory analyses; the same traits were also predicted from spectra acquired at the abattoir on the intact muscle surface of the same animals 1 d after slaughtering. Genetic parameters were estimated for both laboratory measures of meat quality traits and their spectra-based predictions. Results The prediction performances of the calibration equations, assessed through external validation, were satisfactory for color traits (R2 from 0.52 to 0.80), low for pH and purge losses (R2 around 0.30), and very poor for cooking losses and tenderness (R2 below 0.20). Except for lightness and purge losses, the heritability estimates of most of the predicted traits were lower than those of the measured traits while the genetic correlations between measured and predicted traits were high (average value 0.81). Conclusions Results showed that NIRS predictions of color traits, pH, and purge losses could be used as indicator traits for the indirect genetic selection of the reference quality phenotypes. Results for cooking losses were less effective, while the NIR predictions of tenderness were affected by a relatively high uncertainty of estimate. Overall, genetic selection of some meat quality traits, whose direct phenotyping is difficult, can benefit of the application of infrared spectrometers technology.

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