Genetic parameters forNematodirusspp. egg counts in Romney lambs in New Zealand

2004 ◽  
Vol 79 (1) ◽  
pp. 33-39 ◽  
Author(s):  
C. A. Morris ◽  
A. Bisset ◽  
A. Vlassoff ◽  
C. J. West ◽  
M. Wheeler
Keyword(s):  
Genetic Correlations ◽  
Selection Criterion ◽  
Weighted Average ◽  
Breeding Lines ◽  
Faecal Egg Count ◽  
Genetic Mechanisms ◽  
Resistance To Infection ◽  
Selection For ◽  
Standard Deviations ◽  
Sampling Times

AbstractGenetic analyses were carried out on Nematodirus spp. egg counts (NEM) of lambs from a set of Romney breeding lines. The lines had been under selection for 22 seasons (1979 to 2000) for divergence in resistance to infection by strongyle nematodes other than NEM, using faecal egg count (FEC) as the selection criterion. Heritabilities and genetic correlations for NEM were estimated using residual maximum likelihood procedures. Correlated responses in NEM were also determined. Heritability estimates for loge(NEM + 100) in lambs at 4 months of age (NEM1) or 6 months of age (NEM2) were 0·15 (s.e. 0·03) and 0·26 (s.e. 0·04) respectively (c.f. 0·28 (s.e. 0·02) and 0·35 (s.e. 0·02) for loge(FEC + 100)). The genetic correlation between loge(NEM1 + 100) and loge(NEM2 + 100) was 0·85 (s.e. 0·08), while the genetic correlations between measurements of loge(NEM + 100) and loge(FEC + 100) on both sampling occasions had a weighted average of 0·43, with estimates ranging from 0·30 (s.e. 0·08) to 0·52 (s.e. 0·07). Divergence in loge(NEM + 100) between the high and low FEC lines, estimated over both sampling times combined, was 1·07 phenotypic standard deviations, compared with 3·6 phenotypic standard deviations for loge(FEC + 100). Expressed in terms of back-transformed eggs per g, the high and low FEC lines differed by factors of 7·6 and 32·2 for NEM and FEC, respectively. The results support earlier parasitological data indicating that the genetic mechanisms in sheep which are responsible for resistance to other strongyle nematodes probably also influence resistance to Nematodirus infection.

Estimation of genetic parameters using health, fertility and production data from a management recording system for dairy cattle

1998 ◽  
Vol 66 (3) ◽  
pp. 577-584 ◽  
Author(s):  
J. E. Pryce ◽  
R. J. Esslemont ◽  
R. Thompson ◽  
R. F. Veerkamp ◽  
M. A. Kossaibati ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Genetic Parameters ◽  
Genetic Relationships ◽  
Genetic Correlations ◽  
Selection Criterion ◽  
Production Traits ◽  
Linear Type ◽  
Cell Counts ◽  
Estimation Problems ◽  
Selection For

AbstractThe Dairy Information System (DAISY) was developed to record fertility and health information for use in research and to help farmers manage their farms. Data from 33 herds recording health and fertility over a 6-year period were used to study genetic relationships of several health, fertility and production traits. There were 10 569 records from 4642 cows of all parities. These were used to estimate genetic parameters for health: mastitis, lameness and somatic cell score (SCS), for fertility: calving interval, days to first service, conception to first service and for production: 305-day milk, butterfat and protein yields. Heritabilities for these traits were also estimated for the first three lactations. (Co)variances were estimated using linear, multitrait restricted maximum likelihood (REML) with an animal model. Mastitis and lameness were treated as all-or-none traits. The incidence of these diseases increased with lactation number, which may lead to variance component estimation problems, as the mean is linked to the variance in binomial distributions. Therefore, a method was used to fix the within-lactation variance to one in all lactations while maintaining the same mean. The heritability for SCS across lactations was 0·15. Heritabilities for other health and fertility traits were low and ranged between 0·013 and 0·047. All genetic correlations with the production traits were antagonistic implying that selection for yield may have led to a deterioration in health and fertility. The genetic correlation between SCS and mastitis was 0·65 indicating that indirect selection for improvements in mastitis may be achieved using somatic cell counts as a selection criterion. The potential use of linear type scores as predictors of the health traits was investigated by regressing health traits on sire predicted transmitting abilities for type. The results indicate that some type traits may be useful as future selection criteria.

Genetic relationships between faecal egg count and production traits in commercial Merino sheep flocks

2004 ◽  
Vol 79 (1) ◽  
pp. 21-32 ◽  
Author(s):  
G. E. Pollott ◽  
J. C. Greeff
Keyword(s):  
Host Resistance ◽  
Genetic Correlations ◽  
Production Traits ◽  
Eye Muscle ◽  
Merino Sheep ◽  
Sire Model ◽  
Faecal Egg Count ◽  
Selection For ◽  
Staple Strength ◽  
Body Production

AbstractIn several countries the gastro-intestinal parasites of sheep show evidence of resistance to the commonly used anthelmintic treatments. The use of animals with genetic resistance to such parasites has been shown to be a viable alternative in a number of resource flocks. However, the genetics of host resistance to parasites in industry flocks and the effects on production traits of using resistant sheep is relatively unknown. This study addresses these questions using data from 55 commercial Merino flocks in Australia. The heritability and genetic correlations were estimated for faecal egg count (FEC), an indicator of host resistance, and eleven fleece and body production traits. The heritability of FEC (0·26 (s.e. 0·018)), using a sire model, was found to be similar to other estimates reported in the literature from resource flocks. The heritabilities of production traits were also consistent with published reports from resource flocks. The genetic correlations between FEC and the 11 production traits, calculated using a sire model, were mostly zero, except for staple strength (-0·17 (s.e. 0·096)), fat depth (-0·26 (s.e. 0·088)) and eye-muscle depth (-0·18 (s.e. 0·091)). Animal model estimates of heritability and the genetic correlations between the traits were largely similar to the sire model estimates. Correlated responses to selection for reduced FEC based on the sire model genetic parameters were calculated to be less than 0·15% of the trait mean per generation for all traits except staple strength, fat depth, muscle depth and live weight. These were expected to increase slightly under selection for reduced FEC. Thus industry-based selection programmes to increase host resistance to parasites should be effective and have no detrimental effect on production characteristics of Merino sheep in Australia. The full benefit of such industry-based schemes could be improved by a better level of recording in the flocks studied.

scholarly journals Genetic parameters for faecal egg count following mixed, natural, predominantly Ostertagia circumcincta infection and relationships with live weight in young lambs

1996 ◽  
Vol 63 (3) ◽  
pp. 423-428 ◽  
Author(s):  
S. C. Bishop ◽  
K. Bairden ◽  
Q. A. McKellar ◽  
M. Park ◽  
M. J. Stear
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Live Weight ◽  
Gastrointestinal Parasites ◽  
Phenotypic Correlations ◽  
Selection Decisions ◽  
Faecal Egg Count ◽  
Resistance To Infection ◽  
Faecal Egg Counts ◽  
Small Measurement Error

AbstractFaecal egg counts and live weights were measured on approximately 200 predominantly twin-born Scottish Blackface lambs each year for 3 years, from 1 to 6 months of age. Measurements were made at 4-week intervals following anthelmintic treatment. Heritability estimates (with s.e.s) of log transformed faecal egg count at each age were 0·01, 0·00, 0·12 (0·10), 0·14 (0·12), 0·15 (0·07) and 0·22 (0·13), for ages 1 to 6 months respectively. Therefore, genetic variation exists for acquired but apparently not for innate resistance to infection. Maternal common environmental effects (with s.e.s) were 0·36 (0·11), 0·20 (0·05), 0·27 (0·09), 0·06 (0·08), 0·15 (0·09) and 0·16 (0·08), for ages 1 to 6 months respectively. Genetic correlations between faecal egg counts in lambs older than 3 months were not significantly less than 1·0, indicating that faecal egg counts at different ages are expressions of the same trait. Phenotypic correlations between faecal egg counts were generally positive but small. Measurement error contributed one-third of the observed variation for individual egg counts. The heritability of mean faecal egg count from 3 to 6 months was 0·33 (s.e. 0·15), indicating that selection decisions can be made more accurately using multiple egg counts per animal. Phenotypic correlations between faecal egg counts and live weight were generally negative but close to zero. However, genetic correlations between faecal egg counts and live weight in lambs older than 3 months were close to -1·0, indicating that resistance to gastrointestinal parasites may be an important genetic determinant of growth rate in this environment.

Ratios as criteria for selection in animal or plant breeding, with particular reference to efficiency of food conversion in sheep

1959 ◽  
Vol 10 (4) ◽  
pp. 565 ◽  
Author(s):  
HN Turner
Keyword(s):  
Body Weight ◽  
Plant Breeding ◽  
Genetic Correlation ◽  
Genetic Correlations ◽  
Selection Criterion ◽  
Skin Area ◽  
Wide Range ◽  
Selection For ◽  
Range Of Values ◽  
Criteria For Selection

Ratios are frequently advocated as criteria for selection, in either animal or plant breeding; for example, production per unit of food eaten is currently receiving attention, particularly with Merino sheep. Clean wool weight per head (W) is already widely used as a selection criterion, but suggestions have been made that wool weight per pound of body weight (B) or per unit skin area (estimated as B0.6, or measured) should be used instead, as estimates of the efficiency of conversion of food into wool. This paper develops formulae for writing the heritability of any ratio, as well as its genetic correlations with its numerator and its denominator, in terms of the relationships between the numerator and the denominator. From these formulae the likely result of selecting for the ratio can be predicted, for a given range of values of the genetic and phenotypic parameters of the numerator and denominator. The formulae can be used for any ratio, provided gene x environment interactions and epistasis can be neglected. In particular, it is shown that the genetic correlation between W and W/B or W/B0.6 is consistently positive for a wide range of values of the parameters of W and B, so that selection for high wool weight will also increase efficiency, as measured by either ratio. The genetic correlation between B and W/B or W/B0.6, on the other hand, is nearly always negative, sometimes very strongly so, and selection for high values of W/B or W/B0.6 will decrease body weight. The theoretical predictions are confirmed by results from experimental selection groups, in which the observed correlated responses are all in the predicted direction, and in most cases agree well in magnitude. It is suggested that more information is required on the importance of body size itself, in relation to factors such as fertility and survival, before the value of selection on W/B or W/B0.6 can be accurately assessed.

Resistance to nematode parasites in Merino sheep: correlation with production traits

1998 ◽  
Vol 49 (8) ◽  
pp. 1201 ◽  
Author(s):  
S. J. Eady ◽  
R. R. Woolaston ◽  
R. W. Ponzoni ◽  
R. P. Lewer ◽  
H. W. Raadsma ◽  
...  
Keyword(s):  
Variance Components ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Correlated Response ◽  
Production Traits ◽  
Merino Sheep ◽  
Nematode Parasites ◽  
Faecal Egg Count ◽  
Selection For ◽  
Fleece Weight

Merino sheep representing a range of bloodlines in resource flocks located across Australia were tested for resistance to gastro-intestinal nematodes. These flocks included the JB Pye Flock (Camden, NSW), Katanning Base Flock (Katanning, WA), Turretfield Merino Resource Flock (Rosedale, SA), and the CSIRO Finewool Flock (Armidale, NSW) and included a total of 328 sire groups. Resistance to nematodes was measured by faecal egg count (FEC). Data were also available for greasy and clean fleece weight (GFW and CFW, respectively), fibre diameter (FD), and body weight (BW) at a range of ages from weaning to 21 months. Variance components were estimated by restricted maximum likelihood, fitting an animal model and estimating covariances in a series of bivariate analyses. Phenotypic correlations between FEC0·33 and production traits were all close to zero ( –0·09–0·02). Genetic correlations between FEC0·33 and production traits were –0·20, –0·18, and –0·26 for weaning weight, 10-month BW, and 16-month BW, respectively; 0·21, –0·06, and 0·21 for 10-month GFW, 16-month GFW, and 21-month GFW; 0·21, –0·05, and 0·07 for 10-month CFW, 16-month CFW, and 21-month CFW; and –0·09, –0·12, and 0·04 for 10-month FD, 16-month FD, and 21-month FD. When estimates were pooled for all fleece traits and all BW traits, the genetic correlations between FEC0·33 and GFW, CFW, FD, and BW were 0·15, 0·10, –0·06, and –0·21, respectively. Using pooled estimates for CFW, FD, and BW, selection for a breeding objective based on production traits alone would lead to an unfavourable correlated response in FEC0·33 of approximately 1% per year.

129 Genomic Relationship Between PRRSV Wild-type Infection and PRRSV Vaccination for Antibody Response and Reproductive Performance

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 18-18
Author(s):  
Leticia P Sanglard ◽  
Felipe Hickmann ◽  
Yijian Huang ◽  
Kent A Gray ◽  
Daniel Linhares ◽  
...  
Keyword(s):  
Antibody Response ◽  
Reproductive Performance ◽  
Genetic Correlations ◽  
Clinical Signs ◽  
Respiratory Syndrome Virus ◽  
Wild Type ◽  
Large White ◽  
Selection For ◽  
Indicator Trait ◽  
Type Infection

Abstract Immunoglobulin G antibody response, measured as sample-to-positive (S/P) ratio, to Porcine Reproductive and Respiratory Syndrome virus (PRRSV) has been proposed as an indicator trait for improved reproductive performance in PRRSV-infected purebred sows and PRRSV-vaccinated crossbred gilts. In this study, we investigated the genetic correlations (rg) of S/P ratio following a PRRSV outbreak and PRRSV-vaccination with performance in non-exposed and PRRSV-exposed sows. PRRSV outbreak phase was defined based on previously described methodologies after the detection of typical clinical signs of PRRSV infection. 541 Landrace sows had S/P ratio measured at ~54 days after the beginning of the PRRSV outbreak (S/Poutbreak), and 906 Landrace x Large White naïve F1 gilts had S/P ratio measured at ~50 days after vaccination with a commercial modified live PRRSV vaccine (S/PVx). 711 and 428 Landrace sows had reproductive performance recorded before and during the PRRSV outbreak, respectively. 811 vaccinated F1 animals had farrowing performance for up to 3 parities. All animals were genotyped for ~28K SNPs. The estimate of rg of S/Poutbreakwith S/PVx was high (rg±SE = 0.72±0.18). Estimates of rg of S/Poutbreak with reproductive performance in F1 sows were low to moderate, ranging from 0.05±0.23 (number stillborn) to 0.30±0.20 (total number born). Estimates of rg of S/PVxwith reproductive performance in non-infected purebred sows were moderate and favorable with number born alive (0.50±0.23), but low (0 to -0.11±0.23) with litter mortality traits. Estimates of rg of S/PVx were moderate and negative (-0.47±0.18) with the number of mummies in PRRSV-infected purebred sows and low with other traits (-0.29±0.18 for total number born to 0.05±0.18 for number stillborn). These results indicate that selection for antibody response following a PRRSV outbreak collected in purebred sows and to PRRSV vaccination collected in commercial crossbred gilts may increase litter size of non-infected and PRRSV-exposed purebred and commercial crossbred sows.

Selection for components of efficient lean growth rate in pigs 2. Selection pressure applied and direct responses in a Landrace herd

1994 ◽  
Vol 59 (2) ◽  
pp. 263-269 ◽  
Author(s):  
N. D. Cameron ◽  
M. K. Curran
Keyword(s):  
Growth Rate ◽  
Genetic Correlations ◽  
Correlated Response ◽  
Selection Line ◽  
Control Line ◽  
Direct Response ◽  
Lean Growth ◽  
Ad Libitum ◽  
Selection For ◽  
Ad Libitum Feeding

AbstractResponses to divergent selection for lean growth rate with ad-libitum feeding (LGA), for lean food conversion (LFC) and for daily food intake (DFI) in Landrace pigs were studied. Selection was practised for four generations with a generation interval ofl year. A total of 2642 pigs were performance tested in the high, low and control lines, with an average of 37 boars and 39 gilts performance tested per selection line in each generation. The average within-line inbreeding coefficient at generation four was equal to 0·04. There was one control line for the DFI and LFC selection groups and another control line for the LGA selection group. Animals were performance tested in individual pens with mean starting and finishing weights of 30 kg and 85 kg respectively with ad-libitum feeding. The selection criteria had phenotypic s.d. of 32, 29 and 274 units, for LGA, LFC and DFI, respectively, and results are presented in phenotypic s.d.Cumulative selection differentials (CSD) were 5·1, 4·5 and 5·5 phenotypic s.d. for LGA, LFC and DFI, respectively. Direct responses to selection were 1·4,1·1 and 0·9 (s.e. 0·20) for LGA, LFC and DFI. In each of the three selection groups, the CSD and direct responses to selection were symmetric about the control lines. The correlated response in LFC (1·1, s.e. 0·19) with selection on LGA was equal to the direct response in LFC. In contrast, the direct response in LGA was greater than the correlated response (0·7, s.e. 0·18) with selection on LFC. There was a negative correlated response in DFI (-0·6, s.e. 0·18) with selection on LFC, but the response with selection on LGA was not significant (0·2, s.e. 0·16).Heritabilities for LGA, LFC and DFI ivere 0·25, 0·25 and 0·18 (s.e. 0·03), when estimated by residual maximum likelihood, with common environmental effects of 0·12 (s.e. 0·02). Genetic correlations for LFC with LGA and DFI were respectively positive (0·87, s.e. 0·02) and negative (-0·36, s.e. 0·09), while the genetic correlation between DFI and LGA was not statistically different from zero, 0·13 (s.e. 0·10). Selection on components of efficient lean growth has identified LGA as an effective selection objective for improving both LGA and LFC, without a reduction in DFI.

Biological and chemical features of Poltava Meat breed pigs bacon depending on genotype

2021 ◽  
pp. 74-80
Author(s):  
N. Garskaya ◽  
L. Peretyatko
Keyword(s):  
Subcutaneous Tissue ◽  
Morphological Structure ◽  
Live Weight ◽  
Fatty Degeneration ◽  
Fat Cells ◽  
Breeding Lines ◽  
Meat Content ◽  
Group I ◽  
Significant Difference ◽  
Selection For

The research goal is to carry out comprehensive studies to define the biological and chemical characteristics of the young Poltava Meat Breed boars’ bacon for further work with existing genotypes and creating new ones.Materials and methods. The research was carried out on bacon samples taken from Poltava Meat Breed boars of different genotypes during the «control slaughter» at the age of reaching the live weight of 100 kg. Purebred Poltava Meat Breed boars were divided into two groups according to the principle of paired analogs: the group I (control) contained animals of «clean» breeding lines (16 heads), and the group II (experimental) contained animals with 12,5% of the Finnish Landrace blood (14 heads). The thickness of the bacon, its morphological structure and its chemical features were studied. All the results obtained were then processed by statistical methods.Results. It was found that Poltava Meat Breed boars, regardless of the genotype, had bacon thickness values below the Poltava Meat Breed target standard after reaching the live weight of 100 kg, with very low variability of the indicator (1,05–1,69%). However, there was no significant difference between the groups. During the morphological study of the samples, qualitative differences in the bacon of animals from different groups were noted. In the first group, the subcutaneous tissue (bacon) is subject to more pronounced destructive changes due to the intensified process of fatty degeneration. The fat cells of animals with Finnish Landrace blood were slightly smaller, but no significant difference between the area of fat cells in boars of different genotypes was found. The variability of morphological parameters in both groups was average (23,91% and 16,23%). The infusion of Finnish Landrace blood to the Poltava Meat Breed boars led to a change in the chemical composition of bacon, such as: an increase in the amount of moisture by 8,58% (p≤0,01), protein by 3,62% (p≤0,01), a decrease in the amount of fat by 9,25% (p≤0,01), to a decrease in the saponification number by 8,36% (p≤0,01) and the iodine number by 10,48% (p≤0,01).Conclusion. The bacon of Poltava Meat Breed boars is characterized by biological and chemical features due to both species and genotype. The established features of the bacon of Poltava Meat Breed boars indicate a significant decrease in its quality in the case of Finnish Landrace blood infusion. Intensive selection for meat content of Poltava Meat Breed pigs leads to a significant decrease in the thickness of the bacon and excessive selection pressure.

Genetic variation in fatty acid composition of subcutaneous fat in cattle

2013 ◽  
Vol 53 (2) ◽  
pp. 129 ◽  
Author(s):  
M. J. Kelly ◽  
R. K. Tume ◽  
S. Newman ◽  
J. M. Thompson
Keyword(s):  
Fatty Acids ◽  
Genetic Variation ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Saturated Fatty Acids ◽  
Genetic Correlations ◽  
Subcutaneous Fat ◽  
Monounsaturated Fatty Acids ◽  
Selection For

Genetic parameters were estimated for fatty acid composition of subcutaneous beef fat of 1573 animals which were the progeny of 157 sires across seven breeds grown out on pasture and then finished on either grain or grass in northern New South Wales or in central Queensland. There was genetic variation in individual fatty acids with estimates of heritability for the proportions of C14 : 0, C14 : 1c9, C16 : 0, C16 : 1c9, C18 : 0 and C18 : 1c9 fatty acids in subcutaneous beef fat of the order of 0.4 or above. Also substantial correlations between some fatty acids were observed. Genetic correlations between fatty acids and fat depth at the P8 site suggested that much of the genetic variation in fatty acid composition was related to changes in fatness. Selection for decreased fatness resulted in decreased proportions of C18 : 1c9 with concomitant increases in C18 : 0, C14 : 0 and C16 : 0. This suggested that selection for decreased fatness at a given weight will result in a decrease in the proportions of monounsaturated fatty acids in the subcutaneous fat in the carcass with a corresponding increase in the proportions of saturated fatty acids.

scholarly journals PSVIII-38 Late-Breaking Abstract: Estimating genetic parameters of feed efficiency traits in American mink

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 347-347
Author(s):  
Pourya Davoudi ◽  
Duy Ngoc Do ◽  
Guoyu Hu ◽  
Siavash Salek Ardestani ◽  
Younes Miar
Keyword(s):  
Body Weight ◽  
Genetic Correlation ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
American Mink ◽  
Genetic Correlations ◽  
Final Body Weight ◽  
Selection For

Abstract Feed cost is the major input cost in the mink industry and thus improvement of feed efficiency through selection for high feed efficient mink is necessary for the mink farmers. The objective of this study was to estimate the heritability, phenotypic and genetic correlations for different feed efficiency measures, including final body weight (FBW), daily feed intake (DFI), average daily gain (ADG), feed conversion ratio (FCR) and residual feed intake (RFI). For this purpose, 1,088 American mink from the Canadian Center for Fur Animal Research at Dalhousie Faculty of Agriculture were recorded for daily feed intake and body weight from August 1 to November 14 in 2018 and 2019. The univariate models were used to test the significance of sex, birth year and color as fixed effects, and dam as a random effect. Genetic parameters were estimated via bivariate models using ASReml-R version 4. Estimates of heritabilities (±SE) were 0.41±0.10, 0.37±0.11, 0.33±0.14, 0.24±0.09 and 0.22±0.09 for FBW, DFI, ADG, FCR and RFI, respectively. The genetic correlation (±SE) was moderate to high between FCR and RFI (0.68±0.15) and between FCR and ADG (-0.86±0.06). In addition, RFI had low non-significant (P > 0.05) genetic correlations with ADG (0.04 ± 0.26) and BW (0.16 ± 0.24) but significant (P < 0.05) high genetic correlation with DFI (0.74 ± 0.11) indicating that selection for lower RFI will reduce feed intake without adverse effects on the animal size and growth rate. The results suggested that RFI can be implemented in genetic/genomic selection programs to reduce feed intake in the mink production system.

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