Estimation of genetic parameters for somatic cell count in the first three lactations using random regression

2003 ◽  
Vol 79 (2-3) ◽  
pp. 239-247 ◽  
Author(s):  
R.A Mrode ◽  
G.J.T Swanson
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Random Regression ◽  
Estimation Of Genetic Parameters

Estimates of genetic parameters for test day somatic cell count fitting orthogonal polynomials

2001 ◽  
Vol 2001 ◽  
pp. 15-15
Author(s):  
R. A. Mrode ◽  
G. J. T. Swanson ◽  
C. M. Lindberg
Keyword(s):  
United Kingdom ◽  
Orthogonal Polynomials ◽  
Somatic Cell ◽  
Cell Count ◽  
Environmental Effects ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Random Regression ◽  
The United Kingdom ◽  
Genetic Evaluations

Genetic evaluations in the United Kingdom (UK) for Somatic Cell Count (SCC) are currently based on a single trait repeatability model using the first five lactations. Only cows with completed lactations are included. However, to utilise information from cows with part lactation records and to achieve a better correction for environmental effects, a test day model (TDM) evaluation would be preferred. The objective of this study is to estimate genetic parameters needed for such a TDM evaluation by utilising a random regression (RR) approach.

scholarly journals Genetic Parameters for Somatic Cell Count, Logscc and Somatic Cell Score of Breeds: Improved Valachian, Tsigai, Lacaune and their Crosses/Genetski Parametri Za Broj Somatskih Ćelija, Logscc I Skor Somatskih Ćelija Kod Rasa: Poboljšana Vlaška, Cigaja, Lakon I Njihovih Meleza

2014 ◽  
Vol 64 (3) ◽  
pp. 386-396 ◽  
Author(s):  
Makovický Pavol ◽  
Makovický Peter ◽  
Nagy Melinda ◽  
Rimárová Kvetoslava ◽  
Diabelková Jana
Keyword(s):  
Animal Model ◽  
Maximum Likelihood ◽  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Clinical Mastitis ◽  
Somatic Cell Score ◽  
Primary Data ◽  
Dairy Sheep

Abstract In the last few years there has been increasing emphasis on reducing milk somatic cell count to improve the milk quality in dairy ruminants. Genetic parameters for somatic cell count (SCC), LOGSCC and somatic cell score (SCS) were estimated. About 1193 measurements were included in the analysis for each character of 358 ewes of 9 genotypes. Nine breeds and genotypes were included in these experiments: purebred Improved Valachian (IV), Tsigai (T), Lacaune (LC) ewes, and IV and T crosses with a genetic portion of Lacaune and East Friesian (EF) - 25 %, 50 % and 75 %. Primary data were processed using restricted maximum likelihood (REML) methodology and the multi-trait animal model, using programs REMLF90 and VCE 4.0. Heritability coefficients for somatic cell count were low: h2=0.03, for LOGSCC h2= 0.08 and for somatic cell score h2=0.06. Somatic cell score can be considered for inclusion in a breeding program aimed at reducing somatic cell count and frequency of clinical mastitis in dairy sheep.

scholarly journals Genetic Parameters of Bovine Milk Fatty Acid Profile, Yield, Composition, Total and Differential Somatic Cell Count

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2406
Author(s):  
Tania Bobbo ◽  
Mauro Penasa ◽  
Martino Cassandro
Keyword(s):  
Animal Models ◽  
Somatic Cell ◽  
Cell Count ◽  
Milk Yield ◽  
Milk Fat ◽  
Fixed Effects ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Bovine Milk

The growing interest of consumers for milk and dairy products of high nutritional value has pushed researchers to evaluate the feasibility of including fatty acids (FA) in selection programs to modify milk fat profile and improve its nutritional quality. Therefore, the aim of this study was to estimate genetic parameters of FA profile predicted by mid-infrared spectroscopy, milk yield, composition, and total and differential somatic cell count. Edited data included 35,331 test-day records of 25,407 Italian Holstein cows from 652 herds. Variance components and heritability were estimated using single-trait repeatability animal models, whereas bivariate repeatability animal models were used to estimate genetic and phenotypic correlations between traits, including the fixed effects of stage of lactation, parity, and herd-test-date, and the random effects of additive genetic animal, cow permanent environment and the residual. Heritabilities and genetic correlations obtained in the present study reflected both the origins of FA (extracted from the blood or synthesized de novo by the mammary gland) and their grouping according to saturation or chain length. In addition, correlations among FA groups were in line with correlation among individual FA. Moderate negative genetic correlations between FA and milk yield and moderate to strong positive correlations with fat, protein, and casein percentages suggest that actual selection programs are currently affecting all FA groups, not only the desired ones (e.g., polyunsaturated FA). The absence of association with differential somatic cell count and the weak association with somatic cell score indicate that selection on FA profile would not affect selection on resistance to mastitis and vice versa. In conclusion, our findings suggest that genetic selection on FA content is feasible, as FA are variable and moderately heritable. Nevertheless, in the light of correlations with other milk traits estimated in this study, a clear breeding goal should first be established.

Genetic and economic relationships between somatic cell count and clinical mastitis and their use in selection for mastitis resistance in dairy cattle

2001 ◽  
Vol 73 (1) ◽  
pp. 19-28 ◽  
Author(s):  
H. N. Kadarmideen ◽  
J. E. Pryce
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Clinical Mastitis ◽  
Parameter Estimates ◽  
Data Set ◽  
Selection For ◽  
Genetic Regression ◽  
Genetic Responses

AbstractClinical mastitis (CM) and monthly test-day somatic cell count (SCC) records on Holstein cows were used to investigate the genetic and economic relationship of lactation average (of natural logarithms of) monthly test-day SCC (LSCC) with CM. After editing, there were 23663 lactation records on 17937 cows from 257 herds. Three groups of herds were first identified as having low (L), medium (M) and high (H) incidences of CM from the original or pooled (P) data set. Genetic parameters were estimated for the original and three data sub-sets (derived from the three herd groups). Expected genetic responses to selection against CM were calculated using genetic parameters of each data set separately, with an adapted version of the UK national index (£PLI-profitable lifetime index). Indirect economic values of SCC (EVSCC) were calculated as the direct cost of CM per cow per lactation weighted by the genetic regression coefficient of CM lactation records on their sires’ predicted transmitting ability for SCC (PTASCC). All genetic regression analyses were based on linear and threshold-liability models. Heritabilities and repeatabilities, respectively, were 0034 and 0·111 for CM and 0120 and 0·347 for LSCC in the original data set. Genetic, permanent environmental, residual and phenotypic correlations between CM and LSCC for the original (pooled) data set were 0·70, 0·44, 013 and 0·20, respectively. Parameter estimates for the three herd groups differed, with magnitude of the estimates increasing with increase in incidence from L to H herd groups. The EVSCCper unit of PTASCCfor L, M, H and P herd groups, respectively, were £004, £0·15, £0·33 and £018 on the observed and £0·86, £0·96, £1·22 and £110 on the underlying-liability scales. Selection for mastitis resistance, using SCC as an indicator trait in an extended version of £PLI, resulted in a selection response of 0·9, 21, 1·7 and 1·9 more cases per 100 cows after 10 years of selection in L, M, H and P herd groups, respectively. These results suggest that genetic responses to selection for CM resistance as well as the EVSCCare specific to herd incidence and hence would be appropriate for customized selection indexes. The increase in CM cases was greater when CM was excluded from the £PLI (2·8v1·9), hence it is recommended that CM should be included in the breeding goal in order to arrest further decline or to make improvement in genetic resistance to clinical mastitis.

scholarly journals Genetic parameters of the linear body conformation traits and genetic correlations with udder traits, milk yield and composition, and somatic cell count in dairy ewes

2011 ◽  
Vol 91 (4) ◽  
pp. 585-591 ◽  
Author(s):  
L. Fernando de la Fuente ◽  
Carlos Gonzalo ◽  
Juan Sánchez ◽  
Roberto Rodríguez ◽  
Juan Carriedo ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Cell Count ◽  
Milk Yield ◽  
Somatic Cell Count ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Dairy Sheep ◽  
General Body ◽  
Body Conformation ◽  
Linear Body

de la Fuente, L. F., Gonzalo, C., Sánchez, J. P., Rodríguez, R., Carriedo, J. A. and San Primitivo, F. 2011. Genetic parameters of the linear body conformation traits and genetic correlations with udder traits, milk yield and composition, and somatic cell count in dairy ewes. Can. J. Anim. Sci. 91: 585–591. This study was designed to estimate the inheritance of linear body conformation traits and their genetic correlations with linear udder traits, milk yield and composition, and somatic cell count (SCC) in dairy sheep. A total of 10 189 records of five body conformation traits, five linear udder traits, milk yield, protein and fat content, and SCC were obtained from 3977 adult ewes that were daughters of 268 sires belonging to 23 commercial flocks enrolled in the Churra breed selection nucleus. All type traits were scored on a nine-point linear scale. Genetic correlations and heritabilities were estimated using a repeatability multitrait animal model. Body conformation (stature, rear leg-rear view, feet angle, rump width, and general body score) had heritabilities (0.19, 0.18, 0.24, 0.14 and 0.17) and repeatabilities (0.34, 0.42, 0.42, 0.36, and 0.35), which indicate good potential for selection. For udder traits (udder depth, udder attachment, teat placement, teat length and udder shape) heritabilities varied between 0.09 and 0.26, and repeatabilities between 0.35 and 0.53. General body score (composite trait) had high phenotypic and genetic correlations with rear leg-rear view (0.64 and 0.80) and rump width (0.42 and 0.58). The phenotypic and genetic correlation between general body score and udder shape (composite trait) was 0.23 and 0.44, respectively. In addition, phenotypic and genetic correlations between body conformation traits and milk yield, protein and fat percentages, and SCC were low in most cases; therefore, no significant correlated genetic response is expected in body conformation traits when selecting for milk yield, protein and fat percentages, and SCC variables, in Churra breed. In conclusion, the heritability and repeatability values found in this study for body conformation traits, combined with the ease of recording by linear scale, make improvement by selection possible in dairy sheep.

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