DESCRIPTION OF NATIONAL GENETIC EVALUATION SYSTEM FOR MILK SOMATIC CELL AND CLINICAL MASTITIS

Country (or countries):	United Kingdom	
Main trait group:	Health	
Breed(s):	Ayrshire	
Trait definition(s) and unit(s) of measurement 
Attach an appendix if needed	Somatic Cell Count (thousands/ml)
Loge SCC used for evaluation	
Method of measuring and collecting data	Milk Recording Organisations using ICAR Procedures	
Time period for data inclusion	1991 to date – First evaluation 1998	
Age groups (e.g. parities) included	Lactation 1-5	
Other criteria (data edits) for inclusion of records	Heifers must have at least 6 tests for SCC lactation average to be used.  Same validation as Production System.	
Sire categories	All sires	
Environmental effectsa, pre-adjustments 	None
	
Method (model) of genetic evaluationa	BLUP Animal Model                  Herd Year Season (F)
                                                   Herd Sire Interaction (R)                                                                                
                                                   Permanent Environment (R)                                                                                
                                                   Animal (R)	
Environmental effectsa in the genetic evaluation model	Age within lactation, Lactation number, Month of calving	
Adjustment for heterogeneous variance in evaluation model	No	
Use of genetic groups and relationships	Groups by year of birth and sex of animal, sex of parent & country of origin	
Blending of foreign/Interbull information in evaluation	Yes	
Genetic parameters in the evaluation	see PART 3 for heritability/genetic variance estimates; for multiple-trait genetic evaluations, provide genetic correlation estimates between traits separately	
System validation	Interbull Validation	
Expression of genetic evaluations
If standardised (e.g. RBV), give standardisation formula in PART 3	
% Predicted Transmitting Ability	
Definition of genetic reference base
Next base change	Average PTA of cows born 1995

2005	
Calculation of reliability		
Criteria for official publication of evaluations	Bulls 30% reliability, cows not published	
Number of evaluations / publications per year	4	
Use in total merit indexb	No	
Anticipated changes in the near future	Test Day Model.  Include SCC PTAs in Economic Index	
Key reference on methodology applied	R. A. Mrode; G. J. T. Swanson and M. S. Winters (1998) Animal Science 66 : 569-576	
Key organization: name, address, phone, fax, e-mail, web site	MDC Evaluations Ltd
Fox Talbot House
Greenways Business Park
Bellinger Close
Chippenham
Wiltshire.  SN15 1BN

Telephone:  (+44) 01249 467 272            
Fax: (+44) 01249 467 273
E-mail:  enquiry@mdcevaluations.co.uk   
Web site: www.mdcevaluations.co.uk
	
a	Use abbreviations for most common effects (see document with list of abbreviations at http://www-interbull.slu.se/service_documentation/General/framesida-general.htm) and indicate random (R) or fixed (F)
b	Please give economic weights and indicate how they are expressed (preferably in genetic standard deviation units).

Parameters

Trait	h2a	genetic
variancea	official proof
standardisation formulab	
Milk Somatic Cell:

	0.11	554.07		
a	If lactations, or part of lactations, are treated as separate traits, provide heritability estimates and genetic variances separately for each lactation, as well as for all lactations pooled, i.e. for the trait submitted to Interbull.
b	Expressed as follows:
StandEval=((eval-a)/b)*c+d where a=mean of the base adjustment, b=standard deviation of the base, c=standard deviation of expression (include sign if scale is reversed), and d=base of expression.