Table 4.

Comparison of the goodness of fit of models A and A + D based on conservative maximum likelihood (ML) ratio test for calving interval (CI), milk, fat and protein yields in Holstein and Jersey cows

Breed	Parameter	Model	Trait
			CI	Milk yield	Fat yield	Protein yield
Holstein	Log of ML	A	−112,604	−154,634	−85,995	−80,469
		A + D	−112,603	−154,629	−85,990	−80,465
	P value*		0.0569	0.00095	0.00095	0.0026
Jersey	Log of ML	A	−52,292	−69,655	−39,350	−35,684
		A + D	−52,292	−69,650	−39,343	−35,676
	P value*		–	0.0012	5.91E-05	3.23E-05

Model A = taking only additive effects into account

Model A + D = taking both additive and dominance effects into account

* P values of the Chi square tests calculated as χ ² = −2(log ML_A − log ML_A + D) with 1 degree of freedom from a mixture of Chi squared distributions with 1 and 0 degree freedom