Relationship between survival of cows and milk production during first lactation. 1. Genetic correlations and correlations between breeding values
Ponce-De-Leon, R.; Guzman, G.
Cuban Journal of Agricultural Science 27(1): 17-23
Genetic (rg) and phenotypic (rp) correlations were determined between survival till 3.5 and 4 years of age (S 3.5A and S 4A) and during 1.5 and 2 years of productive life (S 1.5 PL and S 2 PL) with 12599 observations and between survival till 5 years of age and during 3 years of productive life (S 5A and S 3 PL) with 10874 observations with the traits: milk yield, fat yield and fat corrected milk (at 3.3% fat) at 244 days and at 305 days using data of Holstein cows of three enterprises of Havana province. The simple Pearson correlations and the quadratic and cubic regressions of 102 bulls with BLUP estimations of the breeding value of milk yield and survival traits were determined. The rp were low and non-significant (0.02-0.16). The rg became more antagonic on increasing the length of the period considered since for S 3.5A these were of 0.06 to 0.26 and with S 1.5 PL they became slightly negative (-0.04 to -0.19) with S4 A they reached -0.35 and later (S 5 A and S 3 PL) the correlations with milk yield were completely antagonic ranging from 0.49 to 0.72. The correlations between the breeding values varied from 0.01 to 0.18. There was a quadratic adjustment between the breeding values for S 4 A and milk yield. 20 to 27% of the bulls show positive breeding values for S 4A or S 2 PL and for milk yield. The same favorable relations between milk yield and survival were not observed under our conditions and survival should be considered independent of the milk progeny tests.