RELATIONSHIP BETWEEN SURVIVAL OF COWS AND MILK-PRODUCTION DURING 1ST LACTATION .1. GENETIC CORRELATIONS AND CORRELATIONS BETWEEN BREEDING VALUES

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 observ ations and between survival till 5 years of age and during 3 years of productive life (S 5 A and S 3 PL) with 10874 observations with the tr aits : milk yield, fat yield and fat corrected milk (at 3.3% fat) at 2 44 days and at 305 days using data of Holstein cows of three enterpris es of Havana province. The simple Pearson correlations and the quadrat ic and cubic regressions of 102 bulls with BLUP estimations of the bre eding 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 th ese were of 0.06 to 0.26 and with S 1-5 PL they became slightly negati ve (-0.04 to -0.19) with S 4 A they reached 0.35 and later (S 5 A and S 3 PL) the correlations with milk yield were completely antagonic ran ging 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 th e breeding values for S 4 A and milk yield. 20 to 27% of the bulls sho w positive breeding values for S 4A or S 2 PL and for milk yield. The same favourable relations between milk yield and survival were not obs erved under our conditions and survival should be considered independe nt of the milk progeny tests.