[Evaluation of dog sperm].

2,025 ejaculates were screened for correlations between a number of characteristics. There was no difference between the effect of body size or breed. There was a negative correlation between the motility and morphology of the spermatozoa (P = 10(-6), independent of the total number of spermatozoa per ejaculate (P = 0.

The development of two White Plymouth Rock lines resistant to Marek's disease by breeding from survivors.

A programme to develop resistance to Marek's disease (MD) in chickens in two non-inbred White Plymouth Rock (WPR) lines by breeding from survivors was initiated in 1968 and since then nine generations have been produced. In each generation only sires and dams which survived heavy exposure to virulent MD virus (MDV), Dutch strain K, either by inoculation (for the first two generations) or by contact-exposure (for the following seven generations) were used. In this long term trial a high level of resistance to MD was reached within five generations; thereafter no marked further increase in resistance could be obtained.