Administrativo

The objective of this study was to compare the immune response of Holstein and Norwegian Red × Holstein calves on 13 commercial Canadian dairy farms. Data were collected on 135 calves, 68 Holstein and 67 Norwegian Red × Holstein calves aged between 2 and 6 mo. The calves were immunized with hen egg white lysozyme to induce antibody-mediated immune response. Candida albicans was used as an in vivo indicator of cell-mediated immune response, with delayed-type hypersensitivity used as the indicator. Antibody response to hen egg white lysozyme (IgG, IgG1, and IgG2) was measured by ELISA. Calves of both breed groups produced a significant primary and secondary antibody-mediated immune response, as well as a delayed-type hypersensitivity reaction. The Norwegian Red × Holstein produced a greater primary IgG antibody-mediated immune response (d 14, and d 14 minus d 0) when compared with the Holstein. No differences were observed between the breeds for secondary response or anti-hen egg white lysozyme isotype (IgG1 or IgG2) production or the ratio of IgG1:IgG2. There was no effect of breed on delayed-type hypersensitivity. Nonetheless, high and low immune responders could be identified in both breed groups, but with no difference in the proportion of high and low responders observed for either antibody-mediated immune response or cellmediated immune response between breed groups.

The objective of the study was to characterize body growth, testicular development, and puberty from 8 to 14 mo of age in bulls (n = 120) produced by mating sires from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu breeds to MARC III (¹⁄₄ Hereford, ¹⁄₄ Angus, ¹⁄₄ Red Poll, and ¹⁄₄ Pinzgauer) cows. Traits evaluated were birth weight, weaning weight (at 215 d), yearling weight, ADG from 8 to 14 mo of age, paired testicular volume growth from 8 to 14 mo of age, age at puberty (determined by production of 50 × 10 6 sperm with 10% motility), age at freezable semen (determined by production of 500 × 10 6 sperm with 50% motility), and, at 15 mo of age, paired testicular weight and daily sperm production per testis pair. There was an effect of sire breed (P = 0.03) for age at puberty; animals with Wagyu and Swedish Red and White inheritance reached puberty at a later date (302 and 302 d of age, respectively) compared with Angussired bulls (268 d). Age at puberty for Hereford-, Norwegian Red-, and Friesian-sired bulls was 270, 271, and 278 d, respectively. Differences in BW were observed (P = 0.03) at birth; bulls with Hereford and Friesian

The traditional distinction between active and passive euthanasia requires critical analysis. The conventional doctrine is that there is such an important moral difference between the two that, although the latter is sometimes permissible, the former is always forbidden. This doctrine may be challenged for several reasons. First of all, active euthanasia is in many cases more humane than passive euthanasia. Secondly, the conventional doctrine leads to decisions concerning life and death on irrelevant grounds. Thirdly, the doctrine rests on a distinction between killing and letting die that itself has no moral importance. Fourthly, the most common arguments in favor of the doctrine are invalid. I therefore suggest that the American Medical Association policy statement that endorses this doctrine is unsound. (N Engl J Med 292:78-80, 1975)