New mechanisms for chemistry at surfaces

It is becoming increasingly apparent that chemistry at surfaces, whether it be heterogeneous catalysis, semiconductors etching, or chemical vapor deposition, is controlled by much more than the nature and structure of the surface. Recent experiments that principally make use of molecular beam techniques have revealed that the energy at which an incident molecule collides with a surface can be the key factor in determining its reactivity with or on the surface. In addition, the collision energy of an incident particle has proven essential to the finding of new mechanisms for reaction or desorption of molecules at surfaces, collision-induced activation and collision-induced desorption. These phenomena are often responsible for the different surface chemistry observed under conditions of high reactant pressure, such as those present during a heterogeneous catalytic reaction, and of low pressure of reactants (< 10(-4) torr), such as those present in an ultrahigh vacuum surface science experiment. This knowledge of the microscopic origins of the effect of pressure on the chemistry at surfaces has allowed the development of a scheme to bypass the high-pressure requirement. Reactions that are normally observed only at high reactant pressures, and which are the ones most often of practical importance, can now be carried out in low-pressure, ultrahigh vacuum environments.     

Calving patterns in seasonal dairy herds

Two field studies examined the calving patterns of cows in seasonal dairy herds in the Waikato (Field Study 1) and South Taranaki regions (Field Study 2). The first study examined patterns for cows commencing their second or subsequent lactation in herds which had used an inseminating service during the previous season. The second study included first lactation heifers only in 15 herds where animals had been naturally mated, and in 15 herds in which they had been synchronised and then artificially inseminated at the synchronised oestrus. The parameters describing calving patterns were based on the date for each herd's planned start of calving (PSC), which was 282 days from the date on which breeding commenced in the preceding season. The average interval from PSC to mean calving date for the 35 herds in Field Study 1 was 22 days, with individual herds ranging from 15 to 30 days. In herds with heifers which had been naturally mated (Field Study 2), it was 17.6 days compared to 11.0 days for previously synchronised animals. Calculating the intervals from PSC to median calving date and separately for the last two quartiles more effectively described a herd's calving pattern. The duration for the last quartile of the calving pattern was influenced by the extent and timing of induced calving. In Field Study 1, 88.6% of the 35 herd owners induced premature parturition in at least one cow. In these herds, 11.3% of cows were treated and calved prematurely. Only 61.7% of heifers which had previously been naturally mated calved by 3 weeks after PSC. Their calving dates were not evenly distributed over this 3-week period, with 9.8% in the first week and 25.6% in the third week. The calving pattern for heifers which had been previously synchronised showed several distinct peaks. Calvings to the synchronised mating were completed 15 days after PSC, by which time 64.7% of animals had calved. By 3 weeks after PSC, 72.9% of these heifers had calved. The results showed that there was considerable variation in calving patterns in seasonal dairy herds. This variation would have been due to differences in conception pattern, and the way induced calving had been applied. The calving pattern in heifers which had been naturally mated was less concentrated than had been expected. Synchronisation can significantly concentrate the calving pattern of these first lactation animals. The parameters used to describe calving patterns may be less applicable in herds in which a high proportion of animals is induced to calve prematurely, or where a whole herd is synchronised. Nonetheless, they do serve as an illustrative example of the variation in calving patterns among herds.     

Teaching animal welfare in the land grant universities

Colleges and universities have an obligation to teach the basis of animal husbandry and welfare and must prepare students so that they can respond effectively to challenges by proponents of the animal welfare and animal rights movements. Veterinary curricula must now contain formal instruction in professional ethics and humane stewardship of animals for accreditation by the American Veterinary Medical Association. It is helpful if students have an understanding of farm animal behavior, stress physiology and methods of assessing welfare prior to learning about the animal welfare/rights movement's philosophies and issues. A review of early judicial practices, "classical" Judeo-Christian philosophy, the philosophy of Rene Descartes, Jeremy Bentham, Albert Schweitzer, and current philosophers and the entertainment media places the movements in perspective. Students should be familiar with such concepts as the mind-body controversy, equality of suffering, self-awareness or intelligence, and speciesism. After acquiring an appreciation of the basics, a knowledge of the issues facing animal agriculture and the arguments for and against each issue are necessary. Graduates of colleges of agriculture need to realize the potential effects the movements can have and take the initiative to improve the image of animal agriculture.