Comparison between dual-purpose and specialized dairy cattle in pasture-based systems: change in body condition, locomotion score and cleanliness from summer to winter season

This study is an exploratory research comparing the changes of body condition score, locomotion score and cleanliness score between pasture and indoor season in purebred Dutch Friesian, 75% Dutch Friesian, 50% Dutch Friesian, Holstein Bakels and Brown Swiss dairy cattle. The dual-purpose cows were expected to cope better with a change in season and harsher environmental conditions compared to specialized dairy cows. Therefore it was expected that the body condition of the dual-purpose cows would be closer to the optimum or even higher and would barely change over season. The specialized dairy cows were expected to cope less well on pastures and during a change of season, with a body condition under the optimum, higher prevalence of lameness and more dirt on the skin, compared to the dual-purpose breeds. Twenty-seven Holstein Bakels cows represented the specialized dairy breed in this study. The dual-purpose cows were represented by fifteen Brown Swiss cows and fifty-two purebred and crossbred Dutch Friesian cows. The Holstein Bakels and Brown Swiss cows were kept at a Polish bio-dynamic farm with an open barn housing concept and a low concentrate feed diet. The purebred and crossbred Dutch Friesian cows were housed at one organic and one conventional farm at different locations in the Netherlands. Body condition score was the highest (just above optimal) for the Dutch Friesian cattle compared to all other breeds and the Holstein Bakels and Brown Swiss breed scored the lowest (under the optimal score). A negative correlation between body condition and locomotion score, as well as a positive correlation between body condition and hygiene score was found. This shows that skinny individuals are more prone to lameness, but not necessarily dirtier. Severely fat individuals show less incidences of lameness, however they are more often covered with dirt. Milk yield was the highest for 50% Dutch Friesian, followed by 75% Dutch Friesian and Dutch Friesian, probably due to the amount of Holstein Friesian genes. The Holstein Bakels and Brown Swiss breed underperformed for milk yield. This shows that the dual-purpose breed Dutch Friesian can cope better with harsher environmental conditions of pasture based systems than more specialised dairy breeds like the Holstein Bakels. Furthermore, the Brown Swiss breed could be considered more as a specialized dairy breed than a dual purpose breed. Change over season might be more dependent on housing, feed quality and quantity and management than genotype

Hypersurfaces and the Weil conjectures

We give a proof that the Riemann hypothesis for hypersurfaces over finite fields implies the result for all smooth proper varieties, by a deformation argument which does not use the theory of Lefschetz pencils or the l-adic Fourier transform.Comment: 12 pages; a few trivial correction

Presume It Not: True Causes in the Search for the Basis of Heredity

Kyle Stanford has recently given substance to the problem of unconceived alternatives, which challenges the reliability of inference to the best explanation (IBE) in remote domains of nature. Conjoined with the view that IBE is the central inferential tool at our disposal in investigating these domains, the problem of unconceived alternatives leads to scientific anti-realism. We argue that, at least within the biological community, scientists are now and have long been aware of the dangers of IBE. We re-analyze the nineteenth-century study of inheritance and development (Stanford’s case study) and extend it into the twentieth century, focusing in particular on both classical Mendelian genetics and the studies by Avery et al. on the chemical nature of the hereditary substance. Our extended case studies show the preference of the biological community for a different methodological standard: the vera causa ideal, which requires that purported causes be shown on non-explanatory grounds to exist and be competent to produce their effects. On this basis, we defend a prospective realism about the biological sciences

Magnetic Moments of Baryons with a Heavy Quark

We compute magnetic moments of baryons with a heavy quark in the bound state approach for heavy baryons. In this approach the heavy baryon is considered as a heavy meson bound to a light baryon. The latter is represented as a soliton excitation of light meson fields. We obtain the magnetic moments by sandwiching pertinent components of the electromagnetic current operator between the bound state wave--functions. We extract this current operator from the coupling to the photon field after extending the action to be gauge invariant.Comment: Talk presented by HW at MRST'03 (Joe-Fest), Syracuse, NY, May 2003, 12 pages, uses AIP style files. Ref. adde

The effect of secular resonances in the asteroid region between 2.1 and 2.4 AU

The asteroid region between 2.1 and 2.4 AU appears to be depopulated at inclinations i greater than 12 deg. This region is surrounded by the three main secular resonances nu(sub 5), nu(sub 6), and nu(sub 16) and is crossed by higher order secular resonances. Secular resonances appear to overlap in this region. Numerical integrations of the orbits of seventeen fictituous asteroids with initial inclinations 12 deg less than or equal to i less than or equal to 20 deg show the following: (1) this particular asteroid region is not depopulated in our computer experiment on timescales of 2.7 Myrs; (2) inclinations are pumped up by successive crossings through higher order secular resonances while eccentricities are not increased sufficiently to produce planet-crossers; (3) bodies located in the bordering nu(sub 6) resonance with semi-major axes a less than or equal to 2.4 AU become Earth-crossers on a time scale of 1 Myr; and (4) we confirm the result that modes due to higher order secular resonances must be eliminated when proper elements are computed