Effects of breed and production system on lameness parameters in dairy cattle

The aim of the present study was to assess the effects of Holstein-Friesian (HF) and Norwegian (N) dairy cattle genotypes on lameness parameters in dairy cattle within different production systems over the first 2 lactations. Following calving, HF (n = 39) and N (n = 45) heifers were allocated to 1 of 3 systems of production (high level of concentrate, low level of concentrate, and grass-based). High-and low-concentrate animals were continuously housed indoors on a rotational system so that they spent similar amounts of time on slatted and solid concrete floors. Animals on the grass treatment grazed from spring to autumn in both years of the study, so that most animals on this treatment grazed from around peak to late lactation. Claw health was recorded in both hind claws of each animal at 4 observation periods during each lactation as follows: 1) -8 to 70 d postcalving, 2) 71 to 150 d postcalving, 3) 151 to 225 d postcalving, and 4) 226 to 364 d postcalving. Sole lesions, heel erosion, axial wall deviation, sole length of the right lateral hind claw (claw length), right heel width, and right lateral hind heel height were recorded as well as the presence of digital dermatitis. The N cows had lower (better) white line and total lesion scores than HF cows. Cows on the high-and low-concentrate treatments had better sole and total lesion scores than cows on the grass treatment. The HF cows had better locomotion scores than N cows. Breed and production system differences were observed with respect to claw conformation, including claw length, heel width, and heel height. Digital dermatitis was associated with worse sole lesion scores and interacted with production system to influence white line lesion scores and maximum heel erosion scores. This study shows that genetic, environmental, and infectious factors are associated with hoof pathologies in dairy cows.

Strength and permeation properties as an indicator of durability of concrete

Durability of concrete is a great concern to all designers, owners and users of reinforced concrete structures. As a result, more restrictive regulations are being introduced in various Codes of Practice dealing with the design of these structures. Attempts are being made by various researchers to develop performance based specification. For this to be successful standard non destructive tests are required which will be used to assess the durability of concretes. In parallel with this approach, a research team in Queen’s University Belfast, U. K., investigated the effect of different mix parameters on workability, strength and various permeation properties. Furthermore, durability parameters such as freeze-thaw salt scaling resistance and carbonation depth were also investigated. The research was part funded by the Department of Environment, Transport and the Regions (DETR). This paper reports of the findings from this study. The results from this investigation showed that some of the non destructive tests used were reasonably well correlated with carbonation and freeze-thaw salt scaling resistance of CEM I concrete. If the mix parameters such as aggregate-cement ratio or water-cement ratio are known, better correlation can be obtained. Further investigation is required varying other mix parameters including various aggregates, admixtures and air entrainments before the result can be used for developing mix design methods for durable concretes. Also long term site tests are required to validate the results obtained from the accelerated laboratory tests used to study the carbonation resistance and freeze-thaw salt scaling resistance.