The local threshold for geographical spread of infectious diseases between farms.

We investigated the influence of the spatial pattern of farms on the geographical spread of infectious livestock diseases, such as classical swine fever, foot-and-mouth disease and avian influenza in a combined analytical-numerical approach. Our purpose of this paper is to develop a method to identify the areas in which an infection has the potential to spread in an outbreak. In our model, each infected farm can infect neighbouring farms and the probability of transmission is a function of the inter-farm distance (spatial kernel).

Vitamin and trace mineral content in feed of breeders and their progeny: effects of growth, feed conversion and severity of malabsorption syndrome of broilers.

1. A study was conducted to investigate the effects of several vitamins and trace elements chickens and in chickens experimentally infected with malabsorption syndrome (MAS). 2.

Selection against genetic defects in conservation schemes while controlling inbreeding.

We studied different genetic models and evaluation systems to select against a genetic disease with additive, recessive or polygenic inheritance in genetic conservation schemes. When using optimum contribution selection with a restriction on the rate of inbreeding (DeltaF) to select against a disease allele, selection directly on DNA-genotypes is, as expected, the most efficient strategy. Selection for BLUP or segregation analysis breeding value estimates both need 1-2 generations more to halve the frequency of the disease allele, while these methods do not require knowledge of the disease mutation at the DNA level.

Lack of association of Mycobacterium avium subsp. paratuberculosis with oocytes and embryos from moderate shedders of the pathogen.

Paratuberculosis is a chronic and progressive disease of the intestine in ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). The bacterium is transmitted to young animals, becomes manifest in adulthood and leads to economic losses.

Robotic milking and its effect on fertility and cell counts.

The aim of this study was to analyze the effect of robotic milking (RM) on fertility and somatic cell counts (SCC) among dairy herds participating in the national Dutch milk recording system. It was hypothesized that RM, and a higher milking frequency in general, would have negative effects on fertility, due to expected and supposed deeper negative energy balance (NEB). Herds increasing milking frequency from two to three times daily consistently had increased production.

Construction of a full-length infectious cDNA clone of swine vesicular disease virus strain NET/1/92 and analysis of new antigenic variants derived from it.

The Dutch swine vesicular disease virus (SVDV) isolate NET/1/92 was one of the first isolates belonging to a new SVDV antigenic group. This strain was completely sequenced and was shown to have 93% similarity with the UKG/27/72 isolate. To enable antigenicity, replication, maturation and pathogenicity studies of NET/1/92, an infectious full-length cDNA clone, designated pSVD146, was prepared.

Robot milking and effect on reproduction in dairy cows: a preliminary study.

The aim of this study was to analyse whether automatic milking has an effect on reproduction in dairy cows. Probably the most important consequence of automatic milking is an increased milking frequency. More frequent milking means more production and thereby an extra threat for the energy balance during the first months of lactation.