BackgroundIsolated syndactyly in cattle, also known as mulefoot, is inherited as an autosomal recessive trait with variable penetrance in different cattle breeds. Recently, two independent mutations in the bovine LRP4 gene have been reported as the primary cause of syndactyly in the Holstein and Angus cattle breeds.ResultsWe confirmed the previously described LRP4 exon 33 two nucleotide substitution in most of the affected Holstein calves and revealed additional evidence for allelic heterogeneity by the identification of four new LRP4 non-synonymous point mutations co-segregating in Holstein, German Simmental and Simmental-Charolais families.ConclusionWe confirmed a significant role of LRP4 mutations in the pathogenesis of congenital syndactyly in cattle. The newly detected missense mutations in the LRP4 gene represent independent mutations affecting different conserved protein domains. However, the four newly described LRP4 mutations do still not explain all analyzed cases of syndactyly.

MudroÀ P., J. Rehage, H. P. Sallmann, M. Höltershinken, H. Scholz: Stress Response in Dairy Cows Related to Blood Glucose. Acta Vet. Brno 2005, 74: 37-42.The aim of this study was to investigate whether different pre-surgical blood glucose concentrations have any effect on the course of cortisol and metabolic responses to surgical stress in dairy cows. Eighteen Holstein-Friesian dairy cows, admitted for treatment of left abomasal displacement (omentopexy), were used in the study. Abdominal surgery (the stressor) was performed in the standing position 16 -24 h after admission and lasted approximately 60 min. Blood samples were drawn from the jugular vein prior to surgery, immediately after and then 2, 5, 24, and 72 h after surgery. In order to test the effect of the different blood glucose levels on stress responses the experimental animals were allocated to two groups: 1) six hypoglycaemic cows (glucose < 2.4 mmol/l); 2) twelve normoglycaemic cows. Surgery increased blood glucose in both groups (p < 0.001), however, the glucose rise was less distinct in the hypoglycaemic cows. The surgical stress resulted in a significant increase in plasma cortisol concentrations in both groups (p < 0.001), however there was no difference in cortisol responses between the groups. Similarly, surgery enhanced the blood concentrations of free fatty acids (FFA) and L (+)-lactate in both groups (p < 0.001). In contrast, β-hydroxybutyrate concentrations slightly declined after surgery. On the basis of this study there appears not to be any effect of different plasma glucose on the cortisol and metabolite responses in stressed dairy cows. Therefore, it can be concluded that mechanisms regulating peripheral cortisol concentrations, and thus the animal stress response, are more dependent on the intensity of the stressful stimulus than on the energetic status of animal.

Dairy cows develop frequently negative energy balance around parturition and in early lactation, resulting in excessive mobilization of body fat and subsequently in increased risk of ketosis and other diseases. Dietary conjugated linoleic acid (CLA) supplements are used in dairy cows mainly for their depressing effect on milk fat content, but are also proposed to have antioxidative properties. As negative energy balance is associated with oxidative stress, which is also assumed to contribute to disease development, the present study was conducted to examine effects of CLA on oxidative and antioxidative status of lactating dairy cows. German Holstein cows (primiparous n=13, multiparous n=32) were divided into 3 dietary treatment groups receiving 100g/d of control fat supplement, containing 87% stearic acid (CON; n=14), 50g/d of control fat supplement and 50g/d of CLA supplement (CLA 50; n=15), or 100g/d of CLA supplement (CLA 100; n=16). The CLA supplement was lipid-encapsulated and contained 12% of trans-10,cis-12 CLA and cis-9,trans-11 CLA each. Supplementation took place between d1 and 182 postpartum; d 182 until 252 postpartum served as a depletion period. Blood was sampled at d -21, 1, 21, 70, 105, 140, 182, 224, and 252 relative to calving. The antioxidative status was determined using the ferric-reducing ability of plasma, α-tocopherol, α-tocopherol-to-cholesterol mass ratio, and retinol. For determination of oxidative status concentrations of hydroperoxides, thiobarbituric acid-reactive substances (TBARS), N'-formylkynurenine, and bityrosine were measured. Mixed models of fixed and random effects with repeated measures were used to evaluate period 1 (d -21 to 140) and 2 (d182-252) separately. Cows showed increased oxidative stress and lipid peroxidation during the periparturient period in terms of increased serum concentrations of hydroperoxides and TBARS, which decreased throughout lactation. During period 1, the supplemented cows had lower TBARS concentrations, which was not detectable in period 2. The other determined parameters were not affected by CLA supplementation. The obtained results show that dietary CLA supplementation in the chosen dosage, formulation, and application period had a marginal antioxidative effect in terms of lipid peroxidation in lactating dairy cows.

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