Effects of livestock breed and grazing intensity on biodiversity and production in grazing systems. 4. Effects on animal diversity

Finding an optimal balance between livestock production and grazing impact on animal diversity is important for the development of sustainable grazing systems. This paper tests the hypothesis that extensification of grazing management enhances animal diversity. Similar treatments were applied over a period of three years to sites in the UK, France, Germany and Italy. There were three treatments at each site: moderate grazing intensity with a commercial breed (MC), lenient grazing intensity with a commercial breed (LC) and lenient grazing intensity with a traditional breed (LT). Animal diversity was studied at the species level for birds, hares, butterflies and grasshoppers, and at higher taxonomic level for ground-dwelling arthropods. Bird and hare numbers were low and showed no overall treatment effects. Species richness and abundance of butterflies and grasshoppers were higher for treatment LC than for treatment MC, both for species preferring short open grasslands and those preferring tall grasslands. There was no difference in the impact of commercial or traditional breeds. Most ground-dwelling arthropod groups did not show consistent treatment effects but some taxa showed site-specific responses, generally indicating a greater abundance at lenient grazing intensity. Overall, the study showed that lenient grazing intensity enhanced animal diversity on grasslands at a small scale within 3 years. By comparison, the effect of livestock breed differences was negligible. Follow-up research is needed to elucidate the processes leading to increased biodiversity in patch mosaics and to establish the generality of these findings at larger spatial scales and longer time scales.     

Rapid estimation of the amylose/amylopectin ratio in small amounts of tuber and leaf tissue of the potato

Summary Small amounts of potato tuber and leaf tissues are extracted in perchloric acid. After staining with I₂-KI solution absorbancies at 618 and 550 nm are measured. The amylose/amylopectin ratio can be estimated from the ratio of the absorbancies by using a formula or a graph in which the specific absorptions of the two compounds are introduced. Weighing of samples is not required. The method can be used for the estimation of the starch composition of minitubers and is especially suitable for the detection of mutants with an altered starch composition.     

Maxillary Granulomatous Inflammation Caused by Halicephalobus gingivalis (Nematoda) in a Connemara Mare in Belgium

A 5-year-old anorexic and lethargic Connemara mare presented with severe facial swelling and dyspnea. No distinct central nervous symptoms were present. Radiographs of the skull showed diffuse radiolucency with loss of definition of the periodontal lamina dura and swelling of the decalcified nasal bones. Given the severe bone damage and its poor general condition, the pony was euthanized. Histological evaluation of the lesion revealed a granulomatous reaction with numerous sections of adult and juvenile nematodes, which were morphologically and molecularly identified as Halicephalobus gingivalis. The position of this facultative parasite within its free-living congeners is reviewed in this article, and the possible infection routes are discussed. This report presents the first record of equine halicephalobiasis in Belgium.     

Crimidine (2‐chloro‐4‐(dimethylamino)‐6‐methylpyrimidine) poisoning in a dog due to ingestion of the rodenticide Castrix®

The diagnosis and treatment of a case of crimidine poisoning in a dog are described. Presenting signs were seizures and vomiting. The vomitus contained a purple coloured cereal grain. The signs and grain colour were suggestive for a rodenticide with convulsive effects The diagnosis of crimidine poisoning was made by thin layer chromatography and was later confirmed by finding the source of the poison. Except for the administration of Vit B6, the specific antidote for crimidine, general treatment principles for poisoning were followed. The treatment of crimidine poisoning is time consuming and requires intensive care facilities.     

Serological detection of chicken flocks naturally infected with salmonella enteritidis,using an enzyme‐linked immunosorbent assay based on monoclonal antibodies against the flagellar antigen

Summary

The Dutch Salmonella enteritidis monitoring and eradication programme for poultry prescribes a periodic examination of all breeding flocks for the presence of S. enteritidis. For the first years of the programme this was done by bacteriological examination of 50 faecal samples per visit per flock.

In this study we compare the results of bacteriological examination of faecal samples taken at 1580 visits from 545 flocks with those of a S. enteritidis enzyme‐linked immunosorbent assay (ELISA) applied on 24 serum samples per visit per flock. Two flocks were found positive for S. enteritidis by bacteriological examination; both flocks were also detected by ELISA. Ten flocks, bacteriologically negative for S. enteritidis were found positive by ELISA. S. enteritidis was isolated from three of these flocks by repeated and extensive bacteriological examination for verification. Verification was not possible in the fourth EL1SA positive flock. S. enteritidis infections were likely in three other flocks because of the farm histories.

On the basis of the results of this study it was decided to use this ELISA, starting from April 1992, as screening technique in the Dutch S. enteritidis programme instead of bacteriological examination of faecal samples. The ELISA is regarded as a flock test; an extensive, confirmatory bacteriological investigation for S. enteritidis is carried out in ELISA positive flocks to decide whether the flocks are truly infected.     

Effect of pasteurella multocida toxin on in vivo immune responses in piglets

Summary

Atrophic rhinitis is characterized by a lack of an immune response towards Pasteurella multocida toxin (Pm‐T). The effects of intranasal administration of Pm‐T on cellular and T‐cell dependent antibody responses of piglets against various other antigens were studied in a 3 by 2 factorial arrangement of treatments: three levels of challenge with Pm‐T (either once; on three consecutive days; or no Pm‐T challenge), and with or without simultaneous immunization with a ‘cocktail’ containing Keyhole limpet haemocyanin (KLH), ovalbumin (OA) and tetanus toxoid (TT). Challenge with Pm‐T affected but did not abolish the in vivo humoral immune response against OA, KLH, or TT. Pigs treated once with Pm‐T showed lower total antibody responses, caused by lower IgG responses to the antigens. We found no clear consistent effects of Pm‐T on cellular immune responses to the various T‐cell‐dependent antigens in vitro. The lack of immune responsiveness to Pm‐T in Pm‐T challenged pigs is discussed. The absence of detectable immune responses does not depend on a general suppression of the cellular immune system.     

Natural antibodies related to metabolic and mammary health in dairy cows

Natural antibodies (NAb) are defined as antibodies that circulate in normal healthy individuals under the absence of deliberate antigenic stimulation. Two types of NAb are distinguished: NAb towards exogenous antigens and NAb towards autoantigens (N(A)Ab). The objectives of the current study were threefold. First, we studied the relation between metabolic health and concentrations of NAb binding keyhole limpet hemocyanin (KLH) or lipopolysaccharide (LPS) in milk and plasma of dairy cows in early lactation. Second, we determined the presence of N(A)Ab binding transferrin, myosin and thyroglobulin in bovine milk. Third, we studied the relation between N(A)Ab in bovine milk and mammary health. For the first objective, dairy cows were either fed a control (C) (n = 8) or a diet where 2 kg of concentrates were replaced by an iso-energetic concentrate containing marine algae (ALG) from week −3 till 8 postpartum (experiment 1). Plasma and milk samples were analyzed weekly for NAb binding either KLH or LPS. Plasma was analyzed for glucose, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA). For the second and third objective, milk samples were collected weekly from 96 dairy cows from week 2 till 9 postpartum and analyzed for milk composition and N(A)Ab binding myosin, transferrin and thyroglobulin (experiment 2). For both datasets, N(A)Ab titers are expressed as ²log values of the highest dilution giving a positive reaction. Data are expressed as means ± SEM. Repeated observations were analyzed in a mixed model. In experiment 1, no diet effect (P > 0.05) was observed on NAb binding LPS in plasma or milk, NAb binding KLH in milk was greater (P = 0.05) for cows fed the control diet. Concentration of NAb binding KLH and LPS in plasma was negatively related to plasma NEFA concentration (P < 0.05). In experiment 2, NAb binding myosin (5.66 ± 0.06), thyroglobulin (4.85 ± 0.06), and transferrin (5.76 ± 0.07) were identified in milk. Clinical mastitis incidence (9%) tended to be positively related to concentration of NAb binding myosin (P = 0.06) and negatively related to Nab binding transferrin (P = 0.08). In conclusion, NAb binding KLH and LPS in plasma and milk are related to metabolic health, as indicated by plasma NEFA concentration. Furthermore, this study demonstrates the presence of N(A)Ab in bovine milk and shows trends for a relation between N(A)Ab binding auto-antigens and mastitis. Future studies should confirm these trends and shed light on the predictive value of N(A)Ab in bovine milk for mammary health.     

Toxicodynamics of malaoxon in house flies

The fate of malaoxon was studied in a susceptible and a resistant strain of house fly following topical application. Sublethal doses were used: 160 pmol for the S-strain (0.17 × LD₅₀) and 1570 pmol for the R-strain (0.1 × LD₅₀). The penetration rates are dose dependent and semilog plots of the external amount vs time show that these rates are not proportional to this external amount. Internal concentrations of malaoxon rapidly increase following administration, reach maximum values between 30 min and 2 hr (depending on dose), and then slowly decrease. The rate of metabolic degradation is highest in the early stage of the intoxication process. A three-compartment pharmacokinetic model is postulated to explain the experimental data quantitatively. The first compartment represents external malaoxon, the other two represent internal parent compound. Statistical analysis shows that the penetration rate is better described with a sum of two exponentials rather than with a single exponential decay. In the model, degradation occurs in the first internal compartment and is assumed to be first order. Malaoxon is distributed between the two internal compartments slowly with first-order kinetics. Parameter estimation with curve-fitting procedures for the internal processes (degradation and exchange) shows that there is not one set of parameter values that can be used for both strains simultaneously. This prompted a study of possible interstrain differences in degradation capacities. It was found that in vitro the R-strain had a fourfold higher oxidative breakdown rate of malaoxon. Taking this difference into account it is possible to explain the two sets of data with one kinetic model, although other alternatives cannot be excluded.