Exploring the landscape of livestock 'Facts'.

The role of livestock in supporting human well-being is contentious, with different perceptions leading to polarised opinions. There is increasing concern about the health and environmental impacts of a high rate of consumption of livestock products in high-income countries. These concerns are heightened by an increase in consumption in middle-income countries. On the other hand, livestock support the livelihoods of many people, particularly in low income countries. The benefits of livestock for poor livestock keepers are multiple, including the important role livestock play in supporting crop production in mixed systems, in supplying nutrients and income, and in fulfilling cultural roles. In addition livestock can provide resilience against economic and climate shocks. In view of these apparent positive and negative impacts, the role of livestock in human wellbeing is highly contested, with arguments 'for' or 'against' sometimes distorted by vested interests or misinterpretation of evidence. The Livestock Fact Check project, undertaken by the Livestock Data for Decisions community of practice, has investigated several ideas concerning livestock commonly taken as 'fact'. By exploring the provenance of these 'facts' we highlight their importance and the risks of both misinterpreting them or using them out of context. Despite the diversity of the livestock sector resulting in equally diverse viewpoints, the project calls for participants in the livestock discourse to adopt a nuanced appreciation of global livestock systems. Judgement of livestock's role in global sustainable diets should be based on clear and well-interpreted information.

The specificity of antibody responses in cattle naturally exposed to Fasciola hepatica.

Fasciola hepatica causes significant morbidity and mortality in dairy cattle in the Andean region of Cajamarca, Peru, where prevalence of infection of up to 78% has been reported. ELISA and Western blot analyses were used to characterise antibody responses in dairy cattle to adult F. hepatica to excretory-secretory (E/S), somatic (SO) and surface (SU) antigens. Three groups of dairy cattle - calves, heifers and adult cows - naturally exposed to F. hepatica in this region, were monitored every 2 months over a 2-year period. Calves, heifers and adult cows all had antibodies which recognised a 28kDa protein in the SO preparation, whereas only adult cows had antibodies that recognised a 28kDa protein in E/S products. All three groups of cattle responded to a 60-66kDa group of proteins in E/S and SU preparations and a 17kDa antigen in SO products was recognised by antibodies from cows and heifers but not calves. The total antibody response to E/S antigens measured by ELISA, increased over time in calves and remained constantly high over the 2-year period in all three groups of cattle. Slight fluctuations in the antibody response occurred in the group of heifers and cows coinciding with seasonal changes in the level of challenge.

The effect of cyclic temperatures on the growth of Fasciola hepatica and Lymnaea viatrix.

The experiment aimed to measure the effect of constant and variable temperatures on the growth of Lymnaea viatrix snails, on the development of a Peruvian isolate of Fasciola hepatica eggs and on the development of F. hepatica in the snails. This was carried out by cultivating infected and uninfected snails and fluke eggs in artificial, temperature controlled chambers. L. viatrix snails were found to develop at a rate dependent on environmental temperature, but developed at least as well under conditions of varying temperature as at the same mean constant temperature. F. hepatica eggs held at constant or varying temperatures, developed at a rate comparable to other reports. However, eggs developing at varying temperatures appeared to have reduced hatchability. Parasite development within the snails was slow, though within the limits calculated from the literature, and varying temperature did not appear to reduce development compared to constant temperatures.

Strategic control of fasciolosis in the inter-Andean valley of Cajamarca, Peru.

Fasciolosis is recognised as a major problem in dairy cattle in Cajamarca, Peru. The infection has an annual cycle, with the major period of infection from January to March. A control programme, involving two doses of the fasciolicide triclabendazole aimed at reducing the passage of Fasciola hepatica eggs on to the pasture, together with the use of the molluscicide, niclosamide, was evaluated against traditional treatment programmes. The double treatment regimen did not significantly reduce the overall parasite burden, as measured by faecal egg counts, but did control the parasites to a level similar to that achieved by traditional programmes averaging 3-7 treatments per year. The cows' eosinophil counts and serum liver enzyme activities were significantly lower than in animals treated by the traditional programmes. The use of niclosamide in addition to the triclabendazole treatments gave no clear advantage, although there was a significant reduction in the number of intermediate host snails after the application of the molluscicide.

Haematological parameters in brown Swiss and Holstein cattle at high altitude.

Standard haematological values have been calculated for female Holstein and Brown Swiss cattle kept at high altitudes in the Andean Sierra. Overall mean values were 5.9 x 10(12) l-1 for the red cell count, 0.321 l-1 for the packed cell volume, 9.6 gdl-1 for the haemoglobin concentration, 55.0 femtolitres for the mean corpuscular volume, 30.5 gdl-1 for the mean corpuscular haemoglobin concentration and 16.7 pg for mean corpuscular haemoglobin. Red cell indices tended to be higher in Holstein cattle than in Brown Swiss kept at the same altitude and were higher in cattle kept at higher altitudes. Mean white cell parameters were 9.7 x 10(9) l-1 for total white cells, 2.6 x 10(9) l-1 for neutrophils, 0.086 x 10(9) l-1 for bands, 6.3 x 10(9) l-1 for lymphocytes, 0.7 x 10(9) l-1 for eosinophils, 0.073 x 10(9) l-1 for monocytes and 0.001 x 10(9) l-1 for basophils.

Comparative study of trypanosomosis in zebu and N'Dama cattle in The Gambia.

An experiment was conducted in The Gambia to compare trypanosomosis incidence between zebu and N'Dama cattle. It was considered important to compare the 2 breeds under identical management conditions and the animals were maintained together at 3 locations, traditionally managed and under a range of tsetse challenges. The results show that trypanosomosis incidence was significantly higher in zebu than in N'Dama. Titre of antibody against Trypanosoma vivax measured by an IFAT showed a significant difference between zebu and N'Dama. Variations in packed cell volume were greater in zebu than in N'Dama.

Trypanosome infections in warthogs (Phacochoerus aethiopicus) in the Gambia.

The prevalence of trypanosome infections in warthogs (Phacochoerus aethiopicus) in The Gambia was found to be 11% of a sample of 62 animals. All isolates were identified as Trypanosoma simiae. Serological evidence indicated a higher level of exposure to T. simiae, but results were inconclusive for the presence of Trypanosoma congolense. The course of T. simiae infection in warthog piglets showed a rapidly rising parasitaemia, with a concomitant fall in packed cell volume, and resulted in a prolonged period of low-level parasitaemia. The same infections killed domestic piglets.

Trypanosomiasis in cattle in Gambia: incidence, prevalence and tsetse challenge.

The incidence of trypanosome infections, measured by a Berenil Index in experimental herds of 10 Zebu and 10 N'Dama cattle, was compared with tsetse challenge and with the prevalence of parasitaemia in local N'Dama at three villages in Gambia. Tsetse challenge was more strongly correlated with the incidence of parasitaemia in the Zebu than in the N'Dama. There was a strong correlation between prevalence and incidence of infection in the N'Dama. There was no correlation, however, between prevalence of infection in cattle and tsetse challenge unless the data were offset by 3-5 months. The Berenil Index in the Zebu increased at about twice the rate as in the N'Dama under corresponding levels of challenge. It is concluded that whereas incidence of infection in susceptible animals is best measured independently, it can, under stable conditions, be inferred from an assessment of tsetse challenge.