Thiamine deficiency in sheep exported live by sea

The welfare of livestock transported by ship

The transport of livestock by ship is growing in importance, but there are concerns about the welfare impact on the animals. Short sea journeys are usually completed in the vehicles that are used to transport the animals by road, and injury and stress can result. Long sea journeys require offloading of the animals into pens, where they are mixed and provided with feed, water and sometimes artificial ventilation. In addition, animals are often exposed to high stocking densities, elevated temperature and ammonia concentration, as well as noise and changes in photoperiod and light intensity. Mortality rate is the main measure of welfare used by the Australian live export industry for long distance shipments, and the rate is higher at sea compared to the same period of transport on land. Heat stress often challenges livestock when they are transported from cold to hot regions at high stocking densities with no diurnal temperature fluctuation. Sheep cope with heat stress better than cattle, but can still develop respiratory alkalosis if hyperventilation ensues. Bos taurus cattle cope less well with heat stress than Bos indicus breeds. High ammonia concentrations may accumulate on long voyages, causing mucosal irritation and pulmonary inflammation. Some sheep and goats do not adapt to the pellets provided after extensive grazing in Australia, resulting in inanition, often in combination with salmonellosis, which together are the main cause of high mortality rates. Long distance transport may also result in disease transmission to the recipient country and high standards of biosecurity are necessary. It is concluded that there are significant risks to the welfare of livestock caused by transporting them in ships, especially over long distances.

Faecal thiaminase, plasma lactate and pyruvate concentrations and erythrocyte transketolase activity changes in apparently normal replacement ewes after the initiation to the pasture

A study was made to investigate faecal thiaminase and the thiamine-related biochemical changes in apparently normal replacement ewes with a feed change, after the initiation without adaptation to the new pasture. Twenty-four female ewes were divided into two groups. Group A was managed in a system based on pasture and was compared with group B system based on a diet of concentrate and straw until moving to pasture 9 weeks after. Blood samples for lactate, pyruvate and erythrocyte transketolase activity determinations and faeces for thiaminase estimation were evaluated chronologically. At the end of a 126 days experimental period, live weights of groups were similar. We confirmed that clinically normal sheep may have thiaminase activity in the faeces and concluded that the thiaminase release increased during the diet changes, from concentrate to pasture, and that their continued excretion could develop some degree of thiamine deficiency.

Biochemical changes in apparently normal sheep from flocks affected by polioencephalomalacia

Blood samples were obtained for determination of the activities of lactate, pyruvate and erythrocyte transketolase, and faeces as samples for estimation of thiaminase, from 190 apparently healthy sheep from 19 flocks in which at least one animal had been diagnosed with polioencephalomalacia (PEM), from 59 control animals and from 7 affected by PEM. Feed and pasture grass samples were collected for thiaminase analysis and thiaminase was assayed in ryegrass and fescue. Decreased erythrocyte transketolase activity, accompanied by a corresponding rise in the thiamin pyrophosphate effect, and estimation of the thiaminase content in faeces, may be useful diagnostic procedures by which to identify periods of greater risk, during which animals could develop PEM. The changes in the diet probably acted as a primary factor for microbial production of thiaminases in replacement ewes. In these, the prevalence was higher in the spring months.