Hot topic: Management of cull dairy cows-Consensus of an expert consultation in Canada.

Many cull dairy cows enter the marketing system and travel to widely dispersed and specialized slaughter plants, and they may experience multiple handling events (e.g., loading, unloading, mixing), change of ownership among dealers, and feed and water deprivation during transport and at livestock markets. The objectives of this study were to describe the diverse management of cull dairy cows in Canada and establish consensus on ways to achieve improvements. A 2-day expert consultation meeting was convened, involving farmers, veterinarians, regulators, and experts in animal transport, livestock auction, and slaughter. The 15 participants, recruited from across Canada, discussed regional management practices for cull cattle, related risk factors, animal welfare problems, and recommendations. An audio recording of the meeting was used to extract descriptive data on cull cattle management and identify points of agreement. Eight consensus points were reached: (1) to assemble information on travel times and delays from farm to slaughter; (2) to increase awareness among producers and herd veterinarians of potential travel distances and delays; (3) to promote pro-active culling; (4) to improve the ability of personnel to assess animal condition before loading; (5) to identify local options for slaughter of cull dairy cows; (6) to investigate different management options such as emergency slaughter and mobile slaughter; (7) to ensure that all farms and auctions have, or can access, personnel trained and equipped for euthanasia; and (8) to promote cooperation among enforcement agencies and wider adoption of beneficial regulatory options.

Distribution of atrophy in the nasal ventral conchae of piglets infected experimentally with Bordetella bronchiseptica.

The distribution and extent of atrophy caused by Bordetella bronchiseptica in the nasal ventral conchae were investigated by intranasally infecting piglets at day 4 of life. Experimental and control piglets were killed at one, two, three, four, five and six weeks of age. Serial transverse 80 microns thick nondecalcified sections were cut throughout the entire length of the nasal ventral conchae, and microradiographed. It was observed that the distribution and extent of atrophy was not uniform along the ventral conchae. The articular and transverse laminae as well as the connecting zone were not atrophied, except at their rostral extremity. The entire dorsal scroll was atrophied. This atrophy was moderate, except at the rostral and caudal extremities of the dorsal scroll, where its size was less than half that of the controls. The ventral scroll was less atrophied than the dorsal scroll, although a marked atrophy was present at its rostral extremity. From these observations, it is suggested that two transverse sections should be made through the nose of pigs in order to establish a diagnosis of atrophic rhinitis at slaughter: one section at the level of the first-second premolar tooth and one more rostral section, at the level of the canine tooth.

Histological changes in the nasal ventral conchae of piglets infected with Bordetella bronchiseptica.

Piglets infected intranasally with Bordetella bronchiseptica were injected with two fluorochrome markers. Transverse sections of undecalcified nasal conchae (cut between the third incisor and the third premolar teeth) were examined by microradiography and fluorescence microscopy; surface-stained sections were evaluated by light microscopy. The fluorescent surface of the nasal ventral conchae from the infected piglets was increased as compared with the controls. This was due to an increased amount of fluorescent mineralization fronts as well as to the presence of abnormal fluorescent areas within trabeculae. Trabecular mineral content of the microradiographs was irregular and varied from hypo- to hypermineralized. When compared with the corresponding surface-stained sections, no correlation could be made between the mineral content and the type of tissue. These findings suggest that an increased number of osteoblasts which secrete prebone matrix but are modified so that mineralization does not occur normally.

Distribution of the mineralized tissues in the nasal ventral conchae (os conchae nasalis ventralis) of piglets after birth: relationship with atrophic rhinitis.

Serial undecalcified cross sections were examined in order to establish the distribution of calcified cartilage, woven and lamellar bones in the nasal ventral conchae of piglets aged between birth and six weeks. The distribution of the mineralized tissues varied according to the age of the piglets and to the level of cross sections. The nasal ventral conchae were found to arise from an ossification center located at the level of the second premolar tooth. A correlation between the distribution of the different mineralized tissues of the nasal ventral conchae and the distribution of the lesions of atrophic rhinitis in the nasal ventral conchae as well as the receptivity period of piglets to the disease as observed in the literature have been discussed.