Vitamin deficiencies in cattle

Deficiencies of vitamins A, D, K, E and thiamin can cause severe limitations in beef production. In particular, vitamin A and E can be common causes of lost profit, secondary to limitations of reproductive and growth potential. Prolonged dry periods will reduce available A and E in pasture forage, as can ensiling and prolonged storage of harvested feedstuffs. Polioencephalomalacia is a thiamin responsive disorder, associated with high concentrate feeding and lush pastures. Antimetabolites, such as amprolium, will cause thiamine deficiency when fed in excess. Recent information has shown improved performance with supplemental beta carotene and niacin. The positive responses in reproductive performance, noted with cattle fed supplemental beta carotene, was independent of vitamin A. Supplementation of vitamins above National Research Council recommendations can be justified. However, proper evaluation of feed and animal status, and documentation of a response to supplementation is necessary before diagnosing deficiencies of specific nutrients.     

Putative uremic encephalopathy in horses: five cases (1978-1998)

OBJECTIVE: To determine historical, physical examination, clinicopathologic, and postmortem findings in horses with putative uremic encephalopathy. Design-Retrospective study. Animals-5 horses with renal failure and neurologic disease not attributable to abnormalities in any other organ system. PROCEDURE: Medical records from 1978 to 1998 were examined for horses with renal disease and neurologic signs not attributable to primary neurologic, hepatic, or other diseases. Signalment, history, physical examination findings, clinicopathologic data, renal ultrasonographic findings, and postmortem data were reviewed. RESULTS: Of 332 horses with renal disease, 5 met selection criteria. Historical findings, physical examination findings, clinicopathologic data, ultrasonographic data, and postmortem findings were consistent with chronic renal failure. Swollen astrocytes were detected in all 4 horses examined at necropsy. CONCLUSIONS AND CLINICAL RELEVANCE: A single criterion was not determined to be pathognomonic for uremic encephalopathy in horses. Uremic encephalopathy should be considered as a differential diagnosis in horses with evidence of chronic renal failure and encephalopathic neurologic sign not attributable to other causes. Astrocyte swelling, which was common to all 4 horses examined at necropsy, may serve as a microscopic indicator of uremic encephalopathy in horses.     

Phenotypic and histological expression of different genetic backgrounds in interactions between lettuce, wild Lactuca spp., L. sativa × L. serriola hybrids and Bremia lactucae

Phenotypic and histological responses of cultivated lettuce (Lactuca sativa) and wild relatives L. saligna, L.␣virosa as well as interspecific crosses derived from L. sativa × L. serriola to two races of Bremia lactucae (CS2, CS9) were investigated. With the exception of L. sativa genotypes, all accessions and hybrids expressed incomplete or complete resistance to both pathogen races, with slight differences at seedling and adult plant stages, respectively. Histological features of the interactions (development of pathogen infection structures and host hypersensitive response to attempted infection) were studied on leaf discs 48 h after inoculation. Interactions with similar phenotypic expression of resistance were characterized by significant variation in rate of development of pathogen infection structures and hypersensitive reactions. Differences found within eight Lactuca spp. accessions and hybrids challenged by two distinct pathogen races are interpreted and discussed.     

Endogenous development of Hemolivia mauritanica (Apicomplexa: Adeleina: Haemogregarinidae) in the marginated tortoise Testudo marginata (Reptilia: Testudinidae): evidence from experimental infection

Six young tortoises Testudo marginata Schoepff, 1792 were experimentally infected with Hemolivia mauritanica (Sergent et Sergent, 1904). The prepatent period ranged from 6 to 8 weeks. Young, smaller, club-like forms (6-9 x 3-6 Am) of gametocytes appeared in the peripheral blood first, whereas mature, elongated, cylindrical forms (9-12 x 5-7 Am) were detected after 1-2 weeks and predominated during later patency. Three of the infected tortoises were euthanized and dissected to study the endogenous stages. Meronts occurred in the cells of the reticulo-endothelial system and in the erythrocytes; these were observed mostly in parenchymatous organs. Mature forms measured 14.2 x 9.3 microm and contained 7-12 merozoites. Cysts with two (exceptionally one) cystozoites were also found predominantly in parenchymatous organs and measured 14.8 x 7.9 microm. Pathological changes attributable to Hemolivia were mild and limited to liver and kidneys. The role of individual developmental stages of haemogregarines is discussed with respect to evolution of heteroxenous life cycle and long-term persistence of parasites in their intermediate hosts.