Induction of bovine polioencephalomalacia with a feeding system based on molasses and urea.

Polioencephalomalacia (PEM), a disease first described in the United States and related to intensive beef production, appeared in Cuba coincident with the use of a new, molasses-urea-based diet to fatten bulls. Because the only experimental means so far of reproducing PEM has been with amprolium, a structural analog of thiamin, the present study attempted to induce the disease using the molasses-urea-based diet. Six Holstein bulls (200-300 kg) were studied during consumption of three successive diets: 1) commercial molasses-urea-restricted forage diet of Cuban feedlots, 2) a period in which forage was gradually withdrawn and 3) a forage-free diet composed only of molasses, urea and fish meal. PEM was reproduced in this way. At ten-day intervals, blood concentrations of glucose, lactate, pyruvate and urea were measured, as well as when clinical signs of PEM appeared. The signs, clinical course and lesions of the experimentally induced disease were comparable to those of field cases. The biochemical results suggested a block in pyruvate oxidation as in PEM elsewhere in the world. No evidence existed of urea intoxication. In addition, brain and liver concentration of total thiamin from field cases and normal animals were found to be similar.     

Use of Mailed Questionnaire Data in a Study of Swine Congenital Malformations

A study was designed to evaluate the representativeness and accuracy of data collected on swine birth defects by mailed questionnaire. The study was conducted in the three contiguous counties of Johnson, Lafayette and Pettis in west central Missouri. A personal interview survey and an examination of malformed pigs were used to validate mailed questionnaire data which estimated the frequency and distribution of malformations observed in pigs over a six month period. This period between April and September 1970 was defined as the study period. The results were compared to a previous six month period (April-September 1969), or baseline period, when only the mailed questionnaire was used. The frequency and distribution of the reported malformations by type did not differ significantly (at the p=0.05 level) between the study period (70.4% response) and the baseline period (31.3% response). Evaluation of this and additional data collected during the study suggested that the mailed questionnaire can be used effectively to estimate the frequency and distribution of swine malformations within a defined geographic area.     

Infectious bovine keratoconjunctivitis II. Antibodies in lacrimal secretions of cattle naturally or experimentally infected with Moraxella bovis.

One or both eyes of 20 calves were inoculated one or more time with variou(s combinations of microorganism (live oor killed Moraxella bovis, infectious bovine rhinotracheitis virus, bovine adenovirus, bovine parainfluenza-3 virus and Mycoplasma bovoculi) by conjunctival instillation or direct inoculation of the conjunctivea or cornea. The eyes of all the calves received natural or artificial ultraviolet irradiation. Neither the adenovirus nor parainfluenza-3 virus became established in the eye or produced keratoconjunctivitis. Both M. bovis and infectious bovine rhinotracheitis virus became established in the bovine eye and produced disease. Subconjunctival or intracorneal inoculation of M. bovis caused a severe disease, simulating natural infectious bovine keratoconjunctivitis. Only the intracorneal inoculation of mycoplasma produced severe keratoconjunctivits. Eyes that on initial exposure to M. bovis became severly inflamed were more resistant to a second or third exposure to M. bovis, presumably by enhanced local defence mechanisms.