A survey of biological productivity of Prince Edward Island swine herds.

Sow and feeder pig productivity were measured on a random sample of 32 Prince Edward Island swine farms (each producing over 1000 market hogs per year). Productivity parameters could be arranged in a hierarchy, with the highest level on farrow-finish operations represented by pigs weaned per sow per year. The 17 farrow-finish farms in this study averaged 19.6 (+/- 2.2 SD) pigs weaned per sow per year. Large variation between farms was observed with a range from 16.2 to 24.9 pigs weaned per sow per year. The major opportunities for improving productivity, as compared to reviewed targets, lie in reducing the average weaning age, reducing preweaning mortality, and reducing non-productive sow days per parity. The 14 feeder operations were characterized by 0.58 +/- 0.07 kg average daily gain. Average daily gain was negatively correlated with mortality (r = -0.662, p = 0.010), suggesting that herds that achieved a high rate of gain also had lower mortality.

The Persistent Isolation of Salmonella typhimurium from the Mammary Gland of a Dairy Cow.

The contamination of cheese by Salmonella typhimurium serotype 10 resulted in the bacteriological examination of raw milk from 327 farms on Prince Edward Island. A milk sample from a bulk tank from one farm was positive for this pathogen. The possible source was linked to the isolation of the strain from the milk from one quarter of one cow. Although the cow was asymptomatic for any clinical illness other than a chronic staphylococcal mastitis in two quarters, the animal continued to shed Salmonella in the milk during a 36 day period. Necropsy failed to reveal a source of the infection.

Mycoplasma felis as a cause of pleuritis in horses.

Mycoplasma felis was the only organism recovered from the thoracic cavity of a horse with pleuritis. Large numbers of mildly degenerative neutrophils were in the pleural fluid. The horse developed a serologic response to M felis and recovered during hospitalization. Experimentally, a pony was inoculated in the thoracic cavity with a pure culture of the M felis isolate suspended in the pony's serum. A control pony was inoculated with serum only. Within 48 hours, the principal pony developed fever, increased respiratory rate, pleural effusion, and signs of pain. A highly cellular exudate with nondegenerative neutrophils and large numbers of M felis was recovered from the thoracic cavity. The control pony remained normal. The principal pony developed an antibody response to M felis. The control pony did not. Fourteen days after inoculation, both ponies were euthanatized. Necropsy revealed pleural inflammation in the principal pony. Pleural lesions were not found in the control pony.

Magnesium oxide induced metabolic alkalosis in cattle.

A study was designed to compare the metabolic alkalosis produced in cattle from the use of an antacid (magnesium oxide) and a saline cathartic (magnesium sulphate). Six, mature, normal cattle were treated orally with a magnesium oxide (MgO) product and one week later given a comparable cathartic dose of magnesium sulphate (MgSO(4)). The mean percent dry matter content of the cattle feces changed significantly (P<0.001) following administration of both MgO (15.6-8.1) and MgSO(4) (17.0-8.7) but there was no significant difference between treatments. The mean rumen pH values changed significantly (P<0.001) following administration of both MgO (7.-8.7) and MgSO(4) (7.3-8.3) but there was no significant difference between treatments. However, use of the MgO product caused a more severe (P<0.001) metabolic alkalosis as determined by base excess values. The base excess values remained elevated for 24 hours in the MgO treated group compared to only 12 hours after MgSO(4) administration. Following MgO administration, mean hydrogen ion concentration (pH), bicarbonate ion concentration ([HCO(3)-]) and base excess were 7.44, 33.3 mmol/L and +8.0 respectively compared to 7.38, 27 mmol/L and +3.0 after MgSO(4). Since the oral use of MgO in normal cattle causes a greater and more prolonged metabolic alkalosis compared to MgSO(4), MgO is contraindicated as a cathartic in normal cattle or in cattle with abomasal abnormalities characterized by pyloric obstruction and metabolic alkalosis.

Congenital esophagotracheal fistula as the cause of bloat in a calf.

A four day old Holstein calf was presented with a history of recurrent free gas bloat. An exploratory laparotomy was performed and no abnormalities were discovered in the gastrointestinal tract. An esophagotracheal fistula was suspected and confirmed by endoscopy. Surgical correction was performed by ligating the tubular connection between the trachea and esophagus and suturing closed the defects in these structures.

Lymphocyte immunostimulation in the diagnosis of Corynebacterium equi pneumonia of foals.

A lymphocyte stimulation test using antigens of Corynebacterium equi was used to compare the response of peripheral blood lymphocytes from foals with C equi pneumonia with those of clinically normal foals and adult horses. The test clearly distinguished infected foals from normal foals when tested in animals less than or equal to 2 months old. After the 2nd month, stimulation response from individual normal foals sometimes exceed those from infected foals, but mean stimulation response to C equi antigens was significantly (P less than 0.025) greater in 3- to 5-month-old infected foals when compared with mean values of 3- to 5-month-old normal foals. Mean stimulation responses in 5- to 7-month-old foals, which had recovered from C equi pneumonia, could not be distinguished from mean responses of normal foals. The test could still, however, be used diagnostically in foals greater than 2 months of age if stimulation responses were low. The test indicated the great extent of exposure to C equi in the normal horse population.