Investigation of the use of three electroencephalographic electrodes for long-term electroencephalographic recording in awake and sedated dogs.

Objective: To compare electroencephalography (EEG) artifact associated with use of the subdermal wire electrode (SWE), gold cup electrode (GCE), and subdermal needle electrode (SNE) over an 8-hour period in sedated and awake dogs.

Animals: 6 healthy dogs.

Procedures: 8 EEG channels were recorded during 20-minute video-EEG recording sessions (intermittently at 0.

Regions in the brainstem and frontal cortex where electrical stimulation elicits parotid and submandibular saliva secretion in sheep.

Acute experiments were conducted in sheep anaesthetized with sodium pentobarbital to identify regions in the brain where electrical stimulation would elicit secretion by the parotid and submandibular salivary glands. This was a prerequisite for single unit studies in the future. In the brainstem, parotid and submandibular secretions were evoked on average between 7 and 16 mm rostral to obex and from 1 to 11 mm lateral to midline, with the parotid gland being active on the caudal and the submandibular on the rostral sides of this region.

Electrical stimulation of the medial frontal lobe elicits a pattern of body movements in sheep.

Acute experiments were conducted in sheep anaesthetized with sodium pentobarbital to identify regions in the brain where electrical stimulation would elicit movements of body parts. Stimulating the dorsal frontal cortex 2 mm from midline from the front of the brain backward for 30 mm caused movements, in order, of the lower jaw, face in general, neck, shoulder and front and back legs.

Technical note: reversible re-entrant cannulation of the parotid duct in cattle using a new injection anesthesia regimen.

A new method for reversible reentrant cannulation of the parotid duct in cattle by use of an injectable anesthetic regimen is described. Ruminal contents were removed before anesthesia instead of food deprivation. The parotid duct was dilated by means of a long hemostatic forceps: its jaws were encased in a piece of plastic tube, and the tip was extended by a piece of flexible wire.

Attempts to modify reperfusion injury of equine jejunal mucosa using dimethylsulfoxide, allopurinol, and intraluminal oxygen.

This study compared the severity of ischemic injury to the equine jejunal mucosa caused by arteriovenous obstruction (AVO) or venous obstruction (VO) with that caused by reperfusion after ischemia. The degree of mucosal damage and regeneration was scored according to a modified version of an established light microscopic classification for ischemic injury. Biopsy specimens taken after 3 and 4 hours of obstruction, and after 3 hours of obstruction and 1 hour of reperfusion, were compared.

Factors affecting the voluntary intake of food by sheep. 6. The effect of monosodium glutamate on the palatability of straw diets by sham-fed and normal animals.

Sheep with oesophageal fistulas were used in sham-feeding experiments to assess how sham intakes were affected by (a) physical form of straw (finely and coarsely ground; ground and pelleted), (b) type of food (straw pellets v. lucerne (Medicago sativa) hay pellets) and (c) additions of monosodium glutamate (MSG) with or without NaCl to the various straw diets. Normal animals were also fed on diets with and without MSG.

A review of the physiological significance of hypertonic body fluids on feed intake and ruminal function: salivation, motility and microbes.

Mechanisms exist in the ruminant to detect changes in osmolality and volume of plasma during feeding to maintain fluid and electrolyte homeostasis. Feed intake during a meal can be limited by the rise in osmolality of ruminal fluid, which is sensed in the wall of the rumino-reticulum. Ruminal microbes appear to be resilient to the short-term changes in ruminal fluid tonicity, but in vitro growth rates are inhibited when the tonicity of the culture medium is increased beyond physiological levels.

Digesta kinetics in sheep and cattle fed diets with different forage to concentrate ratios at high and low intakes.

Effect of maintenance and ad libitum intakes on digesta kinetics was studied with six ruminally fistulated cows and six ruminally fistulated wethers to validate the use of sheep as a model of cattle. Complete diets were made up of ratios of alfalfa:cracked corn and soybean meal of 80:20, 55:45, and 30:70. The rate of passage of Cr-mordanted alfalfa and soybean meal in the reticulorumen was negatively related to percentage of concentrate in the diet in both species at low intakes.

Factors affecting the voluntary intake of food by sheep. 5. The inhibitory effect of hypertonicity in the rumen.

The site where osmotically active substances act to depress food intake was determined in sheep. After 5.5 h of food deprivation, solutions of sodium chloride or polyethylene glycol-200 (PEG-200) were added to either the reticulo-rumen or the abomasum.

Parotid secretion patterns during meals and their relationships to the tonicity of body fluids and to gastrin and pancreatic polypeptide in sheep.

The flow pattern of unilateral parotid saliva in sheep was compared when a total of 800 g lucerne (Medicago sativa) hay was offered as one, two, four or eight distinct meals. These patterns were related to changes in the tonicity of rumen fluid and plasma and to plasma concentrations of gastrin and pancreatic polypeptide. Sheep having ad lib access to hay overnight were offered fresh hay from 08.

The effect of feeding frequency and meal size on amounts of total and parotid saliva secreted by sheep.

Total and unilateral parotid saliva production during eating were measured in response to offering sheep a fixed amount of lucerne (Medicago sativa) hay as one, two, four or eight meals. Total saliva measurements were obtained using sham-fed oesophageal-fistulated sheep. Unilateral parotid saliva was collected from sheep fitted with reversible re-entrant cannulas.

Comparative digestion in sheep and cattle fed different forage to concentrate ratios at high and low intakes.

Effect of maintenance and ad libitum intakes on digestibility of different feed fractions was studied with six ruminally fistulated cows and six ruminally fistulated wethers to validate the use of sheep as a model for cattle. Complete diets were made up of ratios of alfalfa:cracked corn and soybean meal of 80:20, 55:45, and 30:70. The regression coefficient of the line relating organic matter digestibility with proportion of concentrate in the diet was smaller for the cows at ad libitum intake than for the other groups.

Parotid secretion and associated efferent activity inhibited by pentagastrin in sheep.

The inhibition of parotid secretion by pentagastrin increased with dose for jugular and carotid injections (0.01-0.16 micrograms/kg) in acute preparations of 3 sheep anesthetized with sodium pentobarbital.

Factors affecting the voluntary intake of food by sheep. 4. The effect of additives representing the primary tastes on sham intakes by oesophageal-fistulated sheep.

1. Sheep with oesophageal fistulas were sham-fed on pelleted lucerne (Medicago sativa) hay to assess the palatability of added chemicals representing the tastes of sweet (sucrose), sour (hydrochloric acid), salt (sodium chloride), bitter (urea) and umami (monosodium glutamate; MSG). 2.

Effects of buffers on ruminal rate of passage and degradation of soybean meal in steers.

Eight rumen-fistulated steers were randomly assigned to medium- and high-concentrate diets supplemented with 0, .75, 2.5 and 5% of either sodium bicarbonate or an artificial saliva salts mixture.

Pentagastrin in the circulation acts directly on the brain to depress motility of the stomach in sheep.

The mechanism whereby pentagastrin inhibits the frequency of contractions of the reticulo-rumen in conscious sheep was studied by comparing the effects of a range of doses given by continuous infusion into the jugular vein and the carotid artery. The intracarotid infusions at rates of 1 and 2 micrograms/kg per h were more effective than the jugular infusions (P less than 0.05).

Factors affecting the voluntary intake of food by sheep. 3. The effect of intravenous infusions of gastrin, cholecystokinin and secretin on motility of the reticulo-rumen and intake.

1. Sheep given ground and pelleted lucerne hay (Medicago sativa) ad lib. were infused intravenously with pentagastrin, secretin, cholecystokinin (CCK) and its analogues to assess their effects on motility of the reticulo-rumen and on food intake.

Effect of ensiling whole plant corn on voluntary intake, rumen fermentation, retention time and rate of digestion in steers.

The study was designed to determine whether products of fermentation in corn silage could limit its voluntary intake. Six rumen-cannulated Hereford steers were assigned randomly to diets of corn silage (CS) and dried corn forage reconstituted either with water (DC + W) or with extracts from corn silage (DC + CSE) according to a crossover design with three experimental periods. During each period, steers were fed ad libitum for 18 days and then restricted to 65 g DM/kg BW.

Factors affecting the voluntary intake of food by sheep. 2. The role of distention and tactile input from compartments of the stomach.

1. Sheep equipped with rumen and abomasal cannulas were given ad lib. access to ground and pelleted lucerne (Medicago sativa) hay except for periods of up to 6 h immediately before experimental sessions in which food intake was measured while various stomach compartments were either distended or subjected to tactile stimulation from a probe.

Factors affecting the voluntary intake of food by sheep. 1. The role of distension, flow-rate of digesta and propulsive motility in the intestines.

1. Twelve sheep fitted with abomasal cannulas were given ad lib. access to a diet of chopped lucerne (Medicago sativa) hay to a ascertain if the amount of digesta being transported by the intestines was limiting intake.

Distension of the reticulum decreased food but not water intake by sheep.

The intakes of pelleted alfalfa by hungry sheep were depressed in a rectilinear manner in relation to the amount of water (0-800 ml) added to a balloon in the reticulum (p less than 0.005). Since the consumption of water by thirsty sheep was not altered by these treatments, the reduction in food intake produced by distending the reticulum was a specific response.