East coast fever: 3. Chemoprophylactic immunization of cattle using oxytetracycline and a combination of theilerial strains

In the first of two experiments performed, 29 animals were immunized by chemoprophylaxis against either a combination of three theilerial strains, Theileria parva (Muguga), T. parva (Kiambu 5) and T. lawrencei (Serengeti transformed), or against one or two elements of the combination separately, and then challenged with either T. parva (Kiambu 1) or T. lawrencei (Solio KB1), both of which were known to be heterologous to T. parva (Muguga). The animals immunized against the combination had mild or inapparent reactions to challenge, whilst the susceptible control cattle and many of those immunized against one or two strains either had severe reactions of died.In the second experiment, 17 cattle immunized by chemoprophylaxis against the combination were challenged with lethal doses of three theilerial strains, T. parva (Entebbe 1), T. parva (Entebbe 2) and T. parva (Ukunda), recently isolated from two widely separated areas of East Africa. They had mild or inapparent reactions whilst 13 of 15 susceptible control cattle died.Chemoprophylaxis using a combination of theilerial strains and a limited oxytetracycline regimen was shown to be an effective means of immunizing cattle against East African theilerioses. The use of this technique as a method of immunizing cattle before exposure in the field is proposed.     

A study of the effect of variation in the calorie‐protein ratio of a medium energy diet and a high energy diet containing sucrose on the efficiency of egg production in caged layers

Literature pertaining to the variation in the protein content of layers’ diets is discussed and the lack of information on the effect of calorie‐protein ratio on food conversion is mentioned. The experiment described in the present paper was designed to test the effect of variations in calorie‐protein ratio on food conversion on a diet of high energy content (1340 k cal/lb.) based on sucrose supplementation and on a medium energy diet (1160 k cal/lb.). At the same time three types of pullet, Thornber 606, Thornber 404 and Light Sussex x Brown Leghorn pullets were compared on the two types of diet, each being fed at three nominal protein levels of 13, 15 and 17 per cent giving a total of eighteen treatments. The pullets were individually recorded for egg production, egg weight and food consumption. Meta‐bolisable energy crude protein determinations were carried out on each of the six diets employed and the actual calorie‐protein ratios calculated.

There was no significant effect on egg production when the calorie‐protein ratio of the diet was raised from 69 (i.e. k cal M.E./lb. per 1 per cent protein) to 90 but an increase to 103 reduced production and egg weight. It was found that maximum efficiency of food conversion was realised at ratios of 76 to 78.

The efficiency of conversion of dietary energy was unaffected by energy concentration in the diet.

The lightweight hybrid (Thornber 606) produced eggs more efficiently than either the Thornber 404 or the crossbred type.     

The phase of hair growth in hypothyroidism in the dog

The stage of hair growth which predominated in dogs not affected with hypothyroidism appeared to be breed-dependent. For example, in boxers, Labradors and collies, the resting stage (telogen) predominated, whereas in West Highland White terriers and cairn terriers the active stage (anagen) predominated. However, even in pet dogs kept mainly indoors, the proportion of hairs in anagen tended to increase during the winter months.In dogs affected with hypothyroidism, the proportion of hairs in anagen or telogen in members of a particular breed was the same as in the normal dogs of the breed. From this, it appeared that breed was more influential than hypothyroidism in determining the predominant phase of hair growth.     

Lack of peripheral sympathetic control of uterine blood flow during acute heat stress

Peripheral alpha- and beta-adrenergic control of uterine blood flow (UBF) during acute heat stress of the gravid ewe was investigated. An electromagnetic blood flow probe was surgically implanted around the left miduterine artery and catheters inserted in the left carotid artery and right jugular vein in ewes between d 120 and 130 of gestation. Four or more days postsurgery, ewes were fitted with instruments to measure rectal temperature (Tr), heart rate (HR), respiratory rate (RR), blood pressure (BP) and UBF. One-half hour after instrument calibration, a 15-min thermoneutral control period was initiated with carotid artery blood samples taken at 5-min intervals for pH and PCO2 determinations. Ewes were then subjected to a heat challenge that reached 40 C at 2 h. All physiological data were recorded every 5 min as 1-min mean values. In seven experiments on five ewes, an alpha-adrenergic blocking drug, phenoxybenzamine (PB) was infused at 1 mg/min for 15 min subsequent to maximum depression of UBF. A beta-adrenergic blocking drug, propranolol (PR) was infused at .35 mg/min for 15 min in eight experiments on five ewes. Analysis of variance comparisons were made between the control period and heat stress infusion periods within the PB and PR experiments. Further comparisons were made between the start and 5, 10 or 15 min of PB or PR infusion in order to test drug effects during an acute heat stress. Rectal temperature HR, RR and arterial pH were higher (P less than .05) at the start of PR and PB infusions than during the thermoneutral control period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Management program for improving sow and gilt performance by feeding dichlorvos

Treated sows were on a special management program which consisted of feeding 1,000 mg of dichlorvos to the sow each day for the last 30 days of gestation. The dichlorvos was delivered as a slow-release formulation. The late gestation treatment signigicantly (P less than 0.01) improved the productivity of the sows by improving the performance of their litters. The litters from treated sows were superior in 4 ways: (1) increased number of pigs born alive per litter (2.3%); (2) increased pig birth weights (9.6%); (3) improved survival of pigs born alive; and (4) improved growth rate to market weight. The litters from treated sows were 11.6%, 16.5%, and 12.4% heavier than control litters at birth, weaning (35 days), and market (160 days), respectively.     

Modulation of host immune responses by protozoal DNA

The pathology caused by acute Babesia bovis infection is similar to that seen in severe human malaria caused by Plasmodium falciparum infection, which is related to dysregulated production of inflammatory cytokines and nitric oxide (NO). We have observed induction of NO, inducible nitric oxide synthase (iNOS) and inflammatory cytokines in macrophages by B. bovis. Furthermore, proliferation of lymphocytes from individuals never exposed to certain protozoal pathogens can be induced by crude protozoal parasite extracts. We have repeatedly observed stimulation of naive PBMC from cattle to antigenic extracts of Babesia bovis. Based on recent studies demonstrating the mitogenicity of bacterial and other non-vertebrate DNAs for murine B cells and macrophages, the mitogenic properties of B. bovis DNA were examined. B. bovis and E. coli DNAs induced proliferation of PBMC and purified B cells from non-exposed cattle. Stimulatory activity was reduced by DNase treatment and methylation with CpG methylase, indicating the presence of stimulatory non-methylated CpG motifs in the B. bovis genome. B. bovis and E. coli DNAs enhanced IgG secretion by cultured B cells, stimulating IgG1 and more strongly, IgG2. Several hexameric CpG immunostimulatory sequences (ISS) active for murine B cells were identified in an 11 kb fragment of B. bovis DNA. An oligodeoxyribonucleotide containing one of these (AACGTT), located in the rhoptry associated protein-1 (rap-1) open reading frame, stimulated B cell proliferation. These studies identify a potential mechanism by which protozoal parasites may modulate host immune responses, leading to consequences such as hypergammaglobulinemia and splenomegaly. These results also support the use of ISS as vaccine adjuvants to enhance Type 1 immune responses in cattle.     

Equine Degenerative Myeloencephalopathy: A Vitamin E Deficiency That May Be Familial

Two horse farms, on which there was a high incidence of proven and suspected equine degenerative myeloencephalopathy (EDM), were studied. Symmetric ataxia and paresis, along with laryngeal adductor, cervicofacial, local cervical, and cutaneous trunci hyporeflexia, characterized the syndrome. Serum vitamin E concentration reflected a deficient state in affected and unaffected horses on both farms when compared with selected reference groups and with published values. A high incidence of the disease was evident in offspring of two particular sires on one farm. Vitamin E supplementation resulted in correction of the deficient state in most horses and was associated with a drastic reduction in the incidence of EDM on one farm from 40% to less than 10% the year following vitamin E supplementation. In addition, during the last year, the severity of signs in the few cases was dramatically reduced. This information substantiates the hypothesis that EDM is a vitamin E-responsive disorder of Equidae with a possible familial predisposition.     

Preliminary investigation of a possible lung worm (Parafilaroides decorus), fish (Girella nigricans), and marine mammal (Callorhinus ursinus) cycle for San Miguel sea lion virus type 5

Colostrum-deprived neonatal Northern fur seal pups (Callorhinus ursinus) were exposed to San Miguel sea lion virus type 5 (SMSV-5) by feeding them fish (Girella nigricans) infected with virus or fish infected with both the sea lion lung worm larvae (Parafilaroides decorus) and virus. Virus infection was demonstrated in 8 of 9 pups, and 1 of these developed a vesicular lesion on the flipper. In this sequence, P decorus larvae exposed to SMSV-5 were fed to G nigricans held at 15 C in a salt water aquarium; 32 days later, these fish were killed, then fed to the fur seal pups. The vesicle developed 22 days subsequent to this and SMSV-5 was reisolated from the lesion. The SMSV-5 was shown to persist for at least 23 days in infected neonatal fur seals. Attempts to establish P decorus infection in Northern fur seal pups were apparently unsuccessful.     

Mandibular fracture repair in a harbor seal

A 30-year-old captive female harbor seal (Phoca vitulina) bit down upon a metal ring within a hoop-net normally used to assist in securing the seal for routine physical examination. Radiographic examination performed under general anesthesia revealed a unilateral closed fracture of the rostral left mandible between the first and second premolar teeth. The rostral fragment was displaced ventrally and slight laxity of the mandibular symphysis was noted. The fracture was repaired surgically using an oral dental acrylic splint incorporating circumferential mandibular cerclage wire. The mandibular symphysis was stabilized using interdental wire between the right and left canine teeth. The fixation device was removed following evaluation of radiographs that showed signs of bony union 12-months postoperatively.