LEPTOSPIRA INTERROGANS SEROVAR HARDJO VACCINATION OF PREGNANT BEEF COWS AND SUBSEQUENT GROWTH RATE OF PROGENY

Abstract

Five experiments with Leptospira interrogans serovar hardjo vaccine were carried out over a 6-year period in pregnant Brahman-cross and Sahiwal-cross cows in the dry tropics on northern Queensland. The numbers ranged from 127 breeders aged 2 to 5 years in 1972 to 344 breeders aged 2 to 9 years in 1977. Half of the cows were vaccinated twice in mid-pregnancy except for 1977, when they were vaccinated once. In 1975-1977 inclusive, half of the heifers were given an additional dose of vaccine at commencement of mating. Vaccination caused a significant (P less than 0.01) reduction of prenatal loss but not of perinatal or postnatal losses. Growth rates of calves from vaccinated and unvaccinated dams were similar.

Leptospira interrogans serovar hardjo is not a major cause of bovine abortion in Victoria

“…There is some Australian evidence that serovar hardjo can contribute to bovine abortion (Corbould 1971;Hoare and Claxton 1972;Johnson et a/ 1974;. Immunisation against hardjo has been associated with a reduction of prenatal losses in beef cattle in Queensland (Holroyd 1980). On the other hand, a Victorian analysis of the causes of a series of bovine abortions indicated that leptospires were of minor importance, with 2% of abortions attributed to serovar hardjo (Slee et a1 1983;Jerrett et all984).…”

A field study of the effects of a monovalent Leptospira borgpetersenii serovar Hardjo strain hardjobovis vaccine administered with oxytetracycline on reproductive performance in beef cattle

“…Intramuscular administration of a long-acting tetracycline formulation at a dosage of 20 mg/kg (9.1 mg/ lb) and SC administration of tilmicosin at a dosage of 10 mg/kg (4.5 mg/lb) are effective in eliminating persistent renal infection with strain hardjobovis. 20 Holroyd 21 reported a reduction in the abortion rate in beef cows in Australia when they were treated with antimicrobials and vaccinated against infection with strain hardjobovis. However, studies on the effects of combined antimicrobial treatment and strain hardjobovis vaccination on the reproductive performance of beef cattle in the United States are lacking.…”

An Assessment of In-service Training Needs for Agricultural Extension Field Staff in the Scenario of Climate Change using Borich Needs Assessment Model

“…There are few good data on losses associated with leptospirosis in developing countries. In Australia, total loss was estimated at 2.2 percent at the herd level (Holroyd 1980). In Viet Nam, infection with some serovars correlated with one less live pig per litter, equivalent to 8 percent loss of production (Boqvist et al 2002).…”