Contents |
Introduction
Staphylococcus aureus mastitis continues to be a major challenge for the dairy industry because this disease is difficult to treat with antimicrobial drugs, especially during lactation. In some herds, S. aureus mastitis prevalence in unbred and bred heifers serves as a source for infecting the milking herd. Intramammary infections (IMI) in young dairy animals are associated with local inflammation, induration, and extremely high somatic cell counts (SCC), and they have been found in heifers as early as 6 months of age (Boddie et al., 1987). Furthermore, histological analyses have shown that S. aureus infections adversely affect the development of milk-producing tissues of heifers (Trinidad et al., 1990a).
Although intramammary therapy during gestation (Owens et al., 1994; Trinidad et al., 1990b) and during the immediate prepartum period (Oliver et al., 1992; Oliver et al., 2004) has been successful, the most efficient means of controlling mastitis is to prevent this disease in young dairy animals. Vaccination has been attempted to increase adult cows' immunity to S. aureus and to prevent establishment of these bacteria in the bovine mammary gland. Early vaccine formulations were shown to increase the spontaneous cure rates of S. aureus IMI in cows as well as to lessen the severity of infection but did not prevent new cases of mastitis (Adlam et al., 1981; Brock et al., 1975). More recently, various toxoids and adjuvants have been incorporated into experimental pseudocapsular vaccine formulations and have been shown to be effective in preventing new S. aureus IMI when administered to dairy heifers (Giraudo et al., 1997; Nickerson et al., 1999; Nordhaug et al., 1994; Sears et al., 1990). In view of these successes, the present study was designed to evaluate a commercial S. aureus bacterin when administered to Holstein heifers as a primary immunization at 6 to 18 months of age.
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Materials and Methods
One hundred six Holstein heifers from the James River Correctional Center dairy herd in Goochland, Virgina, were used. This herd had a 9,979-kg rolling herd average milk production with an average SCC of ~200,000/ml. Previous microbiological culture of heifer mammary secretions indicated that approximately 35% of animals were infected with S. aureus.
At approximately 6 to 18 months of age, heifers were processed through a restraining chute to collect aseptic quarter mammary secretion samples for microbiological analyses following procedures outlined by the National Mastitis Council (Hogan et al., 1999). Fifty-three heifers were vaccinated with Lysigin® (Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO) using a dose of 5 ml intramuscularly that was administered in the semimembranosus muscle of the rear leg, and the other 53 heifers served as unvaccinated controls. The vaccine was a lysed culture of polyvalent S. aureus somatic antigens representing 5 phage types in an aluminum hydroxide adjuvant base, including serotypes 5, 8, and 336, the most common S. aureus serotypes associated with clinical mastitis. Fourteen days after the initial processing, the vaccinated group was again processed through the chute and boosted with Lysigin®. All animals were maintained on pasture and rotated by age group through calving. At 6-month intervals after the initiation of the trial and through time of calving, the vaccinated group was again processed through the chute for boosting.
At 2-month intervals after the trial initiation and through calving, mammary secretion samples were collected for bacteriological culture and for the determination of electronic SCC (A/SN Foss, Hillerod, Denmark). Microbiological examination of quarter samples collected from bred heifers over gestation demonstrated that 19.8% of heifers (9.4% of quarters) were infected with S. aureus, 68.9% of heifers (34.3% of quarters) were infected with coagulase-negative staphylococci (CNS), 6.6% of heifers (2.3% of quarters) were infected with environmental streptococci, and 1% of heifers (0.3% of quarters) were infected with coliforms.
At time of calving, heifers were enrolled in the Dairy Herd Improvement Program (DHIA), and data were recorded for milk yield, percentages and actual pounds fat and protein, days in milk, and SCC. Data on vaccine efficacy were examined in terms of mean percentage reduction in rate of new S. aureus or CNS IMI achieved among immunized heifers compared with the rate among unimmunized controls at the time of calving; differences between the percentage of heifers becoming infected among treatments were tested with the standard normal approximation (Steel and Torrie, 1980).
Results and Discussion
Immunization with Lysigin® did not cause any adverse reactions at the injection site or systemically. Minimal swelling (<2.5 cm) was occasionally observed, which disappeared within 48 hours of administration. Vaccine efficacy data showed that the percentage of heifers with S. aureus IMI at freshening was lower in vaccinates (13.3%) compared with controls (34.0%), a reduction of 60.9% (P<0.01). Likewise, an examination of health records showed that the percentage of heifers that were culled or died during the trial was reduced by approximately one-third by vaccination: 16.9% in vaccinates and 24.5% in controls (P>0.05). The vaccinated group also experienced a slight, insignificant reduction in mastitis caused by CNS. At freshening, IMI with CNS were lower in vaccinates (64.2%) compared with controls (69.8%), a reduction of 8.1%.
Somatic cell counts in samples collected during the first week of lactation irrespective of infection status were 45% lower in vaccinates compared with controls (287,317 versus 522,345/ml). Somatic cell counts in samples collected during the first week of lactation from uninfected heifers for vaccinates and controls were 66,095 and 132,754/ml, respectively, a 50.2% reduction. For infected heifers, SCC were 441,764 and 892,176/ml, respectively, a 50.5% reduction. Somatic cell counts in samples collected during the prepartum period were highest for S. aureus (6,730 x 103), followed by the environmental streptococci (3,850 x 103) and CNS (3,510 x 103).
An examination of the 305-day lactation milk yield for the first lactation of both vaccinated and unvaccinated control heifers demonstrated an approximate 8.6% increase in vaccinates versus control (11,217 versus 10,332 kg, respectively), or a difference of 886 kg. On a complete lactation basis, vaccinated animals produced 839 kg more milk than controls (12,537 versus 11,698 kg, respectively), an increase of 7.3%.
The percentage of 305-day lactation fat was higher in vaccinates than controls (3.64 versus 3.27%, respectively); however, the percentage of 305-day lactation protein was slightly higher in controls than vaccinates (3.06 versus 2.95, respectively). Actual 305-day kilograms of both fat and protein were higher in vaccinates than controls (fat: 408 versus 339 kg, respectively; protein: 330 versus 315 kg, respectively). Likewise, on a complete lactation basis, actual kilograms of both fat and protein were higher in vaccinates than controls (fat: 460 versus 393, respectively; protein: 370 versus 353, respectively).
An examination of the number of days in milk for the first lactation demonstrated that vaccinates persisted 13 days longer than the unvaccinated controls (349 versus 336 days). In addition, average first lactation SCC were 11,000 cells/ml lower in vaccinates compared with controls (49,000 versus 60,000/ml).
Conclusions
Results of this investigation demonstrated that vaccinating dairy heifers according to the prescribed protocol with a commercial USDA licensed S. aureus bacterin, Lysigin®, reduced the number of new S. aureus IMI at time of calving by 60.9%, lowered the SCC by 50%, and decreased the culling rate by approximately one-third. In addition, overall milk yield, production of fat and protein, and number of days in milk were greater in vaccinated heifers compared with controls.
The decrease in frequency of new S. aureus IMI at calving (60.9%) in vaccinates using Holstein heifers is higher than the 44.7% reduction observed in a Louisiana trial using the same vaccine in Jersey heifers (Nickerson et al., 1999). In both trials, SCC at calving were reduced by approximately 50%. The 60.9% efficacy found in the present trial is also higher than the 40.2% efficacy observed by Giraudo et al. (1989), the 46% efficacy observed by Nordhaug et al. (1994), and the 52% efficacy observed by Sears et al. (1990). However, it is difficult to compare among the latter three trials as the vaccine formulations were all quite different.
The question becomes: Is it economically feasible to use this vaccination protocol on young dairy heifers? Based on an average of 1,864 more pounds milk per vaccinated heifer, which translates to 18.64 hundredweights (cwt) of milk (1,864/100), at the current price of $25.00/cwt, an increased income of $466.00/heifer would be realized (18.64 cwt x $25.00/cwt = $466.00). If each heifer was vaccinated beginning at 6 months of age until calving, this would entail vaccinations at 1) 6 months, 2) a booster 2 weeks later, and subsequently at 3) 12 months, 4) 18 months, and 5) 24 months, or a total of 5 immunizations through calving. At $1.50/dose, this cost would total $7.50, which when subtracted from the increased income from milk production, would yield a net income of $458.50 per heifer ($466.00 - $7.50). This figure does not include the costs of labor involved in the immunization process; however, it is evident that vaccination is well worth the cost of the vaccine. Not only does it reduce new infections in first calf heifers at parturition, it may also reduce the introduction of S. aureus to the milking herd.
Summary
The use of a Staphylococcus aureus bacterin to prevent intramammary infections (IMI) in dairy heifers was evaluated. At 6 to 18 months of age, Holstein heifers were processed for vaccination and collection of mammary secretions. Fifty-three heifers were immunized with a commercial bacterin, and 53 heifers served as unimmunized controls. The vaccine was a lysed culture of polyvalent S. aureus somatic antigens of 5 phage types in an aluminum hydroxide base. Two weeks after processing and at 6-month intervals until calving, vaccinates were processed for boosting. At 2-month intervals after trial initiation and through calving, mammary secretion samples were collected for bacteriological culture and somatic cell counts (SCC). Efficacy data showed that the percentage of heifers with S. aureus IMI at calving was lower in vaccinates (13.3%) compared with controls (34.0%), a reduction of 60.9%. The SCC in samples collected at calving from uninfected heifers for vaccinates and controls were 66,095 and 132,754/ml, and for infected heifers, SCC were 441,764 and 892,176/ml, reductions of approximately 50%. Likewise, average first lactation SCC were lower in vaccinates than controls (49,000 versus 60,000/ml). The 305-day lactation milk yield for the first lactation demonstrated an 8.6% increase in vaccinates versus controls (11,217 versus 10,332 kg). In addition, the 305-day lactation kilograms of fat and protein were higher in vaccinates than controls (fat: 408.04 versus 338.96 kg; protein: 329.77 versus 315.23 kg). Evaluation of the number of days in milk for the first lactation demonstrated that vaccinates persisted 13 days longer than unvaccinated controls (349 versus 336 days), and culling was reduced by one-third in vaccinates (16.9%: vaccinates, 24.5%: controls). Results demonstrated that administration of a commercial bacterin to breeding age and pregnant heifers reduced prevalence of S. aureus mastitis and SCC at calving and increased first lactation performance.
Author Information
Stephen C. Nickerson, University of Georgia
Lane O. Ely, University of Georgia
Ernest P. Hovingh, Pennsylvania State University
Phillip W. Widel, Boehringer Ingelheim Vetmedica Inc.
Selected References
Adlam, C. Kerry, K.B., Edkins S. and Ward P.D. 1981. Local and systemic antibody responses in cows following immunization with staphylococcal antigens in the dry period. Journal of Comparative Pathology 91:105-113.
Boddie, R.L., Nickerson, S.C., Owens, W.E. and Watts, J.L. 1987. Udder microflora in nonlactating heifers. Agri-Practice 8:22-25.
Brock, J.H., Steel, E.D. and Reiter, B. 1975. The effect of intramuscular and intramammary vaccination of cows on antibody levels and resistance to intramammary infection by Staphylococcus aureus. Research in Veterinary Sciences 19:152-158.
Giraudo, J.A., Calzolari, A., Rampone, H, Rampone, A., Giraudo, T., Bogni, C., Larriestra, A. and Nagel, R. 1997. Field trials of a vaccine against bovine mastitis. 1. Evaluation in heifers. Journal of Dairy Science 80:845-853.
Hogan, J.S., González, R.N., Harmon, R.J., Nickerson, S.C., Oliver, S.P., Pankey, J.W. and Smith, K.L. 1999. Testing procedures. In: Laboratory Handbook on Bovine Mastitis. National Mastitis Council Inc., Madison, Wis. pp. 205-217.
Nickerson, S.C., Owens, W.E., Tomita, G.M. and Widel, P.W. 1999. Vaccinating dairy heifers with a Staphylococcus aureus bacterin reduces mastitis at calving. Large Animal Practice 20:16-20.
Nordhaug, M.L., Neese, L.L., Norcross, N.L and Gudding, R. 1994. A field trial with an experimental vaccine against Staphylococcus aureus mastitis in cattle. 1. Clinical parameters. Journal of Dairy Science 77:1267-1275.
Oliver, S.P., Lewis, M.J., Gillespie, B.E. and Dowlen, H.H. 1992. Influence of prepartum antibiotic therapy on intramammary infections in primigravid heifers during early lactation. Journal of Dairy Science 75:406-414.
Oliver, S.P., Ivey, S.J., Gillespie, B.E., Lewis, M.J., Johnson, D.L., Lamar, K.C., Moorehead, H., Dowlen, H.H., Chester, S.T. and Hallberg, J.W. 2004. Influence of prepartum intramammary infusion of pirlimycin hydrochloride or penicillin-novobiocin on mastitis in heifers during early lactation. Journal of Dairy Science 87:1727-1731.
Owens, W.E., Nickerson, S.C., Washburn, P.J. and Ray, C.H. 1994. Prepartum antibiotic therapy with a cephapirin dry cow product against naturally occurring intramammary infections in heifers. Veterinary Medicine B 41:90-100.
Sears, P.M., Norcross, N.L., Kenny, K., Smith, B., Gonzalez, R.N. and Romano, M.N. 1990. Resistance to Staphylococcus aureus infections in staphylococcal vaccinated heifers. In: Proceedings of the International Symposium on Bovine Mastitis. March 23-27, 1990. Indianapolis, Ind. pp. 69-74.
Steel, R.G.D. and Torrie, J.H. 1960. Principles and procedures of statistics. McGraw-Hill Inc., New York, N.Y.
Trinidad P., Nickerson, S.C. and Adkinson, R.W. 1990a. Histopathology of staphylococcal mastitis in unbred dairy heifers. Journal of Dairy Science 73:639-647.
Trinidad, P., Nickerson, S.C., Alley, T.K. and Adkinson, R.W. 1990b. Efficacy of intramammary treatment in unbred and primigravid dairy heifers. Journal of the American Veterinary Medical Association 197:465-470.
