Partial budget analysis of prepartum antimicrobial therapy and Escherichia coli J5 vaccination of dairy heifers and their effect on milk production and milk quality parameters

Pesquisa Veterinária Brasileira

Brito, José R.F.²  Fonseca, Leorges M.¹  Brito, Maria Aparecida V.P.²  Sampaio, Ivan B.M.¹  Cerqueira, Mônica M.O.P.¹  Leite, Mônica O.¹  Souza, Fernando N.¹  Vargas, Renison T.³ 

[1] Universidade Federal de Minas Gerais, Belo Horizonte, Brazil;Empresa Brasileira de Pesquisa Agropecuária, Juiz de Fora, Brazil;Instituto Federal de Minas Gerais, Bambuí, Brazil

关键词:  Mastitis;    milk;    antimicrobial treatment;    vaccine;    dairy cows;   

DOI  :  10.1590/S0100-736X2016000200003

来源: Colegio Brasileiro de Patologia Animal-CBPA

【 摘 要 】

:This study aimed to determine whether prepartum antimicrobial and/or Escherichia coli J5 vaccination in dairy heifers influence the milk production, milk quality, and estimate their economic benefit. Thus, 33 dairy heifers were enrolled in four groups using a split-splot design. Groups were: (G1) prepartum antimicrobial infusion and vaccination with an E. coli J5 bacterin, (G2) prepartum antimicrobial infusion, (G3) vaccination with an E. coli J5 bacterin, and (G4) control heifers. Composite milk samples for somatic cell count, total bacteria count and milk composition were collected 15 days after calving and every 15 days until the end of the experiment. Bacteriological analysis was carried out at the end of study. The milk production and the incidence of clinical cases of mastitis, as well as the costs associated with them were recorded. The results demonstrate a reduction on clinical mastitis rates by preventive strategies, which implicated in lower volume of discarded milk (0.99, 1.01, 1.04 and 3.98% for G1, G2, G3 and G4, respectively) and higher economic benefit. Thus, in well-managed dairy herds the prevention of heifer mastitis by vaccination or antimicrobial therapy can reduce the amount of antimicrobials needed to treat clinical mastitis cases and the days of discarded milk.Index Terms: Mastitis; milk; antimicrobial treatment; vaccine; dairy cowsResumo:O presente estudo objetivou realizar uma análise econômica do tratamento antimicrobiano no pré-parto e/ou da vacinação com Escherihia coli J5 em novilhas leiteiras, e seu efeito sobre a produção e qualidade de leite. Portanto, utilizou-se o delineamento split-splot em esquema fatorial, no qual 33 novilhas da raça Holandesa foram divididas aleatoriamente em quatro grupos: (G1) antimicroianoterapia no pré-parto e vacinação com E. coli J5, (G2) antimicrobianoterapia no pré-parto, (G3) vacinação com E. coli J5 e (G4) controle. Amostras compostas de leite foram coletadas para contagem de células somáticas, contagem bacteriana total e composição do leite 15 dias após o parto, e a cada 15 dias até o término do experimento. A análise bacteriológica do leite foi realizada ao término do experimento. A produção de leite e a incidência dos casos clínicos de mastite, assim como, os custos associados à antimicrobianoterapia no pré-parto e/ou vacinação com E. coli J5 foram registrados. Os resultados demonstraram redução dos casos clínicos de mastite com a implementação das medidas preventivas resultando no menor volume de leite descartado (0,99, 1,01, 1,04 e 3,98% para os animais dos grupos G1, G2, G3 e G4, respectivemente) e maior benefício econômico. Desta forma, em rebanhos bem manejados, a implementação da antimicrobianoterapia no pré-parto e vacinação com E. coli J5 e novilhas pode reduzir a quantidade de antimicrobianos necessário para o tratamento de casos de mastite clínica durante a lactação, resultando em menor número de dias em que o leite é descartado.Termos de Indexação: Mastite; leite; tratamento antimicrobiano; vacina; vaca leiteiraIntroductionMastitis is the most costly disease for dairy farmers and the dairy industry, and although losses have been well characterized in mature cows, intramammary infections (IMIs) in primigravid heifers have been a more recent focus of study (Borm et al. 2006, Fox et al. 2009). Historically, control of mastitis has been driven primarily by economic considerations and public health (Heikkilä et al. 2012, Langoni 2013).Notably, the greatest development of milk-producing tissue in the udder occurs during the first pregnancy. Therefore, it is important to protect the mammary gland from pathogenic microorganisms to ensure maximum milk production during the first lactation (Nickerson et al. 2009, Piepers et al. 2009). Unfortunately, most dairy farmers assume pre-calving heifers as uninfected. However, IMIs in heifers is not uncommon, although it does tend to be less prevalent than in older cows (Costa et al. 1996, Fox et al. 2009, Nickerson et al. 2009, Sampimon et al. 2009). IMIs in heifers have been detected as early as at the age of puberty, but the rate of new infections is higher in the last few days of pregnancy (Compton et al. 2007, Compton et al. 2009, De Vliegher et al. 2012).First-calving heifers have a higher incidence rate of clinical mastitis than older cows, with the highest rate of disease occurring in the first few days after calving (Parker et al. 2007, Compton et al. 2009, Piepers et al. 2009). In the last few decades with the improvement of subclinical mastitis control programs, which has led to herds with a lower somatic cell count (SCC), clinical mastitis has become a major problem in many well-managed dairy herds that have successfully controlled contagious pathogens (Green et al. 2004).The average cost of subclinical heifer mastitis has only been calculated once (Hujips et al. 2009), however the economic cost of clinical mastitis in heifers around calving has never been reported in the literature (De Vliegher et al. 2012). With this in mind, the average costs per case of clinical mastitis, clinical mastitis by Gram-negative bacteria generated the highest cost per case when compared with Gram-positive bacteria and other pathogens that caused clinical mastitis (Cha et al. 2011). Here, the partial budgeting was used to develop a deterministic simulation model to estimate the net cost or benefit of dry antimicrobials and/or Escherichia coli J5 vaccination. Partial budgeting is a relative simple method to calculate economic effects. It is useful in studies that compare relatively small changes in a system such as implementation of a control program vs. no implementation of a control program (Swinkels et al. 2005).Clinical mastitis have been associated with increased use of drug therapy, increase in discarded milk, and increased risk of residues appearing in the milk supply. For these reasons, reductions in heifer mastitis by prevention strategies such as antimicrobial therapy and vaccination can lead to increased profitability to the dairy operator and a more wholesome milk supply. Coliform mastitis continues to increases in importance as a disease complex of dairy cattle, which leads to death of cattle, milk production loss, veterinary and treatment costs, excess labor demand, premature culling, decrease quality of milk, and discarded milk (Wilson et al. 2008, Heikkilä et al 2012). Most of commercially vaccines against coliforms mastitis are E. coli J5 vaccines. The J5 strain has a relatively exposed core antigen, sometimes, called the J5 core antigen that is present in many kinds of gram-negative bacteria (Wilson & González 2003). Thus, to the best of our knowledge, this is the first report that has investigated the effects of antimicrobial therapy and E. coli J5 vaccination alone or in association, on milk quality, and milk production, along with their economic implication, in dairy heifers.Thus, present study sought to explore whether prepartum antimicrobial therapy and/or E. coli J5 vaccination in dairy heifers influenced the milk production, somatic cell count, milk composition, and total bacteria counts in milk. In addition, the economic effects of the implementation of these control programs were also estimated on the first 190 days in milk.Materials and MethodsThe present study was conducted in a well-managed commercial dairy herd with low bulk tank somatic cell counts (≤250,000 cells mL-1) and a history of clinical mastitis by Gram-negative bacteria located in Minas Gerais State, Brazil. Out of this herd, 33 Holstein heifers were randomly selected and enrolled in four groups using a full factorial split-plot design. Cows were milked three times/day, housed in free stalls, and all animals received the same basal diet, which had been formulated to meet their requirements (NRC 2001).The treatment groups were as follows: G1, n=8, intramammary infusion of all quarters with a antimicrobial dry cow preparation containing 400mg of novobiocin sodium plus 200,000 IU of penicillin G procaine (Albadry Plus®, Pfizer Animal Health) 60 days before the expected parturition, as proposed by Trinidad et al. (1990) and vaccination with an Escherichia coli J5 bacterin (Enviracor J5®, Pfizer Animal Health) at 60 and 30 days before the expected parturition and 15 after calving; G2, n = 9, intramammary infusion of all quarters with an antimicrobial dry cow preparation containing 400 mg of novobiocin sodium plus 200,000 IU of penicillin G procaine (Albadry Plus®, Pfizer Animal Health) 60 days before the expected parturition; G3, n = 8, vaccination with an E. coli J5 bacterin (Enviracor J5®; Pfizer Animal Health) at 60 and 30 days before the expected parturition and 15 days after calving and G4, n=8, no intramammary infusion and no vaccination.Clinical mastitis was assessed by udder examination and a strip cup test for the presence of clots, flakes or otherwise obviously abnormal secretion at every milking. When a clinical case of mastitis was detected, the animals were treated with an intramammary infusion of lactation cow antimicrobial preparation once a day for three days or until clinical cure occurred. Any episode occurring more than 14 days after the previous episode was considered a new clinical mastitis case (Barkema et al. 1998). When a recurrent case of clinical mastitis appeared, the animal was treated with an infusion of antimicrobial preparation at all milking times for three days or until clinical cure was observed.Composite milk samples for SCC and milk composition (fat, lactose, protein and total solid contents) were collected 15 days after calving and every 15 days until the end of the experiment (190 days of lactation) in a 40-mL vial containing microtablets of bronopol (2-bromo-2-nitropane-1,3-diol) and analyzed using a calibrated Bentley CombSystem 2300® unit (Chaska, USA). Composite milk samples for total bacteria count (TBC) were also collected in a vial containing azidiol at the same time points described above. The TBC was determined using a Bactocount ICB 150® unit (Bentley Instruments, Chaska, USA). Milk production measurement was assessed every milking for each cow using a milking meter system (DeLaval ALPROTM, DeLaval®, Sweden).Composite milk samples from each cow were collected aseptically for bacteriological analysis at the end of the experiment (190 days of lactation). The milk samples were kept frozen until cultured. Bacterial analysis was conducted by culturing 0.01mL of each sample on 5% ovine blood agar plates and MacCon

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