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

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 cows Resumo: O presente estudo objetivou realizar uma an??lise econ?′mica do tratamento antimicrobiano no pr??-parto e/ou da vacina?§?￡o com Escherihia coli J5 em novilhas leiteiras, e seu efeito sobre a produ?§?￡o e qualidade de leite. Portanto, utilizou-se o delineamento split-splot em esquema fatorial, no qual 33 novilhas da ra?§a Holandesa foram divididas aleatoriamente em quatro grupos: (G1) antimicroianoterapia no pr??-parto e vacina?§?￡o com E. coli J5, (G2) antimicrobianoterapia no pr??-parto, (G3) vacina?§?￡o com E. coli J5 e (G4) controle. Amostras compostas de leite foram coletadas para contagem de c??lulas som??ticas, contagem bacteriana total e composi?§?￡o do leite 15 dias ap?3s o parto, e a cada 15 dias at?? o t??rmino do experimento. A an??lise bacteriol?3gica do leite foi realizada ao t??rmino do experimento. A produ?§?￡o de leite e a incid?ancia dos casos cl?-nicos de mastite, assim como, os custos associados ?? antimicrobianoterapia no pr??-parto e/ou vacina?§?￡o com E. coli J5 foram registrados. Os resultados demonstraram redu?§?￡o dos casos cl?-nicos de mastite com a implementa?§?￡o 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 benef?-cio econ?′mico. Desta forma, em rebanhos bem manejados, a implementa?§?￡o da antimicrobianoterapia no pr??-parto e vacina?§?￡o com E. coli J5 e novilhas pode reduzir a quantidade de antimicrobianos necess??rio para o tratamento de casos de mastite cl?-nica durante a lacta?§?￡o, resultando em menor n?omero de dias em que o leite ?? descartado. Termos de Indexa?§?￡o:??Mastite; leite; tratamento antimicrobiano; vacina; vaca leiteira Introduction Mastitis 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 (Heikkil?¤ 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