Effect of Clinical Mastitis on the Lactation Curve: A Mixed Model Estimation Using Daily Milk Weights

Abstract

The objective of this study was to estimate the milk production losses associated with clinical mastitis using mixed linear models and correlation structures that have not been available previously. Data used included computer-recorded daily milk yields and detailed and accurate recordings of clinical mastitis cases. Two commercial Holstein dairy farms in New York State participated in the study, one with 650 lactating cows and another that began the study with 830 lactating cows and increased to 1120 cows by the end of the study. Cows on both farms were housed in free stall barns and milked 3 times daily in milking parlors. Electrical conductivity was used as a diagnostic aid for clinical mastitis on both farms. Date of clinical onset was recorded for every episode of clinical mastitis as well as for 8 other diseases defined using standardized case definitions (dystocia, milk fever, retained placenta, metritis, ketosis, displaced abomasum, lameness, and cystic ovarian disease) during the study period of October 1, 1999 to July 31, 2001. The mixed linear model for explaining variation in the outcome variable daily milk yield relative to non-mastitic herdmates found the terms for all 9 diseases studied, including clinical mastitis, significant. The model with an autoregressive correlation structure was preferred based on -2 * log likelihood, Akaike's information criterion, and Bayesian information criterion as well as savings in degrees of freedom. Separate analyses were run for first lactation cows and for second-plus lactation cows because their lactation curves were shaped differently. Adjusting for the effects of the other 8 diseases, milk production loss from clinical mastitis during the whole lactation was estimated as approximately 598 kg for second-plus lactation cows. However, cows that contracted mastitis had a daily production advantage of 2.6 kg over their herdmates until they contracted the disease. When compared with this potentially higher milk production, the total loss from clinical mastitis was estimated as 1181 kg.

Mediation analysis to estimate direct and indirect milk losses due to clinical mastitis in dairy cattle

“…It also has several theoretical advantages, in particular, its ability to independently estimate direct and indirect losses. In previous studies, only total losses were provided (RajalaSchultz et al, 1999;Gröhn et al, 2004;Wilson et al, 2004;Hagnestam et al, 2007;Schukken et al, 2009). The ability to separate direct and indirect losses could dictate the choice of preventive and therapeutic approaches.…”

“…This seemed reasonable realistic, since tolerance likely varies among cows (Raberg et al, 2007) and therefore, the nature and severity of their clinical response will vary, as reported for clinical ECO mastitis (Burvenich et al, 2003). Random regression coefficients may also handle correlated within-subject errors, as in auto-regressive models used in previous studies (RajalaSchultz et al, 1999;Gröhn et al, 2004;Wilson et al, 2004;Hagnestam et al, 2007;Schukken et al, 2009).…”

Impacto econômico da retenção de placenta em vacas leiteiras

“…Wilson et al (2004), relataram incidência de retenção de placenta de 7,2% em primíparas e 12,2% em multíparas, Sartori et al (2014) relataram incidência de 14,7% no inverno e 14,8% no verão, englobando primíparas e multíparas. Apesar das diferenças nas condições de cada estudo as incidências foram próximas, o que demonstra que os dados utilizados no presente trabalho, para fazer a estimativa de perdas econômicas devido a essa doença, condizem com a realidade encontrada em fazendas leiteiras.…”

Bovine Mastitis and Its Therapeutic Strategy Doing Antibiotic Sensitivity Test

“…Milk production is reduced considerably in the affected animals and estimated loss of milk yield may range from 100 to 500 kg per cow per lactation [7]. The predictable loss causing clinical mastitis in cows is nearly 700kg in first lactation and 1,200kg in the second lactation [8]. In United States, expenses related to mastitis on dairy farms are around U$ 200 per cow per year and an estimated annual loss of 2 billion dollars for dairy industry [9].…”