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Veterinary Medicine

Cristina Lanzas

2008

Articles 1 - 3 of 3

Full-Text Articles in Medicine and Health Sciences

Improved Feed Protein Fractionation Schemes For Formulating Rations With The Cornell Net Carbohydrate And Protein System, Cristina Lanzas, G A. Broderick, D G. Fox Dec 2008

Improved Feed Protein Fractionation Schemes For Formulating Rations With The Cornell Net Carbohydrate And Protein System, Cristina Lanzas, G A. Broderick, D G. Fox

Cristina Lanzas

Adequate predictions of rumen-degradable protein (RDP) and rumen-undegradable protein (RUP) supplies are necessary to optimize performance while minimizing losses of excess nitrogen (N). The objectives of this study were to evaluate the original Cornell Net Carbohydrate Protein System (CNCPS) protein fractionation scheme and to develop and evaluate alternatives designed to improve its adequacy in predicting RDP and RUP. The CNCPS version 5 fractionates CP into 5 fractions based on solubility in protein precipitant agents, buffers, and detergent solutions: A represents the soluble nonprotein N, B1 is the soluble true protein, B2 represents protein with intermediate rates of degradation, B3 is …


The Effect Of Heterogeneous Infectious Period And Contagiousness On The Dynamics Of Salmonella Transmission In Dairy Cattle, Cristina Lanzas, S Brien, R Ivanek, Y Lo, P P. Chapagain, K A. Ray, P Ayscue, L D. Warnick, Y T. Grohn Nov 2008

The Effect Of Heterogeneous Infectious Period And Contagiousness On The Dynamics Of Salmonella Transmission In Dairy Cattle, Cristina Lanzas, S Brien, R Ivanek, Y Lo, P P. Chapagain, K A. Ray, P Ayscue, L D. Warnick, Y T. Grohn

Cristina Lanzas

The objective of this study was to address the impact of heterogeneity of infectious period and contagiousness on Salmonella transmission dynamics in dairy cattle populations. We developed three deterministic SIR-type models with two basic infected stages (clinically and subclinically infected). In addition, model 2 included long-term shedders, which were defined as individuals with low contagiousness but long infectious period, and model 3 included super-shedders (individuals with high contagiousness and long infectious period). The simulated dynamics, basic reproduction number (R0) and critical vaccination threshold were studied. Clinically infected individuals were the main force of infection transmission for models 1 and 2. …


The Risk And Control Of Salmonella Outbreaks In Calf-Raising Operations: A Mathematical Modeling Approach, Cristina Lanzas, L D. Warnick, R Ivanek, P Ayscue, D V. Nydam, Y T. Grohn Nov 2008

The Risk And Control Of Salmonella Outbreaks In Calf-Raising Operations: A Mathematical Modeling Approach, Cristina Lanzas, L D. Warnick, R Ivanek, P Ayscue, D V. Nydam, Y T. Grohn

Cristina Lanzas

Salmonellosis in calves has economic and welfare implications, and serves as a potential source of human infections. Our objectives were to assess the risk of Salmonella spread following its introduction into a herd of pre-weaned calves and to evaluate the efficacy of control strategies to prevent and control outbreaks. To meet these objectives, we developed a model of Salmonella transmission within a pre-weaned group of calves based on a well documented outbreak of salmonellosis in a calf-raising operation and other literature. Intervention scenarios were evaluated in both deterministic and stochastic versions of the model. While the basic reproduction number (R0) …