Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
POPULATION HEALTH & REPRODUCTION
Non Technical Summary
Introduction: Levels of blood glucose, nonesterified fatty acids (NEFA) and ketone bodies (KB) during the close up period are used to indicate potential health and metabolic problems during calving and early lactation (Chapinal et al., 2011). In addition, fatty acid profiles (FAP) and KB can indicate energy status (Janovick et al., 2011; Toni et al., 2011) and predisposition of the cow for milk fat depression (Zachut et al., 2010; Cozzi et al., 2011). However, these blood nutrients also serve as precursors for milk and milk component production. Blood glucose and total protein (TP) are precursors for milk lactose which is the primary osmol for milk volume (Baldwin and Smith, 1983; Mepham, 1987), blood NEFA and FAP influence milk fat production and levels of long vs. short and medium chain fatty acids in milk (Baldwin and Smith, 1983; Mepham, 1987). Most guidelines established for blood nutrient values are used to indicate health and metabolic status but have not been examined to evaluate milk production. This project focuses on determining if levels of nutrients in blood can influence milk and milk component production and may indicate the cow's potential to be culled due to health issues and / or low milk production. Cows are frequently culled due to low milk production during or after peak milk production (>70 days in milk). Often low production is a result of metabolic and health issues that occurred during the transition period. Therefore the purpose of this proposal is to determine if blood levels of nutrients (glucose, NEFA, KB, FAP, and TP) are related to milk production during the entire lactation and if blood nutrient levels can be used in culling decisions. Relating blood levels to milk production during lactation could be used to not only identify potentially transition problem cows but also cows that are not able to mobilize nutrients to support lactation, for instance fatty liver cows or cows that have compromised digestive systems due to chronic rumen acidosis, decreased nutrient absorption due to old age or compromised immune systems. As part of another project, 150 cows have been followed for 1 lactation cycle. Blood has been collected twice a month and data on calving, milk production, feeding and culling have been collected using DairyComp 305 and FeedWatch. This proposal would support labor and lab analyses required to analyze blood samples for glucose, NEFA, KB, TP and FAP. Dr. Rossow's lab has already developed assays for analyzing blood glucose, KB and NEFA. In addition a Leco Nitrogen analyzer has been refurbished to estimate TP and a Gas Chromatograph is available to analyze the FAP samples in the lab.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
To quantify properties of feeds that determine the availability and utilization of nutrients critical to milk production.
To quantify metabolic and molecular interactions that alter synthesis of milk components.
To use this knowledge of feed properties and metabolic and molecular quantitative relationships to challenge and refine precision feeding systems for dairy cattle
Project Methods
Project Details: Blood samples, milk production and culling data for a lactation cycle (including dry period) of 150 cows of parity 2 or greater have already been collected as part of a previous research project. These samples are frozen and aliquoted for sample analyses of glucose, KB, NEFA, TP and FAP. Therefore funds have not been requested for sample collection; funds are requested for sample analyses. Because blood nutrient are the metabolic precursors to milk nutrients such as lactose (glucose and TP for milk volume), milk protein (TP) and milk fat (NEFA) and are good indicators of metabolic status of the cow, for instance glucose and KB for ketosis, NEFA for energy balance and fat mobilization, TP for edema and FAP for milk fat depression, we anticipate that they will also be correlated with milk production (volume and components). For culling decisions, most dairies record that a cow was culled, died or sold, but very few accurately identify metabolic reasons (ketosis, fatty liver, milk fever, etc.). Therefore this proposal focuses on culling (including death) risk relative to blood nutrient levels rather than reason for culling. In objective 1, blood nutrient values will be compared to milk production using regression analysis with repeated measures on cow. Regression models will be evaluated for goodness of fit (predictability) and bias to determine if blood nutrient values can predict milk production. Then in objective 2, using risk analyses, culling data will be used to determine if low milk production and therefore blood nutrient levels can predict risk of the cow being culled. Based on the statistical relationship between blood nutrients and milk production and risk of culling or exiting the herd, blood nutrient ranges for each stage of lactation will be developed to identify which cows are potentially low producers. This project generates guidelines to be used by veterinary and extension personnel (Tulare, Kings and Merced counties) and data for further development of the dairy cow model used in conjunction with the multistate research project (NC 1040).