Automated simultaneous determination of ammonia and total amino acids in ruminal fluid and in vitro media

Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows.

Influence of hydrogen on rumen methane formation and fermentation balances through microbial growth kinetics and fermentation thermodynamics

Quantitation and diversity analysis of ruminal methanogenic populations in response to the antimethanogenic compound bromochloromethane.

Ruminant animals have two metabolic systems that differ in their nutrient requirements: microbial metabolism in the rumen and mammalian metabolism in the tissues. Maximizing or optimizing ruminant productivity involves meeting requirements in proper amounts and balance for both metabolic systems. Ruminant nutritionists formulate diets with an intention of providing the animal with optimal levels of nutrients to achieve the optimal or maximal level of performance. Ideally, most of the dietary constituents should be digested, absorbed and utilized by the tissues as completely as possible. However, in reality, feed components are digested incompletely, more so with feedstuffs fed to ruminants than to non-ruminants. In ruminants, nutrient inputs are subjected first to fermentative digestion by microorganisms and then to glandular digestion by the host. Fermentative digestion is advantageous for substrates that cannot be digested by the host enzymes but is inefficient for digesting proteins, amino acids and sugars, because of losses in energy and nitrogen. Therefore, a proper balance between fermentative and glandular digestion needs to be achieved for optimal productivity.

Manipulation of ruminal fermentation

Manipulating Rumen Fermentation

This chapter describes our efforts to convert a large dairy cow nutrition model suite into a commercial product. The scientific model chosen as the basis for the product was the Cornell Net Carbohydrate and Protein System (CNCPS) and the product deriving from this effort was the Cornell Pennsylvania Miner Dairy (CPM-Dairy) Program.

The Conversion of a Scientific Model Describing Dairy Cow Nutrition and Production to an Industry Tool: the CPM Dairy Project

Nutrient flow in dairy farming involves animal and field components that are linked by transfers of crops and manure. Connections of the farm to the surrounding environment are created by inputs and outputs of feed, fertilizer, biological N 2 fixation, animals and animal products, and nutrient losses to air and water. Because of these linkages among farm components and connections to the environment, an integrated system-level approach would be useful to evaluate farm performance in terms of production efficiency and environmental protection goals. The purpose of this study was to evaluate dairy farm N flow and management by comparing farm performance data with reference values from the Dairy Nitrogen Planner (DNP), an integrated animal and field spreadsheet planning and evaluation tool. Performance data were from two Pennsylvania dairies: Farm 1, 109 lactating Holstein cows (Bos taurus), with forages produced on 92-ha crop land and supplemental feeds purchased as directed by nutritional services; Farm 2, 65 lactating cows, with nearly all feeds produced on the 111-ha crop land and no forage quality analysis or ration formulation assistance. Farm performances on Farm 1 and 2, respectively, were (with the difference relative to the DNP projection): annual N input, 17 450 kg (-5%) and 10 670 kg (-10%); milk-N output, 3880 kg (-8%) and 2790 kg (-0.4%); feed-N intake, 20 200 kg (-2%) and 18 820 kg (+1%); and manure N for application, 8550 kg (-14%) and 10 200 kg (+11%). The differences between farm performance and DNP projections identified overall farm organization and crop management opportunities for improved farm system performance on Farm 1. Animal ration balancing was identified as a priority area for enhancement on Farm 2, with subsequent action to adopt the services of a professional nutritionist increasing milk production by 20% and decreasing manure N by 10%.

W. Chalupa

Papers

Manipulating Rumen Fermentation

The Conversion of a Scientific Model Describing Dairy Cow Nutrition and Production to an Industry Tool: the CPM Dairy Project

An Integrated Approach to Managing Nitrogen on Dairy Farms: Evaluating Farm Performance Using the Dairy Nitrogen Planner

Dairy nutrition models: their forms and applications.

Precision feeding of nitrogen to lactating dairy cows: a role for Optigen® II.