The Penn State Dairy Center - Integrating Research and Extension
Posted: April 4, 2006
There are limitations to evaluating results using small number of animals and extrapolating the data to real world situations when conducting university trials. One of the objectives of the dairy center is to answer questions that dairy producers and their consultants ask. A question currently being addressed through research at the dairy center is nutritional and feeding management factors that affect milk production and components. Small and large scale projects are being conducted. The large scale version of the trial allows a more practical approach to answering some of these questions.
With the potential for changes in milk price there is a need to evaluate feeding options. The current study focuses primarily on the forage portion of the ration and how monensin affects dry matter intake efficiency and components on various diets.
An intensive small scale project using 30 animals in a tiestall barn is evaluating forage source and level in the ration and how this impacts milk yield and components with and without monensin. Forages generally constitute 50% or more of rations fed to high producing dairy cows. However there is interest in feeding higher forage rations to cows to potentially reduce costs. These scenarios need to be evaluated because of their impact on profit and it may not be for all producers especially if forage quality is a concern.
The scenarios being examined are alfalfa, grass and corn silage based rations formulated to contain 50 or 60% forage of the total ration dry matter with or without monensin. Corn silage represents 45% of the total forage content in the diets based on grass and alfalfa silage. For the diets based on corn silage, alfalfa hay represents 45% of the total forage in the diet. At the same time the intensive portion of the trial is being conducted, the freestall barn with 60 cows on each side are being used to evaluate two of the rations: corn silage and hay based and the grass silage based ration containing 50% forage (on a dry matter basis). Monensin is added to the ration every other month (i.e. January – no monensin; February – monensin, etc.)
The freestall cows started the project with similar days in milk, distribution of age, and stage of lactation. The freestall diets are being evaluated from January to May. Data is being collected that would be useful to producers and their consultants to evaluate the effectiveness of nutritional concepts and feeding management practices. The TMR and individual forage samples are taken once a month for analysis separator is used to determine the particle size distribution of the TMRs twice a month. Milk weights and body weights are recorded on a daily basis. Refusals are measured and dry matter intake monitored on a daily basis. Milk samples are taken twice a month for 2 consecutive milkings. Body condition scores are recorded monthly.
The study will be completed in May. All the information collected will be analyzed to evaluate how nutritional strategies and feeding management practices affect animal performance. The economics of the strategies will also be examined to measure income over feed costs and dry matter intake efficiency. The final step will be to take the results and evaluate it on a whole farm basis, taking into account cropping, harvesting and storage issues for the various forages.
Gabriella Varga, Professor of Animal Science and Virginia Ishler, Nutrient Management Specialist & Dairy Complex Manager