Use of Partial Total Mixed Rations on Pasture-Based Dairy Farms in Pennsylvania and New York

Abstract

ABSTRACT A study was conducted on the use of a partial total mixed ration (pTMR) on 13 pasture-based dairy farms in New York and Pennsylvania. The objectives of the study were to monitor and summarize management decisions made in relation to pTMR formulation throughout the grazing season and to develop recommendations for use of a pTMR in a pasturebased system. In general, haylage or silage replaced pasture in the pTMR diet. The pTMR protein level was often decreased with high pasture protein content; however, total dietary protein still exceeded protein requirements by an average of 39% over NRC requirements on most farms. In some cases, nutritionists or producers underestimated the nutritional quality of pasture. All farms appeared to be feeding adequate levels of energy in relation to NRC requirements. Few farms analyzed pastures for nutrient content, even though forage testing of stored forages was common. The amount of pTMR fed was frequently adjusted on most farms based on bulk milk tank readings, changing pasture availability, and pTMR refusal rates. Outside factors (i.e., water supply on pasture, heat, time on pasture, pasture condition) also have significant impacts on animal productivity and health and must be considered in a whole-farm approach. Flexibility is key in utilizing a pTMR on pasture-based operations to respond to changing pasture quality and quantity and to formulate least-cost rations. The basic principles of nutrition still apply — monitor dry matter intake, forage to concentrate ratios, and milk production.