Articles on Pasture and Grazing
Historically, most dairy farms have remained profitable by achieving higher milk production per cow and along with a higher volume of milk (increased herd size). Dairy producers have adopted grazing systems in an attempt to reduce the input costs and increase the profit margin per cow. The grazing season is typically 6 to 7 months in the upper Midwest and Northeast USA, therefore cows still need to be managed for 5 to 6 months with a confinement system.
High quality pastures are key to high milk production in grazing dairy herds. However, many questions arise as to what defines high quality pasture and how we can develop and maintain a high quality sward in abundant quantity.
Reference table of typical nutrient composition of high quality pasture.
Supplementing the nutritional attributes of pasture to maximize rumen fermentation and microbial protein synthesis is a challenge to efficiently utilizing pasture for high producing dairy cows. The basic supplemental nutrients needed are energy from NFC in grains, RUP and NFC to maximize rumen microbial protein synthesis and rumen bypass protein, effective fiber from forages or high fiber feed ingredients, and minerals that are deficient in the pasture.
Supplementation of fat to pasture appears to increase milk production by dairy cows grazing high-quality pastures, though the effect depends on type of fat supplement and stage of lactation. Increases in milk production may be related to an improvement in energy utilization rather than an increase in energy intake.
With pasture-based systems, the amount of concentrate fed, the types of feed ingredients in the concentrates, the processing of feed ingredients, and the method of feeding, such as using a partial TMR, influence milk yield and components. We must look at component yield in addition to percentages, since many nutritional factors increase milk yield.
Feeding a partial TMR to grazing cows offers more “control” over the entire feeding program compared to offering pasture and grain separately. As with all pasture supplementation strategies, there are advantages and disadvantages associated with feeding a partial TMR that should be considered along with the goals of the dairy producer.
Determining the optimum amount of concentrates or supplemental forages to feed to achieve the most profitable milk production response by lactating cows depends on several factors. This paper discusses the influence of milk and feed prices, substitution rates, and expected milk yield and component responses. Long-term effects on body condition, herd health, and reproductive performance also merit consideration.
Pasture can be a cost-effective feed for dry cows and heifers, but must be managed to ensure animals meet performance goals. Just like for any other group of grazing animals, pastures must be rotated, supplements must be provided, and animals must be observed on a regular basis. This article discusses special considerations for successful grazing of dry cows and heifers.
Grazed pasture represents the cheapest source of nutrients for dairy cows. Management of dairy cows and pasture is a major challenge, given the variation in grass growth and grazing conditions during the grazing season. Allocation of the correct amount of area and pasture to achieve maximum intake is an important decision that the manager must make each day.
Discussion of the CNCPS, how we have used it as a valuable tool at Penn State, and the strengths and weaknesses of using a computer model for grazing dairy cows. In addition, there is a brief discussion on the NRC model.
At times the crude protein content of pasture can be too high and can be detrimental to cow performance. Strategic feeding of concentrate supplements that contain the proper types and amounts of rumen fermentable carbohydrates can improve utilization of excess protein and improve milk yield.
The responses to BST are contingent upon cows being adequately fed, whether grazing or not grazing. Both grazing and BST have the potential to improve profitability and should be considered together if they can improve dairy profitability. Good nutritional and grazing management will enhance the opportunity of obtaining a profitable response from the two technologies.
A cow's energy status during late lactation and the early part of the subsequent lactation is critical to her health and reproduction, as well as to the economics of the dairy farm. Pasture systems often result in lower BCS or greater loss of BCS during the first 1 to 2 months of lactation, and proper concentrate supplementation during lactation to restore body condition has immediate benefits of higher production as well as long term economic benefits.
Pastures are often deficient in several minerals compared to the NRC requirements. Even with grain supplementation of pasture-based diets, most rations need to be supplemented with concentrated sources of certain minerals.