Grazing of dairy cattle is one of the more difficult feeding practices to control and manage especially when trying to meet the animal’s daily nutrient needs for optimal performance. Well managed grazing systems offer an opportunity to reduce costs of producing forage during the pasture season and are a major reason why some producers are trying to increase the utilization of pasture as a forage for dairy cattle. Studies have indicated the use of pasture can increase returns per cow, as there can be a reduction in total purchases feed costs.
Benefits for pasture based systems include:
- Increased yield and quality of forage from the pasture
- Decreased total feed inputs
- Decreased equipment and fuel needs
- Decreased manure handling
- Lower bedding requirements
- Better animal health
Critical control points to grazing success:
- Maintenance of forage yield and quality over the entire grazing season
- Extending the grazing season as long as possible
- Use of appropriate types and amounts of energy, protein and mineral supplements to optimize milk production, maintain body condition and reproduction while maximizing profitability
What Are The Missing Nutrients In Pasture?
Protein
Dairy cattle consuming forages of varying quality may not ingest sufficient nitrogen or energy to meet the requirements of the rumen microorganisms – this can depress feed intake and nutrient digestibility. High quality pasture tends to be low in rumen undegradable (UIP) or metabolizable amino acids. This can limit milk production and milk protein yield in dairy cows. Pasture, especially early in the season, are high in soluble protein (SIP). Although rumen bugs require SIP for optimal growth and fiber digestion, excess SIP can actually reduce rumen microbial efficiency and increase the need for UIP that is already in short supply. The process to remove excess SIP from the rumen costs the animal energy, another nutrient already in short supply. Together these factors can limit milk production, milk protein yield and reduce body condition. This results in lost profits!
Energy
Forage intake from well-managed pastures should provide sufficient energy to support 18 to 23 kilograms of milk per day with little or no supplemental energy and protein. Since most dairy cows have the potential to produce above 25 kg per day, supplemental feed and energy are needed to achieve maximum milk production.
Supplemental
energy provides a long-term benefit as it can improve total milk production, body condition scores, and reproductive performance.
Vitamins & Minerals
Pasture does not contain adequate mineral levels to optimize profitable performance. Minerals support various functions that are essential to growth and production such as: immune status & health, reproductive efficiency and milk production. As the pasture matures there is a decrease in the amount of phosphorus and other key minerals (i.e. magnesium, copper, zinc, selenium and cobalt) as well as the levels in Vitamins A and E.
Fiber Changes
As a pasture matures, other anti-nutritive factors can – an increase in the cell wall components (NDF and ADF) and a decline in the availability of digestible nutrients. This results in a decreased digestibility of the pasture and an overall decline in nutrient intakes. This causes a reduction in rumen fermentation, a slower rate of forage passage and a lower forage intake from pasture.
Supplementation For Pasture
A Key Strategy on Pasture!
The success of a grazing system is dependent on planning, frequent monitoring, and the re-evaluation of supply of pasture nutrients in relation to the dairy cow’s nutrient demand. One of the primary management challenges is the difficulty of matching pasture growth and quality with feed demands. Synchronizing the forage available to production requirements becomes a much more serious problem with lactating dairy cows, due to the adverse physiological effects on the milk production curve if requirements are not met on a regular basis. Cows usually have 3 to 4 major grazing bouts during a 24-hour period and are often fed grain twice daily at milking. These feeding patterns suggest that rumen synchrony of energy and protein breakdown may not occur during a day to optimize the rumen environment and maximize rumen microbial protein synthesis.
By providing additional protein and energy source(s), pasture supplements can enhance the nutritional value of forage and pasture. Protein and/or energy supplementation provides the necessary nutrients to fill the void between the dairy animal’s requirements and the nutrient intake from forages. Supplements can also augment the reproductive efficiency of heifers on pasture bringing about an earlier age at first calving, an increased pregnancy rate and a shorter calving interval. The production benefits of providing supplements to pasture include: proper calf growth, increased milk and milk component yields and an improved body condition.
The critical factor in all of this becomes providing a properly balanced feed program. Designing such a program is not different than designing your winter confinement ration. You and your feed consultant need to know forage quality and intake, cow size, age, condition, milk production and milk component yields. With this information you are well equipped to estimate intake and nutrient requirements for your herd. Talk to your Nutritionist about the various feeding strategies that you can use to improve your herd’s productivity and profitability during the pasture season.