[MUSIC] Hello, my name is Kathy Soder. I am a research animal scientist with the USDA Agricultural Research Service. Today, I will be presenting the second of two lessons on grazing management from the dairy production and management MOOC series. In the last lesson, we focused on pasture management. Today, we will focus on the animal, to look at the nutritional aspect of dairy grazing systems. While grazing cows is a low cost resource for feeding dairy cows, intensive grazing systems present challenges to nutritionists and farmers. The forage quality of pastures is usually higher than the same forage harvested as silage or dry hay due to maturity level of harvest. Seasonal variation, species composition such as legumes mixed with grass species, fertilization management and grazing preferences by animals makes supplemental feeding with pasture based systems more difficult than with confinement systems where forage quality is known. High quality pastures are key to optimal milk production in grazing dairy herds. However, there are many questions regarding what defines a high quality pasture and how we can develop and maintain high quality forages in sufficient quantities to meet the dry matter and nutrient needs of lactating dairy cows. High quality pasture has many positive attributes for lactating dairy cows, but it also has nutritional imbalances and deficiencies. Total protein is usually high in frequently exceeds crude protein needs of the lactating cow, especially if nitrogen fertilization or legumes are part of the pasture management. This protein is highly degradable in the rumen. This rumen degradable protein, or RDP, is rapidly broken down by the rumen microbes into ammonia. Ideally, this ammonia is recaptured into more microbial protein to maintain rumen function and provide protein to the animal further down the digestive tract. However, if energy is lacking in the diet, which can be the case with pasture based diets, this ammonia cannot be recaptured into microbial protein. Rather it is converted to urea, a less toxic form, and excreted in urine and milk. Not only is this a potential environmental issue with additional nitrogen excreted in urine, and can have negative effects on cow productivity through elevated milk urea nitrogen or MUN levels, but the conversion of ammonia to urea requires energy that otherwise could have been used to produce additional milk. For high producing cows, producing greater than 70 pounds of 32 kilograms of milk per day on pasture, rumen undegradable or bypass protein, also known as RUP, may be inadequate and a supplemental source of rumen undegradable protein may be necessary to maintain optimal milk production. The fiber content of high quality pasture may be too low, particularly in the spring and fall. To stimulate adequate cud chewing and rumination. This may result in reduced milk fat content and metabolic issues such as acidosis. Some grazing dairies will allow some pastures to get a bit more mature to increase the fiber content of the diet. However, this will also result in reduced protein and energy of the pasture forage, so supplemental feeding may be needed to meet those nutrient needs. Other farms will supplement with hay or baleage to provide long fiber. The amount of several minerals including calcium, phosphorus, magnesium, sulfur, zinc, and salt are usually inadequate in pasture. In general, these minerals should be added to the supplemental feeding program or to a free-choice trace mineral mix. Potassium and phosphorous may be too high in some regions relative to nutrient needs, particularly in areas that historically have had heavy lumen application. High potassium diet can result in milk fever, or hypocalcemia, while high phosphorous is an environmental concern as it is excreted in the minora and it can get into the water supply. Vitamins A and E are high in fresh pasture forages and vitamin supplementation is often not needed during the grazing season, but may be necessary during the non-grazing season when conserved forages are fed. In addition to the high protein content, the other notable nutrient imbalance is a relatively low fermentable carbohydrate content. The major source of energy for both the rumen microbes, and the cow, in most pastures compared to the needs of the cow. Therefore, strategic supplementation with grain or other energy sources may be desirable to maintain milk production, milk components, and animal health. Research at Penn State University has shown that high quality pastures in the Northeastern United States can support 18-23 kg or 40-50 lb of milk production. However, this was a short-term study that did not account for long-term effects on body condition or reproduction. In addition, many grazing farms target higher levels of milk production or need supplemental feeds to fill in gaps in forage production such as summer slumps or poor quality forage. Therefore, strategic supplementation of grazing dairy cows is often needed to maintain animal productivity and farm milk production goals. The most common supplementation strategies are grains for energy, effect the fiber from forage or high fiber feed ingredients, and minerals that are deficient in pastures. In addition, some very high producing herds may supplement with fat or rumen bypass protein source to improve production and components. Before we discuss supplementation, the first step in a successful grazing system is to provide adequate quantities of high-quality pasture, which is the cheapest feed source available. If pasture availability is limited, cows cannot maintain adequate dry matter intake. In addition, they will spend more time walking around searching for more to eat. The energy spent walking could have been used to produce more milk. Therefore, we want to make sure the cows get the most high quality forages possible in every bite taken. When deciding how much area to give cows, the farmer must consider the following options. How much time with the cow spend in this pasture will she be out half a day, one day, or longer on the same pasture? How many cows are on the pasture? How big is that pasture? Estimated dry matter intake of group. How much forage is available? And how much will cows actually consume versus what they will waste or leave behind? This last point is important. Cows will not eat every single bite of grass available in a pasture. Some forage will be wasted due to rejection, manure and urine spots and preference for other plants. It is important to allocate more pasture than is expected to be consumed probably 50 to 100% over and above expected requirements. For cows to maintain dry matter intake, select the highest quality forages, avoid manure and urine patches and allow enough forage residual to maintain plant regrowth. Even with sufficient quantities of high quality pasture, the nutrient needs of lactating cows are often not met, especially energy. Therefore, strategic supplementation is a crucial part of dairy nutrition in most grazing herds. Any type of supplement will reduce the cows' intake on pasture. If forage is supplemented, you can expect an approximate one to one substitution rate. That is, for every pound or kilogram of supplemental forage fed, on a dry matter basis, you can expect pasture intake to decrease by one pound or kilogram of dry matter. This results in no change in total dry matter intake. One pound or kilogram of concentrated grain on a dry matter basis will reduce pasture intake by ony one-half a pound or kilogram of dry matter. Supplementing with grain or concentrate will not ony result in greater total dry matter intake due to a lower substitution rate, but greater nutrient intake, especially energy, due to the increased nutrient density of the grains. Substitution rates for biotic feeds may vary depending on source and nutrient content. Another factor that can influence pasture intake and grazing behavior is when supplemental feed is fed in relation to the grazing period. Some farms will feed supplemental feed in the milking parlour or immediately after milking. The cows are then turned out to pasture. Other farms will turn cows out on pasture after milking and feed supplemental feed later in the day. When cows are fed supplements prior to grazing, appetite will be reduced when turned out on pasture. And just like humans, when they are less hungry, cows get pickier about what they eat. They may only nibble on the tips of the forage plants or select certain species of plants which result in decreased pasture intake and utilization. When cows are turned out hungry with no supplemental feed prior to grazing, appetite is high. Grazing is more aggressive and cows will be much less selective about what plants and plant parts they eat, thereby increasing pasture intake and utilization. Grazing dairy farmers can use this behavior to meet their farm goals, whether it is to maximize pasture intake or stretch pasture resources with supplemental feed. Due to grain prices and availability, farm philosophy and milk markets, some grazing dairies have gone no grain. Feeding only forages to their cows in the form of pasture or conserve forages but not corn silage. While this can be successfully done, it does take a higher level of management and adaptation to go no-grain. High forage quality is a must at all times, as there is no grain to fall back on if forages are not of sufficient quality. Cows must be adapted to a no-grain diet, as well. It is not advisable to put cows with high milk production potential on a no-grain diet. They will continue to try to produce high quantities of milk at the expense of their body condition and health and eventually fall out of the system. Cows should be of moderate body frame, moderate milk production, with enough body capacity to process high forage diets. Farmers must also make adjustments. Milk production will likely drop but must be maintained at profitable levels. There are some premium markets for grass-fed milk, but at this time, they are limited to the United States. Farmers must keep a close eye on pasture quality and availability and often be thinking weeks or months ahead to insure there's adequate pasture available as well as have a backup plan in place in the event of adverse weather conditions such as drought or flooding. Management of a profitable grazing system requires higher and different management skills compared with confinement systems. Successful grazers acquire these skills with experience, education and mentorship from other grazers. Keeping adequate amounts of high quality pasture is one of the most important aspects of nutritional management of raising dairy herds. Thank you for joining us for the grazing management section. More information will be provided in the lesson resources on the MOOC website. [MUSIC]