[MUSIC] Hello, and welcome back. We continue our lecture on formulating diets for lactating dairy cows. In our last lecture, we talked about balancing dietary. While the diet meets the energy and fiber needs of the cow, we continue balancing it for the second most important nutrient, which is protein. Although metabolizable protein is the proper unit for using diet formulation for dairy cows, crude protein is still widely used by nutritionists in the field. Normally, dairy diets range in crude protein from 15, 16 to 17, 18%. If for example the total crude protein in a diet is 16%, around 10% should be as rumen degraded protein, and the remaining 6% as rumen undegraded protein. Nutritionists also pay attention to protein solubility, which is a relatively easy and accurate laboratory analysis. A good target for soluble protein is about a third of the total dietary protein. As indicated in our previous lecture, gramatine intake a is a critical part of protein nutrition as well. We cannot meet protein requirements of the cow if the ramen intake is not accounted for in estimating protein supply. One important factor to consider when formulating dietary protein is its effect on the environment. This will be discussed in the end of this course. Nutritionists are increasingly paying attention to balancing amino acids for dairy cows. There are several amino acids that are important in lactating cows, referred to as limiting amino acids, because their deficit could potentially lead to decreased milk production or milk protein yield. These amino acids are methionine, lysine, and histidine. Balancing for amino acids becoming more important when dietary protein levels are relatively low, for example below 17% good protein. Methione is considered the most important amino acid in North American dairy diets. Target concentration should be around 2.2% of the metabolizable protein. What this means is that the normal diet which is around 10-11% metabolizable protein on the dry matter basis, should have methionine concentration of around 0.23% of dietary dry matter. Lysine is also an important amino acid for dairy cows, particularly in corn based diets, because its low concentration in corn and other cereal grains. Target dietary level is around 6.6% of the metabolizable protein. Histidine is the third amino acid to identify thus limiting milk production in dairy cows. Its target concentration in metabolizable of protein should be around 2.2 to 2.4%, or similar to that of metianine. Amino acid analysis are expensive and rarely performed in the field. This means that nutritionists have to rely on tabular data, which brings a significant uncertainty particularly with forages and by-product feeds. It's also to point out that synthetic rumen protected amino acids are commonly supplemented to dairy diets in intensive production systems. For these products, it is important that accurate room and bypass and intestinal digestibility specifications are provided by the manufacturer. Good sources of rumen-degraded protein in dairy diets include soy, canola, and sunflower meals, alfalfa forages or dehydrated meal, and in certain situations, plain or slow release urea products, particularly with well producing cows. Good sources of rumen-undegraded protein include heat treated oil seed meals, whole roasted soybeans, corn gluten meal, blood meal, and animal proteins where are allowed to be fed to ruminants, and to some extent by-products of the ethanol industry, such as distillers grains. In general, all animal protein and fish meals will be high in limiting amino acids. Good sources of Lysine are a dehydrated alfalfa meal, soy and canola meals, fish and blood meals. Good sources of Methionine are corn grain, and corn by products such as corn gluten meal, sunflower meal, fish meal, and to some extent canola meal. A good source of Histidine is blood meal. With all protein supplements, it is important to know the intestinal digestibility of their rumen-undegraded protein. Excessive heat generated during processing, for example, will render rumen bypass protein and amino acids indigestible in the small intestine. As a rule of thumb, various protein feeds provide different amino acids to the diet, and where possible, the diet should include more than one protein source. After balancing the diet for energy, fiber, protein fractions and amino acids, the next step is to meet the mineral and vitamin requirements of the cow. Usually the minerals and vitamins in a dairy diet are supplied to a mineral vitamin premix, manufactured by the feed company, based on specifications provided by the farm nutritionist. The mineral vitamin primerl sandring can be included separately in the diet or in combination with other feed's, usually protein, and in some cases fat supplements. Important macro minerals in daily diets include calcium, phosphorous, magnesium, sodium, from salt, and potassium. Acceptable for potassium, dairy diets are usually supplemented with micro minerals to meet the requirements of the cow. Another exception may be phosphorous, which is a nutrient of environmental concern, and may be in excess if the diet contains large amounts of cereal grains and by-products. The macrominerals are also important for maintaining the body acid-base balance, and are used to calculate the cation-anion difference of the diet, which is DCAD. Requirements for a number of microminerals are also specified in dairy diets, but nutritionists usually are mostly concerned with meeting the IMO requirements for copper, zinc, manganese, and selenium. Typically dairy diets are supplemented with the fat soluble vitamins A, D, and E. Please read the supplemental material for this lecture for more detailed information on mineral and vitamin nutrition of dairy cows, including dietary cation-ion difference. Here are a couple of examples of typical lactating cow diets from the eastern and western United States, Pennsylvania and Idaho. Note the high inclusion rate of corn silage in the Pennsylvania diet, and the alfalfa hay in the Idaho diet. This reemphasizes the point that foragers used in dairy diets are going to be locally produced, and therefore region specific and concentrate feeds will be more or less common across the industry. Also here's an example of typical chemical composition of dairy diets fed to high producing, over 30,000 pounds or 13,000 kilograms of milk per lactation, dairy herds in the US. Note the high level of dramatine intake up to 26 kilograms per day. The relatively moderate quick-protein concentration, the neutral detergent fiber concentration being around 30%, and non-fiber carbohydrates being around 40%. Total fat in these diets did not exceed 7% of dietary gramat. Now we will briefly discuss some recommendations for the various stages of the lactation cycle. Specific recommendations for fresh cow diets include feeding a small amount, two to five pounds or two to two and a half kilograms per day of high quality long or chopped if a TMR is fed, grass or alfalfa hay or straw to maintain lumen function. Feed intake is depressed in this stage of the lactation. And increasing the ration nutrient density is recommended. This have to be done cautiously because cows in this stage are most susceptible to digestive disturbances. Inclusion of rumen-degraded fiber sources such as soy house, is also recommended. Grains with rapidly digestible starch such as wheat or barley should be avoided. If fat is supplemented to the diet, it's recommended that it is in a ruminated form. Total dietary proteins should be kept at around 18 to 19%, and the diet should contain increased amounts of high quality feed and degraded protein. For example, a 680 kilograms or 1500 pound cow milking 35 kilograms or 77 pounds per day, would require about 2200 grams of metabolizable protein, which is about 19% crude protein on dry matter basis. Fresh cows should be housed and fed separately from the rest of the herd. With enough feed bunks space if it's a free stall bunk, and fresh water available at all times. In early lactation, up to 100 days in milk, cows will be losing body weight. Therefore maximizing dry matter intake during this period is critical. Every effort should be made to provide palatable feeds and avoid feeds, that may decrease dry matter intake. Forage quality and digestibility feed processing, frequency of feeding, consistency of the ration ingredients, are all important factors affecting dry matter intake in this period. Here's a simple way of estimating dry matter intake of your cows. Multiply the body weight of an average adult cow, by 0.02 for 2% and add 25% of the average milk for the group. In this example, a herd milking on average 80 pounds, with average body weight of 1400 pounds, should have a minimum dramatine intake of 48 pounds, which is around 2200 kilo [INAUDIBLE] per day. A more complex equation to predict dry [INAUDIBLE] intake based on cow body weight, milk production, and stage of the lactation can be found in the supplemental materials for this lecture. The diet should contain at least 45 and preferably 50% forage on dry matter basis. Crude proteins should be around 17%, although a well balanced diet with 16% crude protein will also produce good results. About a third of the dietary protein should be ruminary un-degraded. Feeding frequency is usually once or twice a day. Feed should be pushed as frequently as possible, six or more times daily. Cows like fresh feed and will eat the most when fresh feed is first delivered and after milking. Pushing the feed also stimulates feed intake. Dietary changes should be avoided and implemented gradually when necessary, for example if concentrate inclusion is increased. In mid-lactation, 100 to 200 days in milk, cows have already reached peak milk production and drimine intake, and are not losing body weight. The goal in this stage is to maintain peak milk production as long as possible. Forage quality is again the most important factor in the diet. Digestible fiber could gradually replace some of the dietary starch, and good protein concentration can be reduced to around 16%. The proportion of forage in the diet can be increased to 60% or more. Driamine intake is still critical. Cows are a breath during this period, and improving their energy status is important for success of the reproductive program. In late lactation, which is above 200 days in milk, cows continue to gain weight, and their milk production decreases. The quality of the dietary sources of energy and protein are not that critical in this stage of the lactation. Protein concentration of the diet can be further decreased to around 14-15%. And non protein nitrogen sources can be included. Diets can be formulated with cheaper feeds, and greater proportion of forages to avoid over conditioning of the cows. Now a few words on diet preparation. Most dairies in the US deliver feed to the cows as total mixed ration, or TMR, which is all processed feeds mixed together and fed to a group of cows. Advantages of TMR include consistent delivery of a balanced ration, which results in a more stable rumen fermentation, and increased microbial protein synthesis in milk components, reduced labor, and improved accuracy of nutrient delivery. The biggest disadvantage of feeding TMR is that cows cannot be fed based on their individual needs. And also that it requires expensive feed-mixing equipment. There are two basic types of TMR, mixes vertical and horizontal, with different configurations and models within each category. Although some reduction in particle size occurs during mixing, a more important consideration should be the uniformity of the mix. It is recommended that mixing times between three and six minutes. TMR preparation guidelines are provided in the supplemental material for this lecture. Dry matter intake of the forages in a dairy farm constantly changes, and should be monitored on a weekly basis, at least twice monthly. And corrections to the ingredient composition of the TMR should be made when necessary. Target dimethyl content of the diet should be around 48 to 52%. To assure maximal dymeth intake, TMR should be offered to result in about 3 to 5% refusals. This means that no less than 3% of the feed should remain in the feed bunk prior to feeding the new TMR. Attention should be paid to sorting, the particle size of the refusals and the fresh TMR, should look like more or less the same. Sorting can occur when forages are not properly processed and should be avoided. Check the feed processing lecture for recommended TMR and forage particle size distribution. The above recommendations are for feeding TMR. When forages and concentrate feeds are fed separately, sometimes called component feeding, the following recommendations should be considered. Concentrates should be fed after the forages and several times during the day. As with TMR, feed should be available to the cows at all times. Usually, it is preferred that energy and protein concentrates are combined. When two or more forages are fed, they should be mixed and fed together. For the remaining materials on component feeding of dairy cows are provided in the supplemental literature to this lecture. Finally, we should always remember that feed is the largest expense on a dairy farm, and nutrition of the cow is the most important component of a dairy production system, directly affecting milk production and composition, animal health and reproduction, and overall farm profitability. This is the end of the dairy nutritional segment of our course. Next, you will be introduced to dairy cattle reproduction. [MUSIC]
