Nutrition on Dairy Cattle Production and on Milk Composition and Quality - Term Paper Example

Nutrition (grain vs. fоrаgе) on dairy саttlе рrоduсtiоn and on milk соmроsitiоn and quality Name Institutional affiliation Tutor Date Introduction Forages have continually been used as the main feed for lactating dairy cows; particularly, alfalfa has gained more popularity than other forages. Recently as a result of farm nutrient issues, there have been considerable efforts in using grass forage as the primary source of food for the lactating dairy cows. Though perceived quality and yield are expected to be low when grass is used over legumes, grasses are turning to be more preferred due to agronomic factors like longer stand life, more tolerance to manure application and nitrogen requirement over alfalfa. Forages have also been proven as better supplements for majority of co-products from food industries better than grains particularly because forages have less crude proteins (CP) as compared to grains while most co-products are rich in CP. This paper discusses the feeding value of forages and grains and to determine the nutritional differences between forages and grains. Feeding forages vs grains The differences between grains and forage in lactation studies are based on the level of neutral detergent fiber (NDF) in the two feeds. Generally proven is that forages contain more NDF than in grains. The dry matter (DM) fed to the lactating cow should be balanced in a manner that the NDF is not too much as it may result to less milk produced (Vargas, Mustafa & Seguin, 2008). The dry matter and the milk production levels in a dairy cattle is not always affected even when the NDF concentration in forage is very high because there are other factors that come into play. The impact of NDF concentration in the rumen is not consistent because it may be influenced by the chemicals present and the digestibility of the NDF and the size of the particles (Jukenvicius & Sabiene, 2007). In the case where diets are prepared to contain equal levels of NDF concentrations, little amount of forage and concentrate is needed in forages while compared to grains. Low forage to concentrate ration is likely to increase milk production as long as the concentrate inclusion does not reach a level that it may suppress the functions of the rumens. This mean that a diet of forage will result to the same yield in milk or even more as compared to a diet grains because of low forage-concentrate ration as well as the high amount of energy (concentrate) in a diet containing grass when compared to a diet of grains prepared to equal NDF (Bradford & Mullins, 2012). Preparing a dietary NDF concentration usually increases the amount of concentrates in forages as opposed to grains. However, this does mean that increasing concentrates in the DM intake would result to more milk production. Unlike forage, grains must undergo proper processing, fed with the correct levels of dietary forage in order to avoid off-feed problems, reduction in milk production as well as low fat in milk (Moran & McDonald, 2010). In other words, only high-quality grains that have been tested for nutrients composition should be used in determining the rations to be fed on lactating dairy cattle (Cuhna, 2009). Variability of the grain quality can have a significant impact of performance of the grains in the quality and cattle production. When grading the grains, specific factors that determine the feeding values should be considered (Schingoethe, Kalscheur, Hippen & Garcia, 2009). Nutrients composition The composition of nutrients in grains and forages is dependent on many factors such as fertilization, maturity, harvesting methods and soil fertility. Key differences are noted between forages and grains irrespective of the mentioned factors. Forages generally contain more NDF and acid detergent fiber than legumes. Most of the fiber in forages is to be found in the leaves and the stems while grains do not have such parts. For instance, the leaves of a mature alfalfa approximately contain 25 percent NDF while the stem contain between 40 and 55 percent NDF (Jung & Engels, 2002). This is quite low compared to mature leaves of grasses like brome grass and orchard grass which contain around 50 and 70 percent NDF respectively. The digestibility of NDF in both grains and grass forages happens to be similar particularly because grasses have low forage quality index than legumes of the same maturity stage (Zebeli et al. 2010). Grains have more crude protein than forages. Whether grains or forages, the amount of crude protein is determined by the level of non-protein nitrogen (NPN) present; if the level of NPN in the diet reaches 10-15 percent, then it can be termed as true protein. The amount of crude protein available determines the level of NPN. Crude protein is likely to increase when forages are fertilized with high amounts of nitrogen or when grains are fermented (Whitlow, 1995). Grains also contain more micro and macro minerals as compared with forages. Calcium in grains, one of the main macro-nutrients is two to three times of that found in forages (Weiss, Eastridge & Underwood, 2005). Other mineral nutrients like phosphorous and potassium are almost the same level in grains and forages but grains having slightly more amount. The composition of minerals in forages is largely dependent on the stage of growth, type and amount of fertilizer applied and the climatic condition. However, the amount of mineral composition in grains is not much affected by some of these factors (Zebeli et al. 2010). Impacts of NDF and cell wall on digestibility Fiber makes up the largest nutritional fraction of both grains and forage. Hence fiber is a major component that determines the intake level and the amount of energy to be available in the different diets of lactating cows. In lactating cows and many ruminant animals, gravimetric detergent method is used to determine the amount of fiber grains. On the other hand, NDF represents the cell wall material in the forage and grains. The cell wall of grains comprises such elements as cellulose, pectin, lignin and hemicelluloses (Bradford & Mullins, 2012). Pectin easily dissolves in neutral detergent solutions while hemicellulose present in non-lignified tissues dissolves easily. The NDF method of determining the amount of fiber in grains often underestimate the amount of cell wall present in grains; this arises from the fact that grains contain more pectin than forage (Cherney, Cherney & Chase, 2004). Value of forage quality on cow’s performance The quality of forage determines the quality of milk and the energy the cow has. In addition, forage quality determines the amount feed to be fed to the cow as well as the concentrate needed to balance the diet. Digestibility of the diet fed to the cow determines the amount of diet needed by a cow. Fiber rich diet like forage is less digestible compared to low fiber-component food like grains. Some high quality forages like corn silage, vegetative grass and late bud alfalfa are highly digestible such that food intake in a lactating cow is not highly restricted (Hutjens, 2006). Mature forages are generally not highly digestible meaning that feed intake is highly restricted. For instance, late bud alfalfa is approximately 65 percent digestible while full bloom alfalfa may be 55 percent digestible. Various experiments carried out by researchers to determine the relationship between forage intake and dairy cow performances have shown different results. For instance, a herd of dairy cattle fed with alfalfa with 45 percent NDF can consume approximately 1.5 lb/day less dry matter in order to produce 1.75 lb/day less fat-corrected milk than those cattle fed on forage with 40 percent NDF (Moran & McDonald, 2010). Forage of high quality will thus increase the milk production as well as lower the cost of feeding. Full bloom alfalfa will cost the same as late bud alfalfa implying that there are no additional feeding costs. Late bud alfalfa is considered to be of higher quality than full bloom alfalfa because one pound of late bud alfalfa may contain around 0.8 pounds more crude protein and 0.9 mcal more net energy while compared to full bloom alfalfa. Feeding a cow on 50 percent late bud alfalfa saves the farmer about four pounds of a soybean meal (Miller, 2009). Effects of grains on milk component Grains in the diet of a lactating cow may have serious effects on the protein and fat of the milk. To begin with, milk component is one of the most valuable components in the cow’s milk. This has prompted many researchers to undertake research on what factors that may affect it. The most notable factors that affect it are protein content and ration energy as well as how it is utilized. Since grains are fed as rations, the amount of grains fed should be maintained in a manner that it does not affect the milk synthesis proteins (Moran & McDonald, 2010). Dietary proteins are important components when determining the amount of fat and milk protein in the milk. Amino acids for tissues and milk protein are important building blocks that should be considered during protein synthesis. As a result, for the protein to be synthesized, the small intestine must be in a position to absorb much of the amino acids. The source of the amino acids is the rumen bacteria and bypass proteins (Bradford & Mullins, 2012). The form of amino acids that is made in the shortest supply is referred to as limiting amino acids. Methionine which is the limiting ration of amino acids highly depends on animal protein for most of the rumen’s un-degradable supply of protein. For instance, in a diet that contains 20 percent of grains, supplementing it ruminally protected lysine and methionine may result a rise in milk protein as well as the quantity of milk. This implies that nutritionists should focus on the proportion of predicted methinone and lysine when preparing a balanced diet. The best lysine to methionine ration should be 3:1 for the sake of a balanced diet. However, it is difficult to reach such a level but nutritionist can improve the level of amino acids by including lysine protein supplements like soy and fish meal in the diet Vargas, Mustafa & Seguin, 2008). Increasing the amount of fats and proteins in a cow’s milk has been a topic of interest to Multiple Component Pricing (MCP). The main issue in this context is the amount of components present in the milk and not the percentage value of the components. For instance, a cow that produces 60 pounds of milk that contains 3.1% protein gives the same income as that cow that produces 55 pounds of milk containing 3.4 percent protein content Vargas, Mustafa & Seguin, 2008). According to MCP, a diet that maximizes milk yield and maintains the percentage of components as normal is considered profitable. Optimizing rumen fermentation is the most important consideration. A diet that has balanced proteins, fiber, energy and good management is expected to increase yield as well as milk components (Weiss, Eastridge & Underwood, 2005). Ration energy content Energy intake has an impact on the content and yield of the milk protein as most researches have shown. In order to determine this effect, most researches have demonstrated the effect of energy by increasing the amount of grains in a diet. For instance, replacing soybeans and corn with distiller grains has demonstrated that such a diet has higher content of energy (Schingoethe et al, 2009). This difference may be determined by the different concentration of fats in the diet even though the soybean and corn may contain more digestible fiber. Also, the diet contains little starch which should result to the production of less ruminal lactic acid and high PH level; this is likely to reduce the possibility of rumen acidosis. Another important outcome of reduced chances of rumen acidosis is that the diet may increase ration digestibility and feed intake which contribute positively to energy increase in the lactating cow (Penner, Yu & Christensen, 2009). Conclusion This paper has established has established that there are complex factors that determine the composition and digestibility of forages which later determine the quality and yield of milk in dairy cows. High performance is observed when cows are fed on a diet containing forages and grains when the two are made part of the total mix diet comprising multiple ingredients. The most important factors that determine high quality forage is having low fiber content and being high digestible. This should be part of the balanced diet that is meant to feed a lactating cow along with grains mixed in a proper ratio. References Bradford, B. & Mullins, C. (2012). Strategies for promoting productivity and health of dairy cattle by feeding nonforage fiber sources. Journal of Dairy Science, 95, (9): 4735–4746. Cherney, D., Cherney, J. & Chase. L. (2004). Lactation performance of Holstein cows fed fescue, orchard grass, or alfalfa silage. Journal of Dairy Science, 87:2268-2276. Cuhna, T. (2009). Dairy Cattle Feeding and Nutrition. New York: Elsevier. Grant, R. J., (1994). "G94-1229 Importance of Grain Quality, Nutrient Composition and Processing for Dairy Cattle" (1994). Historical Materials from University of Nebraska- Lincoln Extension. Paper 453. Holtshausen, L. et al. (2011). Improved milk production efficiency in early lactation dairy cattle with dietary addition of a developmental fibrolytic enzyme additive. Journal of Dairy Science, 94, (2): 899–907. Hutjens, M. (2006). Successful Feeding Systems for Dairy. New York: Hoard's Dairyman Books. Jukenvicius, S. & Sabiene, N. (2007). The content of mineral elements in some grasses and legumes. Ekologija. 53:44-52. Jung, H.G., & Engels. F. (2002). Alfalfa stem tissues: cell-wall deposition, composition, and degradability. Crop Science 42:524-534. Miller, W. (2009). Dairy Cattle Feeding and Nutrition. New York: Elsevier. Moran, J. & McDonald, S. (2010). Feedpads for Grazing Dairy Cows. New York: Csiro Publishing. Penner, G., Yu, P. & Christensen, D. (2009). Effect of replacing forage or concentrate with wet or dry distillers’ grains on the productivity and chewing activity of dairy cattle. Animal Feed Science and Technology, 153, (1–2): 1–10. Schingoethe, D., Kalscheur, K.,. Hippen, A., Garcia, A. (2009). The use of distillers products in dairy cattle diets. Journal of Dairy Science 92, (12): 5802–5813. Vargas, E., Mustafa, A.F & Seguin P. (2008). Effects of feeding forage soybean silage on milk production, nutrient digestion, and ruminal fermentation of lactating dairy cows. Journal of Dairy Science, 91(1):229-35. Weiss, W., Eastridge, M. & Underwood, J. (2005). Forages for Dairy Cattle. New York: Ohio State University Extension. Whitlow, L.W. 1995. Balancing rations for lactating dairy cattle on pasture. New York: North Carolina State University. Zebeli, Q., Mansmann, D., Steingass, H., Ametaj, B. (2010). Balancing diets for physically effective fibre and ruminally degradable starch: A key to lower the risk of sub-acute r umen acidosis and improve productivity of dairy cattle. Livestock Science, 127, (1): 1–10. Read More