AVAS Annals of Veterinary and Animal Science Uddin et al. Annals of Veterinary and Animal Science 2015 http://naturepub.org/index.php/journal/navas [Received: 12 Jul 15, Accepted: 21 Sep 15, Published: 31 Oct 15] eISSN: 2313-5514 pISSN: 2312-9123 naturepub academics Inc. Natural Science Research Forum (nSRF) www.naturepub.org REVIEW ARTICLE V:2(5) OPEN ACCESS ACCESS Dynamics of microbial protein synthesis in the rumen - A Review Uddin 1* Md Jasim, Khandaker 2 Zahirul Haque, Khan 2 Md Jasimuddin and Khan 3 Mohammad Mehedi Hasan INTRODUCTION Microorganisms in the rumen degrade nutrients to produce volatile fatty acids and synthesize microbial protein as an energy and protein supply for the ruminants. Ruminants establish a symbiotic relationship with rumen microorganisms by which the animal provides nutrients and optimum environmental conditions for the fermentation of feeds, and microorganisms degrade fiber and synthesize microbial protein as an energy and protein supply for animal. Rumen microbial protein represents a major source of amino acids to the ruminant animal. Microbial protein can supply from 70% to 100% of amino acids to ruminant (AFRC, 1992). High microbial protein production can decrease the need for supplementing rumen undegradable protein (Blummel et al., 1999). The amino acids reaching the small intestine are supplied by the microbial protein, the undegraded feed protein, amino acids and peptides from feed which escape degradation, and endogenous secretions. The microbes that are produced in the rumen, and then pass down the digestive tract, may supply 60 to 80 percent of the amino acids absorbed from the small intestine. The efficiency of microbial protein synthesis is a major factor affecting the overall amino acid requirement of ruminants and caecum fermenters, and is influenced by a number of factors including energy source, supply of nutrients (nitrogen, sulfur, branched chain fatty acids) and rumen environmental characteristics such as dilution rate, pH and microbial species present (Caton et al., 1993). An average efficiency of microbial synthesis of 17 grams of microbial protein per 100 grams of digestible organic matter was determined for many diets, although values were generally higher for sheep and forage based diets than for cattle and concentrate diets (Beharka and Nagaraja, 1998). A continuous-culture experiment showed about a 14% to 30% increase in the amount of microbial protein available for use. Microbial protein contributes about two third of the amino ABSTRACT Ruminants establish a symbiotic relationship with rumen microorganisms by which the animal provides nutrients and optimum environmental conditions for the fermentation of feeds, and microorganisms degrade fiber and synthesize microbial protein as an energy and protein supply for animal. Ruminal proteins degradation is affected by pH and predominant species of microbial population. A strong positive correlation was observed between dry matter intake (DMI) and microbial growth. The more carbohydrate digestion the more microbial protein synthesis occur. Fermentation energy is inversely related to microbial growth. Essential oil has domestic anti- microbial activity. Nitrogen compound or crude protein contain (CP) of many practical diets may be greater than the 11% required to support optimal microbial growth. Forage concentrate mixing preparation increase the efficiency of microbial protein synthesis than only forage preparation. The efficiency of microbial protein synthesis greater in forages containing saponin and tannins which reduce ruminal N degradability. As ruminant out flow rate increase microbial protein synthesis, it is supposed that the efficiency of microbial protein synthesis can be increased by about 20% if rumen outflow rate is increased from 0.02 to 0.08 /h. Microbial protein production will be a function of the availability of vitamins, microminerals and protein level in the diet of digestible organic matter. Microbial protein synthesis is dependent upon suitable N and carbohydrate sources. Even though trace minerals and vitamins are adequate for maximal microbial protein synthesis in many feeding conditions, inadequate trace minerals and vitamins, in some cases, could limit microbial protein synthesis. -------------------------------------------------------------------------------- * Corresponding author: jasimsau@gmail.com 1 Department of Animal Nutrition, Sylhet Agricultural University, Sylhet, Bangladesh 2 Department of Animal Nutrition, Bangladesh Agricultural University, Mymensingh, Bangladesh 3 Department of Bio-chemistry and chemistry, Sylhet Agricultural University, Sylhet, Bangladesh