IMPORTANCE OF BYPASS PROTEIN IN DAIRY NUTRITION
Compiled, & shared by-DR. RAJESH KUMAR SINGH, (LIVESTOCK & POULTRY CONSULTANT), JAMSHEDPUR Post no 1377Dt 29/08//2019
JHARKHAND,INDIA 9431309542, rajeshsinghvet@gmail.com
INTRODUCTION
By-Pass protein is protein that is not degraded by rumen microbes, also known as undegraded intake protein (UIP) and rumen undegraded protein (RUP) in USA, UDP or DUP in the UK or PDIA in France.
Dairy Bypass Protein is an animal or plant-based protein source that resists degradation in the cow’s rumen in order to pass into the lower gastrointestinal tract and provide essential amino acids to the cow. By bypassing the rumen, more metabolizable protein is made available to help the cow meet her amino acid requirements for milk production and components. The more consistent a bypass protein source, the easier it is to balance the dairy ration for maximum milk production and feed efficiency. By feeding high-quality bypass protein, dairy producers can increase their metabolizable protein yield and reduce the amount of crude protein in the diet, thus reducing ammonia votalization and nitrogen excretion.
The ruminant animals derive their amino acids and supply jointly from dietary protein source which escapes rumen degradation and microbial protein that synthesized in the rumen. The amount of protein that escapes from rumen degradation depends on their solubility and the rate of passage to the small intestine. Microbial protein synthesis is regulated by the quantity of plant organic matter fermented, ammonia and mineral concentration in the rumen. (Kaufman and Lupping, 1982). It is often evident that animal’s requirements for amino acids not fully met from the normal sources of dietary protein. Rapid and extensive degradation of valuable proteins in the rumen leads the researchers to develop the concept of protein protection from ruminal degradation with the main objective of enhancing the supply of essential amino acids to the productive animal as well as reduction of nitrogen losses as urea in the urine (Annison, 1981). Protein supplements are more expensive and increase the feed cost. By optimizing the use of protein supplement within the ruminant system, we can either reduce the quantity of protein in the diet or can enhance the production of the animals. This review will attempt to emphasize on various methods and techniques of amino acid protection, responses to dietary supplementation in animals.
NATURALLY OCCURRING BYPASS NUTRIENTS———
In some feedstuffs, nutrients are naturally bound to other feed components, thus reducing their rumen degradability. The bonds with which the nutrients are linked remain intact in the neutral environment (pH = 6-7) of the rumen, but they are broken in the acidic environment of the abomasum (pH 2-3). These are referred to as naturally occurring bypass nutrients. Bypass protein values for some of the commonly used feedstuffs are given in Table 1. The feeds with higher bypass protein values are: cottonseed cake, maize gluten meal, coconut meal, fishmeal and leaf meals like Leucaena leucocephala (subabul). Similarly, the fermentation of starch from maize in the rumen is limited, thus, it is good source of bypass starch. With regard to fats, when fed through oilseeds, they are partially degradable in the rumen.
DEGRADATION OF PROTEINS AND AMINO ACIDS IN THE RUMEN
Rumen microorganisms hydrolyse food protein into peptides & amino acids. However, most amino acids rapidly degraded to organic acids, ammonia and carbon dioxide. The ammonia produced is the primary nitrogenous nutrient for bacterial growth. Some species of ruminal bacteria use peptides directly for synthesis of microbial protein. Chalupa (1975) observed that as little as 40 per cent or as high 80 per cent of dietary protein normally degraded in the rumen (RDP) and transferred into microbial protein. Because this protein production is an energy dependent mechanism, the amount of dietary protein transformed into microbial protein must be an important aspect of nitrogen economy, so care should be taken to minimize ruminal degradation by artificial procedures. The rumen microbial population derives 25-50 per cent of their nitrogen from sources other than ammonia (NPN compound). These presumably intact amino acids or peptides which originate either directly from food protein, from recycled nitrogen to rumen or from turnover of bacterial and protozoal protein within rumen (Oldham, 1981). The breakdown of proteins by microorganisms, gives rise to intermediate products such as free amino acids in the rumen. The free amino acids in the rumen can be assimilated directly by microbes and can absorb through the rumen but most are deaminated to yield ammonia and other intermediate products (Hoover and Miller, 1991). The microbial protein alone is likely sufficient to meet the maintenance requirement of an animals. But in young growing cattle and lactating cows in addition to microbial protein bypass protein is essential to meet their metabolizable protein requirements. The protein can be divided in two parts, for the ruminant animals, in most of the feed, major part is degradable in rumen ‘Rumen Degradable Protein’ (RDP) and a small but variable amount of dietary protein escape rumen degradation ‘Un-degradable Dietary Protein (UDP). UDP which enters the lower tract is absorbed mostly as amino acids following enzymatic digestion. Of the RDP fraction, substantial part is utilized as the N source for rumen microbes, for protein synthesis, while the rest is absorbed as ammonia. Only part of absorbed ammonia is recycled back to rumen as urea via saliva, the rest excreted out through urine. The host animal gets amino acids requirement from two sources i.e. microbial protein and UDP, both flowing to lower tract. Although in the case of low yielder, the microbial protein synthesized in the rumen is sufficient, but In high growing animal and high yielding animals microbial supply is limited than the demand of amino acids at the tissue level, so to support the demand, it is necessary to provide proteins in the form of UDP or escape proteins or protected proteins.
PROTECTION OF PROTEIN FROM RUMINAL DEGRADATION
It is possible to protect proteins using several procedures such as heat treatment, chemical treatment/modification and inhibition of proteolysis activity and identification of naturally protected protein (Ferguson, 1975).The use of these techniques in comparison to the usual sources of dietary proteins improves the supply of amino acids without an increase in ammonia production, resulting in a better performance by the animal (Koufman and Lupping, 1982). Protection can be achieved by various methods like:
1. Naturally Protected Proteins —————-
The natural protection depends upon the following properties of feeds.
1. Surface area available for microbial attack
2. Chemical nature of proteins
3. Physical consistency of proteins
4. Presence of other dietary components
5. Passage rate from rumen.
2. Heat Treatment —————
The drying of forage is known to increase the protection of the proteins. During the process of manufacturing oil seed meals, they are subjected to different degree of heating leads to various degree of protection. Thorough heating of protein supplement causes denaturation of protein; it provides effective protection against microbial fermentation in the rumen. Heat treatment at 125- 150 0 C for 2-4 hours could protect proteins very efficiently. High pressure steam treatment with extrusion has shown promising result. Heat treatment has been used to increase the undegradable protein of common feedstuffs such as soybeans and grains (Prestlokken, 1999). However, high temperature and extended heating time have increased the acid detergent insoluble nitrogen content by the Maillard reaction between sugars and amino acids (Broderic et al. 1991). Excessive heating can damage essential amino acids such as lysine, methionine and cysteine (Kung, 1996).
3. Formaldehyde Treatment———
It is most widely used and most successful procedure developed by Ferguson et al.(1967). Normally we add 3-4 kg of commercial formalin (37- 40% HCHO) per 100 kg of CP or 1-1.2 g HCHO/ 100g CP. Generally there is increased fecal nitrogen and decreased urinary nitrogen which indicates effectiveness of protection. The use of formaldehyde to protect dietary protein for ruminants is based on the premise that bound formaldehyde markedly reduces the solubility of the protein at pH 6.0, thereby rendering it highly resistant to microbial attack in the rumen, without significantly reducing its digestibility in the small intestine. Other aldehydes like, acetaldehyde and glutaraldehyde are also effective but they don’t possess any advantage over formaldehyde which is comparatively cheaper and easily available. Treatment of proteins with formaldehyde is the most widely used process at the present time and it has been exploited commercially. Treatment of high quality proteins result in the formation of crosslinks with amino group and makes the protein less susceptible to microbial attack (Czerkawski, 1986).
4. Oesophageal Groove closure ————–
This is normal function in young one. It is done for liquid proteins. Groove closer is influenced by various factors such as age, temperature of liquid, posture of animal while drinking, site of delivery into esophagus, and chemical composition of liquid. Moreover commonly used chemical influencing the closer are salts of sodium, copper, silver and zinc.
5. Post Rumen Infusion (Fistula)————
To avoid rumen microbial degradation of proteins, surgically fistula fitted in the lower tract of intestine after the rumen, so proteins/ amino acids are available in the intestine. This method is only used at research level to generate the data and rumen degradation pattern
6. Encapsulation of Proteins ————-
Encapsulation of Proteins is usually done for good Biological value proteins and also for individual amino acids. Methionine and lysine are limiting amino acids in microbial proteins on feed intake, plasma amino acids and milk production. So they can be given in the form of capsule with a combination of fats or fatty acids sometimes by addition of carbonate, kaolin, lecithin, glucose etc. Methionine and lysine are limiting for milk yield and milk protein synthesis when cows are fed corn based diets. Post ruminal supply of specific amino acids can be increase by supplementing the diet with polymerically encapsulated amino acids. In a number of experiments where protected methionine and lysine have been used to increase protein content and milk yield.
7. Amino Acids Analogs ————-
Structural manipulation of amino acids to create resistance to ruminal degradation is another potential method for rumen bypass of amino acids. Various analogs of amino acids have been tested for resistance to ruminal degradation. The analog must have biological potency in metabolism by tissue. Analogs such as Methionine hydroxy, Nacetyl-DL-Metionine, D L- Homocysteine thiolactone-Hcl, DL-Homocysteine, etc. have given satisfactory results.
8. Coating of Protein with Insoluble Substances ————
The coating of protein sources with insoluble substances like blood meal (Orskov, 1992) or fats (Sklan and Tinsky, 1993) have been used. Since fats, beside their effects on protein protection, these are energy sources that could be important for high producing dairy cows during the first stage of lactation. The coating soybean meal with lipid substances ( Fish oil, beef tallow ) is a protective method against microbial degradation in the rumen. The coating of protein with lipid substances decreased the ruminal degradability. The effect of protection increased with increasing amount of coating agent (Manterola et al. 2001).
9. Feed Processing Normal procedure ————-
following in the manufacture of feed ingredients can influence the magnitude of protein degradation in the rumen. Certain grain processing can either increase or decrease rumen degradation of Proteins. Increased ruminal degradation may be the result of disruption of the protein matrix, whereas heat applied or generated during grain processing can decrease ruminal degradation of proteins.
10. Lowering Ruminal Protease Activity ————
By depressing the proteolysis activity of the rumen microbes we can slowdown the protein degradation within the rumen. Bacteria are mainly responsible for proetolytic degradation. So antibiotics can be used to reduce the protein degradation within the rumen.
11. Metal Amino Acid Complex ————-
Metal complexes that are commonly available such as zinc methionine, zinc lysine, copper lysine, manganese metionine, iron methionine etc. assumed to be stable in the rumen environment and abomasum and be delivered to the small intestine intact, secondly, there is some evidence that mineral chelates are considerably better absorbed than inorganic forms.
12. Plant Secondary Compounds ————-
These are mainly secondary metabolism compounds which are generally not utilized in metabolic process include lignin, tannin, terpenenoids, volatile essential oils, alkaloids etc. have potential to be used as protein protectant in the rumen. Tannin has got good attention, although it is considered as anti nutritional factor but as it is a protein suppresser or decreasing is digestibility so it can be used in the ruminant animal at lower level.
Effects of Bypass Proteins on Animal Performance————
Biochemical and nutritional basis by which bypass protein show its effect on animal performance are
1. Additional supply of amino acids at intestinal and tissue level
2. Lower ammonia production in the rumen because proteins are fermented to ammonia and low degradation of protein will lower ammonia level.
3. Lower urea synthesis in liver as ammonia is being absorbed at lower level which saves energy.
4. Excess amino acids go for Gluconeogenesis
5. Best Utilization of Protein Resources Beneficial Effects of Bypass Proteins
1. Growth Performance———
Feeding of bypass protein meals significant increases the growth rate of animals. A series of experiments conducted at NDRI, Karnal have shown significant increase in growth rates in calves, buffalo calves, and goat kids on feeding bypass protein. These experiments were on HCHO treated GNC and Mustard cake. The increase in growth rate of these animals was found to be in range of 30 -40 %. Feeding of Bypass protein to growing stock, not only increases growth rate, but also improve feed conversion efficiency. In fact, it not only results in reduction in the cost of rearing, but due to higher growth rate, it also results in attaining early maturity by male or female animals. This is definitely a bigger surplus in terms of improvement in reproductive efficiencies of these animals.
2. Lactating Performance————
Most of feeding trails resulted in significant increase in milk yield and FCM yield. The increase in milk yield varied in the range of 8 – 10 percent. The studies conducted on medium producing animals, proved that bypass protein feeding can be beneficial to the animals, producing 8-10 liters of milk per day.
3. Reproductive efficiency————
Because of high growth rate caused through protein feeding, the young stock can attain early maturity to start the reproductive life at an earlier age. It has been shown that bypass protein feeding can improve the reproductive efficiency of breeding buffalo bulls and cross bred bucks, both with respect to sexual behaviour, including libido score as well as the seminal attributes like ejaculate volume, mass activity and sperm count per ml, similar positive results were obtained in females, where the conception rate decreased after feeding of bypass proteins.
How bypass proteins work——-
As protein comes into the rumen, it is broken down into peptides and then further digested into amino acids. The amino acids available to ruminal microbes are utilized directly or deaminated to yield carbon skeletons and ammonia.
CONCLUSION:
Supplementation of bypass protein to medium and high yielding growing animals increases the live weight gain, DM intake and milk production in animals.
