Rumen protection of nutrient (bypass nutrients) technology

The amino acid and energy requirements of medium and high yielding cows and buffaloes are not fully met from the microbial sources and these have to be met by protecting the fats and proteins from breakdown in the rumen. Various techniques are used for protecting the dietary nutrients from rumen hydrolysis and the feeding of rumen inert nutrients is known as bypass nutrients technology. Bypass nutrients called as ‘rumen protected’ has been defined as a nutrient(s) fed in such a form that increases the flow of their nutrient(s), unchanged to the abomasum, yet is available to the animals in the intestine.

Bypass fat
Milk yield is one of the most important factors in determining profitability of dairy cows, and high milk production is almost always more important for high profitability than is the low feed cost. A cow’s level of milk production is determined by the ability of mammary gland to synthesis milk; the ability of the cow to provide the nutrients in mammary gland and the ability of the farmer to manage and consider the nutritional needs of the cows. One of the most important factors limiting the expression of full milk production potentials in high yielding livestock is the inadequate intake of digestible energy during early lactation. A general milk production curve reaches at its peak at 40 to 60 days post-partum and then gradually declines. Feed intake also increases as lactation progresses but usually peaks later than the milk yield. Thus, most cows are in negative energy balance during the first 60 days post-partum.

There are three potential ways for increasing the dietary energy, each with particular advantages and disadvantages-
•  Increasing dry matter intake
•  Increasing the proportion of cereal grains in total ration.
•  Enhancing the energy density of the total ration

Increasing the DMI would be the simplest method to meet the higher energy requirement at early lactation but during this stage, milk production reaches maximum while the animal’s dry matter consumption drops and can not be increased beyond a limit due to limited ingestion capacity. Among other possible solutions, one is to boost energy consumption by increasing the proportion of cereal grains in the ration but incorporation of high amounts of cereal grains in the ruminant diets may cause variety of problems including acidosis, reduced acetate/propionate ratio, loss of appetite and lower fat content in milk.

The alternative mean to increase the dietary energy supply, the energy density of the diet may be increased by the incorporation of lipids (fats or oils) which contains more than two times higher energy than the cereal grains. However, to meet the energy requirement of high and medium yielding dairy cows through lipids, type and level of  inclusion of fat should be taken into consideration. Fats and oils comprising unsaturated fatty acids as well as their inclusion at more than 5 % level in the diet may adversely affect the dry matter intake and rumen fermentation pattern due to the. Physical coating of dietary fibre which limits its microbial digestion and ii.  SsToxic effect of unsaturated fatty acids on cellulolytic microbes.

Therefore, there is a need for a source of dietary energy, which does not affect ruminal fermentation and fatty acid profile of milk fat and can be easily assimilated by animals in lower digestive tract. This is the rationale for the development of ‘rumen bypass fat’ which is inert in the rumen and do not affect ruminal microbial activity but still make available energy to support high milk production, improve milk fat quality and body condition score of the animals. The need for energy, the positive influence of specific fatty acids on reproductive status of animals and human health benefits associated with mono and poly unsaturated fatty acids in milk fat, led to renewed interest in the use of bypass fat to increase the energy density of diets for lactation.

To optimize the utility of fat in ruminant diets, the bypass fat has been developed.The bypass fat can be obtained by encapsulation or by formation of calcium salts of fatty acids. An encapsulation method was originally introduced by Australian workers. In this technique fat source is first emulsified with casein or plant protein and thereafter treated with diluted formalin followed by drying. The resulting product comprising of fat droplets is enveloped in water insoluble protein package. It remains inert in the rumen but is readily soluble in abomasum due to the acidic condition and liberates fat and protein for digestion in the small intestine. Another technique for fat protection is to treat oilseeds with formaldehyde which protects both protein and encapsulated fat from rumen hydrolysis. Calcium salts of fatty acids are produced by the ‘Double Decomposition Method’ of edible oils. Efforts are being made to use non-edible oils and other products such as acid oil (a byproduct of vegetable oil refining) and soapstock by single stage fusion technique due to the economic reason. The calcium salts can be prepared by a method described:

The types of bypass fat supplement available are:
(i)  Calcium salts of saturated fatty acids - 45% protection
(ii)  Extruded fats- 25% protection
(iii)  Formaldehyde treated canola/soybean meal- 80% protection

Poorly protected fat supplements provide large proportions of free oil in the rumen which will have a surfactant effect on the microbes, causing digestive upsets and lowering feed intake. The highly protected fat supplements (>75%) are the most efficient in enhancing milk production. An important feature of these canola/soybean bypass fat supplements is that they also contain significant quantities of rumen undegradable protein and essential amino acids and their intestinal digestibility is not reduced.

Ca-salts are found to be inert in rumen and non-toxic to ruminal bacteria and have no impact on fibre digestion. Supplementation of Ca salts of palm oil fatty acids and prilled fatty acids at 2.5% level to the control diet of mid lactating cows increased milk yield without affecting milk fat. Supplementation of diet with fat through roasted