Volume 59 Issue 5 (May 2025) 715 REVIEW ARTICLE Indian Journal of Animal Research, Volume 59 Issue 5: 715-723 (May 2025) Role of Rumen Bypass Nutrients in Dairy Animal’s Health and Productivity: A Review Srobana Sarkar 1 , Amit Sharma 2 , Hujaz Tariq 2 , Debasish Satapathy 3 , Ravi Prakash Pal 4 , Lamella Ohja 3 , Hunny Sharma 3 , Maneesh Kumar Ahirwar 3 10.18805/IJAR.B-4787 ABSTRACT Ruminants have unique ability to convert poor quality feeds to high value animal protein. The rumen microflora degrades dietary nutrients into volatile fatty acids (VFA) and ammonia for synthesis of microbial crude protein. The microbial protein along with rumen undegradable nutrients reaches small intestine which is sufficient to meet the requirements of maintenance and low producing animals. However, in case of high yielders and physiological stress such as pregnancy, lactation, transition, etc. it becomes a limiting factor. Under above circumstances, rumen protected/bypass nutrients are effective in delivering nutrients directly to the intestine in utilizable and efficient form. Supplementation of rumen protected protein, fat and vitamins improves milk yield, reduces heat stress and boosts immunity. Certain rumen bypass fatty acids can also enhance quality of milk by reducing saturated fat content and also improve the reproductive performance in dairy animals. Thus supplementing nutrients in rumen protected form can result in quantity and quality production from ruminants especially under stressful conditions. Key words: Health, Production performance, Protected nutrients, Ruminants. Nutrient requirement of dairy animals under Indian conditions are being recently refined for precise feeding of animals to get better stimulus in production and reproduction performance in economically efficient way. Nutrient demands of high yielding dairy animals especially during early lactation, transition and heat stress conditions often exceeds to that supplied from microbial biomass synthesis and rumen fermentation. Furthermore, increased milk yield at early lactation is often associated with lower feed intake in milch animals. Peak milk yield occurs 6 to 8 weeks postpartum, while maximum feed intake lags behind peak milk yield by several weeks (Sharma et al., 2021). The disparity between timings of maximum energy output as milk yield and feed intake in first 60 days of lactation renders varying levels of negative energy balance in farm animals. Under such condition, animals utilize their body reserves to support production which ultimately results in metabolic disorders (milk fever, ketosis etc.), weight loss and infertility (Grummer, 1991; Wankhade et al., 2017). Considering above facts, transition nutrition has gained an important significance among researchers worldwide due to various metabolic disorders associated during this phase which determines the subsequent productive and economic losses (Remppis et al., 2011). During transition, dairy animals require better energy supplements to minimize deleterious effects caused by reduced dietary intake and body weight losses (Katiyar et al., 2019). Furthermore, extensive degradation of high quality nutrients in rumen often renders their availability to the host and leads to wastage of nutrients. Therefore, in order to provide quality and precise nutrition to dairy animals during periods of high nutrient demand, use of protected/ by pass dietary nutrients can be a promising strategy for enhancing both the quality and quantity of animal production.Various methods such as heat treatment, chemical treatment, encapsulation, selective manipulation of rumen metabolic pathways have been employed to protect or decrease degradation of nutrients in the rumen (Ganai et al., 2019). These methods help the nutrients to bypass the rumen and increases the outflow of nutrients from rumen to intestine. Initially, dietary proteins were protected as these are the most expensive nutrient in ruminant’s ration. However, in recent years nutrients like fat, vitamins, amino acids and probiotics (Lara et al., 2006; Robinson, 2010) are also given to the animals in rumen protected form to obtain maximum productivity. The potential benefits and level of supplementation of various protected nutrients at 1 ICAR-Central Sheep and Wool Research Institute, Avikanagar- 304 501, Rajasthan, India. 2 Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana-141 004, Punjab, India. 3 ICAR-National Dairy Research Institute, Karnal-132 001, Haryana, India. 4 Punjab Agricultural University, Ludhiana-141 004, Punjab, India. Corresponding Author: Ravi Prakash Pal, Punjab Agricultural University, Ludhiana-141 004, Punjab, India. Email: raviprakashpal61@gmail.com How to cite this article: Sarkar, S., Sharma, A., Tariq, H., Satapathy, D., Pal, R.P., Ohja, L., Sharma, H. and Ahirwar, M.K. (2025). Role of Rumen Bypass Nutrients in Dairy Animal’s Health and Productivity: A Review. Indian Journal of Animal Research. 59(5): 715-723. doi: 10.18805/IJAR.B-4787. Submitted: 23-09-2021 Accepted: 04-03-2022 Online: 03-05-2022