Pashu Sandesh, 13 July 2020

Dr Smruti Smita Mohapatra


Generally, ration of high yielding dairy animals during early lactation is energy deficient. The deficiency is further increased by decreased feed intake and higher quantity of milk production. Under field conditions, animals often shed around 80-100 kg body weight after calving. This leads to delayed conception in animals after calving resulting in longer inter-calving intervals. Such animals produce less milk during this period, thus, decreased lactation yield. At this stage of lactation, farmers usually supplement their animals with oil or ghee. But this is not economical and also hampers fibre digestion in the rumen. Feeding bypass fat supplement to high yielders during advance pregnancy and early lactation helps in minimizing energy deficiency. This, in turn, helps in improving milk production and reproduction.


Rumen protected fat have more melting point and insoluble at rumen pH and temperature. Protected fat is sensitive to acidic pH. Thus it gets digested in acidic pH of abomasum without interfering the fermentative process of the rumen. Supplementation of fat in this form is called as “bypass fat”. There are the methods of preparation of bypass fat. The natural dietary rumen-protected fats are cottonseed and full-fat soya. The hydrogenation of fat/Crystalline/Prilled fatty acids includes tallow. Formaldehyde treatment of oil seeds includes the calcium salt of long-chain fatty acids and made by fusion and indigenous methods. C soap is inert (pH > 5.5), dissociated and absorbed efficiently from the small intestine in acidic pH of the abomasum. C soaps have pungent soapy taste, poor palatability and are not completely rumen inert. The commercial preparations are Dairylac, Magnapac, Megalac, Ener GII, SoyPreme, Nutrijoule and Nutrisacc.


Dietary bypass fats can be supplemented in the ration of animals @ 15-20 g per kg milk production or 100 -150 g per animal per day. Use of the bypass fat should be in the ration of dairy animals for 10 days before and 90 days after calving. Dose rate is 0.4 – 0.8 kg/cow/day in the post-calving ration.


Dietary bypass fat is an ideal energy dense supplement (2 to 5 % of dry matter) for advance pregnant animals and early lactating animals to overcome negative energy balance. It increases milk yield from 1.8-3.5 kg more milk per day. Milk fat of 2-15% is improved depending on fats. Milk protein of 0-6% is reduced. Protein output has no effect and gradually increases. Optimal efficiency increases from the first 120 days of lactation. Conception rate increases from 26% in the first service and 74% in the second service. Pregnancy rate increases by 27%. Open days go by less than 6.8 days. Artificial insemination per conception decreases by 0.4 services. Bypass fat prevents acidosis and laminitis. It lowers the heat production in summer and reduces the dustiness in the feed.


Dietary fat adversely affects crude fibre digestibility. Excess amount depresses dry matter intake leading to milk fat depression. Generally, they are toxic to cellulolytic bacteria.


Since dietary fat is essential and expensive, it should be protected from degradation and biohydrogenation in the rumen to meet the high nutritional demand of high producing ruminants and lactating animals. Since feeding bypass fat does not hamper fibre digestion, it is always beneficial than feeding ghee/oil in early lactation.

Dr Smruti Smita Mohapatra

PhD Scholar,

Dept. of Veterinary Physiology,

Faculty of Veterinary & Animal Sciences

West Bengal University of Animal & Fishery Sciences