122 *Corresponding author email: drsaroj.rai@gmail.com Indian Journal of Animal Sciences 90 (4): 614–617, April 2020/Article https://doi.org/10.56093/ijans.v90i4.104215 Effect of feeding fermentable synbiotics (Lactobacillus rhamnosus ( ( NCDC 298 and fructo-oligosaccharide) to Jersey crossbred calves up to 3 months of age S RAI * , S MANDAL, R BEHERA, J SAHU, T K DUTTA, R JAS, A CHATTERJEE, D K MANDAL, M KARUNAKARAN and M K GHOSH ICAR-National Dairy Research Institute Eastern Regional station, Kalyani, West Bengal, India Received: 27 September 2019; Accepted: 29 October 2019 ABSTRACT The synbiotic combination of L. rhamnosus NCDC 298 and fructo-oligosaccharide (FOS) is known to be effective against diarrhoea by preventing the adhesion of pathogens to the gutt, hereby, preventing infection and pathology. Such synergistic effect of the combination has emerged as a favourable alternative to antibiotic use against diseases and growth promoters in the livestock industry. The present study assessed the health and growth performance of the calves supplemented fermentable synbiotic fortified milk from 4 to 90 days and observed its performance till 120 th day of age. Body temperature and passive immunity (IgG) were significantly better in calves fed synbiotics with notable increase in body weight and heart girth post synbiotic feeding period. These calves had increased dry matter intake per animal/day when compared to the control animals. The populations of Lactobacillus sp. elevated with decreased pathogenic bacteria (Coliform) in faeces on feeding synbiotics and it continued even after 90 days of age indicating colonization of beneficial bacteria. Therefore, feeding of fermentable synbiotics had observable beneficial effects on health, immunity and growth of the Jersey crossbred calves. The findings encourage further verification of fermentable synbiotics fortified milk as a potential growth promoter to young dairy calves. Keywords: Body growth, Calf health, Fructo-oligosaccharides, Lactobacillus bacteria, Synbiotic supplement The healthy calf is essential for a successful and profitable dairy venture but common use of antibiotics against diseases and growth promoters have come to rigorous public scrutiny (Langford et al. 2003). To address the problem there is a need to look for viable alternative strategies to enhance calf performance and reduce the massive use of antibiotics in farms. One method is the synergistic combination of probiotics and prebiotics known as synbiotics which favourably modulated the gut microbiota by preventing the colonization of pathogenic bacteria, produce metabolic substrates (e.g. vitamins and short-chain fatty acids) and enhance feed efficiency and weight gain in calves (Soberon et al. 2012, Zang et al. 2016). Besides, they are also known to stimulate the immune system and reduced the incidence of neonatal diarrhea caused by the enterotoxigenic E. coli (de Vaux et al. 2002) thereby, maintaining the overall calf health (Tuohy et al. 2005). Probiotics commonly used in livestock and poultry industry are Lactobacillus, Enterococcus, Bacillus and Saccharomyces while prebiotics used are mainly Fructo oligosaccharide (FOS), Galacto oligosaccharide (GOS), Mannan oligosaccharide (MOS) (Gaggia et al. 2010). The study, for the first time, investigated the effect of feeding fermentable synbiotic (Lactobacillus rhamnosus ( ( NCDC 298 and fructo-oligosaccharide) fortified whole milk to the Jersey crossbred calves on their health and growth performance. Our hypothesis states that synbiotic combination of Lactobacillus rhamnosus NCDC 298 and fructo-oligosaccharide (FOS) may have beneficial effect on account of its in vitro antibacterial property against E. coli toxin (Anand et al. 2017). MATERIALS AND METHODS The present study was carried out at National Dairy Research Institute (NDRI), Eastern Regional Station, Kalyani, India. Kalyani is located at the lower Gangetic basin of West Bengal in Nadia district. The climatic condition is hot and humid with average annual maximum and minimum temperatures of 39°C and 12°C, respectively. The average annual rainfall is around 1,250 mm with a maximum relative humidity of 90%. The duration of the experiment was 120 days. Housing and feeding of the experimental calves: All the calves born in November–December 2018 and January 2019 were taken into study. Jersey crossbred calves (16) were randomly assigned to 2 groups (8 group), treatment (T) and control (C). Each of the calves was separated immediately after birth from their dams and housed in well- ventilated calf sheds. Colostrum and milk was fed as per the standard farm practices till the calves reached 90 days of age. Ad lib. supply of concentrates and green fodder as the basal diet was offered as early as one week of age to the