Development of Microbial Based Probiotic Feed Supplement and Evaluation of its Impact on Growth, Production and Health of Dairy Cattle

Abstract

Present research work was designed to evaluate the probiotic potential of indigenously isolated microorganisms. Later on selected microorganisms with best probiotic characteristics were applied in dairy cattle feed to check their impact on growth, productivity and health of dairy cattle. In phase I, previously isolated strains comprised of lactic acid bacteria, gram positive bacteria and yeasts (S. cerevisiae, G. candidum) in addition to E. faecium were characterized for probiotic potential. Characterization based on amylolytic, proteolytic and cellulolytic activity in addition to mimic gut survival, cell hydrophobicity, anti-pathogenic activity and cholesterol assimilation yield G. candidum (QAUGC01) as potential Probiotic to be used in dairy cattle. In total, ten lactic acid bacteria (including Enterococcus, Lactococcus, Enterobacter Sp.), three Bacillus species from cow dung, eighteen gram-positive cocci and bacilli from corn silage while five Enterococcus faecium and twelve Geotrichum candidum strains were previously isolated from Dahi. All previously isolated strains were checked for their probiotic potential. Strain with best cumulative probiotic properties was further used in cattle‘s feed as microbial supplement. It was found that among all the isolates only Geotrichum candidum strain has shown best cumulative abilities. Among all G. candidum strains sourced from Dahi, QAUGC02 has shown maximum survival rate of 53.9, 48.770% and 48.770% at 2, 4 and 24 hours respectively, followed by QAUGC10 (44.442%, 41.366% and 40.26%) and QAUGC01 (42.04%, 37.74% and 34.511%). Geotrichum candidum QAUGC12 has shown survival rate of 47.442% at 2 hours but later its survival decreased to 24.142% at 4 hours which is 20% less. G. candidum QAUGC07, QAUGC02, QAUGC06, QAUGC05, QAUGC01, QAUGC09 has shown maximum cholesterol assimilation respectively, QAUGC08 has maximum cell hydrophobicity of 86.10% followed by QAUGC10 (76.87%) and QAUGC03 (75.93%). G. candidum QAUGC01 has cell hydrophobicity of 46.6%. According to above results QAUGC02 has significant mimic gut survival and cholesterol assimilation while its cell hydrophobicity is very low. G. candidum QAUGC10 has low cholesterol assimilation. Only G. candidum QAUGC01 (KT280407) has significant cumulative results for all studied parameters. It is well established that dysbiosis in the gut microbiome leads to compromised productivity and metabolic disorder in dairy cows. The significant impact of gut microbiota on better feed utilization ability and resistance against diseases has been frequently reported. In phase II G. candidum QAUGC01 (KT280407) was used as microbial feed additive in basal diet of experimental cows and was compared with control cows to find the impact of QAUGC01 on dairy cow‘s health and xxiii productivity. After ninety days of trail growth performance, nutrient digestibility, blood parameters, serum biochemistry and milk yield along with milk composition has been analyzed and compared between control and experimental groups. It was found that dry matter intake was high in control cows (14.16 kg/day) in comparison with experimental cows (13.46 kg/day), but average milk yield, and average feed efficiency (FE) was high in experimental cows (15.26 kg, 1.30 respectively) with 1.45 kg more milk as compared to control cows (14.77 kg, 1.12 respectively). The milk lactose was significantly high in milk of G. candidum supplemented dairy cows accompanied by increase in milk fat and protein content as compared to control. The digestibility of dry matter (DM), crude protein (CP), Neutral detergent fiber (NDF), acid detergent fiber (ADF), crude fiber (CF) and ether extract (EE) of probiotic supplemented feed in experimental cows was high as compared to control. Impact of feeding probiotic on hematological parameters was within normal range. RBC count has improved in experimental cows 7.7 x106 -8.72 x106 cells/µl, while in the control cows it decreased from 7.6 x106 - 6.9x106 cells/µl. WBC count decreased both in control and experimental cows, but this decrease was low in experimental cows (9922.2-9524.4 cells/µl) than control cows (9000-7393.3 cells/µl). Neutrophil count increased both in control and experimental groups, but this increase was high in control cows (53.3 to 55 %) than experimental cows (57.33 to 58.55 %). Blood serum profile depicted high glucose level in experimental cows while decreased in control group. The decrease in serum total cholesterol was significantly high while HDL level increased in experimental cows. The serum LDL was decreased in serum of experimental cows (126 mg/dl) after G. candidum supplementation than control serum LDL (176 mg/dl) at end of experiment. Serum butyrate of experimental cows increased than control cows. The milk cholesterol (mg/ 100gm fat) was reduced significantly in experimental cows during experimental period as compared to control milk cholesterol. After analysis of all parameters some cows were selected through principle component analysis (PCA) for metagenomics study in phase III. G. candidum was found in all three experimental cows with high abundance than control. TAC (Total aerobic count) and Lactobacillus count found high in experimental cows. Anaerobic count increased in experimental cows because of G. candidum QAUGC01 supplementation and resulted with high abundance of Bifidobacterium choerinum, Bifidobacterium longum, Bacteroides spp., Rikenella spp., Rikenella microfusus, Clostridial species, Ruminococcus albus, Ruminococcus sp., Eubacterium spp. in gut of experimental cows. Pseudomonas psychrophila, Pseudomonas sp., Pseudomonas spp., Pseudomonas trivialis, Pseudomonas xxiv veronii, Pseudomonas syringae also appeared in experimental cows which is a cellulolytic flora found on phylo-sphere of grasses. While Klebsiella oxytoca, Achromobacter xyloxydanes Enterobacter sp. Salmonella enterica and Serratia quinivorans showed negative co relation with G. candidum due to the antagonistic effect of yeast G. candidum QAUGC01. Shredding of pathogenic flora by experimental cows was less as compared to control cow. In current study G. candidum QAUGC01 appeared as a potential probiotic that could be categorized as pharmabiotic among dairy cattle. Since, it modulated rumen flora, improved blood physiology, serum and milk profile which indicate its direct effects on health and physiology. Molecular mechanisms of all these effects demands further investigation with more comprehensive approach.