RESUMEN
There is a need for newer feed additives due to legal prohibition on inclusion of growth promoting antibiotics in livestock diets in several countries due to antimicrobial resistance. In this context, rare earth elements (REE) have gained attention among animal nutritionists as potential growth promoters. Currently, several studies have reported better weight gain, milk production, egg laying capacity and feed conversion efficiency among different breeds of farm animals following supplementation with REE, with however largely inconsistent results. Furthermore, REE supplementation has also shown to improve ruminal fibrolytic and proteolytic activities as well as flavor of meat with negligible residues in edible tissue, however the mechanism behind this action is still unclear. According to existing research, due to their poor absorption and similarity with calcium REE might exert their action locally on gut microbial populations within the gastrointestinal tract (GIT). Moreover, REE have also shown anti-inflammatory, anti-oxidative as well as immune stimulating effects. The present review aims to broaden the knowledge about use of REE as feed additives for livestock and sum up efficacy of REE supplementation on performance and health of animals by comparing the findings. Till date, researches with REE have shown properties that make them a promising, new and safe alternative feed additive but further exploration is recommended to optimize effects and clarify discrepancy of various results before practical proposals can be drafted.
RESUMEN
Silicon (Si), a newer trace element, is believed to be important for healthy bone formation and to decrease bone resorption, improving the quality of bone by manipulating several hormones and enzymes. Therefore, the current investigation was conducted to determine the impact of Si supplementation on growth, immunity, antioxidant, hormonal profile and biomarkers of bone health in pre-ruminant crossbred calves. Twenty-four crossbred calves (5-7 days) were selected on the basis of their body weight (BW 31.65 ± 0.46 kg) and divided into 4 groups (n = 6) and fed as per ICAR (2013) feeding standards except that these were additionally supplemented with 0 (Si0), 50 (Si50), 100 (Si100) and 150 (Si150) mg of Si/kg dry matter (DM) in four respective groups for 90 days. Every month, peripheral blood samples were drawn (0, 30, 60 and 90 days post supplementing with Si) and analysed for antioxidant status, hormonal profile and bone health biomarkers. It is reported that dietary Si supplementation improved (P < 0.05) net body weight gain (kg), average daily gain (g) and average dry matter intake (kg), whereas feed intake (kg/100 kg BW), was not altered due to Si supplementation. Structural growth measurements were significantly higher (P < 0.05) in Si100 and Si150 groups as compared to Si50 and control groups. However, immune response (humoral as well as cell-mediated immunity), erythrocytic antioxidant enzymes (superoxide dismutase, SOD, glutathione peroxidase, GPx and catalase), plasma ferric reducing total antioxidant power (FRAP) activity and the plasma concentration of total immunoglobulins (TIg) remained unaffected by Si supplementation. Silicon increased (P < 0.05) the concentration of plasma growth hormone (GH), vitamin D3, bone alkaline phosphatase (BALP) and osteocalcin (OCN) in Si100 and Si150 groups, but the levels of calcitonin, parathyroid hormone (PTH) and hydroxyproline (HYP) remained similar among all the groups. As a result of the current investigation, it can be inferred that the inclusion of 100 and 150 mg of Si/kg DM was effective in improving the growth performance, growth hormone, vitamin D3 and bone health status in pre-ruminant calves. However, supplementation of 150 mg of Si/kg DM had no additional benefit; therefore 100 mg of Si/kg DM is the optimum level of Si supplementation in pre-ruminant calves.
RESUMEN
Abstract In neonates, rapid change in diet imbalances gut health allowing colonization of opportunistic pathogens that confer harmful effects on animal health causing reduced digestion and malabsorption of nutrients. In this milieu, probiotic feeding can be a promising approach in promoting animal health and stabilization of gastrointestinal microbiota. Hence, the present study was designed to investigate the effect of Lactobacillus acidophilus NCDC15 enriched fermented milk on nutrient digestibility, faecal biomarkers and immune response in Murrah buffalo calves. Twenty-four, neonatal calves (5-7 days) were randomly allocated into four groups for 90 days. The control group (CT) was provided a basal diet of calf starter and green fodder (maize and jowar), without any probiotic fermented milk (PFM) supplementation. Basal diet was supplemented with probiotic fermented milk at 100, 200 and 300 mL/calf/day, in PFM100, PFM200 and PFM300 groups, respectively. Nutrient digestibility remained similar among the groups. Faecal acetate was higher (P<0.05) in PFM200 and PFM300, while, faecal butyrate was increased (P<0.05) with all levels of probiotic supplementation than control. Faecal Lactobacillus and Bifidobacterium count were increased (P<0.05) with a concomitant reduction in coliform population (P<0.05) among all the treatments. Cell-mediated and humoral immune response were higher (P<0.001) in PFM200 and PFM300 than CT. Overall, it can be concluded that inclusion of Lactobacillus acidophilus NCDC15 in the form of fermented milk upto 300 mL/calf/day improved immunity and faecal biomarkers in Murrah buffalo calves without any adverse effect on nutrient utilization which may positively impact growth performance in Murrah buffalo calves.