Renjith Sebastian

Abstract:The objective of this experiment was to study and compare the effects of dietary supplementation of organic and inorganic zinc (Zn) on growth performance, nutrient utilisation and gene expression pattern of glucose transporter protein in peripheral blood mononuclear cells (PBMC) in Malabari kids. Fifteen, 3–4-month-old goat kids were divided into three groups uniformly by using completely randomised design (CRD). Group G1 was fed on basal diet as per NRC requirement, and G2 and G3 were fed on basal diet + 40 ppm Zn as inorganic zinc sulphate (ZnSO4) and 40 ppm Zn as organic Zn methionine, respectively, for a period of 91 days. Supplementation of inorganic and organic Zn had no significant effect on dry matter (DM) intake. The digestibility of crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), hemicellulose and cellulose was significantly more in the organic Zn–supplemented group. The average daily gain and feed:gain ratio were significantly (p < 0.05) better in group G3 in comparison to G1 and G2, while the nitrogen retention was found to be (p < 0.01) higher in group G3 than in group G1. Zinc balance was found to be significantly (p < 0.01) increased in both supplemented groups with respect to unsupplemented group G1. The blood glucose level was (p < 0.01) lower in group G3 compared to group G1 suggesting the insulin-like activity of Zn. Serum Zn concentration was significantly (p < 0.01) increased in both Zn-supplemented groups. There was a significant (p < 0.05) rise in glucose transporter GLUT1 expression in groups G2 and G3 when compared to control group G1. Moreover, GLUT1 expression was found to be higher (p < 0.05) in group G3 as against the animals of group G2. Lowered blood glucose level might have stimulated more glucose transporter GLUT1 expression in PBMC. Organic Zn supplemented at 40 ppm level resulted in better growth performance, nutrient digestibility and nitrogen as well as Zn retention in goat kids. There was better absorption, and hence, less amount of Zn got excreted in the organic Zn–supplemented group.

Abstract:适当补充微量元素是fundamental to enhance the metabolic status of growing animals and promote an adequate expression of genetic potential. Zinc (Zn) is an essential mineral fundamental in many biological processes that are related to growth, energy balance and immunity. The aim of the present study was to analyse the effect of Zn supplementation on growth parameters in small ruminants by using a meta-analytic approach. Sources of heterogeneity were explored using a meta-regression analysis. The final database was integrated from a total of 53 trials. Only indexed articles that provided an effect size measure, variability measure, sample size and randomisation of the procedure were considered. The dependent variables considered for the study were average daily gain (ADG), dry-matter intake (DMI), feed conversion ratio (FCR), final bodyweight, and glucose blood concentration. The exploratory variables included species (sheep and goat), breed, production level, Zn source and dosage. The ‘meta’ package in R statistical software was used to conduct the meta-analyses. For response variables that showed substantial heterogeneity (I2 > 50%), mixed-effect models (meta-regression analysis) were constructed to explore the sources of heterogeneity using the ‘Metafor’ package. DMI was higher in animals supplemented with Zn (>21.08 g/day, P = 0.0001). Breed, species, production level, and dosage reduced heterogeneity of DMI response from I2 = 84.8 to I2 = 48.1%. Zn-supplemented animals showed higher ADG (17.39 g/day, P = 0.001), which was affected by species, breed dosage and Zn-source. Zn supplementation improved feed efficiency, with lower values of FCR (–1.56 g/g, P < 0.0001). There was a positive relationship between the dosage and effect size in all outcome variables (P < 0.05). Zn-proteinate showed the best response in both species to ADG, FCR and final body weight. Our findings of the systematic review concluded that dietary Zn supplementation improves growth performance in small ruminants and their level of response is influenced mainly by species, production level, and Zn-source and dosage.