The Effect of Different Zinc Sources on Biochemical Parameters, Intestinal Morphology, Carcass Characteristics and Performance in Finishing Lambs

To investigate the effect of different sources of zinc supplements on blood serum parameters, nutrient digestibility, growth performance, carcass characteristics, and intestinal morphology, 18 male Zandi lambs (with initial body weight of 31 ± 1.2 kg and 120 ± 8 days old) were divided into three groups, six animals each in a completely random design. Experimental treatments include (1) control treatment of basal diet without zinc supplementation, (2) basal diet with 40 mg/kg of zinc supplementation from zinc sulfate source, and (3) basal diet with 40 mg/kg of zinc supplementation with origin it was organic (Zn-peptide). All lambs were kept in individual pens with cemented floor and provision of individual feeding and watering. Mean daily weight gain increased with zinc supplementation (P < 0.05), but feed intake and feed conversion ratio were not affected by zinc supplementation in the diet. Zinc supplementation increased the apparent digestibility of the dry matter (P < 0.05), but the digestibility of dietary fat, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were not affected by zinc supplementation. In this experiment, the addition of organic and inorganic supplements to the diet of fattening lambs had no significant effect on serum triglyceride, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and glucose concentrations, and carcass traits. The concentration of aspartate aminotransferase (AST) enzyme in the zinc sulfate group was significantly higher than the control and organic zinc groups (P < 0.05). Concentrations of blood urea nitrogen were lower in zinc fed lambs, compared to control (P ≤ 0.05). The villi width in the duodenum was higher in the zinc supplementation treatments (P < 0.05). Also, in the ileum section, the height of the villi in the treatment of zinc sulfate supplement was higher, compared to the complement and control (P < 0.05). The results of this study showed that Zn supplementation, regardless of its source, improved growth performance in fattening lambs. However, no effect was observed on feed intake and efficiency, carcass traits, and blood parameters.

The Importance of Dietary Antioxidants on Oxidative Stress, Meat and Milk Production, and Their Preservative Aspects in Farm Animals: Antioxidant Action, Animal Health, and Product Quality-Invited Review

The biological effects of oxidative stress and associated free radicals on farm animal performance, productivity, and product quality may be managed via dietary interventions-specifically, the provision of feeds, supplements, and forages rich in antioxidants. To optimize this approach, it is important first to understand the development of free radicals and their contributions to oxidative stress in tissue systems of farm animals or the human body. The interactions between prooxidants and antioxidants will impact redox homeostasis and, therefore, the well-being of farm animals. The impact of free radical formation on the oxidation of lipids, proteins, DNA, and biologically important macromolecules will likewise impact animal performance, meat and milk quality, nutritional value, and longevity. Dietary antioxidants, endogenous antioxidants, and metal-binding proteins contribute to the 'antioxidant defenses' that control free radical formation within the biological systems. Different bioactive compounds of varying antioxidant potential and bio-accessibility may be sourced from tailored feeding systems. Informed and successful provision of dietary antioxidants can help alleviate oxidative stress. However, knowledge pertaining to farm animals, their unique biological systems, and the applications of novel feeds, specialized forages, bioactive compounds, etc., must be established. This review summarized current research to direct future studies towards more effective controls for free radical formation/oxidative stress in farm animals so that productivity and quality of meat and milk can be optimized.

Zinc supplementation improves growth performance in small ruminants: a systematic review and meta-regression analysis

Appropriate supplementation of trace minerals is 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 &gt; 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 (&gt;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 &lt; 0.0001). There was a positive relationship between the dosage and effect size in all outcome variables (P &lt; 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.