Effect of Selenium and Zinc Doses and Interaction between Them on Production Performance and Some Carcass Traits of Awassi Lambs

Abstract

This experiment was conducted in breeding field of sheep that belong to Department of Animal Production / College of Agriculture and Forestry, University of Mosul. The aim of this study was to find out effect of oral dosing of selenium and zinc, and interaction between them on productive performance and some of carcass characteristics of fattening Awassi lambs that lasted for 90 days period. Twenty-four heads of Awassi lambs (males), were selected for this study with close ages ranging between 5.5-6 months, and their initial weights were similar at beginning of experiment, Where average of initial weight ranged between 21.00 - 22.56 kg.The lambs were randomly distributed into four treatments with rate of six lambs per treatment, the first treatment was called a control treatment, and second treatment of lambs was dosed by using oral dosing method, at a dose of 0.5 mg of selenium per head, and the dose was repeated three times a week, the third treatment  of lambs was dosed by mouth with 50 mg of zinc/head, and this dose was repeated three times per week, and fourth treatment was dosed by mouth with combination of selenium and zinc in the same previous doses, and dosing process was repeated three times per week for each head.All lambs consumed a standardized, concentrated diet consisting of 55% crushed black barley, 37.5% wheat bran, 5% wheat straw, 0.5% urea, 1% salts and limestone, with a protein level of 13.65% and metabolize energy level of 2619 K_cal of this concentrated diet. The results of current study indicated that there were high significant differences (P≤0.01) in rates of final weight, empty body weight, daily and total weight increases between control  than  for lambs treated with selenium, zinc and interaction between them. The rates of initial weight of  lambs were 22.273, 22.776, 22.423, 22.686 Kg and final weight 37.656, 38.493, 41.346, 43.250 kg and empty body weight 34.353, 35.156, 37.997, 39.533 kg ,daily weight gain 170, 174, 210, 228 gm /day and total weight gain 15.383, 15.717, 18.923, 20.563 kg/lamb for four transactions.As for carcass characteristics, the results showed high significant differences (P≤0.01) in rates of hot and cold carcass weights between control treatment than for experimental treatments of lambs with dosed of selenium and zinc and interaction between them. The average of  hot  carcass weight was 18,606, 19,846, 20,733, 21,406 kg, and cold carcass weights were 18,326, 19,548, 20,422, and 20,811 kg of four treatments  according to the order. On the other hand, results indicated that there was a significant effect (P≤0.05) of cross-dose on rates of ocular muscle area, subcutaneous fat layer, and dressing percentage  relative to live weight of lambs between selenium and zinc than for control treatment.  Also, results showed significant effect(P≤0.05) of dosing with selenium and zinc and overlap between them than for first treatment without dosing (control) in rates of weights of thighs, ribs, shoulders and back (major cuts) and forearm weight of secondary cuts of Awassi lambs for four treatments according to sequence. We conclude from this study that dosing of lambs with selenium and zinc and interaction between them led to emergence of a significant superiority on lambs growth and daily weight gains, total weight gains. The significant improvement was reflected in weight gain of the lambs that treated with selenium and zinc and interaction between them showed a significant improvement on weights of the hot and cold carcass weights of major cuts , area of ​​ ocular muscle, and a significant decrease in two characteristics of thickness of the subcutaneous fat layer and proportion of the dressing attributed to the live weight compared to the control treatment.