Study of the relationship between the weights of Iraqi lambs and some of their reproductive indicators fed a diet containing Cr-methionine, Zn-methionine, and their mixture

Abstract

This experiment was conducted in the field of lambs affiliated to Tikrit University/College of Agriculture/Department of Animal Production for the period from 25/10/2021 to 3/1/2022, preceded by a 14-day preparatory period for lambs to acclimatize to concentrate feed. In the study, 16 Awassi lambs, aged 4-5 months, with an average initial weight of (25.350±2.25) kg, were used. The lambs were divided into 4 treatments (4 lambs per treatment) and they were randomly distributed to the groups as follows: the first was a control diet, and the second was an addition (1 gm per 100 kg live weight) of Cr-Met, and the third was the addition of (0.33 gm per head) of Zn-Met, and the fourth was the addition of (1 g of Cr-Met + 0.33 gm of Zn-Met), in addition to salts, vitamins and minerals for all treatments with hay throughout the days of the experiment. This study examines how chromium methionine and zinc methionine affect sexual maturity, weight, and hormones in Awassi sheep. On day 35, control lambs showed insulin's positive and cortisol's negative correlations with weight. Treatment 2 (Cr-Met) highlighted insulin's strong negative correlation and TSH's positive effect on weight. Treatment 3 (Zn-Met) showed moderate correlations with hormones affecting weight. Treatment 4 (Cr-Met + Zn-Met) indicated complex interactions, notably cortisol and thyroid hormones' strong negative impacts on weight. On day 70, insulin and cortisol showed opposing effects on weight, with insulin negatively and cortisol positively correlated. TSH and thyroid hormones (T4, T3) also influenced weight differently. Chromium and zinc supplementation altered these effects, improving metabolic balance but not entirely counteracting hormonal impacts.