الفهرس 
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Abstract
The present study was carried out at the Station od Experiment and Agricultural Research, located in Sakha Animal Production Research Station, belonging to the Animal Production Research Institute, Agricultural Research center, Ministry of Agriculture in co-operation with Animal Production Department, Faculty of Agriculture, Kafrelsheikh University, during the period from July to December 2021.
The experimental Friesian cows (n = 50, 547.6±32 kg, 3-5 parity) were selected at prepartum (30 days at pre-calving) and the early postpartum period (120 days post-calving). Cows were divided into five groups of ten as follow: cows in the first group (control, G1) were given an untreated baseline diet, G2 was given a baseline diet supplemented with 2.4g Zn, 0.78g Cu, and 2.4 g Mn /animal/day (100% ITM) daily, G3 was received diet supplemented with the same minerals but in two forms which are 50%ITM and 50% OTM, G4 was received 25% ITM and 75% OTM, while G5 was supplied with 100% OTM. The source of OTM was zinc chelate of glycine hydrate, cupric chelate of glycine hydrate, and manganese chelate of glycine hydrate. All supplementations were given for 150 days started from day 30 of prepartum to 120 days of postpartum. All cows were disease-free and appeared healthy and were kept in separate groups beneath semi-open sheds.