Can i create a new address this way?

Question

I am busy with a project. So I have an array of a struct within another struct. In this case for example array of CattleHealth in Cattle. In my RecordHealth function, I am taking the address of the Cattle struct and adding the current length of its current list to create a unique address. Is this a correct way to do it?

  contract WagyuRecordContract
    {
        address owner;

        struct Cattle
        {
            address RFID;
            string Name;
            uint256 Weight;
            string Gender;
            string Colour;
            string Breed;
            uint Age; 
            uint DOB;
            string Location;
            bool Parent;
            string SireName;
            string DamName;
            bool Active;
            bool ForSale;
            CattleHealth[] HealthRecord;
            CattleGrowth[] GrowthRecord;
            CattleMovements[] MovementsRecord;
            Facility SlaughterDetails;
            Meat[] DistributionDetails
        }


        struct CattleGrowth
        {
            uint DateRecorded;
            uint256 FoodIntake;
            uint256 Growth;
        }


        mapping (address => Cattle) public cattle;
        mapping (address=> CattleGrowth) public growth;           

        modifier Owner() 
        {
            require(msg.sender == owner);
            _;
        }


        function RecordHealth(address rfid, string _bodyCond, string _healthStat, uint256, string _med) Owner public
        {
            health[rfid+cattle[rfid].HealthRecord.length].DateRecorded = now;
            health[rfid+cattle[rfid].HealthRecord.length].BodyCondition = _bodyCond;
            health[rfid+cattle[rfid].HealthRecord.length].HealthStatus = _healthStat;
            health[rfid+cattle[rfid].HealthRecord.length].Medication = _med;
            cattle[rfid].HealthRecord.push(health[rfid+cattle[rfid].HealthRecord.length]);
        }
}

Edit: My Buddy used this method below without using a mapping. I don't understand how this works. What is the -1 for? How is it unique to the cattle?

   function RecordHealth(address rfid, string _bodyCond, string _healthStat, string _med) Owner public
    {
       cattle[rfid].HealthRecord.push(now, _bodyCond, _healthStat, _med)-1;
    }

Answer 1

Negative. While in C or similar languages the pointer arithmetic is the normal rule, in Solidity it is not guaranteed to work, both for eventual packing and for eventual cyclic misalignment. So it is strongly advised not to do so.