There isn't a simple answer to this, so I will quote items mentioning Roddey and Ferrell's Battery from the OR for April 1864. In sum, Hannon's small cavalry brigade from Roddey's command was retained by General Johnston. The section of Ferrell's Georgia Battery may have been apportioned for the Army of Tennessee as well. Note that Federal officers mention Roddey more often than their Confederate counterparts.

O.R. vol. 32, pt. 3, page 732
Apr. 1, 1864, Ferrell's battery, Roddey's division, near Tunnel Hill, 129 effective, 158 present and absent, 2 3-inch rifles, 2-12 lb. howizters, 2 6 lb. smoothbores, 98 horses effective, 12 horses unserviceable. Not counting Freeman's Tenn. Battery, then in route from East tennessee, only 32 serviceable horses are reported in Wheeler's other batteries, then in camp near Oxford, Ala.

Also on this page, General Polk writes, "Four regiments infantry at Decatur fortifying; Dodge's division at Athens; Logan's at Huntsville; enemy's cavalry raiding out from Decatur. Very much in want of Roddey's force in that region."

O.R. vol. 32, pt. 3, page 742
General Order No. 29, Apr. 3, 1864, temprarily assigned the following batteries
"to Wheelers cavalry: Captains Huwald's, Ferrell's, and Wiggins' batteries, Maj. F. H. Robertson commanding."

O.R. vol. 32, pt. 3, page 738
S. COOPER, Adjutant and Inspector General,
RICHMOND, VA., April 2, 1864.

General J. E. JOHNSTON, Dalton, Ga.: Special orders of this date direct General Roddey with his command to resume his former position and to report to Lieutenant-General Polk. General Clanton in same order is directed with his command to replace that of General Roddey and to report to you.*

S. COOPER, Adjutant and Inspector General.

* On July 15, 1864, General Johnston, upon inquiry from War Department, reported that Clantons brigade had never reached his army.

O.R. vol. 32, pt. 3, page 739

J. E. JOHNSTON, General, Commanding, DALTON, April 2, 1864.

General BRAGG: GENERAL: I have just been informed by General Cooper by telegraph that orders just issued send Brigadier-General Roddey to his former position and Brigadier-General Clanton to replace him here. I have suggested, in reply by telegraph, that the latter be sent with his troops to the Atlantic coast. I recommend some locality where Alabama troops will not be encountered. You are aware of the discovery, early in the winter, of a secret society in that brigade. It is unlikely that it was entirely suppressed, especially as it is well known to exist in the part of Alabama in which General Clanton has been stationed recently. Escaped prisoners report that the signs of this society are known in the Army of the Cumberland. I think it dangerous to this army, therefore, to bring into it troops which I regard as so infected. Let me urge, therefore, most respect- fully, that General Roddeys brigade be replaced by other troops.

I ordered Brigadier-General Roddeys brigade to the army because our cavalry with it was far too weak to resist that of the enemy. Of time eight brigades which you had more than five, as Major-General Wheeler informs me, were detached with Lieutenant-General Longstreet. The horses of the remaining force were in such condition from hard service in a barren country that it has been necessary to keep about one-third of it in the rear to recruit, the brigades alternating. This leaves us, exclusive of General Roddey's brigade, about 1,600 effective cavalry. Major-General Martin's division amounts to but 1,500 men, according to his report, instead of 3,000, as you supposed, two-fifths being unarmed. From the verbal reports of General Wheeler and himself, it will be five or six weeks before his horses are fit for service. General Wheeler thinks that he has good information that the horses of the main Federal cavalry force were sent to Kentucky to winter.

In a letter to the President, dated about the end of February, Lieutenant-General Polk estimates his cavalry force for a movement into Middle Tennessee at 15,000. Brigadier-General Roddey's, including the regiment left at Tuscumbia, is 2,000. The enemy has not a strong force in Alabama, Mississippi, and West Tennessee. The transfer in question leaves me about 1,600 effective cavalry, with a powerful army in my front, a very long front to watch, and communications to guard which the enemy may reach by several lateral routes.

Most respectfully, your obedient servant, J. E. JOHNSTON, General.

O.R. vol. 32, pt. 3, page 748

HEADQUARTERS ARMY OF TENNESSEE, Major-General WHEELER, Dalton, Ga., April 4. 1864. Commanding Cavalry

GENERAL : General Johnston directs that you order Patterson's brigade, of Roddey's command, to proceed to North Alabama to operate against the enemy in that section.

I am, general, very respectfully, your obedient servant,
KINLOCH FALCONER, Assistant Adjutant-General.

DALTON, April 7, 1864.

Lieutenant-General POLK: Colonel Patterson has moved with about 900 effective cavalry of Roddey's brigade to the district it formerly occupied.

J. E. JOHNSTON.

O.R. vol. 32, pt. 3, page 767

DALTON, April 9, 1864. General COOPER:

GENERAL: The last mail brought me paragraphs XIII and XIV, Special Orders, No. 28. About one-fourth of Brigadier-General Roddey's troops was left in the former position. I sent back about half in consequence of yonr telegram of the 2d instant, and am retaining the other fourth until the arrival of the Kentucky brigade, which was sent to the rear to put its horses in condition for service. The necessity of an efficient cavalry as part of this army justifies me in desiring the honorable Secretary of War to consider how much that arm of service in it has been weakened since the last campaign, when it was inferior in strength to that opposed to it, and on the contrary how much that of Lieutenant-General Polk has been increased. It is needless to contrast the enemys force in his front with that in mine. On the 28th of February General Polk estimated the cavalry with which he could operate this spring at 15,000. Brigadier-General Roddey has more than 2,000 effectives. His transfer leaves an effective force in the Army of Tennessee (cavalry) of a little above 2,000, mounted on horses not in proper condition to commence a campaign. It is true that Major-General Martin's division has returned from East Tennessee, but he describes it reduced from about 3,000 effectives to 1,300, 1,120 of whom appear by his requisitions to have lost or thrown away their arms. From the condition of the horses of this division, as described by Major-Generals Wheeler and Martin, it cannot be ready for service before the middle of May. With such a force we niust observe a front of near 80 miles and protect the railroad to Atlanta against a cavalry which is estimated by Major-General Wheeler at above 12,000.

Most respectfully, your obedient servant,
J. E. JOHNSTON, General.

O.R. vol. 32, pt. 3, page 801
Roddey's brigade transferred to General Polks department, and has left the army, with the exception of the Fifty-third Alabama Regiment and Twenty-fourth Alabama Battalion, which are on picket in our immediate front and number 471 effectives.... The entire artillery of Wheelers cavalry corps, with the exception of one section of Ferrell's battery (effective total 27), is in rear recruiting horses. The date for this report is Apr. 20, 1864.

O.R. vol. 32, pt. 3, page 872 notes this section with Robertson's Horse Artillery. The note for Ferrell's Battery states "Only one section present; remainder transferred, with Roddeys brigade, to Department of Alabama, Mississippi, and East Louisiana." The date for this report is Apr. 30, 1864. Note the effective present for artillery assigned to the cavalry as 27 total out of an aggregate present of 295. The answer is that except for one section of Ferrell's Battery, all of Wheeler's horse artillery was in the rear, recruiting horses, as noted earlier.