Plaintiffs, John and Donna Hall, began operating a dairy farm in East Montpelier in 1965. In December, 1971, plaintiffs purchased three bred heifers, cattle expected shortly to calve, from defendants, who operated the largest cattle dealership in Vermont. Within the next few months defendants sold two other registered Holsteins to plaintiffs, as well as numerous other cattle to Vermont dairy farmers.
Despite the requirements of Department of Agriculture regulations, defendants did not keep complete and accurate records regarding the movement of their herd. In part because of this lack of tag number recording, it became impossible to follow with precision the sale and resale of every cow. However, for the purposes of this appeal, it is enough to note that, by April of 1972, certain cattle purchased by defendants from a Delaware-based cattle dealership and then resold in Vermont carried brucellosis. Brucellosis is a highly contagious venereal disease which causes cows to abort and to become unsuitable for milk production. As a result of this contamination, all of plaintiffs’ 107 cows were quarantined by the Department of Agriculture and eventually 40 were sold for slaughter. During the next year and a half, seven other Ver *139 mont herds with cows from defendants’ Delaware supplier tested positively to the disease. In the view of some experts, Vermont became host to its worst outbreak of brucellosis in a decade.
Plaintiffs brought suit to recover for their losses caused by selling dairy cattle for slaughter and for expenses associated with the quarantine of their herd. The liability issue was tried separately, and the action went to the jury on the theory of a breach of the implied warranty of merchantability under 9A V.S.A. § 2 — 314. After a jury verdict in plaintiffs’ favor, the damage issue was tried by court, with the consent of the parties, and defendants were ultimately found liable for losses of $62,510.59 and interest of $42,285.27.
I. Liability Issue
On appeal, defendants have preserved two claims related to the liability issue. Other theories advanced on appeal were not raised below and thus will not be considered.
Howard Bank
v.
Iron Kettle Restaurant of Bolton, Inc.,
The second issue is quickly disposed of. Defendants cite us to case law relevant to contracts signed by a known agent acting within the scope of his authority for a disclosed principal, which hold that under such circumstances the agent is not liable thereon. Cf.
Hall
v.
Huntoon,
The gravamen of defendants’ appeal is their allegation that plaintiffs base their case on speculation and compound inferences. They cite
Wellman
v.
Wales,
Brucellosis may be transmitted either directly between infected and uninfected cows, or indirectly through a carrier animal. Viewing the evidence, as we must, in the light most favorable to the plaintiffs,
Quechee Lakes Corp.
v.
Terrosi,
Circumstantial evidence provides an appropriate basis from which to draw reasonable inferences. Vermont Food Industries, Inc. v. Ralston Purina Co., 514 F.2d 456, 462-63 (2d Cir. 1975). As we have said, absolutely irrefutable inferences are not required by law.
In the very nature of things no direct proof of the cause of the trouble can be given. Direct proof is not necessary. Circumstantial evidence may be resorted to, and such evidence will be sufficient to justify the verdict below, if there can be drawn therefrom a rational inference that the [defendants’ product] was the source of the trouble.
*141
Patton
v.
Ballam & Knights,
Defendants attack not only the propriety of inferential evidence, but also the ability of the plaintiffs’ experts to give opinions, notwithstanding the provisions of 12 V.S.A. § 1643. However, defendants made no motion to strike the expert testimony, and it therefore was properly before the jury. See generally
Lambert
v.
Fuller,
II. Damage Issues
Defendants also advance three reasons why the damage award should not stand, which we address in turn.
A. The Collateral Source Doctrine
For more than a century, Vermont courts have applied the collateral source doctrine to deny to a defendant a setoff for payment the plaintiff receives from a third, or collateral, source. See, e.g.,
Harding
v.
Town of Townshend,
It is not of the slightest consequence who reimbursed plaintiff, or under what circumstances, if defendant was not connected therewith, and there was no evidence to warrant an inference that he was. The thief who takes my property cannot escape liability to me simply because some insurance company, or my friends, or neighbors, have compensated me for my loss. . . . “A person committing a tort cannot set up in mitigation of damages that somebody else, with whom he has no connection, has either in whole or in part indemnified the injured party.”
Id.
(citations omitted) (quoting
Weber
v.
Morris & Essex R.R.,
This Court has not, however, previously faced the issue of the applicability of the collateral source doctrine in breach of warranty actions. We do so now because of the particular circumstances of this case. Forty of plaintiffs’ cows were “branded” by the state veterinarian to indicate a positive reaction to the brucellosis tests. The branded animals were required by law to be slaughtered and sold at the prevailing beef price. Under state and federal indemnification programs, designed to encourage prompt compliance with the disposal orders and prevent further spread of the disease, plaintiffs received a total payment of $9,275.50. The federal government, pursuant to 21 U.S.C. § 134a(d), paid plaintiffs $2,850.00. The State of Vermont, under authority of 6 V.S.A. § 1141, paid the remaining $6,425.50.
Defendants maintain that plaintiffs’ recovery should be reduced by this amount, arguing that the collateral source rule *143 does not apply for two reasons. First, plaintiffs’ recovery through the indemnification programs was completely fortuitous and in no way the result of plaintiffs’ foresight or expense. Thus, plaintiffs should not be allowed a double recovery. Second, collateral source rules apply when one party is a wrongdoer, a factor they argue is not present here, as this is not a tort action but one based on contract, and as the breach of the implied warranty was neither alleged nor shown to be intentional or even manifest. Rather, the “defect” in the cattle was latent and not discoverable without testing and attendant expense, which should in any event have been the buyer’s responsibility.
Although the view is not unanimously shared, we think the better rule is that the collateral source rule should apply to actions sounding in contract, as well as in tort. The breaching party in a contract action or, as here, a breach of warranty action, may not be a wrongdoer in the same sense as is a tortfeasor. Nonetheless, as between the two parties, it is better that the injured plaintiff recover twice than that the breaching defendant escape liability altogether.
In 1955, the Seventh Circuit Court of Appeals observed that it was unable to find “a single case in which [the collateral source rule] had been carried over to contract damages.”
United Protective Workers
v.
Ford Motor Co.,
*144
Plaintiffs direct our attention to the factually similar case of
Roundhouse
v.
Owens-Illinois, Inc.,
We note finally that defendants misapprehend the reasoning in
My Sister’s Place
v.
City of Burlington,
B. Lost Profits
Defendants also argue on appeal that plaintiffs would receive a double recovery for another reason. Defendants were *145 ordered to pay plaintiffs $23,624.56 for the difference between the fair market value of dairy versus beef cattle for the 40 cows sent to slaughter. In addition, plaintiffs received from defendants some $36,000.00 for lost profits from those cows, $10,000.00 for the lower milk production of the replacements and $26,000.00 for lost profits due to the smaller herd size. Defendants assert that the fair market value of a dairy cow is determined by its ability to produce milk and therefore the award of damages includes a recovery for the value of that cow’s potential milk production.
Defendants’ position is buttressed by their experts’ testimony, but contradicted by expert testimony from the plaintiffs. We need not chronicle the arguments for or against either side; suffice it to say that credibility of witnesses, even experts, is a matter for the finder of fact. The trial court hearing the issue of damages made lengthy and detailed findings, in which it adopted the plaintiffs’ proof over that of defendants. Error does not appear from the failure to adopt one side’s findings. The additional findings made by the trial court provide “a clear statement to the parties and to this Court '. . . upon all material issues raised by the pleadings and evidence,”
In re Estate of Young,
Moreover, by statute in Vermont, the measure of damages for a buyer when the seller breaches a warranty may include both the price difference between goods delivered and the goods expected, 9A V.S.A. § 2 — 714, and any incidental and consequential damages, including lost profits. 9A V.S.A. § 2 — 715. See, e.g.,
M. K. Metals, Inc.
v.
Container Recovery Corp.,
No error appears in the award of lost profits or in the computation of that award based on fair market value as testified to by plaintiffs.
C. Prejudgment Interest
As their last claim, defendants argue that prejudgment interest should not have been awarded on unliquidated damages. The unliquidated damages component included both the value of the cattle lost and the amount of profits lost due to plaintiffs’ forced sale of their herd. Defendants base their claim on the contention that the damages were speculative and could not be “established with reasonable certainty.”
To the extent that defendants challenge the size of plaintiffs’ milking herd, we must discount their argument. There was ample testimony below to support the trial court’s findings that plaintiffs needed to establish a milking herd of eighty cows. We will not supplement our judgment for a supportable determination by the fact finder on a purely factual issue. Further, the loss of profits from milkers with proven production records is not so contingent as to be unsupportable. Both the plaintiffs and plaintiffs’ experts testified as to plaintiffs’ losses and the dates thereof. The trial court’s decision to award interest on those losses to attempt to make plaintiffs whole was well within its discretion. Cf.
Quinlan
v.
Hamel,
While the above discussion disposes of all the issues presented on appeal, in the course of our examination of the record, we notice two instances of possible mathematical errors: (1) Finding of Fact number 28 indicates a total cost of twenty-five replacement cows at $18,040.00. Defendants correctly point out that the addition of all twenty-five prices yields a total of $17,685.00. This figure should be recomputed either to correct the amount or explain the $355 discrepancy; (2) Conclusion of Law number 19 computes interest at 12% running from April 1, 1979. The effective date of the amendment to 9 V.S.A. § 41 which raised the interest to 12% was July 1, *147 1979. See 1979, Vt. Pub. Acts, No. 82, § 1. Interest should be recomputed to correct this calculation.
Judgment affirmed as to liability. Judgment affirmed in all respects as to the components of the damage award, but reversed for recomputation of damages consistent with the views expressed herein.
