Farmers Union Grain Terminal Association (GTA) appeals from the award of $391,908.21 damages in favor of Wayne Robbins, Charles Robbins and James Robbins for the loss or damage to their cattle allegedly caused by a feed supplement, Rum-Liq, manufactured by GTA. The jury found the defendant liable under alternative theories of negligence, breach of implied warranty and strict liability.
On appeal the defendant has assigned numerous errors. We discuss as relevant to our holding: (1) whether there was sufficient evidence of negligence; (2) whether such negligence was the proximate cause of the plaintiffs’ damage; (3) whether the trial judge properly admitted evidence of a remedial warning; and (4) whether the evidence supports the damages found by the jury. Finding no prejudicial error, we affirm the judgment of the district court.1
Factual Background,
The plaintiffs are partners in a cattle feeding operation near Watertown, South Dakota. In the fall of 1971 they purchased 3,259 calves with an average weight of 412 pounds. The calves were started on a feeding program which included Rum-Liq, a cattle feed protein supplement advertised as aiding in weight gain and being more economical than other protein sources. The main ingredient of Rum-Liq is urea, a widely used non-protein nitrogen substance which ruminant animals are able to convert into protein.
GTA’s product bore a tag which stated:
*790WARNING — Follow directions on back of tag. .
The relevant part of the tag providing the feeding instructions read;
STARTING CATTLE ON FEED: Cattle coming into feedlot have normally been subjected to considerable stress — shipping, changes in feed, water and environment. Fresh, clean water and medium quality hay should be available in the feedlot when the cattle arrive. The first ten days follow the recommended programs using GTA ROUGHAGE ROUSER MEDICATED or GTA BEEF START MEDICATED. At the close of this period, change to a recommended GTA feedlot feeding program.
The plaintiffs started feeding each calf one-quarter pound of Rum-Liq daily. They gradually increased the dosage so that fourteen days after the calves arrived in the feed lot they were receiving one pound of Rum-Liq per day. After the fourteen-day “conditioning period,” the calves were moved to outer pens where they continued to receive one pound of Rum-Liq each day. During the second week in November of 1971 some of the calves died and others were uncoordinated, bloated, urinating frequently, shaking and shivering, showing white foaming saliva, and breathing hard.
The Robbins first suspected that the calves were suffering from a respiratory disease, and they attempted treatment, but the calves did not respond. On December 8, 1971, after 77 animals had died and approximately 600 others were sick, two animals were taken to the diagnostic laboratory at South Dakota State University at Brookings. The lab found that blood of the two calves had a high level of ammonia, and they advised the plaintiffs, on the same day, that this could be the result of urea feeding. The plaintiffs immediately cleaned all the feed containing Rum-Liq out of the feed bunks, and stopped adding Rum-Liq to the feed. The sudden death losses decreased rapidly after December 9 and few animals subsequently developed the above described symptoms.
Beginning on March 7 the plaintiffs shipped their cattle for “finishing” to a commercial feed lot in Nebraska. According to plaintiffs’ proof each of the seven shipments of cattle, when sold, weighed less on an average than normally expected and each shipment incurred extra feed and drug costs. An additional 59 head died at the commercial lot and 64 were sold early.
The plaintiffs sought the following damages: $2,000 for the' Rum-Liq; $12,000 for extra veterinary expenses; $64,000 for the 342 dead animals (this figure took into account normal or expected deaths); $73,-000 for extra feed; and $185,000 for losses on early sales and failure of the cattle to gain weight.
Negligence.
The thrust of plaintiffs’ case is that GTA failed to give adequate warnings for the safe and effective use of its product.2 Plaintiffs claim that GTA knew or should have known that, although their instructions recommended waiting 10 days before *791starting calves on a full feeding program, experts recommended a longer delay.
Plaintiffs’ animal nutrition experts testified that a manufacturer should warn a feeder to wait 28 to 30 days before starting calves on a high percentage urea feeding program such as Rum-Liq. Furthermore, Dr. Britzman, the Director of Animal Nutrition, Research and Management Services for GTA admitted that he knew of one authority who recommended that urea not be fed to calves within four weeks of weaning and that another authority questioned the feeding of urea to unadapted calves during early feed lot stages. From this evidence a jury could find that GTA’s instructions inadequately warned of the danger of feeding urea to unadapted calves and that GTA had or through the exercise of reasonable care should have had knowledge of the dangers of urea.3
Causation.
The defendant claims that the plaintiffs failed to prove that Rum-Liq caused the death and sickness of plaintiffs’ cattle. GTA points out that, if plaintiffs’ experts are believed, the cause of the death and sickness was “ammonia toxicosis.” Because other sources of protein produce ammonia when broken down in the same process as is urea, the defendant argues that plaintiffs have failed to connect the high level of ammonia in the blood supply to its product.
While there is dispute among the experts as to the cause of the death and sickness, three experts testified that they diagnosed the cause as high levels of ammonia in the blood stream with urea as the source— “urea toxicosis.” Other evidence reveals that defendant’s product was the source of urea. Thus there is evidence from which a jury could find that the cause of the deaths and sickness was ammonia toxicosis; that the source of the excess ammonia was urea; and that Rum-Liq was the urea source.
GTA further contends that the plaintiffs did not prove that the defendant’s failure to adequately warn was the proximate cause of its damage since there was no evidence that plaintiffs would have heeded a different warning had one been given. The defendant contends that they rebutted the presumption that plaintiffs would have heeded different instructions,4 by showing that the plaintiffs failed to follow the instructions that were given.5
At best, the instructions were ambiguous and the issue was properly presented to the jury. Cf. Sterner v. U. S. Plywood-Champion Paper, Inc., 519 F.2d 1352 (8th Cir. 1975); Buffington v. Amchem Products, Inc., 489 F.2d 1053 (8th Cir. 1974). The trial court instructed the jury that failure to follow the instructions would be contributory negligence and would bar recovery if it was the proximate cause of the deaths and sickness. We find no error here.
Our examination of the record demonstrates that plaintiffs made a submissible case of negligent failure to warn. Therefore, it is not necessary for us to discuss the *792various issues GTA has raised concerning the applicability of implied warranty and strict liability.6
Subsequent Remedial Warning.
On December 31, 1971, GTA mailed the following notice to its sales personnel:
File copy distributed to all division personnel 1/12/72 SUPPLEMENTARY DIET FOR “NEWLY ARRIVED” FEEDLOT CATTLE
It is not recommended that high urea supplements (liquid or dry) be fed to cattle which have recently been placed in the feedlot. These cattle should be allowed time to overcome the stresses associated with shipment, vaccination, and adjustment to feedlot conditions. This may involve as long as 28-30 days. During this period, GTA ROUGHAGE ROUSER MEDICATED, or a similar low-urea supplement, should be fed.
Additional recommendation for handling and starting newly arrived feeder cattle are given on the attached sheets.
GTA FEEDS
Department of Animal Nutrition, Research and Management Services.
Plaintiffs offered this letter into evidence as relevant to the strict liability count to show an unreasonably dangerous and defective product. Plaintiffs also sought to show the feasibility of issuing such a warning in 1971 under their negligence theory. GTA objected that the exhibit was inadmissible on both counts under Fed.R.Evid. 407.7 The trial court ruled that the letter was admissible as substantive evidence since Rule 407 did not apply to strict liability, but that it would not be admissible on the negligence count unless feasibility was “controverted” as required by Rule 407. Plaintiffs then requested GTA to admit feasibility, and when GTA refused the trial court ruled that plaintiff could show that it was feasible to give the remedial instruction prior to the plaintiffs’ purchase of the feed supplement.
On appeal GTA asserts that the exhibit should have been excluded under Rule 407 on both the strict liability and negligence counts and urges that the feasibility of giving the precautionary measure was not properly controverted. In addition GTA claims that the trial court failed to give any limiting instruction as to the exhibit’s admissibility, and that the plaintiffs improperly argued to the jury that the post-remedial measure was evidence of GTA’s negligence.
We need not consider whether the issue, of feasibility was properly controverted8 because we find (1) that the exhibit was admissible under strict liability and (2) that GTA failed to object to plaintiffs’ argument before the jury and did not request any cautionary instruction, or object to the court’s failure to give a limiting instruction.
*793 Rule 407.
The trial court in receiving the exhibit relied on Ault v. International Harvester Co., 13 Cal.3d 113, 117 Cal.Rptr. 812, 528 P.2d 1148 (1974). In the Ault decision the Supreme Court of California observed that the exclusionary rule governing subsequent remedial measures (Cal.Evid.Code § 1151) is applicable only to negligent or culpable conduct.9 The court said that while the exclusionary rule “may fulfill this anti-deterrent function in the typical negligence action, the provision plays no comparable role in the products liability field.”10 13 Cal.3d at 120, 117 Cal.Rptr. at 815, 528 P.2d at 1151.
The Supreme Court of South Dakota has agreed with this rationale:
A products liability case looks to a defect in the product rather than any culpable act by the manufacturer. In an age of mass production it is not reasonable to assume that manufacturers would forego improvements in a product and subject themselves to mass liability for a defect just because evidence of an improvement is admissible in a pre-improvement liability case. The pure economics of the situation dictate otherwise.
Shaffer v. Honeywell, Inc., 249 N.W.2d 251 at 257 n. 7 (S.D.1976).
We have applied the Ault rationale in allowing proof of post-occurrence design modification11 and to a subsequent remedial instruction,12 and find no reason to bar its applicability to Rule 407 since Rule 407 is, by its terms, confined to cases involving negligence or other culpable conduct. The doctrine of strict liability by its very nature, does not include these elements. See Ault v. International Harvester Co., supra; and Passwaters v. General Motors Corp., 454 F.2d 1270, 1277-79 (8th Cir. 1972).
Relevancy.
Relevancy of post-remedial measures in a defective design ease have been outlined by the Seventh Circuit:
*794[T]he plaintiff must establish that the “product in question has [not] lived up to the required standard of safety.” [Citation omitted.] This, of course, requires proof that, inter alia: 1) the product as designed is incapable of preventing the injury complained of; 2) there existed an alternative design which would have prevented the injury; and 3) in terms of cost, practicality and technological possibility, the alternative design was feasible. Evidence of post-occurrence change which tended to satisfy plaintiff’s burden on any of these issues would therefore, be relevant.
Lolie v. Ohio Brass Co., 502 F.2d 741, 744 (7th Cir. 1974).
Under the view that “foreseeable danger” is still considered an element of strict liability,13 evidence of “technological possibility,” as related to the feasibility of a manufacturer to provide adequate instructions with its product, implies knowledge that such instructions could have been used to make the product safe or, at least, implies that such knowledge could be obtained through “the application of reasonably developed human skill and foresight.” See Restatement (Second) of Torts § 402A, Comment j. In the instant case Dr. Britzman of GTA testified that it was “feasible” to give, in 1971, a warning similar to that contained in the exhibit.14 Although the trial court limited the proof to show that it was feasible “to have sent out the notice,” implicit in this admission is that it was technologically possible to have given the instructions in 1971. It would hardly be possible to concede feasibility to send out such cautionary instructions, if the manufacturer did not have either actual or constructive knowledge of the technological information. More relevant is the fact that a remedial instruction may provide substantial evidence that with a different instruction the harm would not have resulted (causation) and that failure to give the instruction created an unreasonably dangerous product (defect).15 Lolie v. Ohio Brass Co., supra.
*795We conclude that the directive was relevant and properly admitted under the strict liability count. The fact that the exhibit was generally admitted and should have been limited to the strict liability count does not require reversal. As we pointed out the defendant did not offer any limiting instruction or object to the failure of the trial court to give such an instruction. The purpose for requiring specific objection to instructions or to any alleged trial error is to provide the trial court the opportunity to correct the error at the time, See, e. g., Sterling Drug, Inc. v. Cornish, 370 F.2d 82 (8th Cir. 1966). This case is exemplary of the rule since it is clear that the trial judge fully intended to give a limiting instruction concerning Exhibit 38 but it was later inadvertently omitted. Under the circumstances the defendant cannot complain, See Griggs v. Firestone Tire & Rubber Co., 513 F.2d 851 (8th Cir.), cert. denied, 423 U.S. 865, 96 S.Ct. 124, 46 L.Ed.2d 93 (1975).
*796 Damages.
The defendant challenges the amount of the verdict on three grounds: (1) there was insufficient evidence that all the death losses were caused by feeding Rum-Liq; (2) the trial court erroneously instructed the jury on the measure of damages for the cattle that did not die; and (3) the amounts awarded for the extra veterinary and feed costs were not reasonably incurred in mitigation of damages.
Death Losses.
The defendant urges that plaintiffs’ cattle had other ailments which could have caused many of the deaths and that plaintiffs failed to prove that all their losses were attributable to Rum-Liq.
Although there was some evidence of other afflictions the trial court instructed the jury that the “mere fact alone” that the cattle developed certain symptoms or died was not proof that the cause was defendant’s negligence and that the plaintiffs had the burden of proving “that such failure to warn was the proximate cause of said damages.” The court specifically instructed the jury to consider that some cattle may have died in the normal course of operations.16 We find that the trial court properly instructed the jury.
Measure of Damages.
The trial court gave the following instruction on the measure of damages for the cattle that survived:
Further, you are instructed that as to the cattle that lived, you may consider the difference between the market value that the cattle would have sold for if fully fed out but for the interference with their growth and the amount that these cattle actually sold for. To this amount should be added veterinary expenses expended as a result of the interference and the cost of the feed required to finish feeding these cattle which was over and above that required in the normal course of feeding.
The plaintiffs’ measure of damages for their loss is the difference between what they could have obtained for their cattle on the date you find they should have sold them, in the condition they were then in, and what they would have brought at the same date and at the same place, if they had developed normally from the time that they took sick.
The defendant contends that the extra feed costs and failure to gain were not relevant measures of damage. The appropriate measure of damages for non-fatal injury to livestock, GTA contends, is the difference between the value just prior to and immediately after the injury plus the cost of treatment. Overpeck v. City of Rapid City, 14 S.D. 507, 85 N.W. 990 (1901) (damages for injury to a horse).17 Under this standard, GTA argues, the diminution in value would be determined as of December 9, the date plaintiffs ceased using Rum-Liq as a feed supplement, and that no expenses incurred subsequently, except veterinary expenses, would be recoverable.
We find under South Dakota law that December 9 would not be the appropriate date for ascertaining the damages to plaintiffs’ cattle, since the injury took place • prior to maturation. Another South Dakota case, Swenson v. Chevron Chemical Co., S.D., 234 N.W.2d 38 (1975), involving damage to a growing corn crop, is more analo*797gous to the present case. There the court held that:
The method of ascertaining damages for crop injury, under the rule that the measure of damages is the difference between the value immediately before and immediately after the injury, is to take the value at maturity which the probable crop would have had but for the injury [and] deduct the value which the injured crop actually had at maturity.
234 N.W.2d at 43-44 (emphasis added). Thus we find that the trial court properly instructed the jury.
Mitigation of Damages.
The defendant also contends that as a matter of law the extra feed costs were not recoverable. However, the plaintiffs had a duty to take reasonable efforts to mitigate damages. See Overpeck v. City of Rapid City, supra. Reasonable additional feeding of the cattle to produce weight gain and thus increase value, is recoverable as reasonable expenses in mitigation of damages. See, e. g., Ruden v. Hansen, 206 N.W.2d 713, 718 (Iowa 1973); and W & W Livestock Enterprises, Inc. v. Dennler, 179 N.W.2d 484, 486 (Iowa 1970).
Finally the defendant contends that the damage awards for the extra veterinary expenses and feed costs were excessive. GTA claims these amounts were not reasonable expenses in mitigation of damages. The trial court instructed the jury that it was plaintiffs’ duty to exercise reasonable diligence to mitigate damages. The court specifically instructed that plaintiffs were not entitled to continue to expend feed money and effort on “poor doing” or “sickly cattle.” We find this issue was properly submitted.
Finding no error, we affirm the judgment of the district court.