In these two eases, Adele Rand, a citizen of the State of New Mexico, sues the defendants, British insurers, on two policies of livestock mortality insurance indemnifying her against loss through death of her race horse, Tom F., Jr. *344The issues in the two cases are identical except for the amounts of insurance provided for in the two policies, and therefore the two suits were consolidated for trial and remain so upon appeal.
Mrs. Rand purchased Tom F., Jr., then a weanling, in January 1956, for the sum of $38,000. On November 2, 1956, a veterinarian, Arthur H. Davidson, examined the yearling colt at the training farm of one Ward in Kentucky and found him to be sound and normal in all respects. The defendants then issued the policies sued upon, covering the period from November 3, 1956 to November 3, 1957, in the aggregate amount of $38,000. Among the conditions of the policies was the following:
“In event of any illness, lameness, accident, injury or physical disability whatsoever of an insured animal the Assured shall immediately give notice [to the insurers’ agent] * * by telephone or telegram * * * The Assured’s failure to report the illness, lameness, accident, injury or physical disability as above provided * * '* shall render Assured’s claim null and void and release Insurers [Underwriters] * * * from all liability in connection therewith.”
In January 1957, one W. W. Stephens, Mrs. Rand’s trainer, noticed a “weakness” or “slight catch” in the colt’s hindquarters. An X-ray taken January 29, 1957 indicated a fracture of the fibula of the left hind leg, a condition testified to as being “very common” in horses of Tom F., Jr.’s age. Soon the horse was walking normally again, but in early April, while at Belmont Park, New York, for racing, Stephens noticed a recurrence of the “catch,” and the horse, now a two-year-old, was shipped from Belmont back to the Ward farm in Kentucky where he could get “a good long rest” and could be looked at by Dr. Davidson. Between April and July Dr. Davidson noted that Tom F., Jr. improved but then his condition “remained static.” In late July Stephens was in Kentucky for yearling sales, and was told by Ward that the horse had improved to a point and “was kind of holding his own but wasn’t improving as much as we would like for him to have.” Stephens became concerned, because “we gave a lot of money for him.”
In the final days of August the fata! illness of his father again took Stephens to Kentucky. He was then told by Dr. Davidson that Tom F., Jr. was getting worse all the time and that the insurance people should be notified. Stephens then telephoned Mrs. Rand or her husband at Saratoga, N. Y., informed them of the situation, and told them to notify the insurers. The Rands, on September 4, did so. On or about October 30 the defendants denied liability on their policies on the sole ground that Mrs. Rand had failed to comply with the notice conditions contained therein. On November 2, 1957 (the day before the policies were to expire) Dr. Davidson destroyed the horse for humane reasons.
At the close of plaintiff’s case and again at the close of all the evidence, the defendants moved for directed verdicts. Decision thereon was reserved. The consolidated case was submitted to the jury, the defendants taking exceptions to a portion of the judge’s charge. The jury returned verdicts for plaintiff, defendants renewed their motion for directed verdicts, and further moved to set the verdicts aside. All of defendants’ motions were denied, judgments were entered on the verdicts, and the defendants appeal. Appellants claim that, as a matter of law, plaintiffs failed to “immediately give notice * * * by telephone or telegram” as required by the policies, and, therefore, that there was no issue of fact to go to the jury. Moreover, appellants argue that even if it were proper for the jury to determine whether the plaintiff under-the circumstances “immediately gave notice”-there was a portion of the court’s, charge to the jury, properly objected to by defendants, that was prejudicially erroneous. It is our view that the trial judge correctly submitted the question of whether the notice the plaintiffs gave complied with the notice provisions in the policies; but we agree with appel*345lants that the charge was prejudicial to them. Therefore, we reverse the judgments below and remand the cases for a new trial.
This is a diversity suit and so the substantive rights and liabilities of the parties are governed by New York law. Erie R. Co. v. Tompkins, 1938, 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188; see Auten v. Auten, 1954, 308 N.Y. 155, 124 N.E. 99, 50 A.L.R.2d 246; Zogg v. Pennsylvania Mutual Life Insurance Company, 2 Cir., 1960, 276 F.2d 861. The New York courts have construed the phrase “give immediate notice” when it has appeared in insurance policies setting forth requirements that a notice of a loss or of a changed condition must quickly be relayed to the insurer. We are required to follow that construction unless there is a justification for not doing so, and we do not discover any justifiable reason for departing frofii the New York precedents.
When interpreting “immediate notice” the New York courts have consistently applied a so-called rule of “reasonableness” by which to define the time when the insured must give the insurer a notice of a loss or of a changed condition (as an accident) if the contract of insurance is not to be made void for delayed notice. They have held that “immediate notice” means “notice within a reasonable time under all the circumstances.” Greenwich Bank v. Hartford Fire Ins. Co., 1928, 250 N.Y. 116, 164 N.E. 876; Melcher v. Ocean Accident & Guarantee Corp., 1919, 226 N.Y. 51, 123 N.E. 81; Woolverton v. Fidelity & Casualty Co., 1908, 190 N.Y. 41, 82 N.E.2d 745, 16 L.R.A.,N.S., 400; Solomon v. Continental Fire Ins. Co., 1899, 160 N.Y. 595, 55 N.E. 279, 46 L.R.A. 682; Matthews v. American Central Ins. Co., 1897, 154 N.Y. 449, 48 N.E. 751, 39 L.R.A. 433; Reina v. United States Casualty Co., 1st Dept.1930, 228 App.Div. 108, 239 N.Y.S. 196; Keegan v. Excess Ins. Co. of America, 1952, 202 Misc. 126, 116 N.Y.S.2d 687.
Therefore, at the threshold of our consideration of whether the motions for the directed verdict should have been granted we must decide if here “immediately give notice” means “give reasonably immediate notice under the circumstances.” We are unwilling to depart from New York’s “reasonableness” rule and are unwilling to adopt a stricter standard of interpretation for federal courts to apply when adjudicating upon claims arising from livestock policies. We realize that there are jurisdictions outside of New York that strictly interpret the notice provisions in livestock policies. See Hough v. Kaskaskia Live Stock Ins. Co., 1923, 230 Ill.App. 341; Green Bros. v. Northwestern Live Stock Ins. Co., 1893, 87 Iowa 358, 54 N.W. 349. However, New York apparently applies a “reasonableness” standard when interpreting all insurance notice clauses and, though the New York decisions are found in suits arising out of actions brought upon fire and accident indemnity policies, there is no reason why the same standard should not apply to livestock policies. In Zauderer v. Continental Casualty Co., 2 Cir., 1944, 140 F.2d 211, we applied New York’s rule of reasonableness to an automobile liability policy, and in reaching that result we relied on New York cases involving both fire insurance and liability insurance undistinguishably.
The New York courts, likewise, have not applied one standard to one type of policy and another standard to a different type. In Solomon v. Continental Fire Ins. Co., 1899, 160 N.Y. 595, 55 N.E. 279, 280, 46 L.R.A. 682, involving fire insurance, the Court of Appeals stated, “immediate notice is notice within a reasonable time.” In Melcher v. Ocean Accident & Guarantee Corp., 1919, 226 N.Y. 51, 56, 123 N.E. 81, 82, it stated that “it is not every trivial mishap or occurrence that the assured under such a policy of liability insurance must regard as an accident of which notice should be given immediately to the insurance company, even though it may prove afterwards to result in serious injury.” In Reina v. United States Casualty Co., 1st Dept. 1930, 228 App.Div. 108, 239 N.Y.S. 196, 197, the Appellate Division of the New *346York Supreme Court, First Department, declared that an “ ‘Immediate notice,’ under this clause, is notice within a reasonable time under all the circumstances.” (Citing cases.) And in Deso v. London & Lancashire Indem. Co., 1957, 8 N.Y.2d 127, 130, 164 N.Y.S.2d 689, 692, 143 N.E.2d 889, 891, the Court of Appeals said that “the Melcher case is authority for the proposition that ignorance of the fact that injury has resulted from an accident may excuse a delay in giving notice.”
Similarly, a textbook writer finds no distinction justifying a different interpretation of the phrase in different types and kinds of policies. In his Handbook on the Law of Insurance (3d ed. 1951), Vance points out at p. 893: “Notice of loss is held to be ‘immediate,’ within the requirement of the standard policy, when it is given as soon after the fire as is reasonably possible under existing circumstances, in the exercise of due diligence.” And at p. 1001, in the chapter on liability insurance, he states: “The assured is usually required by the terms of the policy to give immediate notice or notice as soon as practicable to the liability insurer of any accident which may result in a claim under the policy. These and like expressions will be construed to mean notice within a reasonable time, and not necessarily notice immediately after the accident.”1
There are distinct practical advantages in applying the New York standard of “reasonableness” to the “immediate notice” phrase. Strict interpretation could result in permitting no leeway for the exercise of judgment in the light of common experience. The New York courts are committed to the doctrine that the “reasonableness” standard is just to insured and insurer, and we believe that the New York courts would interpret the “immediate notice” required by these policies to mean “reasonably immediate notice under the circumstances.”
There now remains the question of whether the decision as to the reasonableness of the notice that was given here should have been decided by the court or was properly submitted to the jury. Although we may not be bound by the law of New York on this issue, inasmuch as the question is not one of substantive law, Zauderer v. .Continental Cas. Co., 2 Cir., 140 F.2d 211, 214, we hold that submission of the issue to the jury was not improper under the circumstances present here. Cf. Byrd v. Blue Ridge Rural Electric Cooperative, 1958, 356 U.S. 525, 527, 78 S.Ct. 893, 2 L.Ed.2d 953. •
In Greenwich Bank v. Hartford Fire Ins. Co., 250 N.Y. 116, at page 131, 164 N.E. 876, at page 881, the Court of Appeals summarized as follows: “The rule has been repeatedly stated that a reasonable time, when the facts are undisputed and different inferences cannot reasonably be drawn from the facts, is a question of law.” (Citing cases.) “This is one of those general rules, however, which is sometimes difficult of application, and results in the question being left to a jury when it is near the border line. Carpenter v. German American Ins. Co., 135 N.Y. 298, 303, 31 N.E. 1015.” See Empire State Surety Co. v. Northwest Lumber Co., 9 Cir., 1913, 203 F. 417. Therefore, in New York, when dissimilar inferences may be drawn from undisputed facts, or when the facts are in dispute, “reasonableness” is a jury question. “It is also well settled that the reasonableness of a delay, where mitigating circumstances such as absence from the State or lack of knowledge of the occurrence or its seriousness are offered as an excuse, is usually for the jury.” Deso v. London & Lancashire Indem. Co., 1957, 3 N.Y.2d 127, 129, 164 N.Y.S.2d 689, 691, 143 N.E.2d 889, 890. See Gluck v. London & Lancashire Indem. Co. of America, 2 N.Y.2d 953, 162 N.Y.S.2d 357, 142 N.E.2d 423; West Virginia Pulp & *347Paper Co. v. Merchants Mut. Ins. Co., 3rd Dept.1960, 10 A.D.2d 451, 201 N.Y.S.2d 314; Zurich Ins. Co. v. Maritez, 1960, 24 Misc.2d 437, 201 N.Y.S.2d 810.
The basic facts relative to the health of Tom F., Jr. that were presented at the trial squarely put in issue the question of whether the proverbial “reasonably prudent man” would have given notice to the insurers of his condition under all the circumstances at any earlier date than September 4, 1957. Certainly the facts are subject to more than one interpretive inference. Under such circumstances the question was properly one for the jury. See American Mutual Liability Ins. Co. v. McFarlane Fire Prevention Corp., D.C.E.D.N.Y.1958, 162 F.Supp. 915. Therefore the motions for directed verdicts were properly denied.
We turn now to a consideration of whether the cases should be remanded for a new trial because of the claim that a portion of the charge was prejudicial to the defendants, and, if prejudicial to them, whether the defendants properly saved the question for review.
Rule 51 of the Federal Rules of Civil Procedure, 28 U.S.C.A., states that:
“ * * * No party may assign as error the giving or the failure to give an instruction unless he objects thereto before the jury retires to consider its verdict, stating distinctly the matter to which he objects and the grounds of his objection. * * ”
Thus in order for us to review a portion of the trial court’s charge to the jury, we must first determine whether a proper objection was taken pursuant to Rule 51. The purpose of this rule, as we stated in Troupe v. Chicago, D. & G. Bay Transit Co., 2 Cir., 1956, 234 F.2d 253, 259:
“ * * * is to expedite the administration of justice by insuring that the trial judge is informed of possible errors so that he may have an opportunity to reconsider his charge, and, if necessary, to correct it.”
The trial judge charged the jury that:
“What factors should you consider in determining whether, under these facts, the Rands gave notice of the serious ailment to the insurance companies within a reasonable time under all the circumstances which was required by these insurance policies ? One of the factors, of course, is when the Rands knew or should have been reasonably expected to know of such condition because, until such knowledge came to their attention, or should reasonably have come to their attention, they could not have been expected or required to give such notice. There might well be a condition of the horse, for example, which nobody would know about and which only became apparent at point X and, until such condition was known to the insured, of course no notice is required.” (Emphasis supplied.)
After the charge had been completed and before the'jury had retired defendants’ counsel stated;
“Your Honor, may we note one exception? You explained the factors that the jury was to take into consideration. The two factors which you stated were, one, when the Rands knew or would be reasonably expected to know of a condition and, two, the condition was to be of a certain type.”
There was then discussion off the record, and the court then stated:
“The defendant takes exception to a sentence which reads that there might well be a condition, et cetera, about point X.
“The defendant may have an exception if it wishes. However, in my view, the sentence, read in context, makes it entirely clear to the jury that the ailment we are talking about is the type of ailment that was defined by the Court and that notice to the insured includes, of course, notice to the insured’s agent, as I repeated three or four times, and I *348will not charge any further on that.” (Emphasis supplied.)
From this language it is evident that the court was referring to his statement to the jury that the first question they were to decide was: “When was the horse found to be suffering from a serious ailment?” and to that portion of his charge reading as follows:
“As you will recall from my reading of the clause,2 it refers to any illness, lameness, accident, injury or physical disability whatsoever of an insured animal. Now, if this were to be taken literally, any indisposition of the animal, no matter how slight or trivial, would require notice to be given to the insurance company. However, the law does not interpret this language literally. It is not construed that way. If, for example, take almost a ridiculous example, an animal gets a small cut or a scratch or a bruise, plainly the owner is not required to give notice to the insurance company under this clause, and this is so even if, because of unforeseen circumstances, the incident, mishap or occurrence may turn out to be much more serious than one would reasonably expect at the time. You don’t have to report to the insurance company every time the horse sneezes.
“On the other hand, this clause in the policy has meaning and is part of the contract between the parties. As these terms are used in the policy they mean an ailment — and I use an ailment in essence to cover all of them — of such a character as to affect the general soundness and health of the animal and not a mere temporary indisposition which does not tend to undermine or weaken the animal’s constitution.
“This does not mean that the illness, accident or mishap must be such as would necessarily lead to the death of the animal. As I have pointed out, it must be of sufficient seriousness as would lead to the reasonable expectation that it would seriously affect the animal’s health or constitution.”
The colloquy between the court and defendants’ counsel at the time the exception was taken demonstrates that counsel was objecting to the instruction that the insured’s duty to give notice arose only when the horse began to suffer from a “serious ailment.” The colloquy also demonstrates that the court understood counsel’s position. Hence we hold that, despite appellee’s claim to the contrary, appellants’ exception to the charge as given was properly preserved.
The court overfavored the plaintiff by instructing the jury to ascertain the time when the horse was found to be suffering from a serious ailment and by constantly reiterating that a showing that the horse’s health was seriously affected was a prerequisite to the giving of immediate notice of the horse’s condition. It is not the insured’s opinion of what is or is not a serious ailment that determines when notice must be given under the policy, for the policy says nothing about serious or non-serious lamenesses. Despite the existence of the “reasonableness” rule as a matter of substantive law in New York, the courts in applying it should not rewrite the insurance contract entered into by the parties. All the circumstances of the situation that gave rise to the suits and that tended to support defenses to them, not merely the one disputed circumstance of the time of plaintiff’s first knowledge of the seriousness of the animal’s ailment, were before the jury; and the jury question was whether, under all these circumstances, the notice the plaintiff gave was a reasonable compliance with the notice requirements of the policies. For instance, the nature of the *349animal’s initial ailment and the undisputed facts with reference to the animal’s subsequent history, as well as the nature of the insurance policies and the language of the insuring agreements therein contained, bore upon this question. The stress the court placed upon seriousness of ailment may well have influenced the jury deliberations to the prejudice of the defendants.
Reversed and remanded for a new trial.
. For further cases demonstrating the validity of the New York position see discussion in 45 C.J.S. Insurance § 1054; Notes in 76 A.L.R. at page 53, and 123 A.L.R. at page 959; and see discussion in Vance, Handbook on the Law of Insurance, p. 895.
. (Our footnote)
The provision in the policies that reads:
“In the event of any illness, lameness, accident, injury or physical disability whatsoever of an assured animal, the assurcd shall immediately give notice to the insurer or its agent by telephone or telegram, who will instruct the veterinarian surgeon on insurer’s behalf if deemed necessary.”