Synchronizing of animal oestrus and intra vaginal devices...

Details Synchronizing of animal oestrus and intra vaginal devices... Synchronizing of animal oestrus and intra vaginal devices...

2001-10-11

2003-12-16

Casler, Brian L. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S515000

Reexamination Certificate

active

06663608

ABSTRACT:

TECHNICAL FIELD
The present invention relates to improvements in and/or relating to the synchronising of animal oestrus and intra vaginal devices useful therein together with related means and methods.
BACKGROUND ART
It is useful for farmers to synchronise the oestrus of animals whether they be cattle beasts (whether for dairy or beef purposes) sheep, goats, horses, or the like where artificial insemination is practised. By way of example, in relation to cattle beasts, in a normal 365 day year 282 days on average is taken up of the year with the gestation period itself. With approximately 30 days to recover after delivery of its progeny each cow therefore has an average of only two and a half cycles if there is to be a timely management of the herd. Thus it is important over that remaining period of less than 53 days to ensure each cow in a herd becomes pregnant.
The traditional method of mating dairy cows with bulls is now largely superseded by the use of artificial insemination procedures which offer the prospect of rapid herd improvements although bulls are still presented to the herd frequently to catch those animals that have not conceived by the artificial insemination procedure.
There is therefore a great advantage attached to bringing such herd animals into oestrus simultaneously so as to make it easier to ensure effective usage of the artificial insemination procedure and subsequently to enable still within the “window” a further prospect of artificial insemination of those animals synchronistically brought to oestrus that have not already conceived.
Various means of achieving such a management of the synchronisation of the coming into oestrus of cows (whether heifers or lactating cows) and even sheep and goats has been disclosed in the art which includes the “EAZI-BREED CIDR Controlled Breeding and Reproductive Management” booklet made available to interested parties by InterAg a division of the applicant company in respect of its intra vaginal Eazi-Breed™ CIDR® product line.
The disclosures in the aforementioned publication, the full contents of which are here included by way of reference, comprehensively describe treatment protocols applicable at least to New Zealand herds of cattle beasts for synchronising oestrus and treatment of anoestrus.
These treatment protocols often utilise Eazi-Breed™ CIDR® devices in combination with drugs such as prostaglandin and/or oestradiol benzoate, and extend in general for periods of 7, 10 or 12 days.
If both control of the oestrus cycle and high fertility are to be optimised in cattle, studies have shown that an intra vaginal device must deliver sufficient progesterone (when used with combination drugs i.e. oestradiol or GnRH) to produce a minimum plasma progesterone concentration of 2 ng/mL over the terminal period of treatment (1, 2).
1. Kesner, J. S., Padmanabhan, V. and Convey, E. M. Biol. Reprod. 26 (1982) 571-578.
2. Kinder, J. E., Kojima, F. N., Bergfeld, E. G. M., Wehrman, M. E. and Fike, K. E. J. Anim. Sci 74 (1996) 1424-1440.
A cost factor arises in the adoption of such protocols as a farmer is faced with the costs of the intra vaginal progesterone containing device as well as the use of the combination drugs. This ignores also the economic cost of the artificial breeding materials themselves.
The intra vaginal progesterone containing devices hitherto used in New Zealand and to a large extent elsewhere are typified by the CIDR® product of the applicant company depicted hereinafter in
FIG. 1
being a variable geometry device for vaginal insertion and retention which comprises a structural frame of a metal or appropriate plastics material encased in a progesterone impregnated plastics material from which the material can leach in the vaginal environment and from which it can be timely withdrawn by appropriate means (e.g: a string, tail or a tool) to allow the animal to progress into oestrus shortly after the removal. Hereinafter the aforementioned device will be referred to by its registered trademark CIDR®.
Another product available in the market place of this kind is another variable geometry device and such a device is depicted hereinafter in FIG.
2
. Such a device is a helical coil capable of being helically tightened and which is retainable in its helical form in the animals vagina. The device includes a withdrawal cord and carries a gelatine capsule which includes oestradiol benzoate so that there can be co-administration of the progesterone to be released over a protracted period and the oestradiol benzoate which is to be released at a different rate. Such a device includes a progesterone impregnated plastics matrix about a helical spine. Such a device is available from Sanofi Animal Health Limited, PO Box 209, Rhodes Way, Watford, Herts, WD24QE, England under its registered trademark PRID®.
The aforementioned CIDR® and PRID® devices are manufactured in large volumes with the most expensive material being the progesterone active ingredient and thus small reductions in the progesterone inclusion in such devices will provide an economic advantage to a producer and to a farmer. Also any such reduction provides a reduced risk to the environment owing to a likely reduced residual amount of the progesterone in the matrix after the device has been withdrawn from an animal. This reduced residual amount not only provides safety but also dis-encourages the unrecommended reuse of a device in another animal where the unknown condition of such a device will give unpredictable results.
The CIDR® prior art device of the applicant company has been marketed with a silicone plastics matrix about its spine which contains about 1.9 grams of progesterone (USP) which drops to 1.33 grams still retained in the silicone matrix if the device is withdrawn after seven days. The same device drops to 1.05 grams of progesterone if it is not withdrawn until after 12 days.
The PRID® coil intra vaginal device contains at the outset 1.55 grams of progesterone which reduces down to 1.18 grams after 7 days and down to 0.94 grams after 10 days. The leach rate from the PRID® product may be affected in part by the inclusion of inorganic materials in the silicone plastics material such as calcium carbonate. The CIDR® silicone matrix is largely free of any such inclusions.
Hoechst U.S. Pat. No. 5,398,698 discloses the use of milled sheets of silicone rubber in intra-vaginal devices which carry progesterone. The milled sheets (2 to 10 mm thick) are vulcanised for from 4 to 8 minutes at from 70° C. to 120° C.
The accepted test for the delivery of progesterone or its metabolites to the appropriate site of action in order to postpone oestrus is by reference to the progesterone level in the blood plasma of the animal. The design of such devices has to date usually been on the basis of an acceptance of the Higuchi equation based on a square root of time model (see hereinafter) which suggests that progesterone inclusions in such a plastics matrix would achieve plasma levels which decline with time.
Our investigations have found surprisingly that it is inappropriate in the design of such intra vaginal devices to rely upon the Higuchi equation or the square root of time model. In our device release is constant with time up to 7 days resulting in constant steady state plasma levels over that time period.
We have determined that by modifying the levels of progesterone initially in a silicone matrix, by controlling the thickness of the silicone matrix over the spine and by giving attention to the surface area of the device savings to a manufacturer arising from reduced quantities of progesterone being needed while at the same time achieving the same blood levels can be achieved. Savings are also achieved over the prior art devices in terms of the amount of silicone used, since silicone is the second-most costly material used in the devices, with corresponding benefits being able to be passed on to the user.
The present invention relates to intra vaginal devices, methods of producing intra vaginal devices, and the use of such intra vaginal devices for managing oestr

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