WO2000074669A1

WO2000074669A1 - Methods for improving the functional status of sperm

Info

Publication number: WO2000074669A1
Application number: PCT/US2000/040145
Authority: WO
Inventors: William R. Barclay; Andrea Lacorte; Morani Amos
Original assignee: Omegatech Inc.
Priority date: 1999-06-07
Filing date: 2000-06-07
Publication date: 2000-12-14
Also published as: AU5791400A

Abstract

Methods for enhancing the functional quality of sperm in semen are provided that include feeding a male animal a source of omega-3 highly unsaturated fatty acid and/or omega-6 highly unsaturated fatty acid. The preferred omega-3 fatty acid is DHA. The preferred omega-6 fatty acids are ARA, DPA and/or C22:4(N-6).

Description

METHODS FOR IMPROVING THE FUNCTIONAL STATUS OF SPERM

Field of the Invention The invention generally relates to methods of improving the fertility of male animals by enhancing the functional characteristics of their sperm by feeding omega-3 and omega-6 highly unsaturated fatty acids to the male animals.

Background of the Invention The sperm of animals (including humans) contains large amounts of highly unsaturated fatty acids (HUFA). HUFAs are fatty acids with four or more double bonds.

Each group of animals has differing ratios of the long chain omega-3 fatty acid,

C22:6(n-3) (DHA), and the long chain omega-6 fatty acids, C20:4(n-6) (ARA),

C22:4(n-6) and C22:5(n-6) (DP A). For example, as described by Poluos et al. (1973) and Darin-Bennett et al. (1977) the phospholipids of the sperm of bulls, boars, rams, rabbits, monkeys and humans contain the following primary HUFAs (as % total fatty acids):

20:4(n-6) 22:4(n-6) 22:5(n -6) 22:6(n-3)

Bull 4 ~ 61

Boar 3 28 38

Ram 5 trace 61

Rabbit - 39 —

Monkey 9 3 25

Human 5 35

Additionally, the phospholipids of the sperm of rats are rich in C22:5(n-6) while that of roosters are rich in C22:4(n-6) (Kelso et al. 1996; Rettersol et al. 1998). Recognizing the high omega-3 fatty acid content of sperm, Japanese Patent No. 1294649 describes the extraction of docosapentaenoic (sic) acid (DHA) and eicosapentaenoic acid (EPA) from the testicles of walleye pollack.

Work done by NURTURE (Nottingham University Research and Treatment Unit in REproduction) is directed to fats and sperm. A research note authored by Paul Maynard (placed on the Internet as www.nott.ac.uk on 7 May, 1998 ) discusses the presence of DHA in the testis and in sperm. It is noted that "Quite what this fatty acid is doing in any of these tissues, and particularly in the sperm, is not clear." However it is further noted that in semen samples which contain small numbers of sperm there is often a significantly lower proportion of DHA.

The long chain HUFAs have generally been recognized as important fatty acids both structurally (forming membranes) and functionally (serving as precursors to eicosanoids). In one important structural function, the long chain omega-3 fatty acids are thought to help marine microorganisms and animals maintain membrane fluidity at the low temperatures found in some regions of the marine environment.

It has been hypothesized that the maintenance of high fertility in male animals requires the combination of optimal phospholipid fatty acid composition together with an adequate amount of antioxidant protection for the polyunsaturated fatty acids (Kelso et al. 1997). For example, they demonstrated that the decline in the fertility of aging bulls (e.g., correlated with a decline in sperm concentration and motility)is associated with a large reduction in the C20:4(n-6) and C22:6(n-3) fatty acids in the phosphatidyl ethanolamine fraction of the bull sperm combined with a decrease in the C22:6(n-3) content of the phosphatidyl choline fraction of the sperm. They concluded that the lipid composition of sperm membranes may also play a key role in affecting a range of factors associated with male fertility including sperm membrane fluidity and permeability (Hammerstedt 1993), membrane fusion (Bearer & Friend 1982), leukotriene production (Oliw & Sprecher 1989), and signal transduction (Roldan & Harrison 1993). The functional characteristics of semen are an important consideration, not only in humans, but also in domestic animals. The value of semen from a prime breeding bull, boar, ram, stallion, rabbit or champion companion animal can be extremely high. Therefore, it is desirable to improve the functional characteristics of fresh sperm semen (e.g. number of sperm, viability, motility , etc.) or improve the functional characteristics of sperm that has been cryopreserved, for instance by improving the viability and post thaw sperm quality.

There has been a large amount of research in the area of freezing semen from animals, including humans. Frozen semen is especially important in breeding domestic animals such as cows, pigs, sheep and horses, as well as companion animals such as dogs and cats. Frozen sperm can also be used for breeding zoo animals and even wild animals

(e.g., catch and release animals). Semen can also be frozen for human fertility purposes. Therefore, a need exists for methods of improving the functional characteristics of semen. The present invention satisfies this need and provides related advantages.

Summary of the Invention The present invention relates to methods for enhancing the fertility of a male animal by improving at least one functional characteristic of sperm produced by the male animal. The methods are generally accomplished by administering to the male animal an omega-3 highly unsaturated fatty acid (HUFA, an omega-6 HUFA) or a combination of omega-3 HUFA and omega-6 HUFA in an amount effective to improve at least one functional characteristic of sperm.

The present invention further provides methods of enhancing the fertilization of an egg with sperm having at least one enhanced functional characteristic obtained by the above methods. The methods are accomplished by administering to a male animal an omega-3 HUFA, an omega-6 HUFA or a combination thereof in an amount effective to improve at least one functional characteristic of sperm and contacting the egg with the sperm. These methods can also include freezing and subsequently thawing the functionally improved sperm prior to contacting the egg for insemination of a female animal or collection for artificial insemination.

Preferably, the omega-3 HUFA used in the methods of the present invention is DHA. The amount of DHA administered to the male animal is preferably at least 2 mg

DHA/kg body weight/day, more preferably at least 10 mg DHA/kg body weight/day, and most preferably at least 30 mg DHA/kg body weight/day. Effective amounts of DHA is in the range of about 0.5 mg to about 100 mg DHA/kg body weight/day, particularly about 2 mg to about 50 mg DHA/kg body weight/day, and more particularly about 10 mg to about 30 mg DHA/kg body weight/day.

The preferred omega-6 fatty acids include ARA, DP A, C22:4(n-6) or a mixture thereof. The amount of omega-6 HUFA administered to the male animal is preferably at least 0.7 mg/kg body weight/day, more preferably at least 3 mg kg body weight/day, and most preferably at least 10 mg/kg body weight/day. A particularly effective amount of omega-6 HUFA is in the range of about 0.5 mg to about 20 mg/kg body weight/day, and more particularly about 0.7 mg to about 17 mg/kg body weight/day. Preferably, the male animal is administered a ratio of omega-3 HUFA to omega-6 HUFA from about 1 : 1 to about 20:1, more preferably about 1 : 1 to about 5: 1, even more preferably about 2: 1 to about 4: 1 and most preferably about 3: 1. Optionally, the ratio of omega-3 HUFA to omega-6 HUFA can be from about 1 : 1 to about 1 :20, more preferably about 1 : 1 to about 1 :5, even more preferably about 1 :2 to about 1 :4, and most preferably about 1 :3.

The omega-3 HUFA and omega-6 HUFA can be obtained from any source, including, for example, from an organism. The organism, such as algae or fungi for example, is preferably given to the animal in a whole cell form or alternatively as a lipid. Preferably, the organism is selected from the order Thraustochytriales, particularly

Schizochytrium sp. The lipid can be extracted from an animal, plant or microbial source known to contain the desired HUFA.

Male animals that can be given the omega fatty acids to improve their sperm functional characteristics include not only humans, but also any domestic, companion or wild animal. Domestic animals include, for example, bulls, boars, rams, stallions, rabbits and roosters. The functional characteristics that can be enhanced by the present methods include, but are not limited to, sperm concentration, total motility, progressive motility, sperm velocity, percent of anomalies in the acrosomes, percent total anomalies, percent cytoplasmic drops or post thaw sperm quality. The omega-3 and/or omega-6 HUFAs can be given to the male animals as a supplement to their normal diet and can be given, for example, in their feed or in a capsule form if taken orally. Preferably, the HUFAs are given to the male animal for at least fourteen (14) days, and more preferably at least twenty (20) days.

Detailed Description of the Invention

The present invention relates to the discovery that animals fed a source DHA(n-3) and DPA(n-6) produce sperm with improved functional characteristics that positively influence their fertility. In particular, it has been discovered that feeding male animals DHA(n-3) and long chain omega-6 fatty acids (e.g., DPA(n-6), ARA(n-6) and/or C22 :4(n-6)) improves one or more functional characteristics of the sperm and the semen that are contained therein. For example, it has been demonstrated that when a group of bulls (some with known fertility problems) are fed a combination of DHA(n-3) and DPA(n-6), they produce sperm with greater motility, and/or sperm with greater progressive motility, and/or sperm with fewer abnormalities.

As discussed above, suboptimal concentrations of HUFA in sperm can be the result of several factors including, but not limited to, imbalances in lipid metabolism in the animal or the result of aging processes (e.g., decline in elongation enzymes). It has now been found that several of these factors related to HUFAs and fertility can be improved by feeding a source of these long chain omega-6 and long chain omega-3 fatty acids to male animals. Accordingly, the present application relates to improving the functionality of sperm (both fresh and cryogenically stored sperm) by improving the long chain HUFA content and balance in sperm by providing animals with a direct dietary source of these HUFAs.

In a further embodiment, the present invention relates to methods of enhancing the fertilization of an egg in vivo or in vitro. In these methods, a male animal is first administered a combination of omega-3 and omega-6 HUFAs in an amount effective to improve the functional characteristics of sperm produced by the male. Sperm from the male is then contacted with the egg to be fertilized. Optionally, the sperm can be collected from the male, frozen and subsequently thawed according to procedures known to those skilled in the art prior to contacting the sperm with the egg.

The ability of sperm to be successfully cryopreserved can be enhanced by increasing or improving the long chain HUFA content of the sperm prior to freezing.

Omega-3 and omega-6 highly unsaturated fatty acids could contribute to two distinct factors which are important in the cryopreservation of sperm: (1) protection against cold shock; and (2) maintenance of viability.

In the methods of the present invention, the effective amounts of the omega-3 and omega-6 HUFAs to improve the desired functional characteristics of sperm can be readily determined by those skilled in the art using the guidance provided herein. Such amounts can be administered to a male animal by any means known to those skilled in the art, including, for example, feeding such amounts to the animal or otherwise ingesting the HUFAs as well as by infusion or injection. A particularly useful omega-3 HUFA is DHA, which is preferably given in a range from about 0.5 mg to about 100 mg DHA/kg body weight/day, more preferably about 2 mg to about 50 mg DHA/kg body weight/day, and most preferably about 10 mg to about 30 mg DHA/kg body weight/day. Preferably, DHA is fed in an amount greater than about 2 mg/kg body weight/day. Greater amounts of DHA can be fed to a male animal, including greater than about 10 mg/kg body weight/day and greater than about 30 mg/kg body weight/day. Particularly useful omega-6 HUFAs in the present methods include ARA, DPA,

C22:4(n-6) or a mixture thereof, which includes any combination of these omega-6 fatty acids. The amount of omega-6 HUFA fed to the male animal is preferably at least 0.7 mg/kg body weight/day, more preferably at least 3 mg/kg body weight/day, and most preferably at least 10 mg/kg body weight/day. A particularly effective amount of omega- 6 HUFA is in the range of about 0.5 mg to about 20 mg/kg body weight/day, and more particularly about 0J mg to about 17 mg/kg body weight/day.

The reasons for preferably supplying the long chain omega-6 fatty acid in the form of DPA(n-6) are as follows: (1) this is the direct form of omega-6 fatty acid found in many types of sperm; (2) DPA (n-6) can readily retroconvert in animals and man to form the other forms of long chain omega-6 fatty acids found in sperm (e.g. C22:4(n-6) and C20:4(n-6)) (Stoffel et al. (1970); Kunau (1971); Mann et al. (1986); Haagve and Christopherson (1986)); and (3) DPA(n-6) is not the eicosanoid active form of the long chain omega-6 series and could preferentially be incorporated into sperm membranes rather than immediately metabolized to eicosanoids (later to be utilized by the sperm for structural, energy or eicosanoid purposes/production. Similarly, DHA(n-3) is the preferred form of omega-3 HUFA because: (1) this is the direct form of omega-3 fatty acid found in many types of sperm; and (2) DHA(n-3) can readily retroconvert in animals to form the other forms of n-3 HUFA found in sperm (e.g. C20:5(n-3)) (Stoffel et al. (1970)). By supplying the longest chain form of each of these fatty acids, one can circumvent any metabolic problems the animals may have related to elongation of the

HUFAs from the shorter chain fatty acids, and allow the HUFAs to retroconvert if needed.

Although those skilled in the art can readily determine an appropriate ratio of omega-3 to omega-6 HUFAs, preferably, the male animal is fed a ratio of omega-3 HUFA to omega-6 HUFA from about 1:1 to about 20:1, more preferably about 1:1 to about 5:1, more preferably about 2:1 to about 4:1, and most preferably about 3:1. Optionally, the ratio of omega-3 HUFA to omega-6 HUFA can be from about 1 : 1 to about 1:20, more preferably about 1:1 to about 1 :5, even more preferably about 1:2 to about 1 :4, and most preferably about 1:3. One skilled in the art can readily determine the appropriate ratio depending on the functional characteristic to be improved. In addition, fatty acid analysis of semen can be performed to determine if a deficiency in omega-3 HUFA or omega-6 HUFA exists and, if so, the diet of the male animal can be supplemented with the appropriate form of fatty acid.

Although any source for the omega-3 and omega-6 fatty acids is contemplated herein, including for example chemical synthesis or genetically modified organisms, an especially desirable source for the omega-3 and omega-6 fatty acids is using organisms which naturally contain these fatty acids. Preferably, the organism is a microorganism such as fungi or algae which occurs naturally in soil, fresh water or marine and other saline environments and most preferably is of the order Thraustochytriales, particularly Schizochytrium sp. Preferably the organism is fed to the male animal in a whole cell form, although lysed cells may be used or extracted oils may be employed. Feeding in the whole-cell form is especially beneficial when fed to male ruminants as this form provides some natural protection to the long chain fatty acids in the rumen, protecting them from hydrogenation, and delivering more of the fatty acids for incorporation by the animal. It also makes these fatty acids more palatable to ruminants. For example, feeding them fish oil can cause them to go off feed, disturbing their growth and production. This problem is minimized with use of a whole cell microbial oil product.

If using extracted oils, the oil can be microencapsulated to improve stability and palatability of the oil.

Methods for culturing suitable microorganisms are disclosed in U.S. patent applications entitled "MILK PRODUCTS CONTAINING HIGH CONCENTRATIONS OF OMEGA-3 HIGHLY UNSATURATED FATTY ACIDS", U.S. Patent No.5,698,244 issued December 16, 1997 and "A METHOD GROWING MARINE MICROORGANISMS IN A FERMENTER WITH A LOW CHLORIDE CULTURE MEDIUM", U.S. Patent No. 5,688,500, issued November 18, 1997, both of which are incorporated herein by reference in their entirety. The functional characteristics that can be enhanced by the present methods include, but are not limited to, sperm concentration, total motility, progressive motility, sperm velocity, percent of anomalies in the acrosomes, percent total anomalies, percent cytoplasmic drops or post thaw sperm quality.

In a preferred embodiment, the omega-3 HUFA and/or omega-6 HUFA can be fed to the male animals as a supplement to their normal diet. A normal diet is determined by the diet of an average animal of the same species in a particular geographical location.

Although those skilled in the art can readily determine an appropriate dosage schedule to achieve the desired functional improvement, preferably, the omega-3 HUFA and/or omega-6 HUFA can be given to the male animal for at least fourteen (14) days, and more preferably at least twenty (20) days prior to insemination or collection.

The following examples are intended to illustrate, but not limit, the present invention.

EXAMPLE 1 Eight bulls (some with known fertility problems) were each fed 250 g/day drum dried Schizochytrium sp. containing approximately 14% DHA(n-3) and 5% DPA(n-6) as % dry weight for periods of 25 to 52 days. Semen was collected from the bulls before the start of supplementation and at the end of the supplementation period. The sperm were analyzed for a number of functional parameters including total motility, progressive motility, sperm velocity, % of anomalies in the acrosomes, % total anomalies, and % cytoplasmic drops. The results indicated the following:

50% of the bulls produced sperm with a higher motility ~ there was an average

13% increase in total sperm motility in the bulls exhibiting an improvement in this factor. 50% of the bulls produced sperm with a higher progressive motility ~ there was an average 12% increase in sperm progressive motility in the bulls exhibiting an improvement in this factor.

63% of the bulls exhibited a decrease in total anomalies in their sperm ~ there was an average 26% decrease in total anomalies in the sperm in the bulls exhibiting an improvement in this factor. Overall, 8 out of 8 bulls exhibited an improvement in at least 2 of the 6 functional characteristics measured and 7 out of 8 bulls exhibited an improvement in 3 of the 6 functional characteristics measured.

EXAMPLE 2

A normal bull was fed drum dried Schizochytrium sp. microalgae at a concentration providing 50 mg DHA(n-3)/kg body weight/day and approximately 17 mg/kg body weight/day of DPA(n-6). Supplementation of the bull with the DHA-rich microalgae was conducted for approximately 20 days in early July and then as supplementation continued, sperm was collected from the bull for approximately 60 days and utilized to artificially inseminate cows. In July and August, the cryopreserved sperm of the bull exhibited better fertilization of cows (300 cows on 20 farms) on the first insemination compared to cryopreserved sperm from control bulls. The semen of the bull was 25-27% successful on first insemination compared to an average of only 13- 15% on first insemination for the control bulls.

Those skilled in the art will appreciate that numerous changes and modifications may be made to the preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. It is therefore intended that the appended claims cover all such equivalent variations as fall within the true spirit and scope of the invention.

References

Bearer, E & Friend, O. (1982). Modifications of anionic-lipid domains preceding membrane fusion in guinea-pig spermatozoa. Journal of Cell biology 92:604-615. Darin-Bennett, A, White, I & Hoskins, D (1977). Phospholipids and phospholipid-bound fatty acids and aldehydes of spermatozoa and seminal plasma of rhesus monkeys. J. Reprod. Fert. 49:1199-122.

Haagve, T. & Christopherson, B. (1986). Evidence for perixosomal retroconversion of adrenic acid (22:4(n-6)) and docosahexaenoic acids (22:6(n-3) in isolated liver cells. Biochemica et Biophysica Acta 6:165-173. Hammerstedt, R (1993). Maintenance of bioenergetic balance in sperm and prevention of lipid peroxidation: a review of the effect on design of storage preservation systems. Reproduction, Fertility and Development 5:675-690.

Kelso, K, Cerolini, S, Nobel, R, Sparks, N & Speake, B. (1996). Lipid and antioxidant changes in semen of broiler fowl from 25 to 60 weeks of age. Journal of

Reproduction and Fertility 106:201-206.

Kunau, W (1971). Studies on the partial degradation of polyunsaturated fatty acids in subcellular fractions of rat liver. Hoppe-Seylers Z. Physiol. Chem. 352:1297-1305. Mann, C, Kaduce, T, Figard, P & Spector A. (1986). Docosatetraenoic acid in endothelial cells; formation, retroconversion to arachidonic acid and effect on prostacyclin production. Archives of Biochemistry and Biophysics 244:813-823.

Maynard, P. (1998). Research Interests: Fats and Sperm. Nuture Internet Web Page, May 7, 1998. Oliw, E & Sprecher, H. (1989). Metabolism of polyunsaturated fatty acids by a

(n-6) lipoxygenase associated with human ejaculates. Biochemica et Biophysica Acta 1002:283-291.

Poluos, A, Darin-Bennett, A & White, I. (1973). The phospholipid-bound fatty acids and aldehydes of mammalian spermatozoa. Comp. Biochem. Physiol. 46B:541-549.

Rettersol, K, Haugen, T, Woldseth, B & Christophersen, B. (1998). A comparative study of the metabolism of the n-9, n-6 and n-3 fatty acids in testicular cells from immature rat. Biochimica et Biophysica Acta 1392:59-72.

Roldan, E & Harrison, R. (1993). Diacylglycerol in the exocytosis of the mammalian sperm acrosome. Biochemical Society Transactions 21:284-289.

Stoffel, W, Ecker, WQ, Assad, H & Sprecher, H. (1970). Enzymatic studies on the mechanism of the retroconversion of C₂₂-polyenoic fatty acids to their C₂₀-homologues. Hoppe Seylers Z. Physiol Chem. 351:1545-1554.

Claims

WHAT IS CLAIMED:

1. A method for enhancing the fertility of a male animal by improving at least one functional characteristic of sperm produced by the male animal comprising administering to the male animal an omega-3 highly unsaturated fatty acid (HUFA), an omega-6 HUFA, or a combination thereof in an amount effective to improve at least one functional characteristic of the sperm.

2. The method of claim 1 , wherein an omega-3 HUFA is administered to the male animal.

3. The method of claim 1 , wherein an omega-6 HUFA is administered to the male animal.

4. The method of claim 1, wherein a combination of omega-3 HUFA and omega-6 HUFA is administered to the male animal.

5. A method of enhancing the fertilization of an egg comprising:

(a) administering to a male animal an omega-3 HUFA, an omega-6 HUFA, or a combination thereof in an amount effective to improve at least one functional characteristic of sperm produced by the male animal; and

(b) contacting the egg with the sperm having at least one improved functional characteristic.

6. A method of manufacturing a composition comprising an omega-3 HUFA, an omega-6 HUFA or a combination thereof for use in feeding a male animal to enhance the fertility of the male animal by improving at least one functional characteristic of sperm produced by the male animal.

7. The method according to any of Claims 1 to 6, wherein said omega-3 HUFA comprises DHA.

8. The method according to any of Claims 1 to 7, wherein said omega-6

HUFA comprises ARA, DPA, C22:4(n-6) or a mixture thereof.

9. The method of Claim 7, wherein at least 2 mg DHA kg body weight is administered to said male per day.

10. The method of Claim 7, wherein at least 10 mg DHA/kg body weight is administered to said male per day.

11. The method of Claim 7, wherein at least 30 mg DHA/kg body weight is administered to said male per day.

12. The method of claim 7, wherein from about 2 mg to about 50 mg DHA/kg body weight is administered to said male per day.

13. The method of Claim 8, wherein at least 0.7 mg/kg body weight of omega-6 HUFA is administered to said male per day.

14. The method of Claim 8, wherein at least 3 mg/kg body weight of omega-6

HUFA is administered to said male per day.

15. The method of Claim 8, wherein at least 10 mg/kg body weight of omega-6 HUFA is administered to said male per day.

16. The method of claim 8, wherein from about 0J mg to about 17 mg/kg body weight of omega-6 HUFA is administered to said male per day.

17. The method according to any of Claims 1 to 16, wherein the ratio of omega-3 HUFA to omega-6 HUFA is from about 1 :20 to about 20: 1.

18. The method according to any of Claims 1 to 16, wherein the ratio of omega-3 HUFA to omega-6 HUFA is from about 1:5 to about 5:1.

19. The method according to any of Claims 1 to 18, wherein a source of omega-3 HUFA or omega-6 HUFA is an organism.

20. The method of Claim 19, wherein said organism is administered to said male in a whole cell form.

21. The method of claim 19, wherein said organism is algae.

22. The method of claim 19, wherein said organism is a fungus.

23. The method of Claim 19, wherein said organism is selected from the order Thraustochytriales.

24. The method of claim 19, wherein said organism is Schizochytrium sp.

25. The method according to any of Claims 1 to 18, wherein said source of omega-3 HUFA and omega-6 HUFA is a lipid.

26. The method of Claim 25, wherein said lipid is extracted from an animal, plant or microbial source.

27. The method of Claim 25, wherein said lipid is extracted from an organism of the order Thraustochytriales.

28. The method of claim 25, wherein said lipid is extracted from

Schizochytrium sp.

29. The method according to any of Claims 1 to 28, wherein said male is selected from the group consisting of bulls, boars, rams, stallions, roosters, rabbits and humans.

30. The method according to any of Claims 1 to 28, wherein said male is a male domestic animal.

31. The method according to any of Claims 1 to 28, wherein said male is a male companion animal.

32. The method of claim 29, wherein said male is human.

33. The method of claim 5, further comprising the step of freezing and subsequently thawing said sperm prior to use in the fertilization of the egg.

34. The method according to any of Claims 1 to 33, wherein said functional characteristic of said sperm is selected from sperm concentration, total motility, progressive motility, sperm velocity, percent of anomalies in the acrosomes, percent total anomalies, percent cytoplasmic drops or post thaw sperm quality.

35. The method according to any of Claims 1 to 34, wherein the male animal is administered omega-3 HUFA, omega-6 HUFA or a combination thereof as a supplement to a normal diet of the male animal.

36. The method according to any of Claims 1 to 35, wherein the omega-3 HUFA, omega-6 HUFA or the combination thereof is administered to the animal for at least fourteen (14) days.

37. The method of claim 36, wherein the omega-3 HUFA, the omega-6 HUFA or the combination thereof is administered to the male animal for at least twenty (20) days.

38. The method according to any of claims 1 -37, wherein the method further comprises the step of identifying a deficiency in a functional characteristic of said sperm prior to administering the omega-3 HUFA, the omega-6 HUFA or the combination thereof to the male animal.