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Preliminary experiment to induce superovulation in yak

M. Davaa,1 N. Altankhuag,2 Y. Zagdsuren,2 D. Badamdorj,2 A. Magash1 and B. Erdenebaatar2

1. National Yak Research Centre, State University of Agriculture, Zaisan, Ulaanbaatar-210153, Mongolia
2. Research Institute of Animal Husbandry, Zaisan, Ulaanbaatar-210153, Mongolia

Summary

Different hormonal treatments, including follicle-stimulating hormone (FSH) and pregnant mare serum gonadotropin (PMSG), were tested to induce superovulation in yak cows. During superovulation, the average numbers of follicles developed in the right and left ovaries of the cows ovulated were 5.36 ± 0.65 and 4.46 ± 0.43, respectively, and the numbers of ovulated eggs from the right and left ovaries were 2.55 ± 0.30 and 1.94 ± 0.2, respectively. Onset of donor's oestrus was detected on average, at 34.1 ± 0.52 hours after prostaglandin injection.

Keywords: Corpus luteum, follicles, superovulation, yak

Introduction

Studies have demonstrated that it is possible to produce multiple offspring from a highly productive female stock and this has been introduced into livestock breeding practices. The objective of superovulation in the female bovine animals is to obtain 6 to 8 transferable embryos from a highly productive donor. In Mongolia, embryo transfer has been successfully done in the Mongolian goat and Holstein cattle but only limited attempts have been made on the Mongolia native cattle and yak (Galragchaa 1993; Altankhuyag 1994; Begzjav 1995; Bulgaa 1996). This paper reports results of trials on superovulation of yak.

Materials and methods

Superovulation in yak cows was induced by the following hormonal preparations: FSH (Super OV Rom), PMSG (Folligon, Aukland), Anti-PMSG (Intervet), Progesterone (Sponge, controlled internal drug release (CIDR), Hamilton), and prostaglantin F-2 alpha (PGF2-a) (Lutalyse, Aukland; Prosolvin, Intervet).

The following combinations involving FSH preparation were investigated for induction of superovulation: 1) CIDR + Super OV + Lutalyse; 2) CIDR + Folligon + Lutalyse + anti-PMSG; and 3) CIDR + Folligon + Prosolvin.

Results and discussion

The outcomes of three treatments for superovulation were investigated by comparison of numbers of unovulated follicles and corpus luteum (Table 1). Comparison of the numbers of follicles in the ovaries from different treatments showed that there was no significant difference between the 1st and 2nd treatments. In the 3rd treatment, the number of follicles was less than those in the 1st two groups. Of all developed embryos 58.9% were found in the right ovary. The corpora lutea numbers in 1st two treatments were 4.8 and 5.0, respectively, but there were only 3.6 in the 3rd treatment.

Table 1. Effects of hormonal treatments.

Treatment

1

2

3

No. of cows

6

3

3

No. of follicles per cow

6.1 ± 0.6

6.0 ± 0.6

4.0 ± 0.6

Right ovary

3.5 ± 0.3

3.7 ± 0.3

2.3 ± 0.3

Left ovary

2.5 ± 0.3

2.3 ± 0.3

1.7 ± 0.3

No. of corpus lutea per cow

4.8 ± 0.3

5.0 ± 0.6

3.6 ± 0.3

Right ovary

3.0 ± 0.6

2.7 ± 0.3

2.0 ± 0.0

Left ovary

1.8 ± 0.3

2.3 ± 0.3

1.7 ± 0.3

Oestrus time after PGF2-a injection (hour)

34.7 ± 2.8

33.0 ± 1.2

34.7 ± 0.4

Superovulation was induced in all six donors of the 1st treatment by FSH and the average number of ovulated ova was 4.8. In the 2nd treatment with PMSG and anti-PMSG combination, 5.0 eggs were ovulated, on average, while in the 3rd treatment 3.6 ova were ovulated by PMSG. The right ovary shared 2.55 ± 0.3 of all ovulated ova. The corresponding figure was 1.94 ± 0.2 for the left one. The corpus lutea formed in the right ovary amounts to 57.1%; the remainder were formed in the left ovary.

The oestrus onset took place at 34.7 hours after PGF2-a injection in the 1st and 3rd treatment, while the onset was 33 hours in the 2nd treatment. Proctoscopic examination of the numbers of follicles and corpus luteum in the ovaries of three cows treated with FSH confirmed the results from rectal palpation. Morphological and qualitative evaluation of three embryos recovered from a donor revealed that two embryos out of the three embryos were transferable.

Acknowledgements

The authors are most grateful to Dr Dagviikhorol, Director of High Mountain Livestock Research Station, and J. Gombojav, senior researcher, for making animals available and for providing necessary support.

References

Altankhuyag N. 1994. Results of embryo transfer experiment in Mongolian goat. PhD thesis, Research Institute of Animal Husbandry, Ulaanbaatar, Mongolia. pp. 57.

Begzjav V. 1995. Possible bio-technical regulation of reproductive function in Mongolian native cattle species. PhD thesis, Research Institute of Animal Husbandry, Ulaanbaatar, Mongolia. pp. 1824.

Bulgaa T. 1996. Some factors influencing on oestrus synchronization and fertility of dairy and native Mongolian cattle. PhD thesis, Research Institute of Animal Husbandry, Ulaanbaatar, Mongolia. pp. 46.

Galragchaa P. 1993. Experimentation of bovine ET techniques in conditions of Mongolia. PhD thesis, Research Institute of Animal Husbandry, Mongolia. pp. 1012.

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