Growth of the conceptus in alpacas

P. Walter Bravo Centro Experimental La Raya, Universidad Nacional San Antonio Abad, Cusco, Peru.
Present address is Department of Animal and Veterinary Sciences, Brigham Young University, Provo, UT 84601.

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Mario M. Mayta Centro Experimental La Raya, Universidad Nacional San Antonio Abad, Cusco, Peru.

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Cesar A. Ordoñez Centro Experimental La Raya, Universidad Nacional San Antonio Abad, Cusco, Peru.

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Abstract

Objective—To determine growth of the alpaca conceptus during early gestation, using ultrasonography.

Animals—40 pregnant alpacas (20 multiparous, 20 nulliparous).

Procedure—Transrectal ultrasonography with a 5- MHz probe was performed 3 times weekly from days 7 through 45 after copulation (day of copulation = day 0). Blood samples were collected for progesterone assay on days of ultrasonography.

Results—Forty embryonic vesicles and embryos were identified and measured. Embryonic vesicles were first detected on day 12 after copulation and appeared spherical. Cumulative percentage of embryonic vesicles detected was 50, 82.5, and 100% on days 12, 14, and 16, respectively. Embryos were first detected by day 22 and heartbeats by day 24. Similarly, cumulative percentage of embryos detected was 17.5, 82.5 and 100% for 22, 24, and 26 days after copulation, respectively. Embryonic vesicles occupied both uterine horns beginning on day 19. A positive correlation existed between length and width of embryonic vesicles. Size of embryonic vesicles and embryos and progesterone concentrations did not differ between multiparous and nulliparous females. Five sets of twins were detected from days 21 through 33 after copulation, but the conceptus identified in the right uterine horn became nondetectable between days 28 and 33.

Conclusions and Clinical Relevance— Ultrasonography was useful in detecting the earliest appearance of alpaca embryonic vesicles and determining the changes in growth from days 12 through 45 after copulation. Embryos were first detected by day 22. Transrectal ultrasonography was not harmful to animals and did not provoke embryonic death in this study. (Am J Vet Res 2000;61:1508–1511)

Abstract

Objective—To determine growth of the alpaca conceptus during early gestation, using ultrasonography.

Animals—40 pregnant alpacas (20 multiparous, 20 nulliparous).

Procedure—Transrectal ultrasonography with a 5- MHz probe was performed 3 times weekly from days 7 through 45 after copulation (day of copulation = day 0). Blood samples were collected for progesterone assay on days of ultrasonography.

Results—Forty embryonic vesicles and embryos were identified and measured. Embryonic vesicles were first detected on day 12 after copulation and appeared spherical. Cumulative percentage of embryonic vesicles detected was 50, 82.5, and 100% on days 12, 14, and 16, respectively. Embryos were first detected by day 22 and heartbeats by day 24. Similarly, cumulative percentage of embryos detected was 17.5, 82.5 and 100% for 22, 24, and 26 days after copulation, respectively. Embryonic vesicles occupied both uterine horns beginning on day 19. A positive correlation existed between length and width of embryonic vesicles. Size of embryonic vesicles and embryos and progesterone concentrations did not differ between multiparous and nulliparous females. Five sets of twins were detected from days 21 through 33 after copulation, but the conceptus identified in the right uterine horn became nondetectable between days 28 and 33.

Conclusions and Clinical Relevance— Ultrasonography was useful in detecting the earliest appearance of alpaca embryonic vesicles and determining the changes in growth from days 12 through 45 after copulation. Embryos were first detected by day 22. Transrectal ultrasonography was not harmful to animals and did not provoke embryonic death in this study. (Am J Vet Res 2000;61:1508–1511)

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