Vaginal deposition of frozen-thawed semen in Norwegian Dairy goats: comparison of single and double insemination with equal total number of spermatozoa.

In a field trial, a total of 472 Norwegian Dairy goats showing natural estrus were artificially inseminated with frozen-thawed semen. The farmers themselves performed vaginal deposition of 400 x 10(6) spermatozoa; one half of the does received two straws (200 x 10(6) spermatozoa/straw) at the same time (single AI), while the other half received two straws (200 x 10(6) spermatozoa/straw) 12 h apart (double AI). The commercially available extender Andromed was used for dilution. The does were housed at 15 different farms, and on average 31 does were inseminated per farm. Non return rates (NRR) and kidding rates after single insemination were 64.3% and 58.3%, respectively. Double inseminations resulted in a NRR of 62% and a kidding rate of 57%. No significant difference between single and double AI was seen in the study. This study indicates that single or double vaginal insemination with an equal total number of frozen-thawed spermatozoa (400 x 10(6)) can give acceptable fertility results in Norwegian Dairy goats. However, studies on reducing sperm numbers are called for to allow AI donor bucks to be used to their fullest potential.