Two experiments were conducted to determine the effect of insemination time on number of accessory sperm per embryo (ovum), fertilization rate, and embryo quality. Semen was collected from three fertile Holstein bulls and cryopreserved in egg yolk- @entity1792 - @entity653 . In experiment 1, @entity291 were continuously monitored for behavioral estrus by the HeatWatch estrous detection system and were @entity16406 ( @entity16406 ) with one 0.5-ml straw (25 x 10(6) sperm) at the onset of estrus ( @entity16406 0 h), 12 h after onset ( @entity16406 12 h), or received natural service at 0 h (Nat 0 h) from one of three bulls. From 150 inseminations, 115 embryos and ova ( @entity16406 0 h: n = 39; @entity16406 12 h: n = 39; Nat 0 h: n = 37) were recovered 6 or 7 d after insemination. Fertilization rates differed between treatments ( @entity16406 0 h: 67%; @entity16406 12 h: 79%; Nat 0 h: 98%). Median accessory sperm per embryo (ovum) also differed ( @entity16406 0 h: 1; @entity16406 12 h: 10; and Nat 0 h: 27) and paralleled the fertilization rate. Embryo quality was not affected by insemination time or natural service. In experiment 2, @entity291 received @entity16406 at 0, 12, or 24 h ( @entity16406 24 h) after the onset of estrus as determined by HeatWatch. From 154 inseminations, 117 embryos and ova ( @entity16406 0 h: n = 39; @entity16406 12 h: n = 39; @entity16406 24 h: n = 39) were recovered 6 or 7 d after insemination. Fertilization rates did not differ in experiment 2 ( @entity16406 0 h: 66%; @entity16406 12 h: 74%; @entity16406 24 h: 82%); however, a trend toward a higher fertilization rate accompanied @entity16406 24 h. Median accessory sperm values increased from @entity16406 0 h (1) to @entity16406 24 h (4). Embryo quality declined with @entity16406 at increasing intervals after onset of estrus, as percentages of excellent and good, fair and poor, and degenerate embryos were as follows: 77, 15, 8; 52, 38, 10; and 47, 19, 34 for the 0-, 12-, and 24-h inseminations, respectively. Results indicate @entity16406 12 h after the onset of estrus provides a compromise between potential fertilization failure ( @entity16406 0 h) and embryo failure ( @entity16406 24 h), despite increased accessory sperm per embryo (ovum) after @entity16406 24 h. Artificial insemination 12 h after onset of estrus should optimize fertility of dairy @entity291 through an acceptable fertilization rate, number of accessory sperm per embryo, and desirable embryo quality.

Effect of time of insemination on number of accessory sperm, fertilization rate, and embryo quality in nonlactating dairy XXXX .

@entity1792 :: ('MESH:D019343', 'Chemical') :: ['citrate'] @entity16406 :: ('MESH:D060437', 'Disease') :: ['artificially inseminated', 'AI'] @entity291 :: ('9913', 'Species') :: ['cows', 'cattle'] @entity653 :: ('MESH:D005990', 'Chemical') :: ['glycerol']
@entity291 :: (9913,Species) :: ['cattle']
