RESUMO
Inseminated crossbred beef cows and heifers were used in 2 experiments to investigate embryo survival after prostaglandin-induced or spontaneous luteal regression. In Experiment 1, luteal regression was induced by an intramuscular (im) injection of cloprostenol (500 mug) on Day 15 (day of ovulation = Day 0). Progestagen was replaced 24 or 36 h later either by one-and-a-half Syncro-Mate-B (SMB) ear implants (9 mg of norgestomet) and norgestomet solution (2.25 mg, im) containing no estradiol in 1 replicate or by 2 SMB implants (12 mg of norgestomet) and progesterone (100 mg, im) in the second replicate. Combined for both replicates, the Day-24 pregnancy rate in an untreated control group (Group 1, 16/19; 84%) was higher (P < 0.01) than in the 24-h group (Group 2, 9/20; 45%), which also was higher (P < 0.02) than in the 36-h group (Group 3, 3/23; 13%). In Experiment 2, 15 or 16 d after breeding, cattle with a corpus luteum at least 16 x 16 mm were given either 2 SMB implants or no treatment. At 24 to 26 d after breeding, pregnancy rates (48/65, 74% versus 49/68, 72%) were not significantly different, and all but 1 of the pregnant progestagen-supplemented cattle had a functional corpus luteum.
RESUMO
Ejaculates were collected from 17 dogs. After initial evaluation the ejaculates were split into four equal aliquots and diluted with either Triladyl, Pipes, IMV Universal or Tris-fructose-citric acid extender, all containing egg yolk and glycerol. The extended semen was frozen in 0.5 ml straws at a slow, intermediate or fast freezing rate. After thawing, the percentage of progressively motile spermatozoa and the velocity of forward motion was evaluated. There was no difference between the extenders with regard to progressive motility. The slow, intermediate and fast freezing rates resulted in the highest, intermediate and lowest motility values, respectively, regardless of extender. All four extenders were equally suitable for freezing canine semen at a slow freezing rate.
