ABSTRACT
To estimate when, during stallions' extra-gonadal reserves (EGR) depletion period, sperm quality would reach its highest quality, six light breed sexually rested stallions were collected daily for 7 days to deplete EGR. On collection days 1, 3, 5, and 7, sperm output, total (TM) and progressive (PM) motility, morphology, and plasma membrane (PLM) integrity were evaluated. Sperm output decreased as EGR depletion advanced, stabilizing on days 5-7. Sperm motility (TM and PM) and morphology were not different during EGR depletion. Plasma membrane integrity improved from day 1 to 3; however, no further improvement observed on days 5 and 7. Sperm of sexually rested stallions reach the highest quality on day 3 of the EGR depletion period.
Subject(s)
Cryopreservation/methods , Gonads/physiology , Semen Preservation/methods , Sperm Motility/physiology , Spermatozoa/physiology , Animals , Cell Membrane , Cryopreservation/veterinary , Horses , Male , Semen Preservation/veterinaryABSTRACT
Several intrinsic factors (age, genotype, liveweight) influence the reliability of juvenile in vitro fertilisation embryo transfer (JIVET) programs. Limited evidence indicates that variability between lambs is reduced in twin-born lambs. We examined the impact of birth type (single, twin, triplet) and sex of the co-twin (with age, birthweight and liveweight as covariates) on JIVET outcomes. Birth type did not influence any parameter studied. However, blastocysts produced, as a percentage of embryos cleaved or total cumulus-oocyte complexes collected, was higher (P<0.05) for females born with a female co-twin (67.0±6.1, 57.5±6.0 respectively) compared with those born with a male co-twin (26.9±6.5, 22.3±6.2 respectively; least-square mean±s.e.m.). Blastocyst rates for lambs born with a male co-twin did not differ significantly from lambs born either as singles (39.5±6.7%, 34.6±6.5% respectively) or triplets (43.1±10.6%, 36.5±10.3% respectively). Other parameters were not influenced by sex of the co-twin. These results are indicative of an enhancement effect of the female co-twin on oocyte development. From a practical perspective, selecting lambs for a JIVET program based on litter size and sex of the co-twin is warranted.
