Comparison of different diluents based on liposomes and egg yolk for ram semen cooling and cryopreservation.

BACKGROUND: Sperm cryopreservation is an important tool for breed improvement, nonetheless, spermatozoids of rams are extremely sensitive to cryopreservation. AIMS: The present research was to compare a liposome-based (OptiXcell: OX) diluent, a commercial TRIS-egg yolk (Optidyl: OP) and a citrate egg yolk-based (CY) diluent on ovine semen quality through the cryopreservation process. METHODS: Semen was collected from four sexually mature Dorper rams during the natural breeding season. After collection, semen was evaluated and diluted in OX, OP or CY diluent and was cooled from 37°C to 4°C for 2 h (refrigerated semen, RS), after that semen-filled straws were placed in liquid nitrogen (LN) vapour for 10 min, then immersed into LN at -196°C (cryopreserved semen, CS) and stored until evaluation. RESULTS: For fresh semen (FS), similar values (P>0.05) were obtained from the 3 diluents [motility (4.2 ± 0.3), viability (75.4 ± 3.2), hypo-osmotic swelling test (HOST) (59.2 ± 2.1), and normality (84.7 ± 3.5)]. The motility values were higher for RS with OX and CY (4.0 ± 0.2 and 3.6 ± 0.3, respectively) compared to OP (3.0 ± 0.21; P<0.05). The viability was reduced after refrigeration and freezing (P<0.05). Refrigerated semen viability was similar for OX (65%), CY (63%) and OP diluents (60%; P>0.05), but for frozen semen, viability was lower in the CY diluent (P<0.05). Membrane integrity (HOST) in OX (53.6 ± 1.7) was similar to that in OP (50.7 ± 1.5; P>0.05) but higher than in CY (48.7 ± 1.5; P<0.05). CONCLUSION: No difference was found between the OX diluents and those made with egg yolk in terms of sperm parameters; however, the OX diluent was more efficient in protecting the integrity of membrane in freezing/thawing semen.

The use of female estrogenized goats as sexual stimulator of crossbred dairy males subsequently exposed to acyclic goats during two phases of the anestrous season.

This research evaluated the possible influence of exposure of male goats to estrogenized female goats ("female effect") upon males' sexual behavior [appetitive (ASB) & consummatory (CSB)], as well as the induction of reproductive activity of crossbred dairy female goats exposed to such treated males ("male effect") during the early and deep anestrous periods. Crossbred dairy adult male goats (n = 12; 24-48 mo. old) and 80 anovulatory crossbred dairy adult female goats (34-50 mo. old) were used during two experimental periods: March to April and April to May. First, males were separated into four groups (n = 3 each), roughly homogeneous regarding body weight and body condition score and randomly assigned to four experimental groups. The first two groups included males + estrogenized females, then such males were exposed to anestrous females either during March (group 1: three males; 20 females; EFEM-MAR), or during April (group 2: three males; 20 females; EFEM-APR). The second two groups were respective control groups: Males + non-treated-anestrous females, and then such males exposed to acyclic females either during March (group 3: three males; 20 females; CONT-MAR) or April (group 4: three males; 20 females; CONT-APR). Once the male-to-female contact was established, both odor (ODT) and behavior (BEHT) tests (2 d × 2 h) were performed during both anestrous periods. On day 10 after introduction of the males, in both anestrous periods, one ultrasonography scanning ("US") was performed to quantify the presence, number and size of corpus luteum (US-CL) to determine the effectiveness of the "male effect" and indicators of ovarian activity. Then, on day 45 after introduction of the males, a second US was performed to evaluate pregnancy rate (US-PREG). The EFEM-males, regardless of the phase of the anestrous cycle, had an increased (P < 0.05) odor intensity with respect to the control groups. In addition, while an increased (P < 0.05) ASB occurred in the EFEM-males, no CSB differences (P > 0.05) arose when treatments were compared, neither in March-April nor in April-May. The EFEM-males exposed to acyclic goats in March-April (i.e. early anestrous period), promoted not only the largest estrus and ovulatory responses (P < 0.05), but also the largest pregnancy rate (P < 0.05) in these previously anestrus goats, suggesting that in April-May (i.e. profound anestrous), the presence of active males was not enough to completely suppress cyclic reproductive arrest. This study generates interesting out-of-season reproductive outcomes in a goat population with a large proportion of highly seasonal dairy breeds (i.e. Alpine, Saanen and Toggenburg), augmenting the possibility to expand milk production and the economic income of goat producers across the year. Besides, this practice may serve as an interesting reproductive tool to increase the sustainability of marginal goat production systems under semiarid conditions.

Glutamate supply positively affects serum cholesterol concentrations without increases in total protein and urea around the onset of puberty in goats.

Different neurotransmitter and neuromodulatory systems regulate synthesis and secretion of GnRH. Whereas the endocrine and neural systems are activated in response to the metabolic status and the circulating levels of specific blood metabolites, glutamate receptors have been reported at hepatic level. This study evaluated the possible effect of glutamate supplementation upon changes in serum concentrations across time for total protein (TP), urea (UR) and cholesterol (CL) around the onset of puberty in goats. Prepuberal female goats (n=18) were randomly assigned to: (1) excitatory amino acids group, GLUT, n=10; 16.52±1.04kg live weight (LW), 3.4±0.12 body condition score (BCS) receiving an i.v. infusion of 7mgkg(-1) LW of l-glutamate, and (2) Control group, CONT, n=8; 16.1±1.04kg LW, 3.1±0.12 BCS. General averages for LW (23.2±0.72kg), BCS (3.37±0.10 units), serum TP (65.28±2.46mgdL(-1)), UR (23.42±0.95mgdL(-1)), CL (77.89±1.10mgdL(-1)) as well as the serum levels for TP and UR across time did not differ (P>0.05) between treatments. However, while GLUT positively affected (P<0.05) both the onset (207±9 vs. 225±12 d) and the percentage (70 vs. 25%) of females showing puberty, a treatment×time interaction effect (P<0.05) was observed in the GLUT group, with increases in serum cholesterol, coincident with the onset of puberty. Therefore, in peripuberal glutamate supplemented goats, serum cholesterol profile could act as a metabolic modulator for the establishment of puberty, denoting also a potential role of glutamate as modulator of lipid metabolism.