RESUMO
Adding gelling agents to convert the liquid state of the semen extender to a solid state allows for an increased sperm life span. Gelatin and alginate have been used to study the effects of gelling agents on sperm quality. However, there are other gelling agents that have not been studied, such as agar. In addition, studying different sources of gelling agents or the effect of mixing more than one gelling agent with semen extenders on sperm fertility has received little attention. Therefore, the objective of this study was to evaluate the effect of adding agar and a mixture of gelling agents from different sources to semen extender on ram sperm traits and fertility. The first trial evaluated the effect of the addition of 2.5-3 mg mL-1 of gelatin mixed with 0.5-20 mg mL-1 of agar or alginate to ram semen extender on sperm (motility, progressive motility, live/dead, membrane integrity) and semen (pH) characteristics. The response variables were evaluated 1, 72 and 144 h after storage at 4°C. In the second trial, two sources (feed grade and bacteriological) of gelatin and agar were evaluated on the response variables as in Trial 1. In trial 3, a total of 34 ewes were inseminated with doses supplemented (n = 17) with or without (n = 17) agar and gelatin. The pregnancy rate was diagnosed 40 days after insemination. In general, adding agar and gelatin improves (p < .05) sperm motility, membrane integrity and the ratio of live sperm after 144 h of storage compared to the Control group, regardless of the source (bacteriological or feed grade). However, the pregnancy rate in ewes was not influenced (p ≥ .05) by semen doses stored with agar and gelatin. In conclusion, the addition of agar and gelatin preserves ram sperm motility and membrane integrity after 144 of storage at 4°C without affecting the pregnancy rate in inseminated ewes.
RESUMO
BACKGROUND: The collection of ovaries from slaughterhouses is an important source of oocytes for in vitro embryo production. On the other hand, the physiological stage of slaughtered females varies and influences embryo production. OBJECTIVES: The study examined the in vitro efficiency of embryos and demi-embryos from young, non-pregnant adult, and pregnant adult ewes from a local slaughterhouse. METHODS: One thousand three hundred ovaries were collected from August to October 2020. The recovered oocytes were matured, fertilized, and cultured at 5% CO2, 38.5°C, and 100% humidity. Embryo bisection was performed in 96 blastocysts (n = 32 per treatment). The demi-embryo pairs were incubated for their reconstitution for 12 h. SAS was used for data analysis. RESULTS: The number of oocytes collected from the experimental group of non-pregnant adult ewes was higher (p ≤ 0.007) than those collected from the group of pregnant adult ewes (2.67 ± 0.19 vs. 2.18 ± 0.15 oocytes/group, respectively). The blastocyst rate was higher (p ≤ 0.0001) in the non-pregnant adult group (36.39%) than in the young (17.96%). The ratio of demi-embryos that recovered the blastocoelic cavity was higher (p < 0.05) in the young group (81.25%) than in the pregnant adult group (59.38%). The diameter of the demi-embryos was higher (p < 0.05) in the non-pregnant adult group (186.54 ± 8.70 µm) than those in the young and pregnant adult groups. CONCLUSIONS: In conclusion, the in vitro embryo production efficiency was highest when using oocytes from non-pregnant adult ewes under the conditions of this study.
