Influence of inbreeding and crossbreeding on the in vitro embryo development during normal and heat stress condition

• Format: Article
• Language: fas
• Published: Shahid Bahonar University of Kerman 2012-08-01
• Series: مجله بیوتکنولوژی کشاورزی
• Subjects: embryo; inbreeding; cross breeding; heat stress; holstein; sistani
• Online Access: https://jab.uk.ac.ir/article_1185_55bf766691977b459daaaa8f7f5ccbab.pdf

Inbreeding and Heat stress have negative effects on reproductive performance of dairy cattle. Two suggested strategies to overcome to these factors are to use crossbreeding and crossbreeding with thermo tolerant genotype, respectively. The aims of present study were to determine the effects of inbreeding and crossbreeding on cleavage and blastocyst rates at early stages of in vitro development in inbreed (Holstein) and crossbreds (Sistani-Holstein) embryos during normal and heat shock stress. In vitro-matured (IVM) Holstein oocytes (n=623) were inseminated with either Holstein or Sistani spermatozoa, and after incubation period, presumptive embryos were collected and assigned to control (38.5°C) or heat shock at 96 h post insemination (hpi; 41°C for 12 h) treatments. The presumptive embryos were cultured in vitro for 8 days and evaluated for cleavage and blastocyst formation rates per cleaved embryo. Data were analyzed using logistic regression. The results indicated a cleavage at 48 hpi was influenced by the species of the sperm (embryo) genotypes, where percentage of Holstein oocytes cleaving after insemination with Holstein spermatozoa were significantly higher than Holstein oocytes inseminated with Sistani spermatozoa (207/314; 66% vs. 130/309; 42%), (P≤0.05); respectively. moreover, the overall blastocyst production rate during heat shock stress was clearly affected by the crossbreeding, with Holstein oocytes were inseminated with Sistani spermatozoa having a greater blastocyst yield in comparison with Holstein inbreed embryos during heat shock stress (4/49; 8.1% vs. 1/84; 1.1%), (P≤0.05) respectively. In conclusion, the present results indicate that Sistani-Holstein crossbreed embryos are more resistant to heat shock than purebred Holstein at early stages of in vitro development. Moreover, according to this criterion, crossbreeding with Sistani spermatozoa may result in higher pregnancy rates in Holstein cows during heat stress condition.