| Summary: | It was hypothesized that technical factors associated with in vitro production (IVP) of embryos may influence rate of blastocyst development of oocytes matured at 38.5 or 41.0 C. To test this hypothesis, a retrospective meta-analysis was performed. Simple linear regression was performed to analyze continuous variables and ANOVA for categorical variables. Interactions among factors and maturation temperature on blastocyst development were analyzed using dummy regression for continuous variables, and using a factorial treatment design and ANOVA for categorical variables. Month of collection was the only variable that impacted responsiveness of ova to heat stress. Independent of maturation temperature, variables that explained most variation in blastocyst development included technician, total number of sliced ovaries per collection, ova number placed per well of oocyte maturation media, oocyte collection time, bull ID, sperm concentration added to ova, and ova age at IVF. The proportion of 8 to 16-cell embryos at time of cleavage assessment was the best predictor of blastocyst development. Results of model selection showed that development of ova matured at 38.5 C was associated with size of the collection, while development of ova matured at 41.0 C was mainly associated with ova age at fertilization. When data for ova matured at 38.5 and 41.0 C were combined, the effect of number of PZ per well on blastocyst development became evident. Use of these findings for optimizing efficiency of IVP procedures would effectively reduce experimental costs related to embryo production and increase laboratory productivity.
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