Late embryo mortality in Holstein cows inseminated with Holstein or Limousine frozen semen

作者：Melendez, P.^*; Pinedo, P.; Gibbons, J.; Bartolome, J.; Naikare, H.

来源：REPRODUCTION IN DOMESTIC ANIMALS, 2023, 58(6): 734-739.

DOI：10.1111/rda.14343

• beef
• dairy
• late embryo mortality
• P4
• PSPB
• vigour hybrid

The objective of this study was to compare the late embryo mortality (LEM) rate (losses approximately between 32 and 53 days of gestation) and Pregnancy Specific Protein B (PSPB) and progesterone (P4) concentrations on day 32 post AI in Holstein cows bred with either Holstein or Limousine semen. A sample size of 1082 cows per group diagnosed pregnant between 28- and 35-days post breeding was calculated. The study consisted of evaluating LEM (%) in a cohort of Holstein cows bred with Holstein semen (HO x HO) or Limousine semen (HO x LM), to compare pregnancy loss from 28 to 35 days post breeding to 50-57 days post breeding. A logistic regression model to compare embryo losses was developed considering as main explanatory variable the cohort (HO x HO embryo vs. HO x LM embryo), correcting by lactation number, breeding season, days to breeding and AI technician. HO x HO embryos had greater LEM (15.16%) than HO x LM embryos (9.79%). Cows bred in summertime had higher LEM (15.23%) than cows bred in no-summertime (9.88%). There were no differences among AI technicians. Within summertime there was no difference in LEM (%) between groups within each lactation number; yet, within no-summertime, LEM (%) was higher in HO x HO than HO x LM within each lactation number. Pregnancy SPB optical densities were significantly greater in the HO x HO than in the HO x LM (p = .023) group; yet, the concentration of P4 was not different between groups (p > .05).

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