223 Multiple ovulation and embryo harvest in relation to energy balance in Latvian native cow breeds

Abstract

The numbers of animals of two Latvian native cow breeds are very limited because almost all cows intended to be donor cows were used to acquire embryos. Most of these cows were kept on small private farms by local farmers. Many were at an advanced age and did not meet the necessary requirements to be a good embryo donor. Multiple ovulation and embryo transfer (MOET) was restarted after an interruption of more than 35 years in Latvia. The new team was educated to improve saving of these breeds using MOET in the frame of ERAF project no. 1.1.1.1/16/A/025. Energy balance (EB) and metabolic status affect ovarian function and oocyte quality, and impair early embryo development as well as endometrium and udder health. The aim of this study was to investigate success of multiple ovulation (MO), total (ToE) and transferable (TE) embryo harvest in the Latvian native breed donor cows in relation to EB and somatic cell count (SCC) in milk. MO was induced using FSH in 21 cows included in this study. Cows were 6.4 ± 3.26 years (average ± s.d.; range: 2.3 to 15 years), in 4.1 ± 2.45 lactation (range: 1 to 10 lactations), and body condition score (BCS) was in the range from 1.5 to 4.5 (5-point scale). Blood samples were taken on Day 7 after AI. The level of glucose (Glc), β-hydroxybutyric acid (BHB), and triglycerides (TG) in blood and the SSC in milk were determined using Agricultural Data Center information. Means, standard deviations, 2 independent samples t-test, Mann-Whitney test, and bivariate correlations (two-tailed) were calculated using SPSS-21 (SPSS Inc./IBM Corp.). MO was successful in 16 cows and unsuccessful in 5 cows; the main differences were for BHB in blood (0.62 ± 0.25 and 1.1 ± 0.50 mM, respectively) and SCC (673.2 ± 1272.71 and 958.3 ± 1329.66 ×10³ cells mL⁻¹ respectively; P < 0.05). No significant differences within groups were found regarding Glc (3.1 ± 0.57 and 2.9 ± 0.48 mM, respectively) and TG (0.19 ± 0.06 and 0.18 ± 0.06 mM, respectively) relative to success of MO (P > 0.05) in our study. The ToE and TE harvested depended on success of MO (r = 0.51 and r = 0.39; P < 0.05). In total, 9.7 ± 6.5 embryos from cow were acquired, but 6.5 ± 5.05 embryos were TE. The count of ToE was negatively correlated with TG in blood (r = −0.27; P < 0.05). The ToE and TE count were significantly negatively correlated with SCC in milk (r = −21 and r = −0.32, respectively; P < 0.05). Donor cows that produced TE had less SCC in milk compared with those that produced non-transferable embryos (291.8 ± 288.11 and 917.6 ± 1631.41 ×10³ cells mL⁻¹, respectively) and higher BCS (2.8 ± 0.84 and 2.1 ± 0.37 points, respectively; P < 0.05). SCC in milk could be one of the parameters to reject cows as embryo donors.