Comparison of selected data acquisition models using on-farm production records on qualitative parameters of oocytes in dairy cows

Abstract

Dairy cows enter the negative energy balance in the early post-partum period, which negatively affects milk yield, health status and reproduction. This study aimed to determine if milk yield (MY) and fat/protein (F/P) ratio could be used as reliable indicators for predicting the quality of aspirated oocytes and their further use for in vitro fertilisation. A secondary goal was to compare different periods before oocyte aspiration to determine which period had the most significant impact on the oocyte development in donor cows. All tested Holstein cows were at their first lactation (n = 68). The first ultrasound-guided follicular aspiration in donor cows was done on average at 58.7 days in milk (DIM). Usually, a second aspiration followed a week later if no problems were detected. In total, 102 aspirations were performed. Three model equations with different F/P ratio distributions and variants of MY production were tested in statistical evaluation. On average, 3.6 oocytes were retrieved per donor per aspiration, with a minimum of 1 and a maximum of 12. The maturation rate was 62.2%, with a high probability of reaching metaphase II (90.45%). The highest number of oocytes was obtained from low-yielding cows with a low F/P ratio in all evaluated periods (P < 0.01). The quality and expansion of cumulus-oocyte complexes were unaffected by the metabolic status. However, a tendency for better quality oocytes in donors with lower MY and F/P ratios was observed in all models. Our preliminary results showed that the prediction of oocyte quality in a homogeneous group of the first-lactation cows was related to the chosen data acquisition model. Data about milk yield and F/P ratio obtained from on-farm systems provide a valuable source of information for the selection of oocyte donors.

Keywords

• milk yield
• fat to protein ratio
• ovum pick-up
• maturation rate
• lipid droplets