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Introduction: Many high milk-producing dairy cows are culled from the herd at an early age because they frequently suffer from health problems like ovarian, uterine and placental dysfunction, mastitis and impaired wound healing. We hypothesize that many health issues are an effect of altered angiogenesis. The objective of this pilot study was to compare angiogenesis of high-producing Holstein-Friesian dairy cows (HPC) with that of beef cattle and of dual purpose cattle (nonHPC). The corpus luteum was chosen as the reference organ because it has physiological angiogenesis in the adult.
Materials and Methods: Histological samples were obtained from corpora lutea of HPC and nonHPC (Limousin, Fleckvieh) cows (n = 11) at an abbatoir. Blood vessels were labelled in parafﬁn sections with Bandeiraea simplicifolia agglutinin I lectin and the following angiogenesis parameters were analyzed morphometrically using image analysis: number of blood capillaries per mm², percentage of the area covered by blood vessels, distance between two capillaries (lm) and area of blood capillaries lumina (size of blood vessels in lm²).
Results: HPC displayed a signiﬁcantly higher number of blood capillaries per mm² than nonHPC (P = 0.017). With an average value of 8.93%, the percentage of the area covered by blood vessels was higher in the corpora lutea of HPC than of nonHPC (5.85%, P = 0.052). The distance between two capillaries in nonHPC was signiﬁcantly longer (P = 0.009) than that in HPC. The mean luminal area of the blood capillaries of the corpora lutea in HPC was smaller (74.71 lm) than in nonHPC (96.25 lm, P = 0.329).
Conclusion: Higher numbers of blood capillaries per mm² and a larger luminal area of blood capillaries of corpora lutea indicate either activated angiogenesis or defective antiangiogenesis that probably result in an early exhaustion of the HPCs regeneration capability. Further studies are on the way investigating whether this is a local ovarian or systemic phenomenon.