Corpus luteal angiogenesis in a high milk production dairy breed differs from that of cattle with lower milk production levels

Globally, high producing, young dairy cows often have health and fertility problems such as ovarian, uterine and placental dysfunction, mastitis and impaired wound healing. These health issues can result in a shortened average lifespan of fewer than three lactations. We hypothesise that many of these health issues may be an effect of altered angiogenesis. Hence, the aim of this pilot study was to investigate the status of vascularisation in the corpus luteum of a high milk-producing cattle breed (Holstein Friesian) compared with that of low milk producing beef cattle (Limousin) and of dual purpose cattle (Fleckvieh, Rotbunt). The corpus luteum was chosen because as a transient endocrine gland it is one of the few tissues with physiological angiogenesis in the adult. Blood vessels were labelled in paraffin sections of corpora lutea with the lectin Bandeiraea simplicifolia agglutinin I and the following angiogenesis parameters were analysed morphometrically using image analysis: (a) number of blood capillaries per mm(2), (b) intercapillary distance, (c) percentage area occupied by blood vessels and (d) area of blood vessel lumina (mu m(2)). This analysis revealed that the extent of corpus luteal vascularisation is greater in high milk-producing cattle than in beef and dual purpose cattle as shown by a significantly higher number of blood capillaries per mm(2), significantly shorter intercapillary distances and a higher percentage of the corpus luteum area covered by blood vessels (non-significant). Only the average value of the luminal area of the luteal blood capillaries in the high milk-producing cattle is smaller than that measured in the low producing cattle