Ovariectomy improves lactation persistency in dairy cows

Abstract

A current trend in the dairy industry is to reduce milk yield at the peak of lactation and improve lactation persistency. Lactation persistency is influenced by livestock management factors, such as feeding level or milking frequency, or by physiological status, including reproductive status or calving period. These factors modulate mammary gland apoptosis and tissue remodeling, which determine the rate of decline of milk yield after the lactation peak. Previous studies on lactating cows suggested that ovarian steroids have a negative effect on milk yield after the peak of lactation. In the present study, 4 Holstein × Normande crossbred multiparous cows were ovariectomized at the time of the lactation peak, and 5 cows underwent sham operations. All of the cows were maintained in lactation for 14 mo and milk yield was recorded daily. At slaughter, mammary epithelial cell apoptosis and mammary tissue remodeling were assessed. Ovariectomized cows had improved lactation persistency and presented an average daily milk gain of 2.5 kg compared with the sham-operated cows between mo 6 and 14 of lactation. The ovariectomy appears to have limited the decline in the milk yield after the peak of lactation by reducing mammary epithelial cell apoptosis [by reducing poly(adenosine diphosphate-ribose) polymerase expression] and mammary-tissue remodeling (by reducing matrix metalloproteinase activity). In conclusion, removal of ovarian secretion via ovariectomy improved the cows' lactation persistency.

Consequences of dietary energy source and energy level on energy balance, lactogenic hormones, and lactation curve characteristics of cows after a short or omitted dry period

“…A reduced interval from calving to pregnancy may have reduced persistency later on in lactation in cows in the 0-d DP(low) treatment compared with cows in 30-d DP(std). Pregnancy from 3.5 to 6 mo onward negatively influences milk yield and lactation persistency through feto-placental estrogen that strongly stimulates apoptosis of mammary epithelial cells, which decreases both cell number and secretory capacity (Olori et al, 1997;Brotherstone et al, 2004;Yart et al, 2012). Decrease of lactation persistency is related to increasing plasma estrogen produced by the feto-placental unit (Thatcher Journal of Dairy Science Vol.…”

BMP2, 4 and 6 and BMPR1B are altered from early stages of bovine cystic ovarian disease development

“…Ovariectomy: It was conducted when the veterinarian responsible for the reproductive health of animals indicated castration to prolong lactation until shipment to killing (Yart et al 2012). The ovaries from control cows (n = 5) and cows with spontaneous COD (n = 10) were removed by ovariectomy and blood samples were collected just before surgery for hormone analysis (Marelli et al 2014).…”

Review: the cellular mechanisms underlying mammary tissue plasticity during lactation in ruminants

“…To understand the role of hormones in the adaptation process of the mammary tissue, milk production was modulated by hormonal manipulations (Table 4). The withdrawal of ovarian steroid secretion following ovariectomy limited the rate of decrease in milk yield after the peak of lactation (Yart et al, 2012). The reduction of milk yield decline was not accompanied by the modification of milk protein gene expression Boutinaud et al, 2013b.…”

“…Hormonal manipulations also affected indicators of cell number variations in the mammary tissue (Table 7). Greater milk yield in ovariectomized cows than in control cows was associated with a decrease in the expression of the enzyme poly ADP ribose polymerase (PARP) protein (Yart et al, 2012), which intervenes in DNA fragmentation during one of the final stages of cell death. This effect was accompanied by lower MEC exfoliation (Boutinaud et al, 2013b).…”