Periconceptional Heat Stress of Holstein Dams Is Associated with Differences in Daughter Milk Production during Their First Lactation

Abstract

The fertility of lactating Holstein cows is severely reduced during periods of heat stress. Despite this reduction in fertility, however, some inseminations conducted during heat stress result in successful pregnancies from which heifer calves are born. Many of these heifer calves are retained and raised to enter the milking herd as replacement animals. Heat stress experienced by these females around the time they were conceived may confer long-lasting effects that alter subsequent milk production capacity. The objective of this study was to examine the relationship between periconceptional heat stress and subsequent milk production of primiparous cows. National Dairy Herd Improvement Association data was obtained from Dairy Records Management Systems. Records included Holstein cows that had completed at least one lactation in one of three states with large populations of dairy cattle and which are known for having hot, humid summers: Georgia, Florida or Texas. Dates of conception were calculated by subtracting 276 d from the recorded birth date of each individual cow. Records for cows conceived within the months of June, July, and August were retained as heat stress-conceived (HSC) cows (n = 94,440); cows conceived within the months of December, January, and February were retained as thermoneutral-conceived (TNC) contemporaries (n = 141,365). In order to account for the effects of environmental conditions on total milk production for a given lactation, cows were blocked by season of calving (winter, spring, summer or fall). Adjusted 305-day mature-equivalent milk production was evaluated with a mixed model ANOVA using SAS, in which random effects were used to account for variability between herds. Of the cows that calved in the summer, fall and winter, TNC cows had higher milk yield than the HSC cows in all states. Interestingly, the cows that calved in the spring presented a unique relationship, with HSC cows producing more milk. Overall however, heat stress at the time of conception is associated with lower milk production during the first lactation. While this association does not prove cause and effect, it does provide justification for additional investigation into whether heat stress around the time of conception results in long-term, detrimental consequences for the conceptus.

Proteomic analysis to unravel the effect of heat stress on gene expression and milk synthesis in bovine mammary epithelial cells

“…HS can induce a rapid and acute reduction of milk yield (Silanikove et al 2009). A new study suggests that periconceptional hS of Holstein dams impairs cow milk yield throughout their lifetime (Brown et al 2016). Many researches show that the interactions between HS, milk production and milk composition are more complex than previously thought ).…”

“…Several studies also suggested the periconceptional HS of Holstein dams impairs cow milk yield throughout her lifetime (Brown et al . ). As we all know, the basic components of the mammary gland are the alveoli; these alveolar mammary epithelial cells reflect the milk producing ability of dairy cows (Janjanam et al .…”

“…Some reports showed that Holstein milk yield decreased during HS; feed intake and management factors partly account for the decreased milk yield during HS Smith et al 2013). Several studies also suggested the periconceptional HS of Holstein dams impairs cow milk yield throughout her lifetime (Brown et al 2016). As we all know, the basic components of the mammary gland are the alveoli; these alveolar mammary epithelial cells reflect the milk producing ability of dairy cows (Janjanam et al 2014).…”

Heat Stress Impacts Immune Status in Cows Across the Life Cycle

“…Similar outcomes have been observed in in vivo studies with sheep, beef, and dairy cows (37-39), wherein early exposure to environmental heat stress results in decreased embryo viability and development and increased embryo loss. A retrospective study showed that periconceptional heat stress of dairy cows (conceived during summer months) was associated with differences in daughter milk production during their first lactation (40), indicating persistent effects of maternal stress insults early in fetal life. In most mammalian species, by the end of the embryonic stage, ∼90% of the body structures are formed, followed by the fetal stage characterized by the growth of those structures.…”

Invited review: Management strategies capable of improving the reproductive performance of heat-stressed dairy cattle

“…Interestingly, when lactating dairy cattle are exposed to high ambient temperatures during the periconceptional period, the milk production of the resulting female offspring is also reduced. In studies examining tens of thousands of lactation records of primiparous and multiparous cows, those that had been conceived during the summer months produced less milk as an adult (Brown et al, 2015(Brown et al, , 2016Pinedo and De Vries, 2017). This effect was more pronounced in analyses of primiparous cows compared to multiparous cows (Brown et al, 2015(Brown et al, , 2016.…”