Responses of the mammary transcriptome of dairy cows to altered photoperiod during late gestation

Abstract

Cows exposed to short day photoperiod (SD, 8L:16D) during the 60-day nonlactating period prior to parturition produce more milk in their subsequent lactation compared with cows exposed to long day photoperiod (LD, 16L:8D). Although this response is well established in dairy cows, the underlying mechanisms are not understood. We hypothesized that differential gene expression in cows exposed to SD or LD photoperiods during the dry period could be used to identify the functional basis for the subsequent increase in milk production during lactation. Pregnant, multiparous cows were maintained on an SD or LD photoperiod for 60 days prior to parturition. Mammary biopsies were obtained on days -24 and -9 relative to parturition and Affymetrix GeneChip Bovine Genome Arrays were used to quantify gene expression. Sixty-four genes were differentially expressed (P ≤ 0.05 and fold-change ≥ |1.5|) between SD and LD treatments. Many of these genes were associated with cell growth and proliferation, or immune function. Ingenuity Pathway Analysis predicted upstream regulators to include TNF, TGF-β1, interferon-γ, and several interleukins. In addition, expression of 125 genes was significantly different between day -24 and day -9; those genes were associated with milk component metabolism and immune function. The interaction of photoperiod and time affected 32 genes associated with insulin-like growth factor I signaling. Genes differentially expressed in response to photoperiod were associated with mammary development and immune function consistent with the enhancement of milk yield in the ensuing lactation. Our results provide insight into the mechanisms by which photoperiod affects the mammary gland and subsequently lactation.

Exposure to chronic light–dark phase shifts during the prepartum nonlactating period attenuates circadian rhythms, decreases blood glucose, and increases milk yield in the subsequent lactation

“…treatment versus the CTR treatment was similar to what is reported for cattle exposed to short-day versus long-day photoperiod during the nonlactating dry period (Dahl, 2008). A short-day photoperiod during the nonlactating dry period increased expression of genes that regulate proliferation and differentiation of cells in the mammary gland (Bentley et al, 2015); it also attenuated rhythms of expression of core clock genes in mammary tissue of goats (Casey et al, 2018). Our work in cells and rodents supports a role for the circadian clocks in regulation of mammary epithelial growth and differentiation (Casey et al, 2016).…”

Review: Pro-inflammatory cytokines and hypothalamic inflammation: implications for insufficient feed intake of transition dairy cows

“…The transition period of dairy cows is defined as ranging between 3 weeks before until 3 weeks after parturition and is characterised by major changes in metabolism, the endocrine and immune systems. Particular uterine and mammary gland tissue remodelling attract cells of the innate immune system, such as neutrophils, macrophages and dendritic cells (van Engelen et al, 2009;Bentley et al, 2015). Tissue remodelling and accompanied tissue damage facilitate the penetration and entrance of microorganisms in these organs.…”

“…Tissue remodelling and accompanied tissue damage facilitate the penetration and entrance of microorganisms in these organs. In response to tissue damage and microbial infection, immune cells invade into the uterine and the mammary gland during involution or parturition and produce high levels of pro-inflammatory cytokines such as interleukine-1β (IL-1β), IL-6 and tumour necrosis factor-α (TNF-α) (van Engelen et al, 2009;Bentley et al, 2015). These cytokines act locally in a paracrine fashion but are also released into circulation, thereby operating in an endocrine manner.…”

Outcomes from Experimental Testing of Nonsteroidal Anti-Inflammatory Drug (NSAID) Administration during the Transition Period of Dairy Cows

“…Mammary gland tissue remodeling facilitates the entry of microorganisms and thereby actives the innate immune system, attracting neutrophils, macrophages, and dendritic cells [ 9 , 10 ]. Indeed, dairy cows around parturition are more susceptible to mastitis [ 11 ].…”

“…Indeed, dairy cows around parturition are more susceptible to mastitis [ 11 ]. In turn, immune cells produce high levels of pro-inflammatory cytokines such as interleukine-1β (IL-1β), interleukine-6 (IL-6), and tumor necrosis factor-α (TNF-α) [ 9 , 10 ]. A pro-inflammatory state is another difficulty faced by dairy cows during TP, and is well documented in several other species, such as pig [ 12 , 13 ], mice [ 14 ], and human [ 15 ].…”