The research team, led by Gökşad Cemil Kotan, Şeyma Aydemir, and Bülent Bayraktar of Hitit University and Bayburt University, set out to answer a deceptively simple question: how does a dairy cow’s body chemistry change as she moves through the six major stages of her production cycle? To do this, they enrolled multiparous Brown Swiss cows at a large commercial dairy operation in Çorum, Türkiye, and divided them into eighteen subgroups of twenty animals each. The groups crossed three pregnancy stages, early, mid, and the dry period in the final sixty days before calving, with three lactation stages, early, mid, and late, and then crossed each of those with three body condition score categories. Blood was drawn from the jugular vein, serum was separated and frozen at minus eighty degrees Celsius, and a battery of biochemical assays followed.

The analytical toolkit combined old and new. Traditional metabolic markers, non-esterified fatty acids (NEFAs), beta-hydroxybutyrate (BHBA), urea, albumin, globulin, and total cholesterol, were measured on a Roche Cobas 8000 analyzer using spectrophotometric methods. But the real novelty lay in the four molecules measured with bovine-specific enzyme-linked immunosorbent assays: the adipokines spexin, irisin, and visfatin, and the endoplasmic reticulum stress marker GRP78. These are molecules that have attracted intense interest in human metabolic research but remain poorly charted in cattle, particularly across the full arc of pregnancy and lactation in a single breed.

Why do these particular molecules matter? Adipose tissue is not merely a passive fat warehouse; it is an endocrine organ that secretes hormones regulating appetite, insulin sensitivity, and energy expenditure. Spexin, a small neuropeptide, has pleiotropic effects including the regulation of insulin resistance, glucose levels, and lipid metabolism, and it appears to suppress fat accumulation in the liver by stimulating lipolysis while inhibiting lipogenesis. Irisin, a proteolytic fragment of the membrane protein FNDC5, is released largely by skeletal muscle and drives the browning of white adipose tissue, raising energy expenditure and thermogenesis. Visfatin, also known as nicotinamide phosphoribosyltransferase or NAMPT, mimics insulin’s effects on glucose utilization and participates in NAD biosynthesis, linking cellular energy state to whole-body metabolism. GRP78, meanwhile, is a seventy-eight kilodalton chaperone protein of the HSP70 family that resides in the endoplasmic reticulum, where it orchestrates protein folding and triggers the unfolded protein response when folding capacity is overwhelmed, a condition known as ER stress.

The statistical design was rigorous. A two-way factorial analysis of variance tested the effects of physiological stage, body condition score, and their interaction on every measured parameter, with Duncan’s multiple range test used for post hoc comparisons. The interactions between physiological stage and body condition were highly significant for all measured parameters, at p less than 0.001, meaning that a cow’s fatness and her reproductive-lactational state do not act independently on her metabolism but rather in concert. That finding alone carries practical weight, because it suggests that feeding and monitoring strategies cannot be one-size-fits-all across a herd.

The headline results concern the timing of stress. Serum GRP78 peaked during the dry period, reaching a maximum of 0.46 nanograms per milliliter, and remained elevated in early lactation before declining as metabolic stability returned. NEFA, the classic blood signature of fat mobilization, followed the same pattern, peaking at 0.52 millimoles per liter during the dry period, well above the 0.40 millimoles per liter threshold generally used to flag excessive lipolysis. Urea levels also peaked in the dry period and early lactation. Strikingly, during the dry period these stress markers rose even as albumin and globulin, markers of hepatic synthetic capacity and immune status, declined significantly. In other words, the weeks before calving, long before a drop of milk is produced, appear to be the moment when the cow’s cellular machinery is under the greatest strain.

The adipokine story provides the counterpoint. Spexin ranged from a low of 14.02 picograms per milliliter in early pregnancy to a high of 36.04 picograms per milliliter, with levels rising as pregnancy and lactation progressed and showing an inverse relationship with body condition. Irisin climbed steadily from the onset of lactation, from a low of 0.95 nanograms per milliliter in early-lactation thin cows to 2.07 nanograms per milliliter in late-lactation cows with high condition scores, and peaked at 2.66 nanograms per milliliter during the dry period. Visfatin rose specifically during gestation, peaked at 24.09 nanograms per milliliter during the dry period, and continued climbing as lactation advanced toward the late stage. The authors interpret this coordinated rise as evidence of successful metabolic adaptation: as negative energy balance eased, these hormones helped restore insulin sensitivity and energy homeostasis.

Notably, the cows in this study managed the transition remarkably well. Early-lactation NEFA values of 0.34 to 0.41 millimoles per liter and BHBA values of 0.38 to 0.48 millimoles per liter stayed below or near the physiological thresholds for ketosis, and BHBA remained within normal limits throughout. Total cholesterol rose by roughly twenty-two percent across gestation and thirty-four percent across lactation, mirroring the recovery of feed intake and hepatic lipoprotein synthesis as energy balance improved. The researchers attribute this resilience partly to the Brown Swiss breed, which tends to mobilize body reserves more conservatively than high-yielding Holsteins and possesses a robust muscular conformation that may boost irisin secretion. In healthy animals, the GRP78 surge appears to be a protective physiological adaptation rather than pathological ER stress, a sign that the unfolded protein response is keeping pace with the enormous metabolic workload of late pregnancy and milk synthesis.

The authors are candid about limitations. Commercial ELISA kits for bovine matrices, especially for cleaved peptides like irisin, remain a subject of analytical debate, and the team recommends future validation by mass spectrometry or western blotting. No tissue biopsies were taken, so circulating biomarkers could not be linked directly to gene expression in adipose or hepatic tissue. Still, the practical implications are clear. Because spexin and GRP78 track lipolysis intensity and cellular stress so closely, they could serve as prognostic biomarkers for the early detection of metabolic stress and ketosis risk, allowing targeted nutritional interventions and antioxidant strategies during the dry period rather than generic herd-level management. For an industry where subclinical metabolic disease quietly erodes fertility, milk yield, and profitability, a blood test that flags trouble weeks before clinical signs appear could change how transition-period cows are fed, monitored, and protected, turning one of dairying’s most dangerous windows into a manageable, measurable event.

Subject of Research: Metabolic adaptation and adipokine and ER stress biomarker dynamics across pregnancy and lactation in Brown Swiss dairy cows

Article Title: Metabolic, adipokine (irisin, spexin, visfatin), and ER stress (GRP78) responses in multiparous Brown Swiss cows: a multivariate approach across physiological stages and body condition scores

Article References: Kotan, G. C., Aydemir, Ş., & Bayraktar, B. (2026). Metabolic, adipokine (irisin, spexin, visfatin), and ER stress (GRP78) responses in multiparous Brown Swiss cows: a multivariate approach across physiological stages and body condition scores. Archives Animal Breeding, 69(3), 517-528. https://doi.org/10.5194/aab-69-517-2026

Image Credits: AI Generated

DOI: 10.5194/aab-69-517-2026

Keywords: dairy cattle, Brown Swiss, adipokines, spexin, irisin, visfatin, GRP78, endoplasmic reticulum stress, negative energy balance, NEFA, body condition score, transition period