Effects of Prepartum Consumption of Endophyte-Infested Tall Fescue on Serum Prolactin and Subsequent Milk Production of Holstein Cows

Bernard, J.K.; Chestnut, A. B.; Erickson, B. H.; Kelly, F. M.

doi:10.3168/jds.s0022-0302(93)77526-8

Cited by 72 publications

(43 citation statements)

References 15 publications

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“…Despite decreased milk yield by INF and BROMO cows during the initial days of the final lactation (treatment was continued for the initial 10 d of this lactation), milk yield then increased so that the net yield for the lactation did not differ from CON. In agreement with our data, Bernard et al (1993) reported that feeding endophyte-infected fescue grass during the final month before parturition did not reduce milk yield in the next lactation. Because they did not observe a reduction in feed intake and only a small decrease in PRL concentration relative to control (only significant at the time of parturition), consumption of ergot alkaloids was likely more moderate than that in our study.…”

Section: Milk Production In the Final Lactationsupporting

confidence: 95%

“…By using a synthetic ergot alkaloid that markedly inhibits prolactin (PRL) secretion and by restoring plasma PRL by infusion of the hormone, we previously demonstrated that PRL is important for the final stage of mammary differentiation that occurs during the periparturient period, resulting in decreased milk yield during the first 10 d after parturition when the experiment was terminated (Akers et al, 1981a,b). Conversely, feeding endophyte-infected tall fescue grass for approximately 1 mo before calving reduced plasma PRL concentrations, but did not significantly affect milk production during the initial 10 wk after calving (Bernard et al, 1993). The quantity of ergot alkaloids consumed was not assessed in the latter study and, thus, we sought to more fully evaluate the effect of consuming endophyte-infected fescue grass on mammary function.…”

Section: Introductionmentioning

confidence: 97%

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Consumption of endophyte-infected fescue seed during the dry period does not decrease milk production in the following lactation

Baldwin

Capuco

Evock‐Clover

et al. 2016

Journal of Dairy Science

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Ergot alkaloids in endophyte-infected grasses inhibit prolactin (PRL) secretion and may reduce milk production of cows consuming these grasses. We investigated the effects of consuming endophyte-infected fescue seed during late lactation and the dry period on mammary growth, differentiation, and milk production. Twenty-four multiparous Holstein cows were randomly assigned to 3 treatment groups. Starting at 90±4 d prepartum, cows were fed endophyte-free fescue seed (control; CON), endophyte-free fescue seed plus 3×/wk subcutaneous injections of bromocriptine (0.1mg/kg of body weight, positive control; BROMO), or endophyte-infected fescue seed (INF) as 10% of the diet on an as fed basis. Although milk yield of groups did not differ before treatment, at dry off (-60 d prepartum) INF and BROMO cows produced less milk than CON. Throughout the treatment period, basal concentrations of PRL and the prepartum increase in plasma PRL were reduced in INF and BROMO cows compared with CON cows. Three weeks after the end of treatment, circulating concentrations of PRL were equivalent across groups. In the subsequent lactation milk yield was not decreased; in fact, BROMO cows exhibited a 9% increase in milk yield relative to CON. Evaluation of mammary tissue during the dry period and the subsequent lactation, by quantitative histology and immunohistochemical analysis of proliferation markers and putative mammary stem or progenitor cell markers, indicated that feeding endophyte-infected fescue seed did not significantly affect mammary growth and development. Feeding endophyte-infected grasses during the dry period may permit effective utilization of feed resources without compromising milk production in the next lactation.

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Section: Milk Production In the Final Lactationsupporting

confidence: 95%

Section: Introductionmentioning

confidence: 97%

Consumption of endophyte-infected fescue seed during the dry period does not decrease milk production in the following lactation

Baldwin

Capuco

Evock‐Clover

et al. 2016

Journal of Dairy Science

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“…Serum was collected following centrifugation at 3000× g for 10 min at 20 °C. Using the procedures of Bernard et al [47], serum prolactin analysis was conducted by the laboratory of F. N. Schrick (University of Tennessee, Knoxville, TN, USA). Many samples collected in Experiment 2 were rerun to confirm elevated prolactin concentrations that were observed across all treatments.…”

Section: Methodsmentioning

confidence: 99%

Vasoactivity and Vasoconstriction Changes in Cattle Related to Time off Toxic Endophyte-Infected Tall Fescue

Klotz

Aiken

Bussard

et al. 2016

Toxins

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Previous research has indicated that serotonergic and α-adrenergic receptors in peripheral vasculature are affected by exposure of cattle grazing toxic endophyte-infected (E+; Epichlöe coenophialia) tall fescue (Lolium arundinaceum). The objective of this experiment was to determine the period of time necessary for the vascular effects of ergot alkaloids to subside. Two experiments were conducted to investigate changes in vascular contractile response and vasoconstriction over time relative to removal from an ergot alkaloid-containing E+ tall fescue pasture. In Experiment 1, lateral saphenous vein biopsies were conducted on 21 predominantly Angus steers (357 ± 3 kg body weight) at 0 (n = 6), 7 (n = 6), 14 (n = 5), or 28 days (n = 4) after removal from grazing pasture (3.0 ha; endpoint ergovaline + ergovalinine = 1.35 mg/kg DM) for 126 days. In Experiment 2, lateral saphenous veins were biopsied from 24 Angus-cross steers (361 ± 4 kg body weight) at 0, 21, 42, and 63 days (n = 6 per time point) following removal from grazing tall fescue pastures (3.0 ha; first 88 days endpoint ergovaline + ergovalinine = 0.15 mg/kg DM; last 18 days endpoint ergovaline + ergovalinine = 0.57 mg/kg DM) for 106 total days. Six steers (370 ± 18 kg body weight) off of bermudagrass pasture for the same time interval were also biopsied on Day 0 and Day 63 (n = 3 per time point). Additionally, in Experiment 2, cross-sectional ultrasound scans of caudal artery at the fourth coccygeal vertebra were taken on Days 0, 8, 15, 21, 29, 36, 42, and 45 to determine mean artery luminal area to evaluate vasoconstriction. In both experiments, steers were removed from pasture and housed in a dry lot and fed a corn silage diet for the duration of biopsies and ultrasound scans. Biopsied vessels used to evaluate vasoactivity were cleaned, incubated in a multimyograph, and exposed to increasing concentrations of 4-Bromo-3,6-dimethoxybenzocyclobuten-1-yl) methylamine hydrobromide (TCB2; 5HT2A agonist), guanfacine (GF; α2A-adrenergic agonist), and (R)-(+)-m-nitrobiphenyline oxalate (NBP; α2C-adrenergic agonist) in both experiments and ergovaline (ERV) and ergotamine (ERT) in Experiments 1 and 2, respectively. In Experiment 1, days off pasture × agonist concentration was not significant (p > 0.1) for all four compounds tested. In Experiment 2, GF, NBP, TCB2 and ERT were significant for days off pasture × agonist concentration interaction (p < 0.02) and vasoactivity increased over time. Vasoactivity to agonists was reduced (p < 0.05) when steers were initially removed from E+ tall fescue pasture compared to bermudagrass, but did not differ by Day 63 for any variable. Luminal areas of caudal arteries in steers grazed on E+ tall fescue relaxed and were similar to steers that had grazed bermudagrass for 36 days on non-toxic diet (p = 0.15). These data demonstrate changes in peripheral vasoactivity and recovery from vasoconstriction occur beyond five weeks off toxic pasture and 5HT2A receptors appear to be more dramatically affected in the lateral saphenous vein by...

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“…To determine the presence and concentration of PRL in seminal fluid PRL RIA assays were performed by the F. Neal Schrick laboratory as previously described [34] for serum with mean inter-and intra-assay coefficients of variation of 9.7% and 6.0%, respectively.…”

Section: Radioimmunoassaymentioning

confidence: 99%

Identification of bovine prolactin in seminal fluid, and expression and localization of the prolactin receptor and prolactin-inducible protein in the testis and epididymis of bulls exposed to ergot alkaloids

et al. 2015

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Effects of Prepartum Consumption of Endophyte-Infested Tall Fescue on Serum Prolactin and Subsequent Milk Production of Holstein Cows

Cited by 72 publications

References 15 publications

Consumption of endophyte-infected fescue seed during the dry period does not decrease milk production in the following lactation

Consumption of endophyte-infected fescue seed during the dry period does not decrease milk production in the following lactation

Vasoactivity and Vasoconstriction Changes in Cattle Related to Time off Toxic Endophyte-Infected Tall Fescue

Identification of bovine prolactin in seminal fluid, and expression and localization of the prolactin receptor and prolactin-inducible protein in the testis and epididymis of bulls exposed to ergot alkaloids

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