Dietary melatonin alters uterine artery hemodynamics in pregnant Holstein heifers

Brockus, KE; Hart, C. G.; Gilfeather, C.L.; Fleming, B. O.; Lemley, Caleb O

doi:10.1016/j.domaniend.2015.10.006

Cited by 39 publications

(34 citation statements)

References 25 publications

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“…This finding is unexpected as we previously reported a 25% increase in total uterine artery blood flow in MEL‐ vs CON‐treated heifers (Brockus et al. ). Considering that 75% of the growth of the ruminant foetus occurs during the last two months of gestation (Robinson et al.…”

Section: Discussionmentioning

confidence: 55%

“…In our previous work (Brockus et al. ), maternal melatonin supplementation during late gestation did not alter mean arterial pressure of the dams.…”

Section: Discussionmentioning

confidence: 58%

“…In relation to the current experiment, dams treated with dietary melatonin during late pregnancy showed a 43% increase in total serum antioxidant capacity compared to control‐supplemented dams (Brockus et al. ). Moreover, melatonin treatment increased superoxide dismutase activity in bovine uterine epithelial cells, which was partially blocked by treating with the melatonin receptor antagonist luzindole (Brockus et al.…”

Section: Discussionmentioning

confidence: 74%

“…Briefly, uterine artery blood flow was increased by 25% in the melatonin‐treated heifers (7161 ± 346 ml/min) compared to the control‐treated heifers (5733 ± 346 ml/min; Brockus et al. ).…”

Section: Methodsmentioning

confidence: 99%

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Effects of Supplementing Holstein Heifers with Dietary Melatonin during Late Gestation on Growth and Cardiovascular Measurements of their Offspring

Brockus

Hart

Fleming

et al. 2016

Reprod Domestic Animals

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The objective was to examine the effects of supplementing dams with dietary melatonin during late gestation on offspring growth and cardiovascular measurements. On day 190 of gestation, heifers (n = 20) were blocked by body weight and randomly assigned to one of two dietary treatments consisting of 20 mg of dietary melatonin per day [melatonin (MEL)] or no melatonin supplementation [control (CON)]. Dietary treatments were terminated on day 262 of gestation. At birth, calves were separated from their dams with no further treatments. Calf (n = 18) blood pressure, cortisol, nitrites and total antioxidant capacity were collected on weeks 0, 1, 2, 3 and 4 of age. Calf hepatic portal blood flow and concentrations of insulin-like growth factor 1 were determined on weeks 0 and 4 of age. Calf body weight, abdominal girth, hip height and wither height increased (p < 0.05) with age. An age by treatment interaction (p < 0.01) was observed for calf body weight, which was increased at weeks 8 and 9 of age in calves born to MEL heifers compared to calves born to CON heifers. Pulse pressure, mean arterial pressure, absolute hepatic portal blood flow and blood flow relative to calf body weight were not different (p > 0.05) between treatments. A main effect of calf age (p < 0.05) was observed for concentrations of insulin-like growth factor 1, which was decreased at week 4 compared to week 0. An age by treatment interaction (p < 0.05) was observed for cortisol, which was decreased at week 2 in calves from MEL-treated dams compared to calves from CON-treated dams. Early post-natal growth was altered in offspring born to dams supplemented with dietary melatonin. This could lead to further foetal programming implications in conjunction with post-natal development.

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Section: Discussionmentioning

confidence: 55%

“…In our previous work (Brockus et al. ), maternal melatonin supplementation during late gestation did not alter mean arterial pressure of the dams.…”

Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 74%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Supplementing Holstein Heifers with Dietary Melatonin during Late Gestation on Growth and Cardiovascular Measurements of their Offspring

Brockus

Hart

Fleming

et al. 2016

Reprod Domestic Animals

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“…Maternal plasma IGF-I at day 271 of gestation was negatively associated with calf crown length at birth (Sullivan et al, 2009b). In Holstein heifers, compared to controls, those that had melatonin included in their diet between days 190 and 262 of gestation had an increase in uterine blood flow of 25%, from day 210 of gestation (Brockus et al, 2016). The role of hormones should be considered for measurement in future calf mortality research.…”

Section: Calf Ability To Sucklementioning

confidence: 99%

Dehydration as a risk factor for calf mortality in northern Australia

Muller¹

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It is estimated that approximately one million calves die in Australia every year, with the majority unexplained. This thesis reviews losses associated with dehydration-mediated mortality during neonatal life, when there is highest risk of mortality, and reports three studies of neonatal calf dehydration.For 12 neonatal Brahman calves at Spyglass research site (northern forest land type, Queensland), variation in hydration status was investigated (Experiment 1). Change in live-weight from birth was used as the primary measure of hydration. Half of this cohort had low live weight gain between birth and day 3 of life (p = 0.01) compared to calves growing at 0.95±0.24 kg/day from birth. Low growth and associated reduced plasma protein (p = 0.04) in 6 calves indicated reduced colostrum, milk uptake and therefore reduced body fluid replenishment compared to other calves. This positions them at high risk of mortality under adverse environmental conditions. Urea space was tested as a measure of body water; however, percentage body water estimates were unrealistically elevated (> 80% of live weight) and therefore not representative of actual calf percentage body water.Descriptive analysis of risk factors for calf mortality was conducted for 478 and 378 tropically adapted newborn calves, respectively at Spyglass and Brian Pastures (southern forest land type, central Queensland) research sites (Experiment 2). The incidence risk of neonatal mortality in the southern forest of Queensland and northern forest of Queensland was 3.1% and 4.7%, respectively. Some risk factors and the percentage of calves exposed to high mortality risk included: dam body condition score ≤2 (8%), birth weight ≤28 kg (18%), low birth vigour (2%), large udder size (1%), at least two large teats (2%) and poor maternal protectiveness (5%). The low proportion of cows in poor body condition and good nutritional management limited the opportunity for dehydration-mediated neonatal mortality. There were no cases of prolonged heat stress around calving at the level previously associated with foetal and calf mortality. Experiment 2 indicates that low calf mortality may be achieved in any country type, provided that a low proportion of calves are exposed to high risk of mortality. A simple mechanistic model was developed to describe milk uptake volumes and ambient temperature (heat stress) impacts on neonatal hydration. This model provided clarification for the possible risk of dehydration mediated mortality across breeding herds of northern Australia.This thesis demonstrated variation in milk delivery, modelled that low milk delivery is associated with dehydration-mediated mortality and demonstrated that risk of mortality is low at a herd level when the risk factors associated with reduced milk delivery have low frequency.3

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