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1.
J Dairy Sci ; 104(4): 5021-5033, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33516558

RESUMEN

The objective of this study was to examine the effects of evaporative cooling and dietary supplemental Zn source on heat shock responses and mammary gland development of lactating dairy cows during summer. Seventy-two multiparous lactating Holstein cows were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement. Cows were either cooled (CL) or not cooled (NC) and fed diets supplemented with 75 mg of Zn/kg of dry matter (DM) from Zn hydroxychloride (IOZ) or 35 mg of Zn/kg of DM from Zn hydroxychloride plus 40 mg of Zn/kg of DM from Zn-Met complex (ZMC). The 168-d trial included a 12-wk baseline phase when all cows were cooled and fed respective dietary treatments, and a subsequent 12-wk environmental challenge phase when NC cows were deprived of evaporative cooling. Plasma was collected from a subset of cows (n = 24) at 1, 3, 5, 12, 26, 41, 54, 68, 81 d of the environmental challenge to measure heat shock protein (HSP) 70 concentration. Mammary biopsies were collected from another subset of cows (n = 30) at enrollment (baseline samples) and at d 7 and 56 of the environmental challenge to analyze gene expression related to heat shock response, apoptosis and anti-oxidative enzymes, and to examine apoptosis and cell proliferation using immunohistochemistry. Supplemental Zn source did not affect milk yield but NC cows produced less milk than CL cows. Supplemental Zn source had no effect on mammary gene expression of HSP27, 70, and 90 or plasma concentrations of HSP70. The NC cows had greater mammary gene expression of HSP than CL cows. Circulating HSP70 of NC cows gradually increased and was higher at 81 d of environmental challenge compared with CL cows. Relative to IOZ, ZMC cows tended to have lower total mammary cell proliferation but greater mammary apoptosis. There was a tendency of greater TNFRSF1A mRNA expression for ZMC compared with IOZ cows, which may suggest upregulated extrinsic apoptosis. At d 7 of environmental challenge, NC cows had numerically higher mammary apoptosis than CL cows although not statistically significant. The NC cows tended to have greater mRNA expression of CAT and SOD3 regardless of time, and had greater mRNA expression of GPX1 at d 56 and FAS at d 7 of the environmental challenge than CL cows. Relative to CL cows, mammary cell proliferation rate was higher for NC cows at d 56 of the environmental challenge. In conclusion, dietary source of supplemental Zn has substantial effect on mammary cell turnover in lactating dairy cows, and prolonged exposure to heat stress increases mammary cell proliferation.


Asunto(s)
Respuesta al Choque Térmico , Lactancia , Animales , Bovinos , Dieta/veterinaria , Suplementos Dietéticos , Femenino , Leche , Zinc
2.
Neuroimage ; 194: 283-290, 2019 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-30898654

RESUMEN

Recent findings have been challenging current understanding of how fast the human brain change its structural and functional connections in response to training. One powerful way to deepen the inner workings of human brain plasticity is using neurofeedback (NFB) by fMRI, a technique that allows self-induced brain plasticity by means of modulating brain activity in real time. In the present randomized, double-blind and sham-controlled study, we use NFB to train healthy individuals to reinforce brain patterns related to motor execution while performing a motor imagery task, with no overt movement. After 1 h of NFB training, participants displayed increased fractional anisotropy (FA) in the sensorimotor segment of corpus callosum and increased functional connectivity of the sensorimotor resting state network. Increased functional connectivity was also observed in the default mode network. These results were not observed in the control group, which was trained with sham feedback. To our knowledge, this is the first demonstration of white matter FA changes following a very short training schedule (<1 h). Our results suggest that NFB by fMRI can be an interesting tool to explore dynamic aspects of brain plasticity and open new venues for investigating brain plasticity in healthy individuals and in neurological conditions.


Asunto(s)
Encéfalo/fisiología , Imaginación/fisiología , Vías Nerviosas/fisiología , Neurorretroalimentación/métodos , Plasticidad Neuronal/fisiología , Adulto , Método Doble Ciego , Femenino , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Actividad Motora
3.
J Dairy Sci ; 101(10): 9048-9051, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30077447

RESUMEN

Eighty-two multiparous Holstein cows were fed diets differing in dietary cation-anion difference (DCAD) and Ca concentrations in a randomized block design experiment beginning 4 wk before anticipated calving to determine the effects on colostrum yield and quality and acid-base balance and mineral status of newborn calves. Treatments were arranged as a 2 × 2 factorial to provide 2 DCAD [-22 mEq/100 g of dry matter (NEG) or -3 mEq/100 g of dry matter (NEU)] and 2 supplemental Ca concentrations (1.3 or 1.8% of dry matter). After calving, cows were milked within 2 to 8 h and colostrum yield was recorded. Calves were fed 200 g of IgG of a commercial colostrum replacer within 4 h of birth. No differences were observed in birth weight or dystocia score among treatments, which averaged 42.7 kg and 1.12, respectively. Colostrum yield was not different among treatments and averaged 8.75 kg. Colostrum quality, as measured using a Brix refractometer, was not affected by DCAD but was higher for 1.3% compared with 1.8% Ca: 21.58% and 19.87%, respectively. Colostrum IgG concentrations were higher for NEG compared with NEU and for 1.3% compared with 1.8% Ca. No differences were observed in concentrations of serum IgG, Ca, P, K, Cl, anion gap, or whole-blood pH, partial pressure of O2, or SO2 of calves among treatments. Serum Mg and lactate concentrations were higher and CO2 tended to be lower for calves born to cows fed 1.3% compared with 1.8% Ca. Interactions of DCAD and Ca were observed for serum Na and Cl, which were higher for NEU-1.3% Ca and NEG-1.8% Ca compared with NEU-1.8% Ca and NEG-1.3% Ca. Whole-blood partial pressure of CO2, and HCO3 exhibited an interaction of DCAD and Ca and tended to be lower for NEU-1.3% Ca and NEG-1.8% Ca compared with NEU-1.8% Ca and NEG-1.3% Ca. Results of this trial indicate that feeding prepartum diets with 1.8% compared with 1.3% supplemental Ca reduced colostrum quality and serum concentrations of Mg and lactate in calves immediately after birth. Feeding NEG supported higher colostrum IgG concentrations. Blood mineral concentrations and blood gas balance tended to differ, but the effects were not consistent across DCAD and Ca.


Asunto(s)
Análisis de los Gases de la Sangre/veterinaria , Calcio/administración & dosificación , Calcio/sangre , Bovinos/metabolismo , Calostro/química , Alimentación Animal , Animales , Animales Recién Nacidos , Aniones , Cationes , Dieta , Femenino , Concentración de Iones de Hidrógeno , Minerales , Embarazo
4.
J Dairy Sci ; 101(3): 2617-2630, 2018 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-29290442

RESUMEN

Dietary Zn and heat stress alter gut integrity in monogastric animals. However, effects of Zn on mammary epithelial integrity in heat-stressed lactating dairy cows have not been studied. Multiparous lactating Holstein cows (n = 72) were randomly assigned to 1 of 4 treatments with a 2 × 2 factorial arrangement to study the effects of environment and Zn source on performance and mammary epithelial integrity. Treatments included 2 environments [cooled (CL) or not cooled (NC)] and 2 Zn sources [75 mg/kg of supplemental Zn as Zn hydroxychloride (IOZ) or 35 mg/kg of Zn hydroxychloride + 40 mg/kg of Zn-Met complex (ZMC)]. The experiment was divided into baseline and environmental challenge phases of 84 d each. All cows were cooled during the baseline phase (temperature-humidity index = 72.5), whereas NC cows were not cooled during environmental challenge (temperature-humidity index = 77.7). Mammary biopsies were collected on d 7 and 56 relative to the onset of environmental challenge to analyze gene expression of claudin 1, 4, and 8, zonula occludens 1, 2, and 3, occludin, and E-cadherin and protein expression of occludin and E-cadherin. Deprivation of cooling increased respiration rate (64.8 vs. 73.9 breaths/min) and vaginal temperature (39.03 vs. 39.94°C) and decreased dry matter intake (26.7 vs. 21.6 kg/d). Energy-corrected milk yield decreased for NC cows relative to CL cows (24.5 vs. 34.1 kg/d). An interaction between environment and Zn source occurred for milk fat content as CL cows fed ZMC had lower milk fat percentage than other groups. Relative to CL cows, NC cows had lower concentrations of lactose (4.69 vs. 4.56%) and solids-not-fat (8.46 vs. 8.32%) but a higher concentration of milk urea nitrogen (9.07 vs. 11.02 mg/mL). Compared with IOZ, cows fed ZMC had lower plasma lactose concentration during baseline and tended to have lower plasma lactose concentration during environmental challenge. Plasma lactose concentration tended to increase at 3, 5, and 41 d after the onset of environmental challenge in NC cows relative to CL cows. Treatment had no effect on milk BSA concentration. Cows fed ZMC tended to have higher gene expression of E-cadherin relative to IOZ. Compared with CL, NC cows had increased gene expression of occludin and E-cadherin and tended to have increased claudin 1 and zonula occludens 1 and 2 gene expression in the mammary gland. Protein expression of occludin and E-cadherin was unchanged. In conclusion, removing active cooling impairs lactation performance and affects gene expression of proteins involved in the mammary epithelial barrier, and feeding a portion of dietary zinc as ZMC improves the integrity of the mammary epithelium.


Asunto(s)
Bovinos/fisiología , Células Epiteliales/fisiología , Calor/efectos adversos , Glándulas Mamarias Animales/fisiología , Estrés Fisiológico/fisiología , Zinc/metabolismo , Alimentación Animal/análisis , Animales , Dieta/veterinaria , Suplementos Dietéticos/análisis , Femenino , Lactancia , Distribución Aleatoria , Zinc/administración & dosificación
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