Effects of Feed Intake and Thermal Stress on Mammary Blood Flow and Other Physiological Measurements in Lactating Dairy Cows

Lough, D.S.; Beede, DK; Wilcox, C.J.

doi:10.3168/jds.s0022-0302(90)78677-8

Cited by 76 publications

(56 citation statements)

References 9 publications

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“…In the cow, the mammary blood flow was shown to be halved after fasting for 24 h, and only returned to normal 10 to 12 h after feeding restarted [13]. Similarly, Lough et al [45] observed a 5.1 to 4.3 L.min −1 reduction in the mammary blood flow during a 70% restriction of feed. A lowering of the heart rate was observed in heifers not receiving concentrate [46].…”

Section: Arterial Flow Of Glucose In the Mammary Glandmentioning

confidence: 90%

Changes in mammary uptake and metabolic fate of glucose with once-daily milking and feed restriction in dairy cows

et al. 2006

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-The aim of this review is to better understand the regulation of milk yield in response to once-daily milking and feed restriction. Glucose is the principal precursor for the synthesis of lactose (a major osmotic agent in milk), and participates in determining the milk volume produced. When applying these two breeding factors, reductions in milk yield are associated with a reduction in milk lactose yield and in the arterial flow of glucose, due to a decrease in the mammary blood flow. The ability of the udder to extract glucose is altered with once-daily milking but not necessarily with feed restriction. Lactose synthesis is down-regulated in response to once-daily milking and feed restriction but the percentage of the extracted glucose which is converted into lactose is differently affected in response to treatments. No marked change is observed with once daily milking whereas this would be increased with feed restriction and in contrast, depressed with fasting. milk yield / glucose / mammary gland / uptake / metabolic fate / ruminants

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Section: Arterial Flow Of Glucose In the Mammary Glandmentioning

confidence: 90%

Changes in mammary uptake and metabolic fate of glucose with once-daily milking and feed restriction in dairy cows

et al. 2006

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“…Studies of blood flow during lactation indicate that there is no major redirection of blood away from the mammary glands to facilitate heat loss (cattle, Lough et al 1990; goats Capra hircus, Sano et al 1985;rabbits, Lublin & Wolfenson 1996). There is a substantial body of behavioural literature following the pioneering work of Leon et al (1978), which suggests that suckling behaviour of small mammals may be influenced by the risks of maternal hyperthermia.…”

Section: Indirect Costs (A) Optional Compensatory Costs (I) Thermoregmentioning

confidence: 99%

The physiological costs of reproduction in small mammals

Speakman

2007

Phil. Trans. R. Soc. B

633

694

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Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional 'compensatory costs' whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.

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“…However, no differences in milk yield were observed among CCI categories (P = 0.19). When body temperature increases causes an increased up to one degree Celsius in rectal and tympanic temperature, increased respiratory rate (panting), causing severe reductions in voluntary feed intake (Lough et al 1990), a decline on growth rates and also milk production (Elvinger et al 1992), as well as impaired reproductive function and secretion of thyroid hormones (Al-Haidary et al 2001). Mader et al (2010) concluded that cattle with moderate levels of heat stress were able to cool down at night keeping a moderate TT the next day.…”

Section: Scoresmentioning

confidence: 99%

Behaviour, tympanic temperature and performance of dairy cows during summer season in southern Chile

2016

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RESUMENEl objetivo del estudio fue evaluar los efectos de las condiciones climáticas del verano sobre la producción de leche, actividad animal y temperatura timpánica (TT; n = 15), utilizando variables climáticas y tres índices de comodidad térmica. Los datos se analizaron considerando hora del día y categorías del índice comprensivo del clima (CCI). Se estimaron modelos de regresión simple para predecir la tasa de respiración (RR) de las vacas (α = 0,05). Los índices termales fueron normales y pobres predictores de RR (r 2 < 0,35; P < 0,001). La proporción de animales en pastoreo, echados y rumiando se redujo (P < 0,002) en 9,4; 1,7%; y 5,4 cuando el valor de CCI ≥ 25, mientras que los animales en pie y bajo sombra aumentaron 7,4 y 6,3%. Además se registró una correlación positiva entre RR y CCI. Las vacas tuvieron mayores TT en las categorías de CCI "moderado" y "suave" vs. "normal", así como también para PM vs. AM. El mayor valor de TT se observó en los días con máximos valores en los índices térmicos. Hubo diferencias tanto en la producción de leche como en los valores de CCI entre AM vs. PM (P < 0,001). Sin embargo, no hubo diferencias en la producción de leche entre las categorías de CCI (P = 0,19). Aunque las vacas mostraron signos de estrés por calor la producción diaria de leche no disminuyó al asociarlas a las categorías de CCI, demostrando que los animales fueron capaces de enfrentar las condiciones climáticas estivales.Palabras clave: comodidad térmica, cambio climático, bienestar animal. SUMMARYThe objective of the study was to assess the effects of summer weather conditions on animal performance and behaviour in southern Chile. Data of milk yield, animal activity, tympanic temperatures (TT; n = 15), and three comfort thermal indices were collected in La Araucanía Disctrict. Time of day and comprehensive climate index (CCI) categories were considering as influential factors. Simple regression models were estimated to predict the respiration rate of cows as an estimator of thermal comfort. Daily values of thermal indices were poor predictors of respiration rate, as well as climatic variables (r 2 < 0.35; P < 0.001). During days with CCI ≥ 25 there was a reduction (P < 0.002) in the proportion of animals on grazing (9.4%), lying (1.7%), and ruminating (5.4%). The proportion of animals standing and under shade increased 7.4 and 6.3%, respectively. Respiration rates were positively correlated with greater CCI values. The TT was higher for CCI categories "moderate" and "mild" vs. "normal" also for PM vs. AM. The highest TT was observed on days that had higher values of the thermal indices, especially CCI. There were differences for milk production and CCI values between AM vs. PM (P < 0.001). However, no differences for milk production were observed between CCI categories observed (P = 0.19). In conclusion, although cows showed signs of heat stress daily milk production did not show differences among CCI categories, showing that they were able to cope adverse climatic conditions of summer in southern Chi...

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Effects of Feed Intake and Thermal Stress on Mammary Blood Flow and Other Physiological Measurements in Lactating Dairy Cows

Cited by 76 publications

References 9 publications

Changes in mammary uptake and metabolic fate of glucose with once-daily milking and feed restriction in dairy cows

Changes in mammary uptake and metabolic fate of glucose with once-daily milking and feed restriction in dairy cows

The physiological costs of reproduction in small mammals

Behaviour, tympanic temperature and performance of dairy cows during summer season in southern Chile

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