The influence of season and management system on intake and productivity of confined dairy cows in a Mediterranean climate

Moran, James

doi:10.1017/s0003356100032554

Cited by 4 publications

(3 citation statements)

References 7 publications

(14 reference statements)

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“…In the present study, heat stress reduced daily milk yield by 21% as the THI values went from 68 in the spring period to 78 in the summer period. Lower milk yields were recorded for confined Holstein cows in a the Mediterranean climate during the spring as compared to summer [22]. The adverse effect on milk yield was most likely mediated through a reduction in DMI, which decreased by 1.73 kg or 9.6%, and changes that occurred in body temperature and plasma hormone concentrations.…”

Section: Environmental Conditions During the Experimental Periodsmentioning

confidence: 87%

“…Research on THI as an indicator of heat stress and its effects on milk production of cows managed under the Mediterranean climatic conditions is limited and the effects of heat stress on milk yield and milk composition are, in most cases, assessed using days with a maximum temperature exceeding 27 o C as the index [22]. However, when high Ta is coupled with a high RH, stress intensity increases.…”

Section: Introductionmentioning

confidence: 99%

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The relationship of temperature-humidity index with milk production of dairy cows in a Mediterranean climate

et al. 2002

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-Two experiments were conducted using lactating Friesian-Holstein cows to measure the effects of heat stress, using temperature-humidity index (THI), on milk production, milk composition and dry matter intake (DMI) under the Mediterranean climate. These trials were carried out in two periods differing in average THI values (68 ± 3.75 vs. 78 ± 3.23 for the spring and summer periods, respectively). Daily THI was negatively correlated to milk yield (r = -0.76) and feed intake (r = -0.24). When the THI value increased from 68 to 78, milk production decreased by 21% and DMI by 9.6%. Milk yield decreased by 0.41 kg per cow per day for each point increase in the THI values above 69. Milk fat (3.24 vs. 3.58%) and milk protein (2.88 vs. 2.96%) were lower for the summer group. THI was positively correlated to respiration rate (RR) (r = 0.89), heart rate (HR) (r = 0.88), rectal temperature (RT) (r = 0.85) and cortisol (0.31), and negatively with free thyroxin (-0.43). As the THI values increased from 68 to 78, RT increased by 0.5 o C, HR by 6 beats, and RR by 5 inspirations per min. The average concentration of cortisol increased from 21.75 to 23.5 nmol·L -1 (P > 0.05), while that of free thyroxin decreased from 15.5 to 14.5 pmol·L -1 , (P > 0.05). Summer heat stress reduced milk yield and DMI, altered milk composition and affected the physiological functions of confined lactating Holstein cows managed under Mediterranean climatic conditions. dairy cow / temperature-humidity index / milk production / intake / physiology Résumé -Relation entre l'index température-humidité et la production laitière chez la vache Frisonne élevée sous un climat méditerranéen. Deux essais ont été menés sur des vaches laitières Frisonne-Holstein pour étudier l'effet du stress thermique sur la production et la composition du lait et sur l'ingestion de la matière sèche sous un climat méditerranéen. Ces essais ont été réalisés en deux périodes qui diffèrent seulement par leurs valeurs d'index température-humidité (THI) (68 ± 3,75 et 78 ± 3,23 pour le printemps et l'été, respectivement). Le THI journalier est négativement corrélé à la production laitière (r = -0,76) et à l'ingestion (r = -0,24). Lorsque la valeur THI est passée de 68 à 78, la production laitière a diminué de 21 % et la matière sèche ingérée de 9,6 %. Pour chaque unité d'augmentation du THI au delà de 69, la production laitière chute de 0,41 kg par vache par jour. Les teneurs du lait en matière grasse (3,24 et 3,58 %) et en protéines (2,88 et 2,96 %) étaient plus faibles (P < 0,05) pendant la période estivale. Le THI est positivement corrélé à la température rectale (r = 0,89), aux rythmes cardiaque (r = 0,88) et respiratoire (r = 0,85) et au cortisol (r = 0,31), mais né-gativement avec la thyroxine libre (r = -0,43). La variation de la valeur THI de 68 à 78 a engendré une augmentation de la température rectale, de la fréquence cardiaque et du rythme respiratoire de 0,5 o C, 6 battements par min et 5 inspirations par min, respectivement. La concentration plasmatique moyenne ...

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Section: Environmental Conditions During the Experimental Periodsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

The relationship of temperature-humidity index with milk production of dairy cows in a Mediterranean climate

et al. 2002

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“…A hot environment negatively affects milk quality as well (Moran, 1989;Bernabucci and Calamari, 1998;Calamari and Mariani, 1998). Above 72 THI, milk protein content declines, whereas the response of milk fat content seems delayed and results are contradictory.…”

Section: Reproductionmentioning

confidence: 99%

Metabolic and hormonal acclimation to heat stress in domesticated ruminants

Bernabucci

Lacetera

Baumgard

et al. 2010

Animal

721

492

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Environmentally induced periods of heat stress decrease productivity with devastating economic consequences to global animal agriculture. Heat stress can be defined as a physiological condition when the core body temperature of a given species exceeds its range specified for normal activity, which results from a total heat load (internal production and environment) exceeding the capacity for heat dissipation and this prompts physiological and behavioral responses to reduce the strain. The ability of ruminants to regulate body temperature is species-and breed-dependent. Dairy breeds are typically more sensitive to heat stress than meat breeds, and higher-producing animals are more susceptible to heat stress because they generate more metabolic heat. During heat stress, ruminants, like other homeothermic animals, increase avenues of heat loss and reduce heat production in an attempt to maintain euthermia. The immediate responses to heat load are increased respiration rates, decreased feed intake and increased water intake. Acclimatization is a process by which animals adapt to environmental conditions and engage behavioral, hormonal and metabolic changes that are characteristics of either acclimatory homeostasis or homeorhetic mechanisms used by the animals to survive in a new 'physiological state'. For example, alterations in the hormonal profile are mainly characterized by a decline and increase in anabolic and catabolic hormones, respectively. The response to heat load and the heat-induced change in homeorhetic modifiers alters post-absorptive energy, lipid and protein metabolism, impairs liver function, causes oxidative stress, jeopardizes the immune response and decreases reproductive performance. These physiological modifications alter nutrient partitioning and may prevent heat-stressed lactating cows from recruiting glucose-sparing mechanisms (despite the reduced nutrient intake). This might explain, in large part, why decreased feed intake only accounts for a minor portion of the reduced milk yield from environmentally induced hyperthermic cows. How these metabolic changes are initiated and regulated is not known. It also remains unclear how these changes differ between short-term v. long-term heat acclimation to impact animal productivity and well-being. A better understanding of the adaptations enlisted by ruminants during heat stress is necessary to enhance the likelihood of developing strategies to simultaneously improve heat tolerance and increase productivity.Keywords: ruminants, heat stress, metabolism, acclimation, adaptation ImplicationsHeat stress is a significant financial burden to animal agriculture in most areas of the world. Acclimation to heat stress imposes behavioral, physiological and metabolic adjustments to reduce the strain and enhances the likelihood of surviving the stress, and it also frequently reduces ruminant performance and compromises health. Improving our knowledge of physiological and metabolic mechanisms of acclimation may contribute to the development and adoption of proce...

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