Hormonal interelationships and physiological responses of lactating dairy cows to a shade management system in a subtropical environment

Roman-Ponce, H.; Thatcher, W.W.; Wilcox, C.J.

doi:10.1016/0093-691x(81)90097-2

Cited by 88 publications

(36 citation statements)

References 23 publications

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“…These include a suppressed intensity of oestrus, a reduced preovulatory LH surge and decreased secretion of luteal progesterone [25], altered ovarian follicular development [33], decreased embryo development [38] and lower fertility [39]. In an attempt to minimize these effects, modifications to dairy cattle housing environments have been implemented to alleviate thermal stressors and improve cow comfort, through the use of shade, fans, sprinklers, and evaporative cooling [11,37,40]. These methods can enhance pregnancy rates significantly [24,41].…”

Section: Effects Of Heat Stress On Reproductionmentioning

confidence: 99%

“…In an attempt to minimize these effects, modifications to dairy cattle housing environments have been implemented to alleviate thermal stressors and improve cow comfort [11,37,40,42]. The major objective of any cooling system is to keep the cow's body temperature as close to normal for as much of the day as possible.…”

Section: Effect Of Environmental Modification For Dairy Cows Under Trmentioning

confidence: 99%

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Alleviating Heat Stress Leads to Improved Cow Reproductive Performance

Suadsong¹

2012

Milk Production - An Up-to-Date Overview of Animal Nutrition, Management and Health

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Section: Effects Of Heat Stress On Reproductionmentioning

confidence: 99%

Section: Effect Of Environmental Modification For Dairy Cows Under Trmentioning

confidence: 99%

Alleviating Heat Stress Leads to Improved Cow Reproductive Performance

Suadsong¹

2012

Milk Production - An Up-to-Date Overview of Animal Nutrition, Management and Health

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“…As THI increased from 68 to 78, the free thyroxin concentration decreased from 15.5 to 14.5 pmol·L -1 , while the average cortisol concentration went from 21.75 to 23.5 nmol·L -1 . Generally, cows that are heat stressed have decreased concentrations of thyroid hormones [17], but increased plasma concentrations of corticoids [28,29]. The lack of significance in hormone concentrations between the two periods could be attributed to the previous exposure of summer cows to high temperatures prior to the trial.…”

Section: The Effects Of Heat Stress On the Physiological Responses Anmentioning

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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-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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“…A previous study found that heat stress caused an increase in the plasma follicle-stimulating hormone (FSH) concentration in cows . On the other hand, conflicting findings concerning the effect of heat stress on plasma luteinizing hormone (LH) have been reported; heat stress has been reported to cause the plasma LH concentration in cows to decrease (Madan & Johnson 1973, Miller & Alliston 1974, remain unchanged (Gwazdauskas et al 1981, Rosenberg et al 1982, or increase (Roman-Ponce et al 1981). More recently, Kanai et al (1995) found that heat stress did not change the pituitary LH secretion in long-day-treated anoestrous goats that were injected with exogenous gonadotrophin-releasing hormone (GnRH) to induce artificial LH pulses, whereas it reduced the follicular responsiveness to LH.…”

Section: Introductionmentioning

confidence: 99%

Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats

Ozawa¹,

Tabayashi²,

Latief³

et al. 2005

Reproduction

103

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We investigated the changes in follicular dynamics and steroidogenic activity during heat stress in goats. Adult female goats were exposed to heat stress at 36 8C and 70% relative humidity for 48 h and then injected with prostaglandin (PG) F 2a (the time of PGF 2a injection was designated as 0 h). In experiment 1, every follicle greater than 2 mm in diameter was monitored by ultrasonography to investigate the follicular dynamics, and plasma concentrations of FSH, LH, progesterone, and oestradiol were measured from 248 h to 120 h. In experiment 2, the follicles were recovered from the goats at 48 h, and the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles were determined. In control (non-heatstressed) goats, ovulatory follicles were mainly recruited from 224 h to 0 h, whereas no follicles recruited during that period were ovulated in the heat-stressed goats. The timing of the recruitment of ovulatory follicles was delayed by heat stress by approximately 24 h. The plasma concentration of oestradiol in the heat-stressed goats was significantly lower from 36 to 54 h compared with the controls, although the concentrations of FSH and progesterone did not differ between the treatments. In addition, the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles from heat-stressed goats were significantly lower compared with the controls. These results indicate that heat stress during follicular recruitment suppresses subsequent growth to ovulation, accompanied by decreased LH receptor level and oestradiol synthesis activity in the follicles.

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Hormonal interelationships and physiological responses of lactating dairy cows to a shade management system in a subtropical environment

Cited by 88 publications

References 23 publications

Alleviating Heat Stress Leads to Improved Cow Reproductive Performance

Alleviating Heat Stress Leads to Improved Cow Reproductive Performance

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

Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats

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