Seasonal heat stress: Clinical implications and hormone treatments for the fertility of dairy cows

Rensis, F. De; García-Ispierto, Irina; López‐Gatius, F.

doi:10.1016/j.theriogenology.2015.04.021

Cited by 172 publications

(134 citation statements)

References 127 publications

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“…Heat stress disrupts both physiological processes and reproductive performance of high-yielding dairy cows (De Rensis et al, 2015). The consequences of this thermal stress are not only manifested during periods of high ambient temperature, but present long-lasting effects on the fertility of the dairy cow (García-Isperto et al, 2006, 2007.…”

Section: Introductionmentioning

confidence: 99%

Prevalence and risk factors for stillbirths in Holstein cows in a hot environment

Mellado

Chávez

Macías‐Cruz³

et al. 2017

Span. j. agric. res.

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Risk factors for stillbirth were studied in a dairy operation in northern Mexico (25°N). Data set consisted of 29406 full term calving records. Factors affecting stillbirths were analyzed using a step-wise multivariable logistic regression models. The predictive indicators of stillbirth risk were: temperature-humidity index (THI) during pregnancy and at calving, season of calving, calf birth weight, gestation length, semen characteristics (conventional or sexed), gender of calves, hour of calving and type of parturition (normal or dystocic). Throughout the study period, 7.3 (95%, confidence interval= 7.0-7.6) of every 100 calving events had a stillborn calf. Stillborns were higher with severe dystocia compared with non-assisted births (29.0% vs. 6.2%, p<0.0001) and calves with birth weights <35 kg compared with heavier calves at calving (19.3% vs. 2.3%, p<0.0001), and was lower in calves whose gestation length was >278 d compared with calves with shorter gestation periods (2.8% vs. 30.0%, p<0.0001). Cows in a severe state of heat stress prenatally and at birth (THI >83 units) had 1.3 higher risk of stillbirths than cows suffering reduced heat stress (p<0.0001). Evidence for a greater (p<0.001) stillbirth rates in cows with parturitions between 18:00 and 19:00 h compared with cows calving during other hours of the day was found (9.1% vs. 7.1%). Together, these results demonstrate that ameliorating heat stress during the peripartum period is an important management practice to reduce stillbirths in Holstein cows in this warm climate. Additionally, a greater attention of parturition around sunset can lower the current stillbirth rates.Additional keywords: heat stress; sexed semen; birth weight; dystocia; gestation length

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Section: Introductionmentioning

confidence: 99%

Prevalence and risk factors for stillbirths in Holstein cows in a hot environment

Mellado

Chávez

Macías‐Cruz³

et al. 2017

Span. j. agric. res.

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“…The physiological responses to heat stress in dairy cattle include altered hormonal status, reduction in rumination and nutrient absorption, suboptimal immune function, and increased maintenance requirements resulting in a net decrease in nutrient/energy available for growth, reproduction, and lactation (Baumgard and Rhoads 2013;De Rensis et al 2015).…”

Section: Dairy Cattlementioning

confidence: 99%

“…Heat stress reduces fertility by affecting the ovaries, uterus, and the hormones regulating their function (De Rensis et al 2015). Furthermore, heat stress increases embryo mortality and results in birth of smaller and less vigorous calves.…”

Section: Dairy Cattlementioning

confidence: 99%

“…Heat stress causes longer estrous cycles and a shorter duration of estrus. Dairy cattle can handle extremes of heat and cold for short periods of time, but efficient production requires that cows stay within their TNZ (De Rensis et al 2015). Cows in the Southeast (SE) and Southwest US exhibit reduced fertility that can be mitigated by artificial cooling (fans, sprinklers, shade, etc.).…”

Section: Dairy Cattlementioning

confidence: 99%

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Climate change effects on livestock in the Northeast US and strategies for adaptation

et al. 2017

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The livestock industries are a major contributor to the economy of the northeastern United States. Climate models predict increased average maximum temperatures, days with temperatures exceeding 25°C, and higher annual precipitation in the Northeast. These environmental changes combined with increased atmospheric CO 2 concentration are expected to either increase or decrease forage productivity depending on the crop, and may decrease protein content and forage digestibility. Winter damage to sensitive forage species may also increase. Predicted temperature increases are expected to reduce fertility in dairy cattle and heat stress-induced inflammation may limit energy available for productive functions.

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“…Previous studies indicate that high temperature has a negative effect on the reproduction process of dairy cows owing to undetected estrous cycle, decreased estrous period intensity (De Rensis and Scaramuzzi 2003; De Rensis et al 2015), effects on the physical activity (García-Ispierto et al 2006; García-Ispierto et al 2007), and low fertility (López-Gatius 2012; López-Gatius 2013). High environmental temperature has a detrimental effect on embryo survival (García-Ispierto et al 2006) as well as on the survival and motility of sex-sorted sperm (García-Ispierto et al 2007; Mellado et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Artificial insemination of Holstein heifers with sex-sorted semen during the hot season in a subtropical region

Chang

Chou

Shiu

et al. 2017

Trop Anim Health Prod

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Our aim was to investigate insemination techniques in order to improve pregnancy rates of artificial insemination (AI) using sex-sorted semen (sexed AI) in cattle in tropical and subtropical (T/ST) regions. In T/ST regions, the pregnancy rates by sexed AI are reportedly the lowest in the hottest months of the year, with less than 15% in cows and 35–40% in heifers (PMID 24048822). We compared sexed AI by depositing the semen into the uterine body (UB-AI, n = 12) versus the unilateral uterine horn (UUH-AI, n = 14) of pre-ovulation heifers. The ovary and follicle were assessed by rectal ultrasound before AI. After insemination, pregnancy was determined by ultrasound at approximately 40 days and approximately 70 days. In the present study, we demonstrated that high pregnancy rates (>70%) by sexed AI in the hottest season in a subtropical region such as Taiwan can be achieved when heifers with pre-ovulation follicles are used. The overall pregnancy rates were 54% higher in the UUH-AI (71%) group than in the UB-AI (42%) group (P = 0.06), examined on approximately 40 days post-sexed AI. Surprisingly, however, the pregnancy outcome appeared to be higher in the hot season (62%) than in the cool season (46%) although this difference was not statistically significant. Based on the present study, we recommend that cattle breeders perform UUH-AI using sex-sorted semen for heifers with pre-ovulation follicles in order to achieve satisfactory pregnancy outcome in the hot seasons in T/ST regions.

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Seasonal heat stress: Clinical implications and hormone treatments for the fertility of dairy cows

Cited by 172 publications

References 127 publications

Prevalence and risk factors for stillbirths in Holstein cows in a hot environment

Prevalence and risk factors for stillbirths in Holstein cows in a hot environment

Climate change effects on livestock in the Northeast US and strategies for adaptation

Artificial insemination of Holstein heifers with sex-sorted semen during the hot season in a subtropical region

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