A note on the effect of air temperature during gestation on birth weight and neonatal mortality of kids (original) (raw)
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Thermal environment and human birth weight
2002
Human birth weight is known to be in#uenced by several factors, including maternal energy supply, maternal stature, disease status, smoking status and gestation length. This article proposes that the thermal environment may be a further factor in#uencing birth weight. Experimental animal studies demonstrate clear e!ects of thermal stress on placental function and birth weight, but may have limited relevance for humans due to between-species di!erences in pregnancy physiology. Observational studies suggest an inverse relationship between environmental temperature and birth weight within and between human populations. Variation in maternal size, body fatness, pregnancy weight gain and heat production is predicted to in#uence maternal thermoregulatory capacity, as are the size and composition of the foetus. These associations generate the hypothesis that low birth weight in hot environments may in part represent an adaptation to environmental heat stress.
Factors associated with neonatal dairy calf mortality in a hot-arid environment
Livestock Science, 2014
A field study involving 7734 Holstein calves from eight large intensive dairy herds in northern Mexico (261 N; 24.2 1C mean annual temperature; same location) was conducted to determine factors associated with early postnatal (one to 21-d of age) dairy calf mortality. The effects of season of birth, size of dairy operation, birth type (single or twin), sex of calves, type of feeding (milk or milk replacer), herd and temperature-humidity index (THI) shortly before, during or shortly after calving were analyzed by the GENMOD procedure of SAS. The total mortality rate was 14% (range among dairy operations 7.0-29.1%). Mortality of calves was associated with the THI during birth, with a decreased (Po0.05) mortality rate from 16 to 12% with THI above 81 units. Mortality rates were 4 percentage point higher (Po0.05) in winter than all other seasons. Single-born calves had fewer deaths (14%) than twin-born calves (19%). The mortality rate was higher (Po0.05) in male than in female calves (17% vs. 12%). Calves that were born in dairy operations 41800 cows were more likely to die than calves born in smaller dairies. Both respiration rate (74.4715.6 vs. 67.8716.3) and heart rate (119.2719.6 vs. 113.9 717.0) were higher (Po0.05) in calves born in winter than in summer. Rectal temperature was not altered by high ambient temperature and panting was not observed in calves during days with high ambient temperature. It was concluded that in this particular zone characterized by an intense heat load for most of the year, calf mortality was not linked to high ambient temperature around calving, rather, winter weather negatively affected survival of calves. Thus, efforts to protect calves from cold weather would likely alleviate calf losses.
Birth weight and environmental heat load: A between-population analysis
American Journal of Physical Anthropology, 2002
Low birth weight, a major cause of infant morbidity and mortality, is caused by different factors in Western and developing-country populations. In addition to differing in terms of ethnicity, maternal size, maternal nutritional status, and disease load, developing-country and Western populations are also characterized by different environmental heat loads. Thermodynamic theory predicts that heat stress is mitigated by reduced size of both mother and offspring, and therefore generates the hypothesis that reduced birth weight may be an adaptation to environmental heat load. The aim of this study was to test the hypothesis that environmental heat load is associated with between-population variability in birth weight. Data on birth weight and thermal environment were obtained from the literature for 140 populations.
Prenatal heat stress effects on gestation and postnatal behavior in kid goats
2019
Consequences of heat stress during pregnancy can affect the normal development of the offspring. In the present experiment, 30 Murciano-Granadina dairy goats (41.8 ± 5.7 kg) were exposed to 2 thermal environments varying in temperature-humidity index (THI) from 12 days before mating to 45 days of gestation. The environmental conditions were: gestation thermal-neutral (GTN; THI = 71 ± 3); and gestation heat stress (GHS; THI = 85 ± 3). At 27 ± 4 days old, GTN-born female kids (n = 16) and GHS-born ones (n = 10) were subjected to 2 tests: arena test (AT) and novel object test (NOT), the latter was repeated at 3 months of age. Additionally, 8 months after birth, a subset of growing goats (n = 8) coming from GTN and GHS (16.8 ± 3.4 kg BW) were exposed consecutively to 2 environmental conditions: a basal thermal-neutral period (THI = 72 ± 3) for 7 days, and a heat-stress period (THI = 87 ± 2) for 21 days. In both periods, feeding behavior, resting behavior, other active behaviors (explori...
Environmental Health Perspectives, 2021
Research meta-analysis, Chersich et al. (2020) summarized existing evidence on the association between fetal growth and high ambient temperature. They reported that in 18 out of 28 studies higher temperature was associated with lower birth weight, and that in 10 of 16 studies higher temperature was positively associated with LBW, though there was considerable statistical heterogeneity among studies. Zhang et al. (2017) concluded that future studies should focus on more sophisticated study designs than ecological studies, more accurate estimation of temperature exposure during pregnancy, and more efficient methods to evaluate exposure windows, as well as associations between cold temperatures and birth outcomes. Effects of in utero environmental exposures on fetal development (and subsequently, future health) may require exposure during specific phases of development, resulting in distinct time windows of vulnerability during gestation (Barr et al. 2000). Identifying windows of vulnerability to an environmental exposure may shed light on potential mechanisms of effect. Several studies have evaluated trimester-specific associations between temperature and birth weight [see review by Chersich et al.
Exposure to low outdoor temperature in the midtrimester is associated with low birth weight
The Australian and New Zealand Journal of Obstetrics and Gynaecology, 2004
Although seasonal variation of birth weight has been reported previously, contributing factors such as the meteorological factor and its specific period of exposure remain unclear. To investigate the effect of season on birth weight and to determine the meteorological factor and its specific period of exposure which can contribute to any seasonal variation in birth weight. Retrospective analysis of 3333 singleton live births after 36 completed weeks of pregnancy. Maternal age, parity, route of delivery, sex and individual meteorological variables for the first, second, and third trimesters of each pregnancy were analysed using multiple regression analysis with the birth weight as the dependent variable. A seasonal pattern was observed with lowest birth weights in women who had their last menstrual periods in summer and autumn. Upon multiple regression analysis, sex, parity, mode of delivery, and the temperature which the mother was exposed to in the second trimester were the independent determinants of birth weight. Exposure to low outdoor ambient temperature in the midtrimester can be associated with low birth weight.
2022
Introduction: Exposure to high environmental temperature during pregnancy has been associated with lower birth weight, and an increased risk of preterm birth (PTB). The province of Piura is a region with a higher environmental temperature than the rest of the country; however, it is unknown how temperature would be impacting reproductive health in populations exposed to high basal temperatures.Objective: To determine the association between maximum apparent temperature (HImax) during pregnancy with birth weight and preterm birth in newborns in the province of Piura, 2011-2016.Methods: Semi-ecological study, where maternal-perinatal data from Santa Rosa Hospital (N=17,788); and maximum apparent temperature data were evaluated. Four exposure windows were analyzed: the entire pregnancy, and each gestational trimester, which were assigned according to date of birth and gestational age, categorized into quartiles. The association with birth weight was assessed by linear regression; and C...
2016
This experiment evaluated the effects of heat stress across multiple generations. In a previous experiment, pregnant gilts were housed in either heat stress or thermoneutral (control) conditions for the entirety of gestation. Female offspring from those pregnancies (F1 generation) were retained, grown to breeding age and then inseminated. The data collection phase for the current experiment began at farrowing and specifically included: 1) post-farrowing lactational measurements, and 2) measurements of growth and carcass quality of offspring (F2 generation). The weigh-suckleweigh method was used to evaluate the milk production of the F1 generation approximately 19 days after their first farrowing. The results of the weigh-suckle-weigh procedure indicated that milk production did not differ between dams based upon exposure to heat stress in utero. Some aspects of the milk nutrient composition were affected by in utero treatment. Protein content tended to be higher in milk from dams that were heat stressed in utero. Conversely, lactose content was lower in milk from dams that were heat stressed in utero. Milk fat, solids non-fat and somatic cell count did not differ based upon in utero treatment. At the time of weaning, a subset of offspring (male and female) from these litters were retained and grown to slaughter weight in mixed pens under identical management and environmental conditions. Thus, these pigs were the offspring of gestationally heat stressed dams (OgHS) or the offspring of gestationally thermoneutral dams (OgTN). The environment which the dams were exposed to while they were developing in utero did not impact growth of their offspring to market weight. Days of age and live weight at the time of slaughter did not differ between treatment groups, indicating that the number of days needed to reach a similar market weight was not affected by treatment. Interestingly, carcass analysis after 24 hrs post-mortem showed that the OgHS tended to have greater backfat and dressing percentage. There were no detectable differences in loin eye area or lean percentage. The tendency for greater adiposity as indicated by increased backfat thickness indicates that transgenerational effects of in utero heat stress may be diluted, but still evident. These findings suggest that the effects of heat stress on production go beyond the immediate impacts that can be easily measured, indicating that the financial losses associated with heat stress are generally underestimated.