Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico

Mellado, Miguel; Gaytán, Leticia; Macías‐Cruz, Ulises; Avendaño, L.; Meza-Herrera, C.A.; Lozano, E.A.; Rodríguez, Andrés; Mellado, Jesús

doi:10.4067/s0719-81322018000100106

Cited by 17 publications

(11 citation statements)

References 31 publications

(37 reference statements)

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“…Correlation analysis was used to determine the correlations between THI [10,49] and core temperature, between THI [10,49] and respiration rate, and the correlations between THI [10,49] and skin temperature. According to the correlation analysis between THI and three physiological parameters, the physiological parameter that had a strong connection with the thermal index was determined, and this physiological parameter was used as the dependent variable for creating the ETIS.…”

Section: Data Analysis 231 Correlation Analysis Between Temperature and Humidity Index And Physiological Parametersmentioning

confidence: 99%

“…The stress threshold categories are mild, moderate, severe and urgent. Mellado et al [49] used THI [10] to analyze the pregnancy rate of sows. In their study, when THI < 74, the pregnancy rate was 93%; when 74 < THI < 78, the pregnancy rate was 91.8%; when 78 < THI < 82, the pregnancy rate was 91.4%; when THI > 82, the sow pregnancy rate was 89.8%.…”

Section: Stress Categories (Thresholds)mentioning

confidence: 99%

“…In their study, when THI < 74, the pregnancy rate was 93%; when 74 < THI < 78, the pregnancy rate was 91.8%; when 78 < THI < 82, the pregnancy rate was 91.4%; when THI > 82, the sow pregnancy rate was 89.8%. Following the categorization from the study of Mellado et al [49], heat stress level can be classified as follows: THI < 74 indicates an appropriate environmental level, 74 ≤ THI < 78 indicates mild thermal stress, 78 ≤ THI < 82 indicates moderate thermal stress and THI ≥ 82 indicates severe thermal stress. A relationship between THI and ETIS has been established, and the ETIS defines heat stress thresholds according to the fitting equation.…”

Section: Stress Categories (Thresholds)mentioning

confidence: 99%

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Modeling of Heat Stress in Sows—Part 1: Establishment of the Prediction Model for the Equivalent Temperature Index of the Sows

Cao

Zong

Wang

et al. 2021

Animals

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Heat stress affects the estrus time and conception rate of sows. Compared with other life stages of pigs, sows are more susceptible to heat stress because of their increased heat production. Various indicators can be found in the literature assessing the level of heat stress in pigs. However, none of them is specific to assess the sows’ thermal condition. Moreover, thermal indices are mainly developed by considering partial environment parameters, and there is no interaction between the index and the animal’s physiological response. Therefore, this study aims to develop a thermal index specified for sows, called equivalent temperature index for sows (ETIS), which includes parameters of air temperature, relative humidity and air velocity. Based on the heat transfer characteristics of sows, multiple regression analysis is used to combine air temperature, relative humidity and air velocity. Environmental data are used as independent variables, and physiological parameters are used as dependent variables. In 1029 sets of data, 70% of the data is used as the training set, and 30% of the data is used as the test set to create and develop a new thermal index. According to the correlation equation between ETIS and temperature-humidity index (THI), combined with the threshold of THI, ETIS was divided into thresholds. The results show that the ETIS heat stress threshold is classified as follows: suitable temperature ETIS < 33.1 °C, mild temperature 33.1 °C ≤ ETIS < 34.5 °C, moderate stress temperature 34.5 °C ≤ ETIS < 35.9 °C, and severe temperature ETIS ≥ 35.9 °C. The ETIS model can predict the sows’ physiological response in a good manner. The correlation coefficients R of skin temperature was 0.82. Compared to early developed thermal indices, ETIS has the best predictive effect on skin temperature. This index could be a useful tool for assessing the thermal environment to ensure thermal comfort for sows.

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Section: Data Analysis 231 Correlation Analysis Between Temperature and Humidity Index And Physiological Parametersmentioning

confidence: 99%

Section: Stress Categories (Thresholds)mentioning

confidence: 99%

Section: Stress Categories (Thresholds)mentioning

confidence: 99%

See 1 more Smart Citation

Modeling of Heat Stress in Sows—Part 1: Establishment of the Prediction Model for the Equivalent Temperature Index of the Sows

Cao

Zong

Wang

et al. 2021

Animals

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“…The mean gestation day at the start of treatment (27.0 ± 1.0; mean ± SD) did not differ (P > 0.10) for GHS or GTN or for replicates 1 to 3. The ambient temperature of the GHS chamber was increased so that the maximum temperature, relative humidity (RH), and temperature humidity index (THI; Mellado et al, 2018) cycle (28 to 38 °C; 65% to 88% RH; THI = 81 to 92) was reached on treatment day 6. The ambient temperature, RH, and THI of the GTN chamber remained the same for the entire treatment period (17 to 22 °C; RH 56% to 65%; THI = 62 to 68).…”

Section: Animals Facilities and Treatmentsmentioning

confidence: 99%

Reproduction and reproductive tract morphology of male and female pigs whose mothers were heat stressed during the second month of gestation

Bernhard

Sharp

Safranski

et al. 2020

Journal of Animal Science

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The primary objective was to assess the development of fetal gonads and measure subsequent reproductive capacity of boars and gilts whose mother was either subjected to gestational heat stress (GHS) or thermoneutral (GTN; control) conditions during pregnancy. Gilts were subjected to either GHS (28 to 38 °C; 65 to 88% relative humidity; n = 30) or GTN (17 to 22 °C; 56 to 65% relative humidity; n = 29) for the second month of gestation (a period that coincides with a critical window of gonadal development). A subset of GHS (n = 12) and GTN (n = 11) gilts were sacrificed immediately following treatment for the collection of pregnancy data. The remaining gilts (n = 18 GHS and n = 18 GTN) were allowed to farrow. Female offspring from the farrowed gilts were studied through puberty, first insemination, and early pregnancy when fetal tissues were again collected. During the treatment period, GHS gilts had greater (P < 0.001) rectal temperature and respiration rate at both measurement timepoints (morning and afternoon) compared with GTN gilts. When assessed at the end of the second month of gestation, the total number of viable fetuses did not differ (P > 0.10) for GHS vs. GTN. Likewise, the weight of the fetus, placenta, fetal testes, and fetal ovaries were similar (P > 0.10) for GHS and GTN pregnancies. There was a tendency for an effect of treatment (63.3 ± 2.3 vs. 70.1 ± 2.6; GHS vs. GTN; P < 0.073) on the number of oogonia per histological section in the fetal ovaries. There was no effect of treatment on the number of prespermatogonia per histological section in the fetal testis. For gilts farrowing after treatment, litter size, piglet birth weight, and weaning weight were similar (P > 0.10) for the GHS and GTN gilts. Testes collected from castrated GHS boars had fewer prespermatogonia per seminiferous tubule cross section (P < 0.049). Female offspring from the GHS (n = 30) or GTN (n = 37) sows reached puberty at a similar age and their pregnancies (ninth week of gestation) had fewer corpora lutea (15.6 ± 0.5 vs. 17.1 ± 0.4; GHS vs. GTN; P < 0.038) but the number of fetuses was similar for GHS and GTN. In summary, compared with GTN, GHS during a critical window of gonadal development tended to reduce the number of oogonia in the fetal ovary, reduced the number of prespermatogonia in the neonatal testes, and reduced ovulation rate at first pregnancy in gilts.

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“…Yosuke et al [ 27 ] also studied the effects of THI2 and maximum temperature on the farrowing rate of sows. Mellado et al [ 28 ] used THI2 to analyze the relationship between THI2 and the reproductive performance of sows. When THI2 < 74, the pregnancy rate was 93%, and as THI2 further decreased, the pregnancy rate continued to increase.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Heat Stress in Sows Part 2: Comparison of Various Thermal Comfort Indices

Cao

Zong

Zhuang

et al. 2021

Animals

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Heat stress has an adverse effect on the production performance of sows, and causes a large economic loss every year. The thermal environment index is an important indicator for evaluating the level of heat stress in animals. Many thermal indices have been used to analyze the environment of the pig house, including temperature and humidity index (THI), effective temperature (ET), equivalent temperature index of sows (ETIS), and enthalpy (H), among others. Different heat indices have different characteristics, and it is necessary to analyze and compare the characteristics of heat indices to select a relatively suitable heat index for specific application. This article reviews the thermal environment indices used in the process of sow breeding, and compares various heat indices in four ways: (1) Holding the value of the thermal index constant and analyzing the equivalent temperature changes caused by the relative humidity. (2) Analyzing the variations of ET and ETIS caused by changes in air velocity. (3) Conducting a comparative analysis of a variety of isothermal lines fitted to the psychrometric chart. (4) Analyzing the distributions of various heat index values inside the sow barn and the correlation between various heat indices and sow heat dissipation with the use of computational fluid dynamics (CFD) technology. The results show that the ETIS performs better than other thermal indices in the analysis of sows’ thermal environment, followed by THI2, THI4, and THI7. Different pigs have different heat transfer characteristics and different adaptability to the environment. Therefore, based on the above results, the following suggestions have been given: The thermal index thresholds need to be divided based on the adaptability of pigs to the environment at different growth stages and the different climates in different regions. An appropriate threshold for a thermal index can provide a theoretical basis for the environmental control of the pig house.

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Effect of climate and insemination technique on reproductive performance of gilts and sows in a subtropical zone of Mexico

Cited by 17 publications

References 31 publications

Modeling of Heat Stress in Sows—Part 1: Establishment of the Prediction Model for the Equivalent Temperature Index of the Sows

Modeling of Heat Stress in Sows—Part 1: Establishment of the Prediction Model for the Equivalent Temperature Index of the Sows

Reproduction and reproductive tract morphology of male and female pigs whose mothers were heat stressed during the second month of gestation

Modeling of Heat Stress in Sows Part 2: Comparison of Various Thermal Comfort Indices

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