An attempt of using public ambient temperature data in swine genetic evaluation for litter-size traits at birth in Japan

Abstract

Context Large-scale genetic evaluation is promising for efficiently improving sow lifetime productivity, and therefore, a reasonable operational model should be pursued to analyse phenotypic data collected from around Japan, where unique seasonality exists. However, the information on establishing the model is currently insufficient. Aims To obtain the fundamental information on using ambient temperature information in developing the model for routine swine genetic evaluation in Japan, by analysing total number born, number born alive, and number stillborn collected at a Japanese farm, together with off-farm ambient temperature measured at the nearest Automated Meteorological Data Acquisition System station. Methods Five repeatability animal models were exploited, considering the effects of farrowing season (Model 1), farrowing month (Model 2), quadratic regressions of daily maximum ambient temperature of farrowing day (Model 3), season and temperature (Model 4), or month and temperature (Model 5). Key results Patterns of the effects of daily maximum temperature of farrowing day estimated using Model 3 were similar to those of farrowing season by Model 1 and those of farrowing month by Model 2. Adding the effect of daily maximum temperature of farrowing day (Models 4 and 5) could explain phenotypic variability better than only considering either of farrowing season or month (Models 1 and 2). Estimated heritability was stable among the models and the rank correlation of predicted breeding values among models was >0.98 for all traits. Conclusions The results indicated the possibility that using public ambient temperature can capture a large part of the phenotypic variability in litter-size traits at birth caused by seasonality in Japan. Implications This study could support the availability of public meteorological data in the development of flexible operational models for future swine genetic evaluation in Japan.

Effect of ambient temperature on average daily gain of pigs evaluated using public weather data and a plateau‐linear regression model

“…According to this equation, ADG is expected to decrease by 12.6 g per 1°C increase in T when T > 21.1°C. Hara et al ( 2022 ) presented a scatter plot of the daily maximum temperatures in barns at the Japan National Livestock Breeding Center's Miyazaki Station and those at the Kobayashi station on the same day. When the daily maximum temperature at the Kobayashi station was 20°C, those at the Miyazaki Station were roughly in the range of 10°C to 20°C.…”

“…This might be due to the seasonal variation in temperature, and there may be a confounding or overlap in the phenotypic variability of ADG, which can be explained by these effects. Hara et al ( 2022 ) reported a positive correlation between the phenotypic variability for total number born, number born alive, and number still born explained by the farrowing season and month and that explained by the daily maximum temperature on the farrowing day (quadratic regression).…”

“…The result would be different when analyzing data collected from multiple prefectures, such as those in northern and southern parts of the main island, because the temperature could vary among them while the effects of season might be assumed to be the same. In such a case, using temperature information might explain the phenotypic variation of a trait not captured by considering the effects of region by season (Hara et al, 2022 ). In the future, the performance of various indicators of heat stress should be evaluated in terms of genetic parameter estimation and breeding value prediction.…”

“…Note that the information about daily relative humidity was not available. Previous studies on pig farms in Miyazaki Prefecture have reported high coefficients of determination (>0.8) between on‐farm and off‐farm temperatures measured at the nearest weather stations (Hara et al, 2022 ; Sasaki et al, 2018 ).…”

“…Previous studies have reported the effects of seasons on production and reproductive traits in Japanese pig populations (e.g., Harada et al, 1992 ; Kakuma, 2018 ; Ogawa et al, 2019 ; Saito & Koketsu, 2009 ), and the observed effects might be related to seasonal changes in ambient temperature. The effects of ambient temperature on female reproductive traits have been investigated using public weather and field performance data obtained in Japan (e.g., Hara et al, 2022 ; Iida & Koketsu, 2013 , 2014a , 2014b ; Sasaki et al, 2018 ). However, few studies have examined the effects of ambient temperature on pork production.…”