Cold and heat climatic variations reduce indigenous goat birth weight and enhance pre-weaning mortality in subtropical monsoon region of China
The subtropical monsoon climate characterized by high or low temperature and humidity can induce cold and heat stress for newborn animals, which results in adverse effect on birth weight and even pre-weaning mortality. However, this early growth performance on indigenous goats is affected by cold and heat climatic environments and is still unclear in subtropical climate. In this study, we continuously measured (July 2011 to June 2016) the birth weight and mortality of an indigenous goat species (n = 530), and collected temperature, humidity, temperature–humidity index (THI) in original farming area, Chongqing, southwest China. As the result, the mean birth weights in cold months (January and February, mean temperature < 10 °C and THI < 56) and heat months (July and August, mean temperature > 29 °C and THI > 76) were significantly lower (P < 0.05) compared to the other months (June and October, mean temperature = 16~25 °C and THI = 61~75). Meanwhile, the birth weight was positively correlated (P < 0.01) with gestational THI from November to May, and was negatively correlated (P < 0.01) with those parameters from June to October, respectively. The maximum pre-weaning mortality, occurring in the 1st month after birth, is 16.17 ± 2.56%. However, when the birth weight was 20% lower than annual average (2.09 ± 0.54 kg), the mortality was significantly enhanced (P < 0.01) to 46%. In addition, cold and heat climates respectively enhanced mortality in the 1st month and 2nd~4th months after birth. In conclusion, annually chronic heat and cold climates could play important roles in lowering birth weight and their survival in subtropical monsoon region. Low birth weight and cold temperature play critical role to contribute the advent of higher mortality after birth. Our results potentially provide the appropriate ranges of temperature (16~26 °C) and THI (61~75) as pregnant goat and kids raising condition to avoid these negative influences.
KeywordsCold and heat stress Temperature-humidity index Goat Mortality Low birth weight
We appreciate the Chongqing key laboratory of forage and herbivore and Chongqing engineering research center for providing data of this study and technical assistance. And we also thank the China Scholarship Council for providing a scholarship fund to the first author.
N.L. and X.C. contributed to the conception and design of the research; N.L., J.W., H.Y., and X.C. analyzed the data and interpreted the results from experiments; N.L. and J.W. prepared the figures and tables; N.L. and X.C. drafted the manuscript; Y.H., Z.Z., Y.Z., and X.C. edited and revised the manuscript; all authors approved the final version of the manuscript.
This work was supported by the National Natural Science Foundation of China (No. 31602021, No. 31772564), the Research and Innovation Project of Chongqing Graduate Students (No. CYB17073), the Innovation Team Building Program in Chongqing universities (CXTDG201602004), and the National Key Research and Development Program of China (No. 2018YFD0502003).
Compliance with ethical standards
This study was approved by the Southwest University Institutional Animal Care and Use Committee (No.  3). All experiments were carried out at the Dazu Black goat farm in Southwest University, Beibei district, Chongqing, China
Conflict of interest
The authors declare that they have no conflicts of interest.
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