Effect of heat stress on the expression patterns of different growth related genes in Malabari goats
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Date
2018
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Academy of Climate Change Education and Research, Vellanikkara
Abstract
The impact of heat stress on growth performance of goats has been established fairly based on changes associated with phenotypic traits. However, not many reports are available on the genotypic traits which get altered on exposure to heat stress in livestock. Therefore, the study is an attempt to elucidate the molecular mechanisms governing growth performance during heat stress in goats. The primary objective of the study was to establish the influence of heat stress on the expression patterns of different growth related genes in Malabari goats. The study was conducted for a period of 45 days in twelve Malabari goats randomly allocated into two groups: MC (n=6; Malabari control) and MHS (n=6; Malabari Heat stress). Goats were stall-fed with a diet composed of 60% roughage and 40% concentrate. All animals had access to adlibitum feed and water and they were fed and watered individually. The MC goats were placed in the shaded pens while MHS goats were exposed to heat stress in outside environment between 10.00 h to 16.00 h. At the end of study period, all 12 animals were slaughtered and their liver tissues were collected for gene expression and histopathological studies. The temperature-humidity-index (THI) inside the shed (74.9) proved that the animals were not stressed while in the outside environment (86.5) the animals were extremely distressed. The hepatic growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1), leptin (LEP) and leptin receptor (LEPR) gene expression patterns were significantly (P<0.05) lower in heat stress group as compared to the control group animals. In addition, negative correlation (P<0.05) was also established between THI and all the growth related gene expression in the study. The hepatic histopathological section showed more fatty and degenerative changes (P<0.05) in hepatocytes in MHS group as compared to MC group. The study offers the first thorough insight into the expression patterns of different growth related genes during heat stress exposure in goats. Further, the study established GH, GHR, IGF-1, LEP, LEPR genes to be the ideal markers to reflect growth potential in Malabari goats. The findings from this study provide some crucial initial information on how different growth relatedgenes are expressed when Malabari goats are subjected to heat stress. This information might be of high value in assessing the growth performance of goats and may provide useful information pertaining to nutrient supplementation to the heat stressed goats.
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174565