PHYSIOLOGICAL, BEHAVIOURAL AND MOLECULAR CHANGES IN PIGLETS IN RESPONSE TO WEANING STRESS
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Date
2018-07
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College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati
Abstract
The present experiment was conducted to study the effect of weaning stress on various physiological, biochemical, hormonal, hematological response including behavioural changes and pattern of gene expression profile of HSP27, HSP70 and HSP 90 in piglets weaned at different age. The present investigation was carried out in Hampshire x Ghungroo cross-bred piglets of instructional farm of NRC on pig, Rani. Three litters of six piglets were taken for the study and were weaned at different age of 28 days (Gr-I), 35 days (Gr-II) and at 42 days (Gr-III).
Blood collection was scheduled from the day of weaning (0d) , 7th day, 15day followed by subsequent collections at 15 days interval up to six months of age. Physiological and behavioural studies were done at the piggery farm and molecular studies were done in the laboratory of NRC on pig, Rani whereas biochemical, hormonal and hematological studies were conducted in the laboratory of the department of Biochemistry, Nuclear research laboratory of the department of Physiology and in the laboratory of Teaching Veterinary Clinical Complex of C.V.Sc., Khanapara, Guwahati respectively.
No significant difference was found in average growth rate and body weight at maturity among the groups. There was significant difference in rectal temperature (day 30, 45 and 60) and respiration rate (day 0 and 15) found between Gr-I and Gr-II. The mean heart rate (beats/ minute) was found towards decreasing trend in all the groups.
The level of biochemical indices were found to be varied within normal range on day 15 post-weaning and the variations in the level in later part were found to be associated with hormonal level and age related. Higher level of phosphorus was found in piglets of Gr-III as compared to Gr-I and Gr-II. During the initial phase of experimental period significantly lower level of iron was found in piglets of Gr-I as compared to Gr-II (day 15 and 30) and Gr-III (day 0 and 15). Significantly higher level (P<0.001) of zinc was found in Gr-III as compared to Gr-I and Gr-II from day 75 onwards. Significantly lower level of copper was found in Gr-II as compared to Gr-I and Gr-III on day 15 and 30 which may be the cause of subnormal hemoglobin level (%) in this group during this period. The range of cortisol level was comparatively higher throughout the experimental period.
Significant differences (p<0.001) were found in the level of hematological parameters viz TEC, Hb% and PCV between younger and older pigs on day 0 to 45. Significantly higher level of neutrophils and cortisol were observed in younger piglets. Initially, there was increase in neutrophil (%) and decrease in lymphocyte (%) indicating a stress response on day 15 post-weaning in all the groups, with significantly higher level in Gr-I. The mean values of DLC viz. neutrophil (%) (day 15, 30, 45, 60, 75, 90) and lymphocyte (%) (day 30, 45, 60, 75, 90) were found to be significantly higher and lower respectively in Gr-I as compared to Gr-II.
Significantly higher number of feeding bouts (P<0.05) and higher level of aggression (P<0.05) on d+2 and d+7 was observed in Gr-III compared to Gr-I and Gr- II
The level of mRNA expression of HSPs viz; HSP27, HSP70 and HSP90 were found to be increased significantly (P<0.001) on day 7 in piglets of Gr-I. Significantly higher level of mRNA of HSP90 was expressed in Gr-I on day 15 as compared to piglets of Gr-II and Gr-III` indicating that adaptive process were slower in younger piglets.