Effect of Chromium Supplementation on Endocrine Variables in Summer Exposed Murrah Buffaloes (Bubalus bubalis) Calves

Summary

In present study, we elucidate the effect of chromium (Cr) supplementation on the endocrine variation, plasma glucose and Cr concentration in summer exposed buffalo calves. Twenty-four female buffalo calves, either received a basal diet devoid of supplemental Cr (control) or were supplemented with 0.5, 1.0 and 1.5 ppm trivalent Cr from an inorganic source CrCl₃.6H₂O. Dietary Cr supplemented buffalo calves had low plasma concentration of insulin, glucose and cortisol during summer season. In contrary, plasma Cr concentration increased with increased dietary Cr levels. However, thyroid hormones showed no alteration in their plasma concentration among different groups. In conclusion, dietary addition of Cr improved glucose utilization and reduced stress in summer exposed buffalo calves.

Keywords: Buffaloes, Chromium, Summer exposed, Endocrine variables

Introduction

The effects of heat stress are costly to dairy farmers due to reduced performance of farm animals specially crossbred and buffaloes. Buffaloes exhibit signs of great physical distress when exposed to environmental stress as compared to other farm animals (Das et al., 1999). This is due to fact that their body absorbs a great deal of solar radiation because of their dark skin and sparse coat or hair. In addition, they possess a less efficient evaporative cooling system due to their rather poor sweating ability. Exposure of animals to heat stress increased the production of adrenal cortisol (Kim et al., 2009) which antagonizes synthesis, release and action of insulin hormone. In domestic animals, Cr has been recognized as a newer essential trace mineral (Anderson, 1987) and suggested to alleviate stress-associated effects (Garg, 2000).

Materials and methods

Twenty four female buffalo (Bubalus bubalis) calves were selected from the herd of National Dairy Research Institute, Karnal and randomly assigned to four treatment groups (n= 6) and fed for 120 days. Calves either received a basal diet devoid of supplemental Cr (control) or were supplemented with 0.5, 1.0 and 1.5 ppm trivalent Cr from an inorganic source CrCl₃.6H₂O. Peripheral blood samples were collected at days 0, 15, 30, 45, 60, 75, 90, 105 and 120 post-supplementation of Cr for estimation insulin, glucose, cortisol, thyroid hormones and Cr level.

Insulin was determined in plasma of calves by "bovine insulin ELISA test kit" (ERK B1009, Endocrine Technologies, New York, USA). Plasma glucose was quantified by glucose oxidase method with the use of an enzymatic colorimetric assay (Trinder, 1969).Cortisol was determined by "cortisol EIA kit" (Cayman's Chemical Company, Ann Arbour, Michigan, USA). Cayman's cortisol EIA kit is a competitive assay that can be used for quantification of cortisol in plasma. The T3 and T4 hormone concentrations in plasma were estimated by radioimmunoassay (RIA) using ISOPHARM kits (Bhaba Atomic Research Center, Bombay, India). Plasma Cr level was estimated by using atomic absorption spectrophotometer (Model Z-5000, polarized Zeeman atomic absorption spectrophotometer (AAS), Hitachi High-Technologies Corporation, Tokyo, Japan).

Results

Plasma levels of insulin, glucose, cortisol, thyroid hormones and Cr in buffalo calves fed on diet supplemented with Cr is presented in Table 1. In present study, plasma insulin and cortisol levels were found significantly low (P<0.001) in 1.5 mg of Cr/kg DM fed buffalo calves. However, dietary addition of Cr in summer exposed buffalo calves did not had any effects on plasma concentration of T3 and T4 hormones. Plasma glucose had negative and plasma Cr had positive correlation with dietary Cr levels. As the level of Cr supplementation increased, level of plasma glucose decreased (P=0.020) and plasma Cr increased (P=0.031).

Conclusion

Dietary Cr supplementation reduced stress by reducing synthesis and release of cortisol during summer season. Supplementation of Cr in summer exposed buffalo calves also increased efficiency of glucose utilization by increased potency of insulin to words its receptors.

References

Anderson RA (1987) Chromium in trace elements in human and animal nutrition, 5th edn. Academic, New York, pp 225

Das SK, Upadhyaya RC, Madan ML (1999) Heat stress in Murrah buffalo calves. Livest Prod Sci 61:71--78

Garg MC, Bansal DD (2000) Protective antioxidant effect of vitamins in streptozotocin induced stress in diabetic rats. Indian J Exp Biol 38:101--104

Kim BG, Lindemann MD, Cromwell GL (2009) The effects of dietary chromium (III) picolinate on growth performance, blood measurements, and respiratory rate in pigs kept in high and low ambient temperature. J Anim Sci 87:1695--1704

Table 1. Effect of Cr supplementation on endocrine variation, plasma glucose and Cr levels

Parameters	Supplemental Cr (mg/kg of DMI, ppm)				SEM	P-value
	0	0.5	1.0	1.5		Group (G)	Period (P)	GxP
Insulin level, ng/ml	1.87b	1.84 b	1.86b	1.76a	0.04	<0.001	0.089	0.999
Glucose level, mg/dl	58.80c	56.28b	54.57a	53.33a	4.17	0.020	0.440	1.000
Cortisol level, ng/ml	4.38b	4.45b	4.52b	3.82a	0.15	<0.001	0.110	1.000
Thyroxine (T4), nmol/l	68.97	71.48	70.93	73.48	6.66	0.431	0.534	0.667
Triiodothyronine (T3), nmol/l	1.68	1.86	1.79	1.93	0.03	0.114	0.133	0.826
Cr, ppb	0.21a	0.29a	0.40b	0.43b	0.01	0.031	<0.001	1.000

Means bearing different superscript differs significantly (P<0.05) and treatments by time interactions were not significant (P > 0.50).