Rhythmicity of follicular growth and plasma hormonal level in low and high producing dairy cows

ABSTRACT

Blood samples were collected from the 18 healthy crossbred low producer (Group I) and high producer (Goup II) cows on day 7, 14, 21, 28 postpartum. Plasma progesterone, cortisol and immunoglobulin (Ig) levels were measured and follicle growth rhythm was examined by ultrasonography on days 30, 45 and 60 of lactation. The size of the ovary and follicles number were recorded from both the groups of cow. Plasma progesterone level varied between the groups (p < 0.05), week (p < 0.01) and animal. Mean plasma cortisol level did not vary between the groups, however, total Ig level was higher (p < 0.01) in high producing than the low producing group in III and IV fortnights of the experiment. The size of follicles increased (p < 0.05) in both the groups of cows with the increasing days in lactation. Size of follicle was more (p < 0.05) in high producers than the low producers. However, the number of follicles and the conception rate (89 vs. 78%) were non-significant in both the groups. The cows of high producing group conceived with less number of AI/conception than the low producers. Plasma progesterone level did not indicate any set pattern of change in both the groups. High producing cows have high cortisol and total Ig levels in comparison to low producing cows. Growth pattern revealed significant differences in the size of follicles in low and high producing cows, while the number of follicles and conception rate did not differ.

KEYWORDS:

• Hormones
• ultrasonography
• immunoglobulin
• follicular development
• crossbred cows

Acknowledgement

The authors are thankful to the Director, National Dairy Research Institute, Karnal Haryana for providing the necessary facilities to conduct this experiment. We are also thankful to the Board of Research in Nuclear Science (BRNS) Mumbai, India for providing the funds under project no. 2013/35/48/2013-RTAC.

Disclosure statement

No potential conflict of interest was reported by the authors.