Superovulatory responses based on ovarian sizes after superstimulation in Thai-Holstein crossbred dairy cows

Rujira Chumchai,Thanaporn Ratsiri,Ruthaiporn Ratchamak,Vibuntita Chankitisakul,Wuttigrai Boonkum

doi:10.12982/vis.2022.005

Abstract

This study was designed (1) to examine the relationship between ovary sides/sizes after superstimulation treatment and ovulatory responses in terms of large follicles, corpora lutea (CLs) numbers, and ovulation rate; and (2) to evaluate the coefficient of determination (R2) as a tool to predict the subsequent superovulatory responses by ovary sizes after superstimulation treatment in the Thai-Holstein crossbreed dairy cows. Data included 33 records from 12 superovulated Thai Holstein crossbreds. Cows were estrus synchronized on day 0 and superstimulated with 400 mg of FSH with decreasing doses twice daily for 4 days. After superovulatory treatment (day 9), the sizes of ovaries were measured and divided into 3 groups by quarters according to the ovarian sizes. Group A (< 816 mm2) ovaries were 25% smaller and group C (> 1449 mm2) ovaries were 25% larger than group B ovaries (816–1449 mm2). On day 9 and 16, there were no significant differences in the average ovary area (p > 0.05). The numbers of large follicles and CLs of group B and C were greater than those of group A (p < 0.05). The ovulation rate did not differ among groups (p > 0.05). The moderate R2 score between ovary size after superovulatory treatment and the numbers of dominant follicles and CLs were calculated (R2 = 0.445 and 0.370, p <0.05) while the beta coefficient (b-value) was positive for both observation parameters. In conclusion, the numbers of large follicles and CLs related to the size of ovaries after superovulation treatment. The moderate R2 score obtained in this study could be indicative of the limited possibility for using ovary size after superovulatory treatment for predicting superovulatory responses

Highlights

Most dairy cattle in Thailand are crossbred between Holstein and Sahiwal or native Thai breeds which aims to get greater milk production from the former together with more tolerant to heat from the latter (Chanvijit et al, 2005)
The b-value was positive for both observation parameters
The numbers of large follicles and CLs related to the size of ovaries after superovulation treatment while there were no significant differences in size of ovaries between left and right side

Summary

Introduction

Most dairy cattle in Thailand are crossbred between Holstein and Sahiwal or native Thai breeds which aims to get greater milk production from the former together with more tolerant to heat from the latter (Chanvijit et al, 2005). Several extrinsic and intrinsic factors including breed (Baruselli et al, 2006), age (Burns et al, 2005; Malhi et al, 2005), gonadotropin preparation (Sumretprasong et al, 2008; Chasombat et al, 2013), route of administration (Bó et al, 2010; Sakaguchi et al, 2018; Ratsiri et al, 2021), and dose used (Nilchuen et al, 2012) affecting superovulation responses have been researched over the last few decades Regardless of those researches, tremendous variation of superstimulatory response continues to be a critical issue in the profitable and efficient implementation of MOET programs (Kafi and Mcgowan, 1997)

Methods

Results

Discussion

Conclusion