Related Experiment Videos
Interrelationships between energy balance and postpartum reproductive function in dairy cattle
1Department of Animal Science, Cornell University, Ithaca, NY 14853.
Journal of Dairy Science
|March 1, 1989
Summary
High milk production in dairy cows is linked to lower conception rates due to negative energy balance. This metabolic state delays ovarian activity and reduces fertility, impacting reproductive performance.
Area of Science:
- Reproductive physiology
- Animal science
- Dairy cattle management
Background:
- Dairy cow genetic improvement has significantly increased milk yield over 30 years.
- This increased production correlates with a decline in conception rates, from 66% in 1951 to 40-50% currently.
- Conception rates in dairy heifers remain higher, suggesting metabolic demands of high production impact cow reproduction.
Purpose of the Study:
- To investigate the relationship between metabolic demands of high milk production and reduced reproductive performance in dairy cows.
- To explore the role of negative energy balance and body reserve mobilization in delayed postpartum ovarian activity and lower conception rates.
- To understand the hormonal mechanisms, including luteinizing hormone (LH) pulsatility, glucose, insulin, and opioid pathways, influencing fertility in lactating dairy cows.
Main Methods:
- The study reviews existing research on dairy cow production, reproduction, and energy balance.
- It analyzes the physiological consequences of negative energy balance during early lactation.
- It discusses the potential impact of hormonal and neural factors on ovarian function and fertility.
Main Results:
- Negative energy balance during early lactation, caused by milk production exceeding dietary intake, is directly related to delayed first ovulation and lower conception rates.
- Delayed onset of ovarian activity limits the number of estrous cycles available for breeding, contributing to decreased fertility.
- Negative energy balance may impair LH pulsatility, similar to undernutrition, by affecting glucose and insulin availability or through opioid-mediated inhibition.
Conclusions:
- The metabolic demands of high milk yield negatively impact dairy cow fertility.
- Negative energy balance and associated hormonal changes are key factors in reduced reproductive efficiency.
- Managing energy balance is crucial for improving fertility and reproductive performance in high-producing dairy cows.