Hormonal and mineral impacts on bone compositionand reproduction
AUTHORS: Wieteska, M., Creedon, L., Hession, Department of Mechanical and Electronic Engineering, Institute of Technology Sligo.
Failure to reproduce greatly affects the cost-effectiveness of animal production. Over the last 30-50 years there has been a recorded drop in the number of cows inseminated successfully. The crucial factor of successful insemination is the time of insemination: cows should be inseminated approximately 20-30h after occurrence of the first symptoms of the heat.
There are several factors accountable for this; including cows’ physiological capabilities, health problems to which they are exposed, inadequate nutrition to volume of lactation, improper balance of minerals, macroelements and vitamins (especially vitamins A and E) as well as errors in maintenance, mainly due to lack of movement, insufficient amount of light available.
Macro and microelements, for instance iodine and calcium concentration available in a cow’s forage also affects bone remodeling activity.
The study will be conducted on cattle. Blood samples will be taken during a 15 week period (7 weeks before and 8 weeks after calving). Several parameters will be studied, such as level of iodine, calcium, concentration of leptin, progesterone, oxytocin, IL-1 and pH of blood.
In addition the following will also be assessed: BCS (Body Condition Score), day length, THI (Temperature-Humidity Index), recorded cow breed, productivity, age, milking frequency, number of lactation, maintenance condition, synchronisation programme used and drugs administrated.
Throughout this period conception and pregnancy maintenance (embryo mortality) rate will be monitored.
In parallel the bone remodelling rate will be assessed by measurements of bone formation biomarker (propeptide of type 1 collagen) concentration.
EXPECTED RESULTS AND DISCUSSION
The aim of this research is to create a mathematical and statistical model to predict reproductive parameters and their impact on bone remodelling.
An impact of inflammation (concentration of IL-1) on both reproduction results and osteoclasts formation rate in bone would suggest that factors influencing occurrence of silent heat and obtained reproduction results may have an impact also on the bone remodelling rate.
The model will allow calculation of the exact time when insemination (AI) should be performed. This model will answer to what extent particular factors contributing to reproduction results in cattle, affects the bone remodelling rate.
 Bó (et al), Theriogenology, 65(1):pp 89-101. 2006
 Orihuela, Applied Animal Behaviour, 70(1):pp 1-16. 2000.
 Yadav (at al) Cell, 138:pp 976-989. 2009.