Poor Fertility in dairy cows (Steady decline in the lifetime productivity…
Poor Fertility in dairy cows
Steady decline in the lifetime productivity of Holstein cattle - number of lactations and age at death decreasing.
Have been some small improvements in the last couple of years but these are minimal
Most likely due to movement from £PIN to £PLI
Nutritional reasons for poor fertility
Negative energy balance
Unavoidable negative energy balance in early lactation
Link between NEB and oocyte quality: lower insulin like growth factor 1, lower leptin, lower insulin, reduced follicular sensitivity to gonadotropins, reduced LH peak and pulsatility.
In short negative energy balance = Infertile ovary
As NEB improves LH pulse frequency improves and Leptin concentration increases
study looking at concentrate levels on hormones - high concentrate levels resulted in higher Leptin, insulin and IGF-1 and lower GH.
Pollution from metabolism of feeds e.g. Fatty acids or Urea
Feeding Fat "poisons embryo"
Feeding protected fat increases concentrations of fatty acids in the blood
Feeding stearic acid in vitro significantly reduced blastocyst function- limiting the ability of the fertilised egg to survive
Low concentrate levels can lead to an increase in fat mobilisation having the same effect as feeding fat
Rumen bacteria need energy and protein in order to make more bacteria, if there is insufficient energy then excess ammonia builds up
This excess ammonia passes across the rumen wall to the liver where it is detoxified to urea
Blood plasma and follicle concentrations of urea mirror each other- in the period leading up to ovulation blood metabolites can gain access to the follicle
Poor feeding programs e.g. highly degradable protein with slow release energy or fast energy release with slowly degradable protein can increase ammonia
detoxifying this takes energy and exacerbates the presence of NEB
pregnancy rates are reduced as urea levels increase - high levels of circulating urea are associated with poorer rates of fertilization and poor development of blastocysts