Some factors are beyond our control but there are steps we can take to increase fertility and reduce embryo mortality
There are tentative signs that the 2020 breeding season is going to be one of the best yet.
Anecdotally, farmers seem to be very impressed with conception rates to first service.
Obviously, there won’t be an exact figure until scanning is carried out, but based on the number of repeats, a lot of farmers I have talked to are quietly confident of an excellent six-week in-calf rate this year.
I was chatting to a farmer recently about dairy cow fertility and he made an excellent point.
“Getting the calf out isn’t the problem, it’s getting him in there in the first place that’s the tricky bit,” he said.
By now, all cows in a spring-calving herd should be submitted for AI. Any non-cycling cows should be scanned by the vet and treated in order to get them in heat ASAP.
Once the cows’ ovaries are functioning normally and the uterus and cervix are healthy, we must turn our attention to external factors that can influence conception rate.
IBR can cause a drop in milk yield, pneumonia-type symptoms and a high temperature.
A cow served at the beginning of May has a potentially 30-day-old embryo growing in her uterus. This embryo is exceptionally delicate and will often be the first thing to suffer when IBR infection develops.
It is very important to ensure that your IBR vaccination is up to date. Ask your vet if in any doubt, as there are varying protocols surrounding the use of live and dead vaccines that can be confusing.
IBR is similar to the cold-sore virus in that it can hide out in the animal without any signs. If the vaccine runs out in the middle of the breeding season, IBR can rear its head, with devastating results.
Tick-borne fever is a disease that we have been seeing more commonly in recent years. The very warm weather following on from a relatively damp spring has made for ideal conditions for ticks.
Signs of the disease include a high temperature, increased respiratory rate and sometimes a cough. Similar to IBR, embryo loss is a very common side-effect.
There is no vaccine against tick-borne fever. Prevention is achieved by using a pour-on that has specific action against ticks throughout the risk period.
Leptospirosis can also cause embryo loss. Vaccination should have been completed prior to the start of the breeding season.
Historically, protein was supplemented in the milking cow’s diet as it helped improve milk quantity and quality.
However, some studies have shown that excess protein can have a negative effect on reproductive performance and fertility.
Excess protein requires additional energy to break it down, which can exacerbate a state of Negative Energy Balance in the cow.
Excess protein also leads to excess urea in the blood stream. Increased urea levels are detrimental to embryo development.
Some of the urea is excreted in milk, which makes milk urea level a good indicator of excess protein in the diet.
A sudden increase in milk urea level or a level consistently above 35 has been linked to embryo death. A milk urea level of 20-35 is advisable.
Your nutritionist and your vet are well placed to advise you on the level of protein that should be fed to your milking cows. This should be based on cows’ body condition, milk solids, and milk yield and milk urea level.
We have been blessed with some wonderful weather over the past week for silage and hay making — 27°C has been seen in some parts of the country.
Poor grass growth is not the only down-side to excessive temperature, however.
Heat stress causes an elevation of body temperature, resulting in early embryonic death.
High-yielding cows are most at risk but it can affect all types of cows.
Heat stress can be avoided by ensuring cows have somewhere to shelter from the sun during the warmest part of the day.
It is also vital to have an adequate supply of fresh clean water during warm weather as cows demand greatly increases during warm weather.
Don’t neglect yourselves either during this warm spell. A bottle of water should be in one hand and a bottle of sunscreen in the other.
There’s enough to be stressed about in the world at present without heat stress.