In high yielding herds, fertility can be compromised due to issues around ‘silent heats’, but there are options available to help combat this. Dairy Farmer reports.
Adding a progesterone insert into a synchronisation protocol could raise conception rates by as much as 43%, says Jim McKinstry, a veterinary surgeon and director of Farmgate Vets, Lancashire.
Mr McKinstry says the extra investment into a progesterone releasing intravaginal device can be useful in combatting problems with ‘silent heats’ in high yielding cows and in heifers.
He says: “As many farmers will be aware, some cows are very good at keeping it a secret when they are on heat. As a cattle vet I scan many cows which are ‘coming on’ in the next 24 hours due to the signs in her ovaries and uterus, but she never shows a standing heat, much to the frustration of the farmer.
To help take the guesswork out of when to serve these quiet cows, there are numerous synchronisation programmes which give a fixed time to serve a cow so she does not have to be seen standing.
Mr McKinstry says: “These synchronisation protocols have been developed over the last 30 years and there are still new concepts developing these days.
“The Ovsynch protocol, a combination of GnRH and prostaglandin injections, is the original synchronisation protocol, developed in 1995, around which we base a lot of our protocols.
“Ovsynch can give a 33% conception rate in a cycling cow which is good compared to a 0% conception rate if a cow is not served. This, however, will be lower for cows which have problems such as cysts, uterine infections or have lost condition pre-bulling, as well as those not cycling.”
Mr McKinstry says that high yielding cows have a lot of blood flowing through their livers carrying metabolites from the rumen to produce glucose for energy production.
He says: “This is vital for milk production, but as well as providing this important function the liver also allows hormones, especially progesterone and oestrogen, to be broken down quickly.
“Therefore, high yielding cows tend to have lower levels of these two hormones which are important with influence on the brain and other vital pathways that have a key role in cow’s fertility.
“Cows which are cycling produce progesterone from the corpus luteum [CL] on their ovary. This is why we like to see big CLs when scanning cows.
“The use of a progesterone device can mimic this natural hormone production and increase circulating levels.”
He adds that progesterone inserts are also useful when synchronising heifers.
He says: “Heifers have a slightly different physiology to cows, so using Ovsynch is not very successful. I find using a protocol with a progesterone insert gives good conception rates in heifers, even when using sexed semen.”
Mr McKinstry explains there are two progesterone devices, which differ slightly, licenced for use in the UK.
He adds that the importance of progesterone in aiding the fertility management in herds should not be underestimated as dairy cows produce ‘more milk and are under more metabolic stress’.
“We need to maximise the amount of progesterone we are delivering in our protocols to give our cows the best chance of getting the all-important tick beside them when they are brought out for pregnancy diagnosis.”
Progesterone has many beneficial effects on the cow to help her to get in-calf, including: