A Year in Estonia - Spring

How the lamb’s childhood sets the path for its future

„Breeding sheep must be your passion if you do that“, says Ants. He must know, he has been in the business for almost twenty years. „The first years it cost us more than it brought in. And still a large portion of our income is from the state supplements that we get as organic farmers.“

After years of learning and trial, this breeder eventually chose the Dorper breed. They have good mothering qualities, do not require much birthing aid and, for a breeder of meat sheep very importantly, they have mostly fur instead of wool. This means that they don’t need to be sheared, as they lose their winter coat by themselves – a lot less work.

So I learn that the breed has a huge impact on the financial stability of the sheep breeder. A sheep sold for slaughtering will bring in approximately 80€, as they are usually slaughtered when they reach 40kg and over the last couple of years, the price was at around 2€ per kg of live weight. Selling the sheep to other breeders is more profitable: a six month old breeding ewe can bring in around 150€, a breeding ram even 500€.

Of course, everybody’s goal in their business is to make money. For the sheep breeder this means: He needs sheep who will grow fast, stay healthy, and give birth to healthy lambs every year for as long as possible. And all of that with hopefully as little assistance by the humans as possible. Every spring, during the lambing time, these traits are being assessed. If the ewe needs assistance at giving birth, she will leave the herd. If the lambs are very weak or even have genetic diseases, the ewe is removed. Only those who give birth by themselves to healthy, normal-sized lambs and allows them to drink her milk will stay in the herd.

But what else could help the breeder? This is where I come into play. Our research group has previously shown that certain serum proteins can be measured in calves’ blood during the first weeks of their life, and from those measurements, predictions about their weight gain can be made. Now we want to see if the situation in sheep is the same, and what factors actually influence those proteins. Is it the mother’s colostrum? Is it the intestinal microbiome? Of course, I have to limit my projects, so these are the factors I am mainly going to look at.

Five weeks, that is how long this year’s lambing season on this farm lasts with its 300 breeding ewes. Every day, I am in the stable and collect the information with which I will answer my research questions.

First of all, of course, to measure weight gain, we need to know the lambs’ birth weight. Of the 121 lambs that meet the criteria to enter the study, the average birth weight is 3,37 kg.

I milk some colostrum, that is: the first milk that is rich in immunoglobulins (Igs) and thus helps develop the immune system of the lambs when they drink it. On the following day, I draw a blood sample from the lamb. Later, in the laboratory, I can measure the proteins I am interested in in both of these samples. The proteins are mainly haptoglobin and serum-amyloid A, but I will also measure IgG and the pro-inflammatory cytokines IL-6 and TNF-α. With the help of statistical programs, we can see if the concentrations in the colostrum and the lamb’s blood are associated, thus, if the lamb’s haptoglobin-levels depend on the haptoglobin it receives from the mother.

I have months of pipetting ahead of me.

To study the intestinal microbiome, I take not only fecal samples, but also swabs directly from the rectum, so that I get some intestinal epithelial cells and can make sure there are no environmental bacteria in my sample. With DNA analysis and microscopic examinations, we will find out what is going on the lambs’ guts – and how it changes over time.

My hypothesis is this: All of the lambs get into contact with the bacteria and the parasites in the stable and on the grassland. Those that have a strong innate immune system, which I measure by those proteins haptoglobin and serum-amyloid-A, have it easier to fight those pathogens and later on grow better. And if the statistical analysis that I will perform once the sheep are all grown-up confirms this hypothesis, then I can tell Ants and his fellow sheep-breeders: If you want to know which of your sheep will grow the best, measure their serum-amyloid A in the second week of life!