Sheep are seasonal breeders. As the day length shortens in autumn (and there is less daylight), sheep come into "season", ie ewes start to ovulate and you'll see testicle size in rams increase. Often a ewe will ovulate just a single egg on her first heat cycle of the season, and as the season progresses is more likely to multiple ovulate, ie have two or more eggs shed from her ovaries. If all these eggs develop and become viable, then they can become fertilised and she could carry twins, triplets or more to full term. Rams have millions of sperm and are unlikely to affect the outcome of this (unless they are sterile, ie no viable sperm).
As the breeding season, ie autumn, carries on and turns into winter we see the highest fertility, on average. So, in the northern hemisphere in places like Canada, UK, Europe and northern USA, ewes start coming into season in late July/August and stay in season until day length begins to lengthen again in late winter (Jan/Feb). In the southern hemisphere, places like NZ, Australia, South Africa and South America, it is the opposite, so breeding typically starts as early as Christmas and goes until March/April. We call the summer period, between the end and the beginning of the next season the "deep anoestrus" period because it's quite difficult to get ewes to cycle at this time.
There are breed differences to seasonality; breeds like the Dorset, Dorset Horn and Merino come into season earlier than other breeds like Suffolk, Hampshires, Cheviot, Romneys and Perendales). Some breeds have a longer season towards the end, like the Finnish Landrace. Crossing a breed that is early with a breed that is later, with selection, can result in a flock with early and late lambing, and these typically work well in an accelerated breeding program (eg Finn/Dorset cross ewes).
If it really doesn't matter when your ewes lamb and you have plenty of feed and/or pasture available in spring, then breeding the ewes at the 2nd, 3rd or 4th cycle will yield the most lambs because you're taking advantage of the increase in fertility as the season progresses. Don't leave it too late or it will start to taper off again.
If you want lambs earlier in the season, to avoid a very sporadic lambing use a teaser ram, or an intact ram with a teaser harness. Have a marking harness on him as well, and monitor how many ewes he mounts each day. He will leave crayon marks on the ewes he mounts. Put him out when you think it is the earliest any ewes may be cycling. Here in NZ just north of Auckland we put teasers out in mid-January. When at least 1/3 are cycling (preferably half), we then feel it's worthwhile putting the breeding rams out. All the ewes that have been marked by the teaser have cycled at least once, and will be bred by your intact rams on their 2nd or later cycle. This will compact your lambing because you won't start too early with too few ewes coming into heat.
The other thing to take advantage of is the ram effect. It is now well known that the presence of rams after a period of absence of rams, brings ewes into season. So if you can, keep the boys far away from the girls for at least a couple of months before breeding season. Then put them in the paddock next door and their lovely odour will attract the ewes and bring them into heat. You'll see the ewes lined up along the fence next to the boys - who is teasing who? So by using a teaser ram, and the ram effect, you'll have more ewes come into season, at roughly a similar time (like within a week of each other, but certainly within a cycle), and if you know the % of ewes coming into heat because you've used a teaser with a marking harness, you can also then reduce the breeding into a single cycle of 17 days. When it comes to lambing all the ewes will then lamb within about 21 days of each other, meaning fewer sleepless nights, and more concentrated effort.
Plan for 10% of your ewes lambing each day with a peak potentially of 15% or more on one or two days (ram effect at work), and then there are no surprises!
This is what we do at Streamland Suffolks. We then use a backup ram about a month later just to clean up any that were missed for whatever reason and most years it is less than 10% of the flock. We get much better control over management of ewes and lambs, lambing, and weaning including weighing, vaccinating, drenching, etc. And this means a better lamb crop and better lambs!
Why drench if you don't have to? When should you drench? And with what? With so many drenches on the market, long and difficult to pronounce names that all sound the same but different, and all this talk of drench resistance ... what to do?
PhD theses have been written about worms, worm resistance to drench, sheep resistance to worms, and pasture management and drenching programs, so we'll only cover a very small bit of it here. Essentially, if you have a worm burden and sheep that have no resistance to worms, you need to drench. As a rule of thumb older animals have more resistance than younger ones (which start out with none), and cows have more resistance than sheep and goats. Worms are more of a problem when it's warmer and wetter, making spring and summer the real problem times of the year, although increasingly we see more issues with worms all year round, at least up here in the north. And Barber's Pole worm is an autumn problem, or has been in the past, now showing up more and more throughout the year.
Ok, so do you drench when you see dirty bottoms? Earlier? How long do you wait? And what drench to use. Well first of all, it's a good idea to chat with your vet about a worm control program. Each area and farm is different, both in terms of worm susceptibility and worm burdens. Your vet can guide you in which products to use when and why. They might even be able to supply you with just enough for your sheep and not have to buy a whole big container if you don't need it.
At Streamland we do a number of things:
So why worry about worms anyway? Well, unless you have resistant sheep (and lambs), worms (except Barber's Pole worm) will cause your sheep to scour. Scouring is too late because the gut damage is done, plus it results in dags. Dags attract flies, aside from being rather unattractive themselves! And flies means flystrike (yet another topic to write about). Your sheep will also lose condition and in the worst case die. It's just not worth it - if you have sheep you need to think about worms and do something about it. Talk to your vet about a good drenching program and about managing your worm burdens.
Sheep are seasonal breeders; the shortening days are the trigger for the breeding season in sheep. Both rams and ewes are affected by this with rams showing little or no interest in the ewes, and the ewes simply not cycling at all. The late spring and summer are the "deep anoestrus" period, the time of year when most sheep will not breed. There are exceptions however, so don't rely on it 100% to keep your ewes from being bred!
So, summer is moving along and we're starting to think about mating the ewes. When to put the ram out? That depends on a few things, including when you want lambs to be born, when you want the lambs ready for the freezer or the market, and of course on the fertility of both ewes and rams. The gestation period of a ewe is 147 days, plus or minus 5 days, so calculate first lambs 142 days from when the ram went with the ewes, and 152 days as the last possible lamb born. We use the calendar on the computer to send us a reminder 142 days after making an entry, or you can use a spreadsheet to put in today's date and calculate when to expect the lambs. There are also some calculators available on the web that do this, but it's quite simple really. Mostly it's about being reminded close to the time!
Most ewes will breed the first time the ram breeds them (he generally isn't interested if they are not on heat), but leave him with them for 2 cycles to be sure. A cycle is 17 days, so 35 days should pretty well cover 2 cycles for all the ewes. We talked about how to determine if they are returning to service in our blog post on readying the ram for breeding. If they are returning you need to determine if it's the ewe or the ram. Usually if it's more than 1 or 2 it's the ram. It's unusual for many ewes to return unless they are very thin or have been affected by something quite serious.
Ewes should be in good body condition and on what we call a "rising plane of nutrition" prior to and during breeding. Too fat is no good, and too thin is no good either. If your ewes are working hard feeding twins, make sure to wean them in time to put some weight back on in time for breeding. If the feed is really good, as it is this year (2012), make them work harder for their feed to keep them from getting too fat. They should be in body condition score 2.5 to 3 when the rams go with them, and continue on reasonably good feed for at least a month after. After that you're feeding her and a lamb or 2 inside so you won't be able to cut back too much on the feed quality. Watch for a post later on managing the ewe through gestation and closer to lambing.
The ram can be easily forgotten if he's out in a back paddock with the old horse, or mowing the grass behind the sheds. It's a good idea to start taking a look at the old boy well before you plan to put him out with the ladies.
What are we looking for? Well, firstly make sure he's healthy and not carrying any injuries, eating well and in good body condition. Some rams will spend a lot of time courting and not eating once out with the ewes so having him in good body condition prior to mating will see him through getting the whole job done. I like to see them quite smooth on the backline with no backbone showing if he's shorn, or that you can't feel it if he's not. Don't worry, in 6 weeks time he won't look the same! Make sure his feet are good and he's walking well. It's hard to do the job if you can't get up on those two back legs. He should also be breathing easily, no snotty nose or rasping.
Next, make sure his breeding parts are in good order. Check the sheath to make sure it's not infected or inflamed. Palpate the testicles to ensure no swelling or tenderness. It's normal for the testicles to enlarge and hang lower during the breeding season, particularly on hotter days, but any swelling can be a sign of injury. If there has been injury to the testicles it can take several weeks for sperm to be viable again.
Breeding time has arrived and you're about to put the ram out with the ewes. Have you thought about using a ram harness? At Streamland Suffolks we use ram harnesses on all our rams so that we can see which ewes have been serviced and when. Changing the ram and the colour on the harness is also a good idea if you want to know how many have returned. You should have a very low return rate if your ram is doing the job and your ewes are healthy. A high return rate would suggest there is a problem with the first service ram. If you only have one ram, change the harness colour anyway so you can see if there are any returns. If there are many or all returning, it's probably not too late to get another ram. Better than missing an entire year! If you only have a small number of ewes you can record their numbers and when they were mated and work out when to expect the lambs.
147 days later, plus or minus 5, brings the most exciting time of the year on the farm. The anticipation of who will produce what lambs! Oh and did I mention the ram is half the flock?
When lambs are born they are extremely vulnerable to the elements, particularly wetness or wind. They can cool down very quickly, lose their mobility and not get that all important first suck of milk, and before you know it ... a year's effort wasted (for that ewe anyway).
A good mother will turn, get up and lick her lamb, gurgling and talking while she is licking. Licking stimulates blood flow and the talking stimulates a response from the lamb. The lamb will try to get up and reach the teats for a suck. Good mothers almost seem to encourage this!
The earlier lambs suck the better chance of survival they have. This is especially true with twins where there is a time the first lamb is on it's own while the ewe is having the second lamb. Good mothers don't ignore their first lamb during the process, continuing to talk and reach out to it while lambing the second lamb. However if the first lamb has already had a drink it's in good stead while waiting for it's sibling to be born.
Good mothers also stay close to their lambs and the place they lambed at for longer. There is research that shows this results in higher lamb survival. Ewes that talk to their lambs, stay close, and get them fed are less likely to lose sight of their lambs, or to have their lambs walk off in search of a mother.
So yes, absolutely, good mothering makes a big difference.
Does the ram make a difference how many twins and triplets he produces? Well, not really. Rams produce 100's of 1000's of sperm, more than enough to produce sextuplets every time, but they don't because it's not up to them.
Twins, triplets or quads are generally the result of multiple ovulation by the ewe. Some ewes produce more than one egg each time they come into heat, and if these make it to term the result is twins, triplets or more. Some breeds are more "prolific" (produce more offspring per ewe) than others, and this trait can be selected and improved by keeping the offspring of ewes that produce twins or triplets.
What role does the ram play? As we've said before, the ram provides 1/2 of the genetics to each lamb. If the ram has twinning in his pedigree, that is if his mother produced many sets of twins or triplets, his father's mother produced twins or triplets, and so on, then chances are very high that his female offspring will also produce twins or triplets. Since rams don't ovulate (produce eggs), we can't measure directly their twinning capability like we can in the ewes where we can see and count how many lambs they produced. So in rams we have to look at their female relatives to make inferences about their genetics for twinning.
If you want to produce twins, you need to keep the female offspring from ewes and rams that have twinning in their pedigrees, and in the case of the ewe that she produced twins regularly.
Another good indicator of twinning potential is early fertility. If a ewe produces her first lamb or lambs when she is a yearling, she is demonstrating early fertility. Many of these will go on to produce twins as 2 or 3 year olds and older. If a ram is born as a single to a ewe lamb, look at her mother to see if she has twinning in her performance history. Also ask about the ram's sire's mother to see if she has twinning in her records.
The old saying "you get what you pay for" is certainly true when it comes to rams. Sure, sometimes you can get lucky and pick up a bargain but most of the time if you buy a ram from the saleyards you're buying someone else's rubbish or problems.
The "ram is half the flock" - and this saying is absolutely true. Every lamb gets half of it's genetics from the ram, so it should be at least as good as the ewes and preferably much better. Why? Because to find one good ram is much easier than to find a whole flock of good ewes! Think of it this way; if you have 100 ewes and 100 rams to choose 60 ewes and 2 rams, you'll have to pick at least 10 ewes that are below average but you can get 2 of the best rams!
You can improve your flock by buying good rams that are much better than your ewes and keeping their female offspring as future breeding ewes. If the rams are not much chop the ewes they produce won't be much chop either. Then what?
So get a good ram and you'll produce good lambs, whether it be for eating or breeding. The qualities of a ram for those purposes might differ, but either way it should be a well-bred ram produced by a reputable breeder that backs their claims up with data and pedigrees.