Dairy Goat Reproduction
Understanding the basics of goat reproductive systems will enable you to manage this process better and make better decisions around mating time for your herd.
Breeding Cycle
Signs of Puberty and Cycling
Doelings will reach puberty around 5 - 7 months of age, with bucks showing signs of maturity around 4 - 6 months.
Does
Cycling does will exhibit the following typical behaviours:
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sniffing or preening against other does
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challenging / head butting other does
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riding other does
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standing with their back arched and tail in the air
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calling out to bucks and generally vocalising more
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tail wagging
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urinating more often than usual (noticable in the milking shed).
Does excrete pheromones in their urine and through their hair follicles when they are cycling, sending signals out to nearby bucks. The vulva may also swell and you might notice discharge.
Cycling does often 'go off their milk', meaning they will either not milk well and/or will be unwillinging to come into the shed for milking. If you think cycling is the reason for this behaviour, it is ok for them to miss a mkilking as they will only stay in this state for approximately 1 day (and even if you bring them into the shed they are unlikely to milk well). Just becareful not to mistake a sick goat for a cycling goat.
Bucks
Prior to, and during mating, bucks will headbutt and challenge each other as they compete for dominance. They will lift their upper lips (the flehmen response) when females are near and will sniff, snort and grunt a lot. In the absence of females, the males will ride each other. As they get closer to the mating period they will urinate on themselves. In some instances, the dominant buck will be so busy defending his territory that less dominate bucks are able to seize the opportunity and mate with more of the does.
Mating
In most commercial settings, young does are mated at the age of 7 months, with a 5-month gestation, to have them coming into the milking herd as one year olds. Research has shown that doelings will continue to grow well in their second year, even when lactating. Doelings are given a toxovax injection prior to their first mating to reduce the likelihood of aborting if infected with toxoplasmosis.
Does have a tendency to self-synchronise their heats, meaning it is normal for a herd to have 85% of does kid in the first three weeks of kidding, with the vast majority of those kidding within 10 days of each other. Typically, a farm will have an empty rate of between 3-6% but the rate varies depending on how long the bucks are left in. The decision around how long the bucks are left in for will mostly be dictated by how many does are needed to kid down in the following season, which in turn will be dictated by any desired changes to the herd size, and whether or not the farm will be using an extended lactation system. Under status quo type conditions, bucks would normally be left in the herd for 6 -7 weeks, thus capturing 2 ovulation cycles. Where extended lactation is taking place, the bucks may only be left in for 4 weeks as this will still give sufficient does in kid for the required herd replacement numbers and any empty does can be milked through.
In order to give doelings the best possible chance to get in kid and enter the lactating herd, the bucks may be left in this mob for 12-16 weeks. A similar mating length may be used if an increase in the herd size for the following season is planned and therefore you want to ensure as many does get in kid as possible (thereby reducing your empty rate), Because of the short gestation period of goats (5 months), late kidding does can still easily be ready for mating again at the same time as the rest of the herd in the following season.
Whilst a number of farmers are utilising AI, natural mating is still the predominant method, mainly because AI in goats has a much lower success rate than cows.
Because a doe has a relately short gestation, along with the farmer's ability to somewhat control the feed supply (in an indoor system), there is the opportunity to manipulate the timing of each year's mating to match either the supply of feed (natural grass growth conditions) or the desired milk supply timing. If a farmer wishes to have more milk production before the end of May (the end of the 'production' year), they can delay mating so that more does remain on a higher lactation for longer before they start to dry themselves off towards late lactation. Alternatively, if a quota is in place and is going to be reached early in the production season, mating can be brought forward so that the majority of the dry period falls within the current production year.
Fertility and Conception Rates
The most significant factor affecting goat fertility is nutrition. Does should be at at 2.5 - 3.0 BCS (Body Condition Score) at mating, meaning they should be in good condition, not over nor under weight. Does should be well fed over the mating period. In line with this is overall goat health. Animals who are unwell or have physical ailements such as sore hooves, will have lower conception rates.
Other factors that affect a does fertility and ability to conceive are the time since last giving birth (late kidders will be late cyclers) and a does lactation strength (high producing goats have longer ovulation cycles).
The older a doe is, the lower her conception rate will be. Contrary to this, older does who do conceive, are likely to have a higher birth rate (give birth to more kids).
Because doelings are first mated before they have finsihed growing fully, the heavier they are going into mating, the more likely they are to conceive within the first few rounds of mating. The ideal target range is to have the kids at 85% of the mature weight, so 40+ kgs at mating. It is common for bucks to be left in with the doelings for much longer than the older does to increase the overall likelyhood of them conceiving.
Bucks must also be in good health nutritionally and physically. They will work hard over mating and loose a considerable amount of weight. It is importnat for them not to be fat prior to mating, but we increase the amount of maize grain they receive daily for approximately 6 weeks prior to kidding. Bucks with sore feet, hips or other ailments will not perform well over mating.
The less stress you can create around the time of mating, the more successful your conception rate will be. Do not make significant changes to diets or housing groups within the month prior to mating.
Buck : Doe Ratio
A typical buck to doe ratio is approximately 1:25 - 1:50. If there are too few bucks, they may not be able to cope with th enumber of does cycling together when they synchronise their first heat. If you put in too many bucks, they may end up spending more time fighting and asserting their dominance than servicing the does. Bucks are physically bigger than does so take care to match the buck size appropriately with the does i.e. don;t use a 4 year old buck over your doelings. We find a ratio of 1:35 works well for our herds.
After the first heat cycle. a large proportion of does will conceive. Following this you should reduce the number of bucks in your mob otherwise the remaining bucks will be too hard on the remaining cycling does.
One year old bucks being introduced to the does for the first time take longer to become active. Putting a smaller 2 year old buck in with the group can help 'show them the way'.
Pregnancy Scanning
An experienced scanner will be able to successfully detect a fetus from 6 weeks gestation onwards and in some instances will be able to identify if a doe is carring multiple kids or not, depending on whether you would find this information useful or not.
Using milk samples from routine herd test to identify in-kid does is a very simple alternative way of testing and recording the pregnancy status of every doe in the milking herd. If needed, this can then be followed up by an ultrasound scan 6 weeks later to re-check any does recorded as not in-kid. The downside to this is that any does not lactating i.e. your doelings and any carry-over does, cannot be tested this way.
3 Week-in-kid Rate
The 3 week in-kid rate is used to identify the number of does that became pregnant in the first 3 weeks of mating. A good 3 week-in-kid rate gives more milk early in the milking season and generally results in these does having a higher total Days In Milk rate than other does..
A good 3 week in-kid rate to aim for is around 70 -80 % of your entire herd.
After 6-9 weeks of mating, your total conception rate should be closer to 90-95%
Abortions
Any health factor severely affecting the doe puts her at risk of abortion at any stage of the pregnancy. A doe that aborts an identifiable feotus is said to have 'slipped'.
Does can abort for a variety of reasons. Toxoplasmosis, a disease often spread through cat feaces which leads to contamination of feed, is the main cause of abortions in NZ dairy goats. Vaccinating all doelings approximately 6 weeks prior to the start of mating is highly effective in reducing losses from this bacteria. Does only need to be vaccinated once in their lifetime and if the vaccine is not effective for some reason, and the doe contracts toxoplasmosis, although she will abort, she will develop natural protection for any future pregnancies.
Cloudbursts are also relatively common in dairy goats. In this instance, the doe's body will think she is in-kid, causing the doe to drop in milk production towards the end of the natural pregnancy cycle and may also develop a 'full looking' belly due to a buildup of fluid in the uterus. Cloudbursts are more common in older does and can occur whether the doe has been running with the buck or not. Cloudbursts will get picked up during a routine pregnancy scan. Whilst in this state, a doe is unable to get in-kid, so giving her hormones to abort the membranes she does have inside her will reset her body's natural cycle. If you have a suspec ted or confirmed case of cloudburst pregnancy, discuss this with your vet for assistance. The earlier it is diagnosed and treated, the sooner the doe can get back into a natural cycling pattern again and potentially re-mate within the same mating cycle as the rest of the herd.
Mycotoxins in the feed, particularly within the first 4-6 weeks of pregnancy, create a high risk for abortion. Maize silage, and to a lesser extent, maize grain, carry high risks of mycotoxins. The availability of the new season's maize silage tends to co-incide with the early stage of doe pregnancy. Carefully inspect your maize for any signs of growths and discuss this with your vet. Feed samples can be taken to identify any toxins present and there are a range of nutitional supplements that can be added to the feed to bind any toxins present and/or boost the does natural gut health with probiotics.
Buck Handling
Most bucks are fairly gentle and non-agrresive, but, like all male animals, should be treated with respect. Bucks that are housed inside and/or have regular contact with people are likely to be more settled than bucks that may have been grazing outside when not required for mating. Look for cues from the bucks and give them plenty of space. If confined tightly or they feel trapped, they will look for an escape path - either over a gate/fence - or through you.
It is likely that you are going to want to sort your bucks into smaller groups based on their genetic merit. Having clear ear tags put in while they are young is ideal - assuming they don't loose them over the years. Smaller tags will have a better retention rate but are then more difficult to read, especially at a a distance. Small EID tags allow you to scan the tag without having to get close enough to read the tag, giving you a positive ID on the buck. We aim to place 2 EID tags in each buck - one at birth and the other in the opposite ear when they are about 6 months old, unless they have been identified prior to that point as unsuitable for use as a breeding buck. Collars with tags can also be used, giving good readability of the ID tag as well as something to hold the buck by. Our experience with collars is that rentention rates are low and holding onto the collar creates the risk of your hand being caught in the collar if the buck twists its body suddenly while you are holding it.
Once bucks have been put in with your milking does, you need to decide if you will allow them to enter the milking shed with the does or not. They are quick to learn to stay behind in the pen if you spend a few days drafting them back each time you bring the does in - but they are also quick to learn their is food in the milking shed - so if you don't want them in there, don't let them in even once just to see how they will behave! If you need them out of the housing pen for cleaning, but don't want them to come into the bales, again, you can train them to stay back and then let them out the back of the yard once the does have been milked. If a doe is cycling strongly, you may have difficulty getting them to remember their manners! If this happens, the doe often doesn't want to come in for milking either so it is often better to skip milking the doe and just let them all stay back.
A final word (or two) of warning:
It is important for your bucks to be used to being handled moved and interacting with people but DO NOT let a buck become a pet! Over friendly bucks become an unwitting danger to people as they try to get too close, waiting for a pat or a rub, opening the possibility of the buck getting a little too friendly and trying to jump on or headbutt/challenge the person. Whilst none of this is usually aggressive or otherwise threatening, it can be intimidating and at times, a genuine safety risk.
Dominant bucks will challenge other males - and this does not stop at other male goats. Whilst everyone should be wary of the bucks at all times, men should take particular care, especially around mating time when bucks are more likely to turn and lower their heads in a phyiscal challenge and/or to assert their doninance by urinating on you.
The breeding cycle begins with ovulation and ends when the doe gives birth. The typical ovulation cycle lasts 21 days. If a doe is successfully mated, she will become pregnant for an average of 150 days (5 months). After giving birth, she will go through an anestrous period before beginning to cycle again. For some does this period will be extended until daylight hours start to shorten after the peak of summer but most does will start to cycle again within 2 -3 months post kidding.
A doe will stand for a buck for approximately 36 hours and if successful, the doe will become pregnant. In a herd setting, you can predict your kidding start and end dates based on the dates you put the bucks in with the does and remove them. As mating is a somewhat stressfull experience, a does SCC tends to rise over this time. You can use the peak SCC data from your milk qulaity results to help predict the peak days of kidding.
Bucks can easily be to trained to wait on the yard until the end of milking, rather than coming up the milking bales.
Letting the bucks come up the bales CAN be ok, but they are physically bigger than the does which can cause problems with them getting stuck or breaking rails, and you definitely DON'T want a buck trying to mount a doe while she is up the bales for milking.
'Batman' hanging with the girls
As bucks progress towards puberty, their body structure becomes more thickset, noticeably around the neck area. They will grow tufts of hair on the tops of their heads and under the chin. As bucks continue to mature, they will start to emit a stronger musk-like smell which intensifies around the time of mating.
Young bucks will start to develop tufts of hair as they approach puberty.
Continuosly check your feed for any signs of mycotoxins.