Unlocking your goat herd potential

Artificial insemination (AI) offers the rapid genetic improvement of your entire goat herd that you may never get with a live animal. Artificial Insemination (AI) is the process of collecting sperm cells from a male animal and manually depositing them into the reproductive track of a female to cause a pregnancy. AI technology offers the goat producer an opportunity to achieve rapid genetic improvement of your entire goat herd that you may never get with a live buck.

In natural service, the prospective breeder has only the buck's pedigree to rely on, whereas AI bucks are progeny tested for their transmitting ability of weight gain, growth rate, weaning weights, size, type conformation, fertility etc. With AI, producers can access high-quality genetics from top sires, even if the sires are located far away in other districts, provinces, countries, or continents.

Adoption of AI supports inclusive development - making sure no village, district, or province in Zimbabwe lags behind with goat improvement. Semen from top sires can be used on tens of thousands of does, spread across all the country’s provinces, in a year instead of the actual buck being only able to cover 30 females in a breeding season.

Farmers are encouraged to use AI to introduce new bloodlines into their herd without need to purchase or maintain several bucks. AI makes it possible to use more than 10 different proven bucks in one herd during one breeding season. In this case, the diversity of sires helps reduce inbreeding which often lead to loss of hybrid vigour, reduced size of animals, genetic defects and reduced fertility.

Furthermore, AI is also a time-saving process. When used in conjunction with oestrus synchronisation, AI allows for precise control over breeding seasons, enabling producers to synchronise kidding times, determine most appropriate time to kid in relation to feed availability, making it easier to manage uniform groups of offspring, and align production with market demands.

Last but not least, AI curtails the spread of sexually transmissible diseases (STDs) which causes infertility and low kidding rates among communally bred does. If you’ve ever wanted to upgrade the genetic quality of your flock, but the cost of a live buck was out of your price range, AI is a great way to reach the same goal at a fraction of the price. Further, the constraints faced with a live buck in terms of coverage (buck to doe ratio), is not an issue with AI because one good inseminator can achieve 100-200 inseminations per day as opposed to waiting for the doe to cover 30-50 does over the entire breeding season.

Overcoming disadvantages associated with AI

One of the major drawback of AI is that if not well executed (i.e.correctly timed; use of high quality semen; applied to eligible, well fed and fertile does; and the AI performed by a qualified and skilled technician used), there is the possibility of low pregnancy rates compared to natural mating.

At the Goat Indaba, an event organised by the Goat Breeders Association of Zimbabwe, Dr Paul Chatikobo from the Bindura University of Science Education (BUSE) informed the audience that the university offers training in goat artificial insemination to prospective AI technicians and extension officers and also trains farmers on how to prepare their does for AI with special focus on nutrition, health, and general management of breeding does.

Dr Paul Chatikobo from the Bindura University of Science Education (BUSE) at the Goat Indaba held recently in Harare

The university also runs a BSc Honours in Animal Health and Production Extension degree program targeting holders of diploma in agriculture or animal health. In addition, the University also produces top quality goat semen from a variety of breeds including, Boer, Kalahari Red, Mashona and Matabele. Fresh/chilled semen is are available at price of USD 3.50 per straw.

Dr Chatikobo has many years of practical veterinary and animal science experience in a wide variety of livestock fields and is driven to build resilience and increase productivity amongst livestock producers - in this instance, goat producers in Zimbabwe.

Debunking the myth that AI is unaffordable and that the process is beyond the means of many, Dr Chatikobo outlined the university’s goat genetics improvement project. This project aims to improve the quality of local goat breeds by breeding with superior exotic and selected indigenous breeds through AI, using locally produced buck semen. A rigorous selection process is involved identifying genotypes and crosses that will sustain improved performance under the prevailing production environments and management systems in Zimbabwe. The goat semen production centre is also a gene bank for the preservation of indigenous goat genetics through frozen semen that can stay for 200-500 years.

AI success rate in goats

To achieve success in AI, four groups of factors must be optimised in order to score high pregnancy rates. These are:

• proportion of females in the herd detected in heat and inseminated;
• inseminator efficiency;
• female herd fertility level; and
• semen fertility.

The four factors are multiplied to give an equation that can be used to predict the outcome of AI.

This is known as the equation of reproduction: Pregnancy rate (%) = A x B X C X D,

Where;

A = Heat detection efficiency (%)
B = Inseminator efficiency (%)
C = Doe fertility (%)
D = Semen fertility level (%)

Simple arithmetic shows an important property of the multiplicative nature of the equation of reproduction; namely that when percentages are multiplied, their product is smaller than the smallest factor. For reproductive performance, this dictates that the effect of low performance in a single factor is cumulative, and never is averaged out or counterbalanced.

As an example, the average of three percentages, 40%, 90% and 100%, is 76%. However, the product of these same three percentages is only 36%. This important principle of the equation of reproduction explains why it is so important to note that if one wants to succeed in AI, one has to pay attention simultaneously to all of the factors influencing reproduction.

The equation of reproduction also shows that a competent and conscientious inseminator can’t make up for does that are not in heat or infertile, nor can the inseminator compensate for semen from a low fertility buck. In an ideal situation such as the Herd 1 example below, performance in all four factors is high. The result is a relatively high percent of pregnancies from AI during that time period.

Herd 1
Factor A = 95%
Factor B = 100%
Factor C = 90%
Factor D = 95%
0.95 x 1.00 x 0.90 x 0.95= 81.2% pregnancies from AI

Consider the case of Herd 2 below, where a low percentage of the herd (60%) is detected in heat and inseminated. All other factors remain at ideal levels, but because of a single low factor, the percent of pregnancies from AI is lowered from 81.2% to 51.3%. This specific example emphasises the importance of management to achieve high performance in all of the factors.

Herd 2
Factor A = 60%
Factor B = 100%
Factor C = 90%
Factor D = 95%
0.60 x 1.00 x 0.90 x 0.95= 51.3% pregnancies from AI

Pregnancy rates achieved with AI using chilled semen in goats (65-75%) compare favourably with pregnancy rates achieved with natural service (74%), but, AI offers advantages in rapid and widespread genetic improvement and disease control which we may not get when using a live buck.

Take home message

• This equation shows us that the final result of an average success rate (50%) for each factor is a pregnancy rate of only 6.3% but when each factor is raised to 90%, the pregnancy rate rise to 65.6%;
• The above equations show that good pregnancy rates are achieved only as a multiplicative product of the optimum values of each factor;
• The key message is: with artificial insemination, average score (e.g. 50%) is not good enough;
• A further consequence of this multiplicative relationship between the factors influencing outcome of AI in goats is that improvement of one factor (let us say buck fertility will have little overall beneficial effect on pregnancy rate if any of the other three factors remain at average efficiency;
• On one hand, it takes only one problem to severely decrease the pregnancy rate following AI
• This is what we mean by saying when it comes to artificial insemination, things you do well will not compensate for the mistakes you make. Instead, the mistakes you make in any one of the four factors, cancel out all the things you do well in the rest;

Dr Chatikobo reminded the audience that general herd health was also important to increase doe fertility for AI and this included deworming, dipping, and vaccinations 6-8 weeks before breeding.

Nutrition is very critical in doe fertility. Farmers should start flushing their does (providing extra feeding) 6-8 weeks before AI, maintain high plane of nutrition during AI and continue for the next 6-8 weeks after AI. He added that if goat does were flushed, the chances of twins and triplets would increase.

It is also important for farmers to keep accurate records of heats (oestrus) in their does. Generally, the more heats a doe goes through before AI, the more fertile the doe becomes. A doe that has gone on heat two times is more fertile than a doe that has not been seen on heat.

In order to improve fertility of the does, it is also important to isolate candidate does from live bucks for at least two months prior to AI. If a live buck is allowed to run with does right up to the time of AI, it means he would have impregnated all the fertile does, leaving behind rejects or infertile females for AI. Standard practice for successful AI is to force the buck to come after AI, as a ‘sweeper’.

AI is widely practiced in the cattle industry, as an established practice in dairy and increasingly so in beef production, and Dr Chatikobo reassured goat producers that it was an easier practice to implement in goats. Although mainly used by stud breeders in the past, the technology is now available to both commercial and emerging producers as a way of improving their herds.

Whilst it is a convenient tool as outlined by Dr Chatikobo, breeding efficiency can be optimised with adherence to the correct procedures; and if done correctly, AI can become an indispensable part of modern day goat farming practices to maximise herd productivity.

Sifiso Agbetorwoka, GBAZ Chair at Goat Indaba

The GBAZ has a strong focus on farmer development and promoting inclusive resilience and production growth of this sector. The producer’s aim should be to maximise output whilst using as few inputs as possible and genetics play a significant part in achieving this goal.