Nutritional flushing of Sheep

In recent times the economic pressure that sheep farmers have experienced has been detrimental. To relieve the pressure that farmers experience, flush feeding could be used as a management tool to maximize the economic viability of their sheep enterprise. The proper nutrition during the breeding season is key.

Flush feeding

Flush feeding is a well-known term used to describe the purposeful elevation in the level of nutrition of a ewe just before breeding. The aim is to increase the ewe’s weight with the objective of ensuring that the number of ewes that come into oestrus is maximized as well as boosting ovulation, conception, and embryo survival. Increasing these rates increases the lambing percentage by 10% – 20% which in turn is a primary factor that influences a sheep enterprise’s profitability. Ovulation rate and live weight are correlated traits when it comes to sheep but only until a threshold is reached. Research shows that the lambing percentage increases with 1.5% and the ovulation rate by 2% for every kilogram that the ewes in the herd are heavier during mating until of course the threshold point has been reached. Ewes that gain weight during the breeding season are more prone to produce twins than ewes that maintain or lose weight.

Body Condition

The focus for success with flush feeding should shift towards reaching an optimal body condition (BC) before and during the breeding season. The optimal BC falls between 3 – 3.5 on a scoring system of 1 – 5. The effectiveness of flushing is much higher on thin ewes because of their quicker response in body condition. Ewes with above average body condition usually do not respond as well to flushing as thin ewes. Managing the ewes by sorting them into different groups according to body condition could help save a lot of money on feed costs as ewes with above average body condition will need less feed to reach the optimal body condition than thin ewes.

Flushing – When and How

The period of flushing before breeding depends greatly on the body condition of the current herd. A group of ewes with a BCS of more than 2.5 will need about 3 weeks of flushing before mating while thinner ewes will need a longer period. Flushing should continue for another 3-4 weeks into the breeding season. This is to ensure that early embryonic deaths are minimized. Research has shown that continuing flush feeding into the breeding season causes embryo implantation and attachment to the uterus to be more successful, this is due to the increased amounts of energy received through flush feeding. It is of great importance not to continue with flush feeding for too long as it is not economically viable to feed the ewe above her maintenance needs for the rest of her gestation period until a month before lambing. Feeding the ewe to her maintenance needs will be more than enough.


Diet and nutritional changes

During the flush feeding period ewes should be allocated the highest quality grazing to stimulate weight gain and allow ewes to reach their optimal body condition. Ewes need a higher dry matter intake and require an increase in energy which should be the focus point when it comes to the ewe’s diet. As important as increasing the energy in the diet is, it is just as important to have high quality bypass protein in the diet. The next important concept is to have enough feed bunk space to allow all animals to consume the correct intakes when supplementing additional feed. It is important to remember that not one farm or supplemented diet is the same and one should consult with your nutritionist so that the correct recommendations and advice regarding your setup can be given.


Flushing rams

Rams should be flush fed 2 months prior to the breeding season to increase sperm production and testes size.  It takes 2 months for sperm to develop and mature. A bypass protein based flush feed is ideal to start rams on 2 months prior to mating. Rams play a critical role in ensuring a high lambing percentage and for that it is best to keep rams in an optimal body condition (3.5) so that their performance is maximized. Rams should not be allowed to get to thin or to fat. This has a definite negative impact on their performance and on the lambing percentage in the end


(By Andries Kruger, Technical Advisor, AFGRI Animal Feeds)









Flush feeding is an effective aid in sheep farming

By JW van Niekerk, technical advisor, AFGRI Animal Feeds

An aspect that can have a major impact on the effectivity of sheep farming, is an increase in conception rate and fecundity (multiplets). Flush feeding is a management aid that can be effectively used, under certain circumstances, to increase the lambing percentage and

profitability of a sheep farm.

It is well known that animal condition plays a very important role at the start of the mating season. Nutrition (especially flush feeding) during this phase has an important objective – to ensure that the greatest number of ewes reach oestrus, that ovulation rate (ovum secretion) is maximised, and that the majority of ova are fertilised, implanted and developed into viable foetuses to maximise  the lambing percentage.


Adjustment in nutrition


Flush feeding is the term used to describe the adjustment in the nutrition of ewes (and rams) before the start of the breeding season, with the aim of increasing the ewes’ weight.

Ewes were customarily fed less for a period prior to mating in order to lose weight. They were then placed on saved grazing and given an additional flush lick three weeks prior to mating, to quickly

regain their weight. However, research showed that ovulation and conception rates decrease when ewes lose weight shortly before the flush feeding phase, and that it should be avoided at all costs.

Later research indicated that the level of nutrition three weeks prior to mating only has a significant impact if the ewes are not in optimal condition. The goal should be to get the ewes into excellent condition (condition score or CS of 3,5) during mating to ensure an optimal ovulation rate, and thus a high lambing percentage. In addition, if ewes gain weight during mating, they are more likely to produce twins than those that maintain or lose weight.


Flush feeding is a handy aid that can be used to ensure weight gain, thereby maximising lambing

percentage. (Photograph courtesy of Trogtek)


 Higher lambing percentage

 An increase in ovulation rate is already noticeable when ewes are started on flush feeding four days prior to mating. However, the best results are observed in ewes that start with flush feeding 14 to 21 days prior to ovulation, which is then maintained for the duration of the mating period. A good rule of thumb is for the lambing percentage to increase by 1,5% for each kilogram of additional weight the ewe carries during mating.

Ewes in good condition during mating require less supplementation during mid and late gestation, and especially during lactation, as the ewe can utilise her body fat reserves as energy. It is therefore of paramount importance that profitable sheep farming enterprises keep their breeding ewes in the right body condition (CS 3,5) during mating.


Sperm production in rams

 Do not forget the contribution that rams make towards ensuring a high lambing percentage. Flush feeding can help maximise their testes size/volume as well as sperm production. Good nutrition for a period of two months prior to the start of the mating season, can double sperm production. Feeding high amounts of grain must be avoided, as it can adversely affect fertility due to excessive fat deposits in the scrotum, which limits heat exchange.

Breeding rams should receive extra energy rations, especially with a very high level of bypass protein, to maximise the growth of testes and sperm production, as roughly 50% of the dry sperm material is protein.

Make sure ewes and rams are in good condition (CS 3,5) before the mating season commences and that their weight increases during the mating season. Flush feeding is a handy aid that can be used to ensure weight gain, thereby maximising the lambing percentage.




Heartwater can be reduced with an animal feed supplement

Heartwater remains a major cause of loss in cattle, sheep, goats and game animals.

Heartwater is a tick borne disease, caused by the organism, E. ruminantium, characterised by a high fever, nervous system symptoms and the accumulation of liquid around the heart in the chest cavity, lungs and brain, which usually leads to the death of animals. The organism is only about 2µm (two thousandths of a millimetre) in size and is transmitted by the African Bont Tick (“bont tick”) (Amblyomma hebraeum, illustrated below) to susceptible ruminants. When an uninfected tick feeds on a sick animal, some of the heartwater organisms make their way to the tick’s intestines where they further develop. The mature stages of the tick will then transmit the organism via saliva glands to a susceptible animal.


Heartwater has been, and still is, a major cause of loss in production and mortality in cattle, sheep, goats and game animals in South Africa. In areas where the disease is endemic, stock farming was practically impossible before the development of immunisation or therapy. The diagram below is an illustration of the areas across South Africa where heartwater is prevalent.

The active immunisation of calves against heartwater was first described in 1941 (Neitz and Alexander, 1941), when calves under three weeks of age inoculated intravenously with heartwater infected blood showed little or no reaction, but developed a solid immunity to the disease. In the 1950’s Weiss, Haig and Alexander showed that Chlortetracycline and Oxytetracycline are effective treatments against the disease. Heartwater infected blood is inoculated intravenously and when a response commences, a Tetracycline antibiotic is intravenously or intramuscularly administered. This is usually sufficient to render animals heartwater resistant as long as they are continually exposed to re-infection which serves to maintain the immune state. If calves are inoculated before four weeks of age, only about 20% will show signs of fever but all will develop a good immunity. This immunity in calves is of a short duration and calves should be reinvested by the bont tick within the next 3 months. Sheep and goat lambs must be inoculated within the first week of birth with an administration of Tetracycline on day 10 and 12 post inoculation to suppress the disease and immunity will develop. Experience shows that Angora’s do not develop sufficient immunity and farmers in the Eastern Cape should treat animals preventatively every two weeks with Tetracycline. These methods are labour intensive and the process should be closely managed and monitored to prevent losses.

AFGRI Animal Feeds has developed specific licks (protein, production and mineral) which suppress heartwater symptoms and increase immunity to prevent herd losses. A trial conducted in the Eastern Cape with Merino lambs indicated that the control group of a 100 animals needed to be injected intramuscularly with Oxytetracycline to prevent losses every 14 days after clinical signs were first observed. However, the 100 lambs receiving a specific production lick containing ingredients to prevent heartwater, showed no signs of heartwater symptoms developing. These lambs were kept on adjacent lucerne pastures with game animals (bushbuck and kudu) gaining free access across the pastures at night. This ensured that both pastures were infected with the bont tick which spreads the disease. Although no production data was kept, the farmer’s response was that the animal’s growth and wool production increased. In a second trial conducted with Angora goats consisting of ewes, replacement ewe lambs and castrated males, showed that during a two month period on the feed, only two animals showed clinical signs of heartwater and needed to be treated with an injection of Oxytetracycline. A constant and regular intake of the lick plays a major preventative role, however monitoring is required to ensure losses do not occur. The intake of the lick will be determined by the quality and quantity of the veld grazed. Daily monitoring of the lick is required to determine either under or over consumption. AFGRI Animal Feeds technical advisors have the necessary information and expertise to ensure correct recommendations are made.

By using these specialised licks, the loss in production and animals can be limited in an easy and effective manner without major labour cost. It further provides the opportunity to introduce animals into heartwater areas without losses. This technology, if applied correctly, could lead to major changes in farming practises and brings about limitations to the disease.