There are four phases of the sheep production cycle that should receive attention if the aim is to increase weaning percentages. These four phases are the flush feeding phase, late gestation, early lactation and of course the weaning phase.

The practice of flush feeding is popular because it leads to a higher ovulation rate and thus an increased lambing and eventually weaning percentage.

Manageable practices

The success of flush feeding depends on the following manageable practices:

  • Flush feeding period: For the best rate of success, it is recommended that flush feeding be given to ewes for at least three weeks (minimum 17 days) prior to mating, so that the weight of the ewes will increase by approximately 100 to 250g per ewe per day and a condition score (CS) of 3,5 is achieved at the beginning of the mating period/season. Flush feeding should be given for a period of three weeks during the mating season, so that two oestrus cycles will fall within this period/stage and each ewe will have the opportunity to conceive.
  • Mating weight: The mating weight of the ewes must be as high as possible without them becoming overly fat. For every additional kilogram added during mating, one can expect a 1,5 to 2% increase in the lambing percentage.
  • Young ewes: Flush feeding is beneficial for young ewes and ensures that they reach the correct bodyweight (60% of their adult bodyweight at the age of twelve months and 80% at the age of 18 months) upon mating to ensure successful conception.
  • Level of nutrition: Regardless of the nutrients provided via the flush feed, the feed must contain a higher level of nutrition in order to bring on the necessary flush effect. If ewes are obese or their nutrition is already of high quality, the flush effect will be too small to have a significant visible effect on the lambing percentage. Likewise, flush feeding will be ineffective when ewes are in poor condition (CS < 2,5). This underlines the importance of condition management in the herd.

Ideal body condition score

The practical recommendation for attaining a body condition score of 3,5 (the optimal CS for good ovulation) upon mating, is to score the ewes six to eight weeks prior to breeding, based on their body condition. Where the infrastructure is suitable, the herd can be divided into groups according to their condition score and their nutrition adjusted to achieve a CS of 3,5 upon mating in the majority of ewes.

A benchmark grouping can be used in each ewe group to determine the average CS. The herd will typically be divided into the following groups: Those with a CS greater than 3,5 which will become overly fat due to flush feeding; those with a CS of 3 that will respond best to flush feeding; and those with a CS of less than 3 that require more flush feeding to improve their condition.

Supplement for a consistent nutritional level

Although any form of improved nutrition such as cultivated grazing or a suitable supplement will provide the necessary stimulus, most natural veld in South Africa is insufficient and will not meet the needs of the ewe in respect of an increased ovulation rate.

The ewe’s needs can be met during the mating season by providing 6420 Nutri Lick Wool Sheep 20 (V 12253) for three weeks prior to the mating season at a rate of 200 to 400g per ewe per day, depending on the quality of the grazing. It is important that this good nutritional level is maintained for a further three weeks after the start of the mating season and even after the mating season itself, as consistent nutritional levels play an important role in allowing the embryo to attach and survive.

When correctly applying flush feeding, once can expect an increase of between 10 and 20% in the lambing percentage, provided that the above requirements are met and the flock’s lambing percentage is not more than 20% higher than the average for the particular breed. – Dr Francois van de Vyver, Nutri Feeds

For more information, phone Dr Francois van de Vyver on 018 011 8888 or 083 419 4562, send an email to fvandevyver@countrybird.co.za or visit www.nutrifeeds.co.za.