by Vlok Ferreira

Feed, tease and succeed

How to ensure a high ovulation rate in your ewes during mating

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It is that time of the year again when sheep farmers start thinking about flushing ewes that will be put in with the rams during November. The success and profitability of sheep farming for wool as well as slaughter lamb production are largely determined by the percentage of marketable lambs. A high body mass at mating (static body mass) and an increase in body mass (dynamic body mass) of ewes during the mating period, ensure a high lambing and thus weaning percentage (weaned lambs per 100 ewes mated).

Prior to mating

From February to May maximum ovulation takes place. The highest conception rate and lambing percentage will be achieved during these months when the natural sexual activity of the flock is the highest.

For maximum conception of young ewes, they must reach a critical body mass of at least 70% of mature body mass on mating; whether they are 10 or 14 months old is of lesser importance.

Ewe lambs that experience nutritional stress during the first few months of their lives will have a lower ovulation rate and produce fewer lambs during their lifetime than ewe lambs that have received optimum nutrition.

To ensure maximum conception and a high lambing percentage, ewes must be in an excellent condition at mating, namely with a condition score of 3.5 on a scale of 1 (very thin) to 5 (over fat). For every extra kilogram increase with mating, a 1.5 to 2% increase in lambing percentage can be expected.

The function of flush feed to enhance ovulation rate

Three weeks before mating, ewes can be given flush feed that will cause a higher ovulation rate and thus lambing percentage as a result of the increase in feed intake (200 – 300 g/ewe/day) and mass.

To prevent resorption of the embryo, ewes should be given the same level of nutrition for at least three weeks after mating.

Flush feed has very little or no effect if it occurs longer than four weeks or shorter than two weeks before mating.

Flush feed increases the lambing percentage with 10 to 20%, provided the lambing percentage of the flock is not 20% higher than the average of the specific breed in a specific area.

The specific feed used as flush feed must contain protein, energy, minerals and trace minerals.

The most economical application of flush feed is to divide ewes according to condition, into two groups (good and thin condition) approximately six to eight weeks before mating and to adapt the nutritional level in such a way that both groups are in a good condition on mating.

Examples of flush feed supplements

  • Molatek Master 20 at 250 to 350 g/ewe/day;
  • Molatek Wool Sheep Lick 28 grain mix (50 kg Wool Sheep Lick mixed with 50 kg maize meal) at 300 to 400 g/ewe/day; or
  • Mix Molatek Wool Master Concentrate 500 kg + 400 kg grain + 100 kg salt for a production lick and provide at 300 to 400 g/ewe/day.
  • Epol Super Lamb and Ewe pellets at 300 to 500g/ewe/day.

The use of teaser rams to increase ovulation rate

For effective stimulation by teaser rams, ewes should have no contact with rams (this includes seeing, hearing and smelling the male animals), for at least 34 days, but preferably three months, before the mating period.

When mating takes place during the early summer months, it happens that only a small percentage of ewes are already in estrous cycle and only approximately 2% per day are in heat. The presence of rams stimulates the ewes that are not in cycle yet, which causes an increase in the secretion of follicle stimulating hormone, so that a large number of ewes will come into heat 16 days later.

Above-mentioned problem can be prevented by making use of 2 to 3% teaser rams. Teaser rams are placed with the ewes for nine days before the breeding rams are introduced. As there are 6 to 8% ewes in heat for 2 to 3% rams from the beginning, it prevents unnecessary fighting amongst rams. Also always use teaser rams with a high sexual drive.

Very important

Rams should be in a good condition two to three months before mating already, to ensure good testis development and sperm production. This will result in maximum conception and lambing percentage.

Dr Vlok Ferreira,

National Technical Manager Ruminants, Molatek, RCL Foods

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