Ewe lamb mating targets: Liveweight is an important contributor to the success of breeding ewe lambs, with the general recommendation being that ewe lambs should weigh at least 60% of mature bodyweight at time of joining with rams.

Taking large-framed breeds such as Suffolk or Texel crosses with a mature weight of 80kg liveweight for example, this translates to 48kg liveweight at mating. For lighter breeds with a mature weight of 75kg, the target reduces to at least 45kg and 42kg for breeds with a mature weight of 70kg.

Teagasc research on the efficiency of ewe lambs shows that the heavier ewe lambs are at mating, the better the chances of each lamb mated rearing a lamb.

The caveat to this is that ewe lambs should be grown naturally and not excessively fed with concentrates to reach target weights as this can have negative consequences on health and fertility.

The time of year ewe lambs begin cycling will depend both on age and weight.

Lambs born earlier in the year will generally begin cycling earlier (at seven to eight months of age), part of which is due to age and part is due to lambs being a heavier weight. This influence reduces as the year progresses and lambs naturally begin to cycle due to the shortening day length.

Some breeds also begin cycling earlier, with continental breeds cycling earlier than hill breeds. The ram effect, which was discussed in recent weeks, may also help to advance the onset of cyclicity. An easy-lambing sire should be selected and ideally mature rams joined with ewe lambs.

Health precision: A question that cropped up after some of last week’s sheep demonstrations at the Ploughing was if it is beneficial to administer ewes with a combined liver fluke and worm drench in advance of breeding. There should be no reason to treat mature ewes in good health for worms as ewes should have developed a natural immunity and doing so where it is unnecessary will only increase the rate of anthelmintic resistance developing.

If farmers are in doubt about hogget ewes which may have reared lambs or ewes falling below target body condition, then a faecal egg count will quickly denote if treatment is required. A word of caution is also warranted on combination fluke and worm products where used for lambs. Many such products target adult liver fluke, which is not an issue at present. The product choice should at least ensure that immature liver fluke is targeted by the product.

Liveweight of ewes: One of the greatest errors at this time of year is underestimating the weight of ewes. A high percentage of Irish flocks are not of a uniform breed, with a significant variance in ewe liveweight.

Condition will also have a major bearing and it is not uncommon to have a 10kg to 15kg spread in liveweight. The recommendation is to treat to the heaviest animal and to split the weight recommendation where there is a wide range.

Calibration of automatic dosing and injection guns is also a major area leading to under-treatment and an increased risk of resistance. Guns should be cleaned thoroughly after use and calibrated before using and at intervals when high numbers are being handled.