With strong lamb prices, the decision whether or not to breed from ewe lambs to boost flock output has rarely been more important.
Delaying breeding until the second year has obvious advantages – it is easier to ensure ewes are happy enough for tupping; fertility is generally better and management around lambing can be easier. However, delayed breeding brings additional feed costs without generating any income to offset these costs.
Breeding replacements as ewe lambs can be equally as successful as breeding from adult ewes but the approach to feeding management during pregnancy can mean the difference between success and failure.
One to 40 days post-tuppingThe main objectives of feeding in early pregnancy are to promote fertilisation and keep embryo losses to a minimum. Department of Agriculture in Northern Ireland (DARD)-funded research undertaken at the Agri-Food and Biosciences Institute (AFBI), based at Hillsborough, has shown consistently that fertility in ewe lambs is highly sensitive to the level of feed intake during the first six weeks after tupping.
Conception rates in ewe lambs are maximised by allowing ewes to lose a small amount of bodyweight in early pregnancy, but there are consequences for lamb output.
When body reserves are depleted post-tupping, ewe lambs struggle to compensate later in pregnancy, lambing down in lower body condition and producing less milk. This often leads to higher levels of lamb mortality around birth.
On the other hand, feeding ewe lambs a high plane of nutrition to promote groeth results in lower conception rates and a higher incidence of repeats, so it is more difficult to maintain a compact lambing pattern.
Excessive feeding, even at this early stage of pregnancy, has also been lined with the birth of oversized lambs, which require extra assistance at lambing time.
To achieve a suitable compromise, it is best to target a small increase in bodyweight (around 0.5kg/week) in ewe lambs during the first six weeks after tupping. This can be achieved by grazing short swards (4cm to 6cm) and monitoring bodyweight accordingly.
Where grass supplies are inadequate, feeding medium quality grass silage should be sufficient to maintain this level of weight gain without the need for additional concentrates.
40 to 95 days post tuppingFollowing implantation (30 to 50 days after tupping), the developing foetus becomes dependent on the ewe’s placenta to meet its nutritional demands.The primary objective of feeding ewes in mid-pregnancy is to promote development of a functional placenta which is capable of sustaining foetal growth later in the pregnancy.
Additionally, when feeding ewe lambs, the level of feeding must be adequate to support growth of the ewe as well.
While it is tempting to feed a high plane of nutrition to increase body size, overfeeding ewe lambs in mid-pregnancy restricts placental development and can result in the birth of small lambs with poor viability.
Research at AFBI has found that a mild degree of overfeeding (ewes gaining 1kg/week) in mid-pregnancy has a relatively small effect on lamb birth weight. However, Scottish research suggests that feeding to achieve higher weight gains (2kg/week) carries a high risk of ewes producing undersized lambs.
Poor maternal instinct at lambing is one reason why some producers choose not to breed from ewe lambs.
However, DARD-funded research at AFBI has identified some scope to improve ewe behaviour at birth through appropriate nutritional regimes.
When ewe lambs are too well fed during mid-pregnancy, they spend less time interacting with their lambs and are less willing to facilitate suckling compared with those maintained on a lower plane of nutrition.
Lambs born to well-fed ewes are also less active and slower to suckle, leading to increased labour requirements around lambing.
During mid-pregnancy, it is advisable to maintain ewe lambs on the same level of feeding recommended for early pregnancy, targeting a modest rate of weight gain (around 0.5kg/week). Since the opportunities to gain bodyweight following tupping are limited, it is essential that ewe lambs reach a suitable liveweight at mating.
Ewe lambs should be at least 60% of their mature weight when they join the ram (45kg for mules). This means that preparation for mating should begin as soon as possible after weaning.
95 to 147 days post-tuppingLate pregnancy is a period of rapidly increasing feed demands, with the foetus doubling in size during the final month of pregnancy.With these added nutritional stresses, feeding ewe lambs to increase body condition is difficult.
Provided feed inputs have been controlled in mid-pregnancy to promote placental development, it is possible to ensure that lambs reach an adequate but not excessive birth weight by implementing a well-planned feeding regime in late pregnancy.
In situations where ewe lambs have been overfed in mid-pregnancy and begin to lamb down with undersized lambs with poor viability, feeding additional concentrates is unlikely to increase birth weight.
Concentrate inputs vary depending on litter size, so it useful to scan ewes to avoid overfeeding or underfeeding. Knowing the quality of your grass silage is also important.
*Ronald Annett is based at the Agri-Food & Biosciences Institute, Hillsborough.
With strong lamb prices, the decision whether or not to breed from ewe lambs to boost flock output has rarely been more important.
Delaying breeding until the second year has obvious advantages – it is easier to ensure ewes are happy enough for tupping; fertility is generally better and management around lambing can be easier. However, delayed breeding brings additional feed costs without generating any income to offset these costs.
Breeding replacements as ewe lambs can be equally as successful as breeding from adult ewes but the approach to feeding management during pregnancy can mean the difference between success and failure.
One to 40 days post-tuppingThe main objectives of feeding in early pregnancy are to promote fertilisation and keep embryo losses to a minimum. Department of Agriculture in Northern Ireland (DARD)-funded research undertaken at the Agri-Food and Biosciences Institute (AFBI), based at Hillsborough, has shown consistently that fertility in ewe lambs is highly sensitive to the level of feed intake during the first six weeks after tupping.
Conception rates in ewe lambs are maximised by allowing ewes to lose a small amount of bodyweight in early pregnancy, but there are consequences for lamb output.
When body reserves are depleted post-tupping, ewe lambs struggle to compensate later in pregnancy, lambing down in lower body condition and producing less milk. This often leads to higher levels of lamb mortality around birth.
On the other hand, feeding ewe lambs a high plane of nutrition to promote groeth results in lower conception rates and a higher incidence of repeats, so it is more difficult to maintain a compact lambing pattern.
Excessive feeding, even at this early stage of pregnancy, has also been lined with the birth of oversized lambs, which require extra assistance at lambing time.
To achieve a suitable compromise, it is best to target a small increase in bodyweight (around 0.5kg/week) in ewe lambs during the first six weeks after tupping. This can be achieved by grazing short swards (4cm to 6cm) and monitoring bodyweight accordingly.
Where grass supplies are inadequate, feeding medium quality grass silage should be sufficient to maintain this level of weight gain without the need for additional concentrates.
40 to 95 days post tuppingFollowing implantation (30 to 50 days after tupping), the developing foetus becomes dependent on the ewe’s placenta to meet its nutritional demands.The primary objective of feeding ewes in mid-pregnancy is to promote development of a functional placenta which is capable of sustaining foetal growth later in the pregnancy.
Additionally, when feeding ewe lambs, the level of feeding must be adequate to support growth of the ewe as well.
While it is tempting to feed a high plane of nutrition to increase body size, overfeeding ewe lambs in mid-pregnancy restricts placental development and can result in the birth of small lambs with poor viability.
Research at AFBI has found that a mild degree of overfeeding (ewes gaining 1kg/week) in mid-pregnancy has a relatively small effect on lamb birth weight. However, Scottish research suggests that feeding to achieve higher weight gains (2kg/week) carries a high risk of ewes producing undersized lambs.
Poor maternal instinct at lambing is one reason why some producers choose not to breed from ewe lambs.
However, DARD-funded research at AFBI has identified some scope to improve ewe behaviour at birth through appropriate nutritional regimes.
When ewe lambs are too well fed during mid-pregnancy, they spend less time interacting with their lambs and are less willing to facilitate suckling compared with those maintained on a lower plane of nutrition.
Lambs born to well-fed ewes are also less active and slower to suckle, leading to increased labour requirements around lambing.
During mid-pregnancy, it is advisable to maintain ewe lambs on the same level of feeding recommended for early pregnancy, targeting a modest rate of weight gain (around 0.5kg/week). Since the opportunities to gain bodyweight following tupping are limited, it is essential that ewe lambs reach a suitable liveweight at mating.
Ewe lambs should be at least 60% of their mature weight when they join the ram (45kg for mules). This means that preparation for mating should begin as soon as possible after weaning.
95 to 147 days post-tuppingLate pregnancy is a period of rapidly increasing feed demands, with the foetus doubling in size during the final month of pregnancy.With these added nutritional stresses, feeding ewe lambs to increase body condition is difficult.
Provided feed inputs have been controlled in mid-pregnancy to promote placental development, it is possible to ensure that lambs reach an adequate but not excessive birth weight by implementing a well-planned feeding regime in late pregnancy.
In situations where ewe lambs have been overfed in mid-pregnancy and begin to lamb down with undersized lambs with poor viability, feeding additional concentrates is unlikely to increase birth weight.
Concentrate inputs vary depending on litter size, so it useful to scan ewes to avoid overfeeding or underfeeding. Knowing the quality of your grass silage is also important.
*Ronald Annett is based at the Agri-Food & Biosciences Institute, Hillsborough.
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