Are your in-lamb ewes getting enough from their diet?

Thursday 06 November 2008 00:00

If you have an early lambing flock, then you’ll be on countdown; it’s those final six weeks of pregnancy that are crucial in preparing for a trouble free lambing and ensuring ewes have sufficient high quality colostrum and milk to get lambs off to the best start, says Volac’s ruminant nutritionist, Dr Richard Kirkland.

“Around 70% of foetal growth occurs in the last third of pregnancy. This means that a ewes’ requirement for energy increases rapidly in the six weeks prior to lambing to meet the needs of the growing lambs. However, the presence of lambs reduces the physical size of the rumen, making it increasingly difficult for the ewe to eat sufficient to satisfy demands for energy. Consequently, she can lose condition rapidly leading to serious health issues, including twin lamb disease,” he explains.

“To minimise these pre-lambing issues, feeding a high energy supplement to ewes carrying multiple lambs and/or in poor body condition score will help bridge the natural energy deficit in late pregnancy and early lactation. Ewes should be neither too thin nor too fat.”

Established trial work carried out by ADAS with their Rosemaund flock featured diets fed to in-lamb ewes during late pregnancy and early lactation containing rumen protected fat as a source of supplementary energy: 100 ewes were fed either a control concentrate - ME 12.7 MJ/kg DM, or a treatment concentrate in which 10% of the cereal ingredients were replaced with Megalac, a rumen protected fat, which increased its ME to 13.9 MJ/kg DM. The concentrates were fed from eight weeks before lambing starting at 0.5 kg/day, rising to 1.1 kg/day.

Post lambing, ewes were fed 1.4 kg concentrates per day, with ME concentrations of 12.5 and 14.0 MJ/kg DM for the control and Megalac-supplemented concentrates, respectively. Ad lib straw was available throughout the trial.

“Ewes offered the higher energy concentrate reared significantly more lambs, with lamb growth rate up to 19.4% higher to weaning compared to the control group,” explained Dr Kirkland. “The trial showed that ewes carrying twins reared 95% of their lambs, 5% more than those fed the control diet. Furthermore, the trend was much more apparent in the triplet group where all the ewes reared 100% of their lambs, compared with only 60% of lambs successfully reared by those fed the control diet. In addition, the ewes fed Megalac were in better body condition at weaning, scoring an average 2.4 compared with 2.0 for the ewes fed the control diet.”

He adds: “Feeding rumen protected fat in late pregnancy and early lactation will increase diet energy density and can be fed by top-dressing or as part of a bought-in compound or blended feed.”

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