26 January 2024

Pregnancy nutrition – the foundation of flock profitability

Pregnancy nutrition is the foundation of flock profitability, Dr Tim Keady, Research Officer in Teagasc Athenry, told this week’s Teagasc National Sheep Conference.

Delving into the vast bank of research conducted in the Teagasc Animal and Grassland Research and Innovation Centre in Athenry, Tim showed how silage quality, ewe body condition score, concentrate supplementation, litter size and shearing at housing can impact on lamb mortality, birth weights and the subsequent performance of both ewes and lambs.

Key points from Tim’s presentation at the National Sheep Conference:

• Pregnancy nutrition impacts on lamb mortality, growth rate, age of slaughter, ewe body condition score and subsequently lactation;
• Shearing at housing increases lamb birth weight and subsequent weaning weight equivalent to the response of feeding 19kg of concentrate per lamb, which is the equivalent of €14/ewe;
• An increase in silage digestibility of 5 percentage units increases ewe weight at lambing by 6kg and lamb weaning weight by 1kg;
• The response to concentrate feeding depends on silage feed value;
• 5 of a unit increase in ewe body condition score at lambing increases lamb weaning weight by 1kg;
• Target a concentrate containing 19% for ewes in late pregnancy. This should be purchased on the basis of composition and ingredients such as soya, rapeseed, maize, barley, soya hulls and beet pulp, rather than purchasing solely on price;
• A €20/t difference in the price of a concentrate is only equivalent to €0.50/ewe – purchase a quality concentrate;
• Develop a nutrition plan to meet the ewe’s requirements and plan now to increase the DMD of your silage for next year by 5 percentage units.

Along with its role in the production of colostrum and the mobilisation of body reserves post lambing to support milk and milk solids production and subsequent lamb performance, pregnancy nutrition plays a vital role in the production of lambs of optimum birth weight – an important factor in limiting lamb mortality in the first 24 hours of birth. Work conducted in Teagasc Athenry, Tim outlined, has identified that birth weights of 6kg for single, 5.6kg for twin and 4.7kg for triplet lambs are optimal to balance lamb survivability and to reduce the incidents of difficult lambing.

In terms of the critical period for foetal development, Tim noted that 70% of foetal growth occurs in the final six weeks of pregnancy and, during this rapid period of growth across litter sizes, farm managers and nutritionists have an important role to play in supplying ewes with the required levels of energy and protein to support this growth.

Providing context as to how the ewe’s requirements for energy and protein alter in the latter stages of pregnancy, Tim explained that between week six and one prior to lambing, a twin-bearing ewe’s energy requirements increase by 60% when measured through metabolisable energy, while the ewe’s metabolisable protein requirements – a combination or rumen bypass and rumen degradable protein – increase by 40% over this same window.

In the below video, Tim joins Brid McClearn to provide an overview of his presentation and to outline his take-home messages:

With the majority of ewes in Ireland being offered grass-silage based diets indoors prior to lambing, Tim also spoke on the importance of silage quality. He urged farmers to make the production of high quality silage on their farms a priority for the year ahead.

Quantifying how silage quality effects performance, Tim said: “Our data from a number of studies in Athenry clearly shows each 5 unit increase in silage DMD increases ewe weight at lambing by 6kg, ewe body condition score by approximately 0.5 of a unit, lamb birth weight by 0.3kg and the weight of a lamb at weaning by 1kg.”

For farmers developing a nutrition plan for their ewes in the coming days and weeks, he encouraged them to complete a silage analysis, as this will form the basis of concentrate supplementation strategies prior to lambing. The examination of the components within the ration selected is also important, he noted, with research work conducted in Teagasc Athenry showing that ewes respond to concentrates containing soyabean meal. Other factors to consider are the grouping of ewes in accordance to their litter size and expected lambing date.

To access Tim’s paper and presentation, where more information on the above is outlined, click here.

Also read: Increase profitability of March-lambing flocks by shearing at housing