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07 February 2023

Late Pregnancy in Sheep and a Lambs First few Weeks of Life

Late Pregnancy in Sheep and a Lambs First few Weeks of Life

Aoife Seymour, Teagasc Walsh Scholar, discusses the effects of ewe nutrition and vaccination during late pregnancy, colostrum and simple husbandry practices that can be used to ensure every lamb gets the best possible start. She includes a simple guide to an expected lamb's weight gain over 12 weeks

There are three key factors to consider during the pregnancy of ewes which can affect the successful chance of lambing: 

  • Ewe Nutrition – all stages of pregnancy.
  • Vaccination and Worm Control.
  • Litter Size – scanning of ewes during pregnancy provides essential information to improve the management of your flock. 

Ewe Nutrition 

In order to have a profitable mid-season lamb production system, appropriate nutrition and management during late pregnancy is essential. In the final 6-7 weeks of a pregnancy, 75% of the foetal growth occurs.  Due to the rapid growth of the foetus, it increases the ewe’s daily nutritional requirements where forage based diets can no longer met these requirements so concentrates must be supplemented.

When feeding concentrates to ewes in late pregnancy, there are some factors to consider;

  • feed should have a crude protein content of 17-18% as high quality protein sources such as soya bean meal enhance milk production, to maximise energy intakes of pregnant ewes.
  • feed a ewe nut as it will have adequate levels of cereals such as maize, barley and wheat.
  • watch the ingredients specification of ewe nuts available in the market and not skimp on the cost of nuts.
  • Finally, introduce concentrates at a low level and build up gradually.

Mineral supplements should always be made available to in-lamb ewes. Mineral supplement should include added salt for increased palatability, along with adequate levels of calcium, selenium, cobalt, copper, iodine and molybdenum, vitamin E and vitamin A.

Vaccination

Approximately 4 to 6 weeks before ewes are to give birth, it is recommended that the ewes receive an immunisation booster with a multiway clostridial vaccine such as Heptavac P Plus that includes antigens effective against lamb dysentery, pulpy kidney, struck, tetanus, braxy, blackleg, black disease and pasteurellosis pneumonia which can all be fatal to sheep. It is critical in sheep production that vaccines are used as they will aid in the passing of immunity from ewe to lamb and contribute to the lamb’s immune defence system once born. To note, farmers need to follow manufacturer instructions carefully in relation to correct administration and product storage with the use of an automatic vaccinator gun which helps facilitate the process. This in return will provide good quality colostrum produced by the ewe which is essential for maximal survival of lambs at the time of birth. Colostrum will provide an easily digestible source of nutrients and energy, it provides maternally derived antibodies which will form the new-born lamb’s passive immune system until it has a chance to develop its own active immune system and it acts as a laxative to clean out the digestive tract of meconium of the new-born lamb.

Colostrum and Colostrum sources 

Colostrum from the ewe is most viable to provide optimum nutrients to the new-born lamb but if it is unattainable at the time of lambing, alternatives from differential species must be obtained. Colostrum replacer is produced using bovine sources but to pose an important question, ‘is the colostrum replacer made from actual cows colostrum or is it whey based?’. Colostrum that is whey-based may not have sufficient levels of immunoglobulins but most importantly, it is difficult for a new-born lamb to digest whey based products. The product Survivor™ is a colostrum powder product that is derived from genuine Johne’s-free cow colostrum which has a high energy content. It is also important to remember the 4 Q’s of colostrum management; Quality, Quantity, Quickly and Quietly. 

For my undergrad thesis, I investigated the effects of different sources of colostrum on the daily live weight gains of artifically reared surplus lambs. From my results, lambs that were fed the product Survivor™ only at the time of birth had good daily weight gains with little difference between their weights and those fed fresh ewe colostrum at the start of life. 

The table below displays the mean percentage daily weight gain of trial lambs from birth to weaning at 5 weeks. Calculations were carried out using a single factor Anova.

Simple husbandry practices can be used to ensure that every lamb gets the best possible beginning to life.

  • The lamb’s navel should be dipped in iodine as it reduce the risk of it being a point of entry for bacterial infection.
  • Make sure to have enough lambing pens available; one pen for every 10 ewes due. This will allow ewes with their lambs to be held inside for longer periods especially during poor weather.
  • Use adequate bedding in lambing pens and disinfect each pen after each use to reduce the spread of disease.

Hypothermia is a common pre-weaning death loss of lambs from winter lambing flocks. To reduce lamb losses, it is recommended that lambs receive warm colostrum, have dry bedding, and shelter from the cold and wet to reduce hypothermia losses. Good size lambs at birth should weigh around 4-5Kgs. A simple guide to an expected lamb's weight gain over the following weeks can vary but on average it is a little under 2Kgs a week. 

For example:  A 4 week old lamb, with a birth weight of 4 Kgs, should be 12Kgs in weight, at 8 weeks it should be 20Kgs and at 12 weeks it should be 28Kgs. 

References:

Aoife Seymour is a Research Walsh Scholar based in the Teagasc Advisory Office, Navan, Co. Meath.

The Teagasc Sheep Specialists and Teagasc Advisors issue an article on a topic of interest to sheep farmers on Tuesdays here on Teagasc Daily.  Find more on Teagasc Sheep here  Teagasc provides a Local Advisory and Education service to farmers. Find your local Teagasc office here