Senior livestock production advisor Rob Inglis and rural products sales representative Grace Corrigan unpack how body fat, nutrition and energy management in late pregnancy support stronger birthweights, improved lamb survival and better overall livestock outcomes.
Fat is three times more energy dense than carbohydrate. One kilo of fat will yield approximately 35MJ of energy. The liver can convert fat to glucose via a multistep process known as gluconeogenesis. This complex system is paradoxically energy demanding, requiring glucose to carry it out. For this process to operate efficiently, ketones – which are produced in an intermediate step in the cycle – must be metabolised at a rate that doesn’t allow them to overwhelm the animal. In other words, if the animals are kept calm, they can cope with burning fat off their backs. The catch is that they must have access to the requisite vitamins and minerals.
The main point here is that body fat is a terrific energy source, and ewes (or cows) with extra condition during late pregnancy will:
- produce progeny which stand a better chance of survival due to:
- higher birthweight*
- higher levels of brown fat, which is essential for progeny surviving the first 48 hours of life
- higher levels of and better-quality colostrum.
- survive on a moderately modest peri-natal diet. Pregnant females can be left alone for the first cycle of lambing or calving, providing they have access to reasonable quality roughage (testing advised) and essential minerals and vitamins.
*Energy and protein intake for heifers and single bearing ewes in the last three weeks of pregnancy should be managed accordingly.
How birthweight and brown fat affect lamb survival
Lamb survival is largely influenced by the careful management of the dam's condition. The condition of the ewe at joining has a direct influence on the conception rate of the ewe and further, the birthweight of the progeny. Focusing on ewe nutrition pre and during gestation will ensure healthy birthweights. Lamb birthweights have a direct correlation to the lamb’s survival during the first few days of their life.
Brown fat is a type of adipose tissue where energy is released directly as heat, rather than being used for growth or movement. It is activated by the sympathetic nervous system and can produce heat quickly without shivering. In lambs, brown fat develops during the last six weeks of gestation and is most effective in the first few hours of life by helping to maintain body temperature immediately after birth. Once these reserves are depleted however, the lamb’s body temperature can quickly drop leading to weakness, increased risk of hypothermia and reduced suckling ability if energy is not replenished through colostrum intake.
The powers of colostrum
Young animals are born without a fully functioning immune system. Until their own immune system is developed, the offspring rely on the transfer of maternal antibodies through the placenta and colostrum. In the first 12 to 24 hours of life, they rely on antibodies transferred from the mother through colostrum to gain passive immunity. The early intake is critical as the intestine is able to absorb the antibodies immediately after birth, and this ability declines after the first day after parturition. The immunity provided by colostrum helps protect the young animal from disease for the first 8 to 12 weeks, giving their own immune system time to develop and become fully functional.
Understanding energy requirements means smarter feeding
Understanding the energy requirements for different classes of stock and stages of gestation through to lactation is essential for effective livestock management. Simple feeding tables can be used to quickly determine how much energy animals need based on their age and production stage. Meeting these requirements is particularly important during pregnancy, as adequate nutrition supports healthy foetal development. It also helps avoid overfeeding or underfeeding, both of which can negatively impact animal health and productivity. In addition, knowing precise energy needs allows better control over feed budgeting, ensuring animals receive the right quality and quantity of feed without unnecessary waste or expense.
For further information on this or any livestock production topics, contact your nearest Elders Livestock Production Specialists.
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