Negative energy balance in small ruminants
All ruminants will experience a state of negative energy balance (NEB) during their lifetime. While most research in this area has focused on dairy cows, and the effect of NEB on milk production and subsequent health, sheep and goats actually face the biggest consequence of NEB. Negative energy balance occurs in sheep and goats prior to giving birth, during the last weeks of gestation and is referred to as pregnancy toxemia. Pregnancy toxemia is primarily caused by low blood glucose levels and affects ~20% of pregnant ewes/does. This condition is exacerbated in pregnancies with multiple fetuses. Goats and sheep are at the greatest risk for pregnancy toxemia in the last 4 weeks of gestation, as metabolic demands rise dramatically (by ~23, 35, and 40% for single births, twins and triplets, respectively) and rumen capacity is decreased due to fetal growth and size at this stage. Nutrition management is crucial in these weeks as a diet of insufficient energy density can increase the risk and severity of pregnancy toxemia. Clinical symptoms of pregnancy toxemia include decreased feed intake and activity, muscle tremors, aimless walking and grinding of teeth. If left untreated, these symptoms will often progress and result in loss of coordination and muscular function, blindness, and even death in 80% of cases. If the doe or ewe, make it to parturition the threat does not end there. Sheep and goats can also experience negative energy balance and ketosis following the onset of lactation, similar to cows, as they cannot consume sufficient dry matter to match the energy being expended into their milk. Therefore, energy supplementation is crucial for these animals both prior to and following parturition to ensure the health, welfare and desired production outcomes of these animals.
Why supplement sugars to small ruminants?
Considering the fact insufficient energy density is a major concern for sheep and goats, what better way to increase the energy in your ration than by adding a palatable and economical additive like liquid molasses? Not only is liquid molasses palatable, but its sticky texture and high energy density has also been proven to reduce ration sorting, increase DMI and improve rumen function and health. Sugar supplementation also supports microbial growth, particularly for fiber-digesting bacteria, speeding up fiber degradation and allowing for greater DMI and rumination. When energy deficiency is an issue, our first solution is often to increase the proportion of grain in the diet. However, overfeeding grain can increase the risk of the ruminant experiencing subacute ruminal acidosis, where the rumen can become acidic for prolonged periods of time, causing unwanted consequences for the animal. Feeding liquid molasses as opposed to increasing starch, will allow the ruminant to get the energy boost it needs, while maintaining a healthy, stable rumen environment.
What does the research say?
Research since the 70’s has demonstrated positive effects of supplementing molasses to small ruminants on pasture to improve feed intake and reduce body weight loss in the weeks following parturition. This has been further supported by multiple research studies across North and South America which reported many positive benefits of molasses supplementation to grazing beef and dairy herds. However, as the dairy industry continues to grow, so must our knowledge and research. Over the last couple of decades research has investigated the benefits of being proactive, and supplementing sugars to goats and sheep directly in their diets prior to kidding/lambing. A study published by Cambridge University Press in 2009, looked at the effect of sugar supplementation on the physiology of sheep and found that sugar supplementation greatly increased available energy for the animal through production of ruminal propionate. Propionate is a volatile fatty acid and is the main precursor required for glucose synthesis in the liver and can supply up to 70% of glucose demands. This research was supported by a study done in 2016, by the Agricultural Research organization in Israel, where ewes carrying at least 2 fetuses were assigned to a control group or a molasses supplementation group from 90d in pregnancy until lambing. This research found that the ewes supplemented with molasses had greater metabolic health (significantly higher glucose, lower NEFA and BHB in plasma, and lost less body condition compared to control ewes). Research has also demonstrated the benefits of sugar supplementation on growth and development. A recent study by BMC Veterinary research in 2020, fed young Nubian goats varying concentrations of molasses (ranging from 0%- 45%) and found that goats supplemented with 30% molasses for 3 weeks had improved growth performance, rumen health and improved protein metabolism.
Conclusions
Ewes and does can experience severe consequences from NEB, both during late gestation and during early lactation. However, NEB in late gestation (aka pregnancy toxemia) has a high and fast death rate if left unmanaged. Therefore, it is crucial to be proactive throughout gestation and ensure does and ewes are being fed diets formulated to meet and maintain their energy demands. Feeding a liquid molasses throughout gestation will encourage DMI, reduce feeding losses, encourage healthy feeding behaviours (i.e., limit feed sorting) and provide ewes and does with enough energy to successfully transition them into lactation, reducing the risk of pregnancy toxemia and ketosis. Give your small ruminants the best shot at a healthy and successful pregnancy, by simply sweetening up their diet!
References:
Bowman, J. G. P., Sowell, B.F., and J. A. Paterson.1995. Liquid supplementation for ruminants fed low-quality forage diets: a review. Animal Feed Science and Technology. 55: 105-138.
Menzies, Paula. 2015. Pregnancy toxemia in ewes and does. MERCK Veterinary Manual. https://www.merckvetmanual.com/metabolic-disorders/hepatic-lipidosis/pregnancy-toxemia-in-ewes-and-does
Moallem, U., A., Rosov, H., Honig and I. Ofir. 2016. Molasses-based supplement improved the metabolic status of late-pregnant ewes bearing multiple fetuses. Animal Feed Science and Technology. DOI:10.1016/j.anifeedsci.2016.06.002
Osman, O., Elkhair, N., and K., Abdoun. 2020. Effects of dietary supplementation with different concentration of molasses on growth performance, blood metabolites and rumen fermentation indices of Nubian goats. BMC Veterinary Research. https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-020-02636-5
Sutoh, M., Obara, Y., and S. Miyamoto. 2009. The effect of sucrose supplementation on kinetics of nitrogen, ruminal propionate and plasma glucose in sheep. Cambridge University Press. https://www.cambridge.org/core/journals/journal-of-agricultural-science/article/abs/effect-of-sucrose-supplementation-on-kinetics-of-nitrogen-ruminal-propionate-and-plasma-glucose-in-sheep/51DB24DDF8554555DE71AFC57B13E567
