Reproductive performance in sheep flocks is the single most important measure of profitability. Investing in a well-balanced trace mineral programme to address trace mineral deficiencies will ensure the flock reaches its full potential and prevent reproductive failures in the future.
When investigating low pregnancy rates in a flock, it is important to first rule out any diseases and address gross nutritional deficiencies. When these are in order, it is time to investigate trace mineral deficiencies. Deficiencies in trace minerals can lead to low conception rates, early embryonic deaths, and suboptimal semen quality. Furthermore, poor supplementation during pregnancy could lead to lambs being born with low birth weights and weak survival and growth prospects.
Zinc is the second most abundant trace mineral in the body and is essential for all six enzyme classes in animals. In rams, zinc supplementation supports sperm quality and motility. In ewes, it contributes to epithelial health and oocyte quality, with better oocyte quality increasing the likelihood of fertilisation and pregnancy. Zinc also supports placental development and uterine maintenance during pregnancy, both of which are important factors in producing strong, healthy lambs.
Manganese acts as an enzyme activator and is vital for cholesterol synthesis. The production of sex hormones such as progesterone and oestrogen can be influenced by manganese deficiency. Due to its influence on sex hormones, deficiencies in manganese can lead to weak heat signs in ewes, reducing the ability of a ram to detect when a ewe is in heat.
Selenium is part of the antioxidant system that enhances semen quality and protects sperm from oxidative stress. In ewes, low selenium levels can result in early embryonic loss, retained placentas after lambing, and compromised lamb viability.
The one trace mineral that is not commonly discussed in sheep nutrition is copper. Due to the risk of copper toxicity, sheep farmers are cautious about supplying copper. Copper is involved in immunity and antioxidant enzymes that protect animals against infections and support oocyte viability. Copper deficiency can lead to increased susceptibility to disease, poor lamb survival at birth, and swayback, which is when animals show paralysis of the hindlegs. Copper deficiencies may also present with symptoms similar to selenium deficiency, making them more difficult to detect.
Proactive care is the best way to prevent reproductive failure, and supplying animals with a properly formulated trace mineral supplement is much cheaper than having to fix reproductive failure later. After all, maintenance is always cheaper than breakages!
Anri Strauss is a scientific adviser in the ruminant team at Chemuniqué, holding a master’s degree in nutrition from the University of Pretoria. She grew up on a farm and still lives in the Free State, where she and her husband also farm with Boer goats.