Getting nutrition correct pre tupping is essential to ensure that ewes are ovulating and improve results come scanning time. However, it is also important to consider mineral supplementation pre tupping as this can be another major inhibitor to mating performance for both ewes and tups with both deficiency and over supply both posing a risk.
Table 1 highlights the key minerals around tupping time that may lead to poor reproductive performance and increased barren rate due to deficiency or toxicity.
Table 1: Trace Elements important for reproductive performance in sheep around mating
|Symptoms of Deficiency
|Symptoms of Toxicity
|Cobalt / Vit B12
|Cobalt is synthesised to B12 in the Rumen and is important in energy and protein metabolism
|Pining, anaemia, poor appetite, reduced reproductive performance
|Rare – reduced feed intake, weight loss, anaemia.
|>0.08 mg/kg DM in grazing = deficiency
Diet should contain 0.1 mg/kg DM
|Antioxidant function with Vitamin E, Thyroid hormone synthesis, immune function
|Ill Thrift and Poor fertility through reduced egg and sperm quality – may cause embryonic death 3-4 weeks post tupping leading to poor scanning results
|Selenium deficiency is thought to occur when the diet provides 0.025 – 0.05 mg/kg DM
0.1-0.2 mg/kg DM required in the diet.
|Energy Metabolism, normal foetal growth, and development.
|Reduced Fertility leading to reduced scanning rate.
|Nasal discharge, excess saliva production, decreased milk production and loss of coat condition.
|Typically, around 0.15 mg/kg DM contained in pasture.
0.2 – 0.5 mg/kg DM required in diet for growing & dry stock and pregnant & lactating stock respectively.
|Energy Metabolism, Immune function, Fertility, Enzyme Production and Wool & Hair production
|Depressed or silent heats, reduced fertility, low immunity, swayback, anaemia, poor energy utilisation
|May build up in liver some breed very susceptible to toxicity. Jaundice, urine-stained blood & Death
|Copper in pasture varies between 2-15 mg/kg DM
Recommended levels in the diets are around 6 mg/kg DM
|Connective tissue and bone formation, blood clotting, production of sex hormones, control of growth, fertility, and ovarian function
|Poorly formed lambs, depressed immunity, poor fertility and impaired cell function and structure
|Rare – reduced feed intake and growth, liver abscesses.
|30 – 300 mg/kg DM range in forage.
Requirement around 22-40 mg/kg in diet.
To assess mineral provision fully, it is a good idea to sample pasture and soil for mineral content. All other sources of minerals should be taken into account, looking at mineral content of bought in concentrate, buckets, licks, drenches, molasses, and bolus’s if administered to identify if requirements are currently being met and to avoid unnecessary oversupply.
If problems with high barren rates do occur, it is also a good idea to blood sample affected ewes to assess if there are issues with metabolic mineral status following analysis of the dietary and additional sources supplied.
For further information please refer to the Farm Advisory Service Guide to Trace element supplementation in sheep flocks.
Lorna Shaw – Ruminant Nutritionist
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