Protect your herd this Spring

Spring calving is gaining momentum on both beef and dairy enterprises, with statistics indicating that early calving rates are broadly in line with that of last year’s figures. Returning cows to grass will now be a priority with this being especially evident on dairy farms.  

Flexibility is key for early spring grazing, tweaking of strategies and embracing on-off grazing is necessary and is dictated by weather conditions. Detailed knowledge of grass covers, growth rates and paddock ground conditions will aid decisions on paddock rotations. Where possible, grazing should commence in paddocks of lower grass covers with good infrastructure which are close to the farm yard. Ground conditions dependant, the target should be to have 30% of the farm grazed by March 1st on light early farms (mid-March for heavy farms), with 65% grazed by March 17th (April 1st for heavy farms). Where possible the second rotation should be commencing in early April (mid-April for heavy farms). Hitting these dates, will give a 40-60 day paddock recovery period, and should allow for 1000kg grass cover at the beginning of the second grazing rotation.    

Spring paddocks will have heavy lush grass covers with low fibre and dry matter (DM) contents. Due to early fertiliser and slurry applications, these pastures, can also contain high nitrogen (N) and potash (K) levels. Importantly, both of these nutrients can negatively impact the magnesium (Mg) uptake within soils. The above combining factors can impact on the already low (Mg) adsorption rates within the grazing animal’s rumen, thus, allowing for the onset of metabolic diseases, especially hypomagnesaemia. Additionally, heightened cow stress levels from calving, the return to lactation and dietary and environmental changes can all have additional negative impacts on animal health.

Ruminants have a poor capacity to retain (Mg) with roughly 70% of the animal’s reserves found in the skeleton and the remainder distributed within the animals’ soft tissues and fluids. Absorption occurs throughout the digestive tract, but is mainly confined to the reticulorumen once the mineral is readily soluble. Hypomagnesaemia, or more commonly known as grass tetany/staggers occurs when (Mg) levels in the blood are reduced below 1.1mg/100ml. Higher yielding, older dairy and beef cows are most susceptible to the disease, as high levels of (Mg) are excreted through the urine and in milk especially in early lactation. 

Deficiency symptoms occur quite rapidly with severe muscle contractions, irregular heartbeat, unnecessary bellowing and convulsions all being clinical signs. Due to the short duration of the indicator’s, affected animals are often found dead with the ground routed and disturbed around them due to thrashing from muscle spasms. Early warning signs can be detected however, milk yield reductions, loss of body condition and changes in temperament can all be evident in the days prior to convulsions occurring. 

A number of different management techniques can help prevent the onset of grass tetany. Feeding high (Mg) concentrate, offering high (Mg) molasses-based licks or blocks, (Mg) dusting of pastures, supplementing (Mg) into the water supply and incorporating hay or straw into the diet to slow down digestion are all options. However, consistency of (Mg) uptake can be an issue with some of these preventative measures, especially in periods of high rainfall.

Supplementing (Mg) through a molasses based liquid feed is a very effective and safe preventative measure. Introducing Premier Ultra-Mag to the diet at a rate of 1kg/head/day will provide 25g of (Mg), therefore, suppling most cow’s daily (Mg) requirement in normal weather conditions. In adverse weather, inclusion levels should be increased to 1.5kg/head/day for periods of moderate risk and 1.5-2.0kg/head/day in high risk periods. Its liquid form, leaves it ideal for feeding through liquid feeding systems on robotic milking machines or via liquid feed milking parlours. Additionally, Premier Ultra-Mag can be topped dressed on forages, mixed with dry feeds, or fed in a diet feeder as part of the TMR. It is important to ensure that uniform mixing of Premier Ultra-Mag and other ingredients occurs prior to feeding out. Its versatility also allows it to be fed free access through lick wheels or ball feeders.