Correctly balancing trace nutrients in transition-cow rations will help to reduce stress and improve cow health and performance when they enter the milking herd. We spoke to a nutritionist to find out more.
TEXT PHIL EADES
Effective supplementation of transition diets will help cows manage the challenges and stress of calving and joining the milking herd, and reduce the consequences of stress to ensure they settle into lactation and produce to their potential.
“We expect a lot from transition cows,” says Adisseo’s Kirsty Farnan. “They have to calve and recover quickly to rapidly increase their dry matter intakes and begin producing high milk yields. They have to withstand severe immune challenges that can lead to production diseases including retained foetal membranes and metritis.
“And then they have to deal with inflammation, which is an unavoidable consequence of calving. Inflammation is the body’s coping mechanism, but cows need help to make sure it is managed.”
Inflammation and immune challenges cause transition and oxidative stress, as well as resulting in a negative energy balance. Boosting the cow’s ability to deal with all these stresses means refining farm management practices and supplying adequate amounts of amino acids and minerals, which are critical to prevent metabolic disease and mitigate the damage caused by oxidative stress.
Ms Farnan explains that dry cows have reduced feed intakes and are commonly fed low crude-protein diets. To manage pre-calving energy intakes, dry-cow diets often contain a higher proportion of low-energy and lowprotein forages and straw. These diets, therefore, require particularly careful supplementation with trace nutrients.
Essential nutrients
Transitions cows have an increased demand for essential nutrients, such as the amino acids methionine and histidine, and vitamin E and selenium, which are both antioxidants. These nutrients are essential to support cow health through this challenging phase. Around calving, there is increased inflammation and the need for antioxidants to manage this.
“It is vital that the diet is balanced for amino acids – particularly methionine, lysine and histidine – to ensure the requirements of the immune system are met and to help the cow manage the typical levels of inflammation seen at every calving,” says Ms Farnan.
Methionine demand
Calving cow: methionine requirement increases during this crucial period
“Around calving and in early lactation the need for methionine increases due to its key role in many crucial processes including immunity, reducing inflammation, and colostrum and milk protein production. This increased demand often coincides with reduced supply due to lower feed intakes and low methionine diets.” Blood methionine can be low for between one and two weeks before calving and between three and four weeks post-calving. “So it is vital to ensure cows receive a sufficient dietary supply.”
During transition, the liver is a critical organ. Due to the increased requirement for fatty acids in the udder, cows need to mobilise more fat from their body. This fat has to be transported initially to and then exported from the liver. This is done through a protein transporter called VLDL.
“Methionine and choline are critical to producing VLDL and data shows that increasing methionine supply boosts VLDL production and fat export from the liver to the udder, supporting good liver function and milk production,” says Ms Farnan.
Feeding the correct antioxidants in a highly bioavailable form is also key. She says that producers should feed a minimum of 1,000mg of vitamin E per cow per day, adding that selenium and glutathione are also critical as cellular antioxidants. “Selenium is not readily available in most feedstuffs, meaning diets need supplementation. It is also important to feed a highly available form of selenium.
“All sources of selenium vary in terms of their bioavailability, in other words how much of the selenium fed can be absorbed by the cow. The more routinely fed inorganic forms have particularly low availability and, even if the diet looks to contain enough selenium, it will not meet cow requirements. This means a significant proportion is just excreted, which has environmental and economic consequences.”
Most forms of selenium cannot be stored by the cow ready to meet heightened demands, so producers need to feed a highly bioavailable form and enough of it to meet requirements. “Feeding selenium in a lower bioavailable form may result in needing to increase inclusion rates,” adds Ms Farnan.
Selenomethionine, where the selenium is bound to methionine, is a highly bioavailable form of selenium. It is also the only form of selenium that can be stored by the cow. Selenomethionine is particularly critical for the regeneration of glutathione peroxide, which is an enzyme essential for an efficient immune system, and methionine supply is critical for the production of glutathione.
Selenium source
“Supplementing diets with selenomethionine provides a source of selenium in a highly bioavailable form combined with a source of methionine. This offers a double boost to help cows cope with the stresses of calving and transition.
Selisseo selenomethionine is a pure selenomethionine product that supplies in excess of a third more selenomethionine per gramme compared to seleniumyeast products. Data shows a 16% increase in plasma selenium when supplementing cows with Selisseo compared to cows fed with sodium selenite during the four weeks prior to calving.
Selenomethionine has an additional benefit in that the selenium is transferred to the colostrum, increasing availability to the calf. Colostrum selenium levels have been shown to be increased by 28% and calf plasma selenium levels were increased by 14%. Antibody levels in the colostrum were also higher.
“This is beneficial to early calf health, improving its ability to fight infection. Increased colostrum selenium results in more selenium available to the newborn calf and significantly reduces the risk of white muscle disease in early life,” says Ms Farnan.
She recommends balancing diets for amino acids and supplementing with a minimum of 5g of digestible methionine per cow per day, either as Adisseo Smartamine or Metasmart.
“Ensure enough selenomethionine is supplied using Selisseo at a recommended level of 0.22mg/kgDM, or between 2.25mg and 3mg per transition cow per day,” she adds.
“These are only guidelines, and producers should discuss them with their nutritionist to ensure the diet is correctly balanced with supplements fine-tuned to reflect the forages and other ingredients in the ration.”
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