Dispelling transition-cow misconceptions (April 22)

Research has revealed that stress and inflammation have a greater role to play in causing transition-cow disease than previously believed. What steps can producers take to keep cows on track?


TEXT KAREN WRIGHT


Transition diseases still plague many high-production cows despite adapting management and feeding. Understanding the causes of these bottlenecks has come under scrutiny, and the findings could help to avoid leading cows in the wrong direction around calving.


Iowa State University’s Lance Baumgard told listeners on a Cargill webinar that cows not performing well in early lactation appeared to be struggling with hidden inflammation due to stressors and an activated immune system.


“Stress affects productivity,” said Professor Baumgard. “High-milk-production cows cannot be stressed. Saying high-milk production is stressful is a common misconception. It can’t and shouldn’t be.


“The best indicators of health are feed intake and milk yield. Managing a cow with an aggressive appetite and optimal milk yield is only possible where there’s no stress or immune activation,” he added.




The cow’s well-being throughout the transition period, around calving, and in early lactation, will determine how well she performs. “Many cows that don’t make it to the next lactation are lost in early lactation, and the problems can be traced back to the transition period,” he added. “Only 50% of cows in North America make this transition without problems such as milk fever, ketosis, fatty liver, retained placenta, left-displaced abomasum, lameness, or death.”


The cow’s negative energy balance, which starts just before calving and continues until around day 50 of lactation, has traditionally been blamed for these problems. But this belief is not true, according to Professor Baumgard. All cows around calving and in early lactation experience a drop in feed intakes and they will mobilise body tissue to ‘access’ energy, which will lead to an increase in non-esterified fatty acids (NEFAs) and ketones. “But not all these cows will succumb to a transition-cow disease.


“We need to dispel the dogma that adipose tissue mobilisation, and the accompanying ketone bodies and NEFAs, is the root cause of poor production and many transition-cow diseases. And that ‘treatment’ relies on reducing ketones and NEFAs.”


His team has seen some cows with elevated ketone levels eating and milking well. “These cows are fine, but some are not. We needed to know the underlying issues affecting cows with reduced feed intake and a drop in milk yield.


Adipose tissue


“The breakdown of some adipose tissue and the production of NEFAs and ketones provides a much-needed energy supply for the body. If this doesn’t happen, the cow uses glucose for energy – glucose that would otherwise have been used for producing milk lactose in the mammary gland.


“A sick cow directs her glucose to ‘survival’ and not to milk yield because glucose is prioritised for immune activation, rather than milk production. It takes 72g of glucose to synthesise 1kg of milk, so if it’s not available then yield will drop.”


Professor Baumgard and his team have found that transition diseases, like ketosis or milk fever (hypocalcaemia), are linked and are all a consequence of inflammation caused by immune activation. This inflammation typically originates in the uterus, mammary gland, the gut or even the lungs of transition cows.


“We’ve shown that minimising the stressors through the dry period, to reduce immune activation and inflammation, will reduce the incidence of transition-cow diseases,” said Professor Baumgard.


His team compared milk yield in the first three weeks of lactation in cows with high inflammation at dry off with those with low inflammation. They found a difference of 6.6kg of milk a day.


“All cows have some inflammation at transition, but it is the degree of this inflammation that makes the difference,” he said. “Those with the highest inflammation have the lowest dry matter intakes, and the highest NEFAs and ketone levels. Cows that don’t eat well are sick. Even insects decrease their intakes if they have an infection and are immune activated.”


Transition strategies


Cargill’s ruminant technology manager Philip Ingram agrees that reduced stress and immune activation supports a smooth transition period. “The aim is to avoid immune activation caused by stress linked to factors like poor diet, poor hygiene or gut irritation,” said Dr Ingram.


This starts at drying off by paying close attention to protocols, such as hygiene and health routines in the parlour and housing, to avoid sources of infections. And then at calving, by making sure pens and equipment are clean. Dry-cow housing should be well ventilated and dry, and cow ‘moves’ should be minimised.


“Every time she moves to unfamiliar surroundings her intake drops for a few days, which disrupts her energy supply just when she needs stability,” he added. A well-balanced diet with good feed access is essential in transition cow care. He recommends enhancing the diet. “Look at products, such as LiFT, which provide a combination of vitamins and essential co-factors. These have been proven to enhance the cows ‘energy pathways’ and help her deal with body fat mobilisation in transition and early lactation.”


LiFT has been extensively trialled and in one of the most recent studies, where it was fed for 21 days pre-calving, resulted in a milk yield increase of 3.1kg in the first 150 days of lactation.


“We must also ensure cows have the correct amount of minerals and vitamins, as well as appropriate antioxidants, such as the partial vitamin E replacement Proviox. We need to support the immune function, so it’s there if needed,” he adds. A strategy evaluated at Iowa State University to support the immune function included Diamond V’s NutriTek. This feed product was found to reduce somatic cell counts and lead to a more consistent pattern of increased milk yields.


“Our work shows immune activation is the root cause of many on-farm problems like transition-cow diseases,” said Professor Baumgard. “This is the most potent factor impacting feed intake and it plays an important role in transition-cow metabolic disorders. “Strategies that minimise this, promote feed intake, and support the immune system should allow cows to progress through the calving and early-lactation period successfully with fewer disorders, and improved longer-term productivity.”

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