This article was originally published in 2021 in the Milk Producer Magazine produced by Dairy Farmers of Ontario.
Written by Michelle Linington
Providing proper care and nutrition to transition cows ensures a problem-free lactation and herd. The transition period occurs between late gestation and the onset of lactation. This is the time when there is a rapid increase in metabolic and nutrient demands.
Cardoso et al, 2020, recently completed a study on the nutritional strategies for improved health, production and fertility during the transition period. The study shows not meeting the cow’s needs during the transition period can leave the animal predisposed to metabolic disorders (ketosis, acidosis and displaced abomasum), infections (metritis and mastitis) and calving disorders (dystocia, retained placenta and decreased fertility). Failure to meet the animal’s needs can be costly, and it’s important to remember prevention is often cheaper than a cure.
Negative energy balances occur when the cow is not ingesting enough energy to meet her energy needs. Though there is no direct link between milk yield and disease occurrence, researchers see the highest milk yield and disease occurrence at the greatest times of negative energy balance.
Typically, the largest negative energy balances are seen in the transition period. Negative energy balances are linked to poor reproductive performance, fatty liver, ketosis, milk fever, retained placenta, displaced abomasum, metritis and mastitis.
Peak disease incidence corresponds with the time of greatest negative energy balance and a peak in blood concentrates of non-esterified fatty acids (NEFA). NEFA is a type of fat molecule that provides energy to the body, but in large quantities, it can have toxic effects. Telltale signs that negative energy balances may be an issue on the farm include loss of milk production, increased incidence of disease and decreased fertility.
Over-conditioned animals face similar issues to animals that have a large negative energy balance. Animals that are fed a high-energy ration during the dry period can face similar side effects to animals that are in a negative energy balance. Animals that have not gained body condition but have still overconsumed energy can experience the same effects to animals that have gained body condition.
There are several nutritional strategies that can be used during the dry and transition period to optimize the cow’s nutrition. Strategies, such as feeding high-quality forages, controlled energy diets and negative dietary cation anion difference (DCAD) diets prepartum, all aim at improving reproduction with no negative side effects on production.
Controlled energy diets contain a combination of low- and high-energy feed ingredients. This brings the energy of the ration down, enabling cows to feed ad lib without overconsuming energy.
Cows fed controlled energy diets have several benefits, such as fewer diseases and disorders, than cows fed higher energy diets. There have also been anecdotal reports of easier calving and greater dry matter intake (DMI) around parturition when energy is controlled. However, not all research has shown positive effects, and typically, this is caused by limiting the energy too much or not limiting energy enough.
Feeding a controlled energy diet is not as easy as just adding straw. The ration needs to be balanced. When feeding a controlled energy diet, energy should be formulated to approximately 1.4 megacalories or NEL per kilogram of dry matter (DM), which would limit daily intake to about 15 to 16 Mcal per day for a typical Holstein.
Diets should have a consistent chop length to ensure animals do not sort out the low energy ingredients. Cows with shorter straw chopped (approximately 2.5 centimetres) had greater total mixed ration DMI. Cows consuming longer straw had a higher blood beta-hydroxybutyrate (BHB) in the three weeks post-calving. This elevated BHB level can increase the risk of health problems in early lactation.
BHB is a ketone body, which, when found in high levels in the blood, can lead to issues, such as ketosis. Balancing ensures animals are still receiving the required minerals, vitamins and protein. Properly balancing a diet will maintain and-or enable rumen adaptation to higher grain diets after calving. Failure to balance may compromise production.
Cows fed a moderate energy diet (1.5 to 1.6 Mcal of NEL/kg of DM) ad lib were found to overconsume energy by 40 to 80 per cent of the required amount in both far-off and close-up situations. Overconsumption of energy can cause issues even if the animal does not become over-conditioned.
Excess energy consumed must be expressed as either heat or fat tissue. This can be found to cause fatty liver, subclinical ketosis and secondary liver function issues. Chronic overconsumption of energy during the dry period can decrease post-calving DMI. It can also have negative effects on metabolic indicators, which can lead to issues, such as decreased DMI and immune systems. Like overconsumption, underconsumption of energy can lead to a variety of issues, including increased incidence of retained placenta and metritis.
Working with a nutritionist to determine the transition cows’ nutritional needs is a great way to ensure their ration is balanced. Monitoring animals to ensure they are not in a negative energy balance, over-conditioned and are in good health is crucial to ensuring a successful transition into lactation.
References:
Cardoso, F. C., Kalscheur, K. F., & Drackley, J. K. (2020). Symposium review: Nutrition strategies for improved health, production and fertility during the transition period. Journal of Dairy Science, 103: 5684-5693.
Grummer, R.R. (2008) Nutritional and management strategies for the prevention of fatty liver in dairycattle. The Veterinary Journal, 176: 10 – 20.
Dairy and Beef Cattle Production 