Dairy cows typically enter a period of negative energy balance in early lactation. This is due, in part, to the milk yield having increased over the years, while their ability to consume enough food hasn’t increased at the same rate.
During periods of negative energy balance, the cow uses her body fat reserves to sustain milk production, and this is reflected in a loss of body condition. Excessive negative energy balance, such as cows getting very thin, can lead to health problems and poor fertility. Milk yields normally ‘peak’ around 50-80 days after calving, while intakes do not normally peak until 70-90 days after calving. However, increasing the quality and nutrient density of the diet can allow cows to have higher nutrient intakes and as such, reduce energy balance to some extent. As expected, both milk yields and intakes increase with increasing lactation numbers.
So, what can we do on farm to help mitigate a negative energy balance?
• Good transition management will ensure optimum rumen function and dry matter intake through the dry period into early lactation. Fresh cow groups are an excellent way of making sure early lactation cows can get the energy required. This isn’t always possible on a lot of farms so having a standard crude protein base diet with a high energy lower protein compound fed in the parlour or out of parlour feeders is an excellent way of targeting fresh calved cows.
• Body condition scoring cows during the dry period and in early lactation can provide valuable information about transition weight loss. Peak negative energy balance occurs typically 2 weeks post calving and cows should return to positive energy balance approximately 50-60 days post calving, loosing more than 0.5 body condition score can lead to significantly more metabolic disease.
• Feeding high energy dense feeds like Propylene Glycol, Molasses or Evolution C18 Fat can increase dietary energy density to help reduce negative energy balance in the early lactation period when dry matter intake is limited. A 400 g/d supplement of Evolution C18 typically increases energy density by 0.4 MJ/kg DM.
• Regular silage testing each month also helps so that the diets can be balanced as efficiently as possible, and ensures fresh cows are getting sufficient energy. Clamp silages do change throughout the season. Forage analysis is free to NWF account holders and results are processed within 48 hours of receipt of sample
By NWF Ruminant Nutritionist, Ryan McPherson.
