Monitor energy intakes and sources in rations this winter

“Energy is a key requirement of the modern dairy cow, as it drives milk production, health and fertility. To meet high yielding cow’s requirements, supplementary feeds are required,” said Bethany May, ruminant nutritionist at Trident Feeds.

“This season, forages are feeding well, with high ME values, resulting in some producers pulling back on the addition of supplementary energy sources in rations, and relying heavily on forages,” she added.

“However, this reduction in other key energy sources, such as fats and carbohydrates, means in some cases, early lactation energy requirements aren’t being met, and productivity is therefore negatively impacted.”

Miss May explains that cows naturally have a suppressed appetite and intake at the start of lactation, and if energy requirements are not met at this point, they are likely to experience negative energy balance (NEB).

“In response to this, cows will mobilise body fat reserves to help maintain the energy levels required for milk production, and this has been shown to have a knock-on effect on fertility,” she said.

“Traditionally the use of supplementary fats in fresh cow rations has been questioned, especially when forages are high in energy. However, new research1 supports the use of protected fats, highlighting the importance of choosing the right types of fat to avoid depressed intakes.

“Producers should therefore look to include rumen protected fats, that are high in C16 and C18 fatty acids alongside good quality forages to boost energy density and minimise NEB.’’

Dairy farmer Geoff Spence includes a balanced C16/C18 rumen protected fat in the diet of his high yielding cows. However, he recently attempted to cut back on the levels in the ration to reduce costs and rely more on the energy provided in his forage.

“In our high yielding group, we’ve always included Golden Flake, a rumen protected fat with a high level of C18fatty acids, to help push yield while maintaining body condition,” said Mr Spence.

“This autumn, because of the high ME value of our first-cut grass silage, we halved the feed rate of Golden Flake from 300g/head/day to 150g/head/day,” he added.

“To our surprise, this decision resulted in an immediate drop in 1.5L/cow/day, which equated to a loss of 30.86p/cow/day*, which across the group of 170 cows was a loss of £15,720 for the month. In addition, bulling activity also reduced, and for this reason we quickly reinstated the higher feed rate to get the yield and fertility back on track.”

Miss May explained that this dramatic drop in yield was a result of the removal of additional energy in the form of C18 fatty acids, which act as an ‘energy balancer’.

“When provided in the diet, C18 fatty acids have a glucose sparing effect which can cause the cow to mobilise less body reserves, which can cause appetite depression, meaning additional energy intake and the C16 fatty acids can be used to lift milk yield and milk fat percentage, increasing the value per litre. If removed, the cow may no longer be able to sustain the high levels of production, which was seen in Geoff’s herd.

“It’s also important to note that rumen protected fats such as Golden Flake, can also help to maintain or increase body condition through offsetting NEB, providing essential energy for the cow, which is linked to improved fertility,” she added.