Using rumen-protected fat to support fertility and milk fat at turnout
Each spring, dairy herds are hit with milk fat depression following turnout. According to Dr Richard Kirkland, Global Technical Manager for Volac Wilmar Feed Ingredients, the cause is two-fold.
“First, the rumen is being challenged by a switch of a more-controlled and consistent winter ration to grazed grass,” explains Dr Kirkland. “The second factor is grass in the early grazing season is low in fibre, high in sugar and highly fermentable, resulting in higher fermentation rate and passage through the rumen. This can lead to the rumen’s pH being thrown off balance and an increased risk of acidosis.”
While milk fat production is the major risk during this diet transition, fertility can also suffer as consequence. While early grass growth is high in energy, variable spring grazing conditions make it harder for the energy supply to be consistently maximised.
For many herds, spring turnout coincides with early lactation when energy demands are highest and cows are unable to eat enough to meet their energy requirements. When not fulfilled, cows fall into a negative energy balance to meet the high energy demands of milk production, which has a knock-on effect on fertility. Research from the University of Nottingham indicates that for each 0.5-unit loss in condition during this period, conception rates can fall by around 10%.
The best option to fill the energy gap without causing further disruption to the rumen is to supplement with rumen-protected fats, says Dr Kirkland.
Containing 2.5-times the energy content of cereals, rumen-protected fat helps maintain rumen stability since they don’t ferment in the rumen. This mitigates the risk of acidosis and milk fat depression brought on by feeding cereals, which push down rumen pH due to their rapidly fermentable starch content.
“The high energy density of rumen-protected fat supplements also makes them an ideal choice to sustain energy supply at grass where conditions can be unpredictable on a daily basis. To further improve milk fat, they pair well with digestible fibre sources such as citrus pulp and soya hulls,” explains Dr Kirkland.
Perhaps one of the biggest benefits of rumen-protected fat is the ability to support specific areas of cow performance based on where she is in the lactation cycle and what best benefits an individual farm’s milk contract requirements.
The so-called ‘high-C16’ products will drive milk fat, but risk condition loss and poorer fertility. The calcium salt products supply oleic fatty acid (C18:1) which will help reduce condition loss and improve fertility. A suitable compromise may be a supplement like Mega-Fat 70 which provides a higher C16 level than the standard calcium salts but still supplies that important rumen-protected source of C18:1.