Cows Need Their Five A Day
9 years ago 
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FAT AN ESSENTIAL 5-A-DAY FOR DAIRY COWS!
We all know we humans need our ‘5-a-day’ as part of a nutritious diet.
Dairy cows likewise need nutrients from a number of sources with fat one of their essential ‘5-a-day’ nutrients. Like protein, fibre, starch and sugar, fat must be balanced in the diet in order to help exploit performance without detriment to herd health and subsequent major losses, says Volac ruminant nutritionist, Dr Richard Kirkland. Here are some reasons why.
1, Increased energy supply
Fat is a highly concentrated source of energy, containing two and a half to three times the metabolisable energy (ME) concentration of cereals. For example, replacing 0.5 kg of wheat (5.9 MJ) with 0.5 kg of a proven rumen-protected fat (15.8 MJ) increases energy supply by 10 MJ of ME, equivalent to approximately two litres of milk. This higher energy density, providing more energy per bite, is particularly beneficial for dairy cows in early lactation when appetite and dry matter (DM) intake are low, but milk production is rising rapidly, causing cows to lose body condition as they ‘milk off their backs’ to make up the energy shortfall.
2, Energy without acid
Increasing energy supply for dairy cows is often achieved by reducing the proportion of forage fibre and increasing supply of higher-energy feeds such as cereals. However, cereals supply energy as starch which is fermented in the rumen to acid and can increase risk of acidosis. Fats have the benefit of providing a high energy diet without fermentation in the rumen and production of acid, hence increasing energy without adding to the acid load in the rumen.
3, Improved fertility
Fat plays an important role in cow fertility, supplying energy to target reduced body condition loss (as a guideline, conception rate decreases by 10% for each 0.5 unit loss of body condition) and as a key nutrient to improve production of progesterone, the key hormone associated with successful pregnancy. Some fat supplements are also proven to improve quality of eggs, increasing the chance of survival after fertilisation.
4, Increased efficiency of energy use
Energy in fat is used very efficiently to produce milk, more so than other sources of energy. Fats can also reduce production of methane, one of the so-called greenhouse gases that are less-desired environmentally, but crucially also represent a major loss of energy from ruminant diets. Hence, fat addition to diets can improve feed efficiency (more production per unit intake), further contributing to improved returns.
What type of fat to feed? High-fat ingredients, or added fish or vegetable oils, can increase diet fat, but the rumen can only tolerate small amounts of these fat sources before problems arise with reduced fibre digestibility and often low milk fat %. Fat supplements provide a much more concentrated source of fat and should be used based on their proven effects e.g. improved milk yield and fertility, improved milk fat production, and rumen-protection - in other words they should pass through the rumen intact for digestion in the small intestine avoiding undesirable effects in the rumen.
How much fat do I need to feed? Cows have specific requirements for fat and by following simple guidelines to determine if the quantity fed is adequate, overall performance can be improved. Initial research, carried out at Ohio State University by Prof Don Palmquist, established that a good rule of thumb when feeding fat to cows in energy balance - those neither gaining or losing body condition, is to feed them an amount equal to that secreted in milk. See Table 1.
Table 1: Dietary fat requirement based on milk fat yield - cows neither
gaining or losing body condition
Parameter
Milk yield (kg/cow/day)
40
Milk fat (%)
4.0
Milk fat yield (kg/cow/day)
1.6
Amount of fat required by the cow (kg/cow/day)
1.6
Source: Ohio State University
While we must be fully aware of this coming winter’s pressures, it’s going to be more important than ever to carefully consider fat together with the other essential ingredients that provide a balanced diet in order to stem losses and ensure the herd is in optimum condition to reap future rewards – remember the ‘5-a-day’ requirement as part of an optimal diet.
· Use Volac’s Fat Calculator to determine your herd’s dietary fat requirements, together with the diet fat supply based on the ingredients used. The calculator will also enable you to make a simple evaluation of diets on farm and the effects of substituting ingredients on total fat concentration. The Fat Calculator can be obtained in DVD format by calling the Volac Helpline on 0800 919808 or logging on to www.volac.com/fat-calculator for an online interactive version.
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“Fat is an essential part of your cows’ diet; so it’s certainly not for dropping from this season’s rations,” Volac ruminant specialist Dr Richard Kirkland of Dungannon.
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