Impacts of dietary fat level and saturation when feeding distillers grains to high producing dairy cowsby J. M. Havlin, P. H. Robinson, K. Karges

J Anim Physiol Anim Nutr


Food Animals / Animal Science and Zoology



Impacts of dietary fat level and saturation when feeding distillers grains to high producing dairy cows

J. M. Havlin1, P. H. Robinson1 and K. Karges2 1 Department of Animal Science, University of California, Davis, CA, USA, and 2 POET Nutrition, Inc., Sioux Falls, SD, USA


This experiment was conducted to determine whether increasing the net energy (NEL) of a total mixed ration (TMR) with mainly unsaturated fat from corn distillers dried grains with solubles (DDGS) vs. rumen inert (RI)saturated fat has similar impacts on animal performance. The experiment was an incomplete Youden square with three treatments and four 28-days periods, completed on a large commercial dairy using three early lactation pens each with approximately 380 multiparity cows. The TMR for all treatments was the same, except for 150 g/kg dry matter (DM) of each TMR which contained 90 g/kg high-protein DDGS (HPDDGS) and 60 g/kg beet pulp (i.e. low-fat control diet; LFC); 150 g/kg DDGS (i.e. high-fat diet with unsaturated fat; HFU); or 111 g/ kg HPDDGS, 20 g/kg beet pulp and 19 g/kg RI fat (i.e. high-fat diet with saturated fat; HFS). The DM intake was highest (p < 0.05) for HFU-fed cows. Milk, fat and true protein yields, as well as milk energy output, were higher (p < 0.01) when cows were fed HFS vs. HFU and LFC diets. Milk true protein concentration was lowest (p < 0.01) for HFS-fed cows, but milk fat % was lowest (p < 0.01) for HFU and highest (p < 0.01) for HFS-fed cows. There were numerous differences (p < 0.01) in milk fatty acid levels amongst diets. The increase in body condition score was lowest (p < 0.01) for LFC. Whole tract digestibility of acid detergent fibre was lower (p < 0.01) for LFC vs. HFS cows, and fat digestion was lowest (p < 0.01) for LFC-fed cows. This DDGS, high in unsaturated fatty acids, was fed at high levels (i.e. 152 g/kg DM) with little impact on animal performance vs. a lower fat control diet, although addition of an RI-saturated fat to create a diet with a similarly higher fat level resulted in higher animal productivity.

Keywords milk fat depression, saturated, unsaturated, RI fat, dried distillers grains with solubles, distillers

Correspondence J. M. Havlin, Department of Animal Science, University of California, 1 Shields Ave, Davis, CA 95616, USA. Tel: +1 209 614 7230;

Fax: +1 530 752 0175; E-mail:

Received: 4 September 2013; accepted: 3 June 2014


High inclusion levels of supplemental fat, a concentrated source of net energy (NEL), are common in rations of high producing dairy cows worldwide.

Added lipids can be of various saturation levels. For example, polyunsaturated fatty acids (PUFA) mainly originate from plant and seed oils while saturated fatty acids (SFA) largely originate from animal by-products or a few plants such as palm oil.

Sources of PUFA, especially oils with high levels of linoleic and linolenic FA, have inhibited microbial activity with resultant decreased forestomach fibre fermentation (Palmquist and Jenkins, 1980; Hartfoot and Hazlewood, 1988; Doreau and Chilliard, 1997).

At high levels, these FA can lead to an altered biohydrogenation pathway in the rumen, resulting in creation of CLA t10c12 and C18:1 t10 intermediates, which can inhibit fat synthesis in the mammary gland (Harvatine and Bauman, 2007).

Saturated FA are less likely to change rumen fermentation, compared to PUFA, due to their insolubility at normal rumen pH (Schneider et al., 1988;

Schauff and Clark, 1989), thereby preventing an effect on fibre digestibility or lipogenesis. Because SFA largely escape the rumen without being degraded or metabolized, as well as having little effect on the rumen environment, these FA are often called rumen inert (RI). Feeding RI FA to dairy cows consistently increases milk fat proportion and, generally, yields (Palmquist and Jenkins, 1980; Scott et al., 1995).

An increasingly common ingredient added to rations of high producing dairy cows worldwide, which can increase dietary fat level, is dried distillers

Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH 1

DOI: 10.1111/jpn.12219 grains with solubles (DDGS). Due to the growing motor fuel ethanol distillation industry in the Midwest

USA and other parts of the world, there has been a steadily increasing level of DDGS from corn grain available to world animal feed market since 2000 (Anonymous, 2013), and DDGS products originating in the USA are now exported worldwide. Conventional DDGS have nutrient levels which are approximately thrice that of the corn grain from which they originate. Thus, as starch makes up approximately two-thirds of its dry matter (DM) and is almost completely fermented to create ethanol, DDGS contain approximately 30% crude protein (CP) and 11% fat on a DM basis. However, DDGS, being high in corn oil, are substantial source of PUFA. Many technical papers (i.e. Hutjens, 2004; Diaz-Royon, 2012) have reported that there is a consensus amongst commercial dairymen that high feeding levels of DDGS play a role in reducing de novomilk fat synthesis.

Unfortunately, recent research on DDGS has produced mixed results. A meta-analysis of 44 trials (Hollmann et al., 2011) could neither accept nor reject their hypothesis that increased inclusion of distillers grains increases the risk of milk fat depression.

This may be a result of using small and statistically underpowered studies, and the authors suggest that their findings are not applicable to commercial settings. Of the recent research that has supported the hypothesis that increasing levels of DDGS may negatively impact milk fat production, all have fed diets with relatively high levels of corn silage and other corn products ranging from 42% (Abdelqaedar et al., 2009) to 63% (Zanton et al., 2013) of the basal diet

DM. However, dairy rations in many parts of the world, including many areas of Europe and North

America, contain much lower levels of corn products.

As well, most recent studies that have shown a negative impact of increasing DDGS levels examined DDGS as a substitute for both soybean meal and corn grain (Leonardi et al., 2005; Benchaar et al., 2013), therefore altering the availability and form of FA as well as the amino acid profile and rumen degradable and rumen undegradable protein levels of the diet. In addition, a review by Schingoethe et al. (2009) finds that, in general, feeding distillers grains per se does not cause milk fat depression. Their explanation is that cows experiencing milk fat depression with increasing levels of distillers grains are suffering from a decrease in effective fibre from forages due to poorly formulated diets. The review also states that milk FA profile is not expected to be altered feeding distillers grains and reports only small increased levels of CLA c9t11 and C18:1 t11 from Leonardi et al. (2005) and Anderson et al. (2006) with DDG feeding, yet neglect to point out that FA are not associated with milk fat depression (Griinari et al., 1998) and fail to note that these same studies found increased levels of C18:1 t10, the C18:1 isomer highly associated with milk fat depression (Griinari et al., 1998).