Abstract
The aim of this research communication was to examine the effect of dietary supplementation with wheat-based dried distillers' grains with solubles (DDGS), a by-product of bioethanol production, on yield, composition, and fatty acid (FA) profile of ewe milk. Forty-five purebred mid-lactating Chios ewes (average milk yield 2.23 kg/d in 96 ± 5 d in lactation) were offered three iso-nitrogenous and iso-energetic diets (15 animals per diet) for a 10 d adaptation period followed by a 5-week recording and sampling period. The diets contained 0, 6, and 12% DDGS on DM basis for the DG0, DG6, and DG12 treatment, respectively, as a replacement of concentrate mix, whilst concentrate-to-forage ratio remained at 60:40 in all treatments. Individual milk yield, milk composition, and FA profile were recorded weekly and analyzed using a complete randomized design with repeated measurements. No significant differences were observed among groups concerning dry matter intake (overall mean of 2.59 kg/d), milk yield or 6% fat-corrected milk and milk protein percentage or protein yield. Milk fat percentage was decreased in the DG12 (4.76%) compared to DG0 (5.69%) without, however, significantly affecting the daily output of milk fat. The concentration of all major saturated FA between C4:0 to C16:0 was reduced, whereas long-chain (>16 carbons), mono-unsaturated and poly-unsaturated FAs were increased in the milk of DDGS groups. Among individual FA, increments of oleic acid and C18:1 trans-monoenes like C18:1 trans-10 and C18:1 trans-11 were demonstrated in DG12 group, whereas linoleic and conjugated linoleic acid (CLA cis-9, trans-11) were elevated in both DDGS groups compared to control. Changes in FA profile resulted in a decline in the atherogenic index of milk by 20% and 35% in DG6 and DG12 treatments, respectively, compared with control. In conclusion, feeding DDGS to dairy ewes increased the levels of unsaturated FA that are potentially beneficial for human health without adversely affecting milk, protein or fat yield.
Highlights
The rapid growth of bioethanol production from grains such as corn, wheat and sugarcane has generated significant quantities of by-products that can be used as alternative feedstuffs in dairy animals (Schingoethe et al, 2009)
This reduction in fat percentage was not accompanied by a reduction in milk or fat yield a concomitant reduction in milk yield with 25% dried distillers grain with solubles (DDGS) inclusion level has been reported (Testroet et al, 2015)
The former study (Cais-Sokolińska et al, 2015) examined only the chemical composition of sheep and goat milk and their products, and not milk yield. They reported that the inclusion of maize DDGS at the level of 3.5% did not affect milk fat and protein percentages, but did affect fatty acids (FA) content showing increased concentrations of total poly-unsaturated FA (PUFA) and trans – mono-unsaturated FA (MUFA) for both ovine and caprine milk, and reduced saturated fatty acid (SFA), as well as increased MUFA and CLA content in caprine but not in ovine milk
Summary
The rapid growth of bioethanol production from grains such as corn, wheat and sugarcane has generated significant quantities of by-products that can be used as alternative feedstuffs in dairy animals (Schingoethe et al, 2009). The majority of studies in dairy cattle investigating DDGS from different grains with inclusion rates up to around 20% of DM intake showed that milk production and fat yield were increased or not adversely affected, when diets contained adequate levels of forage fiber (Schingoethe et al, 2009; Chibisa et al, 2012; Gaillard et al, 2017a, 2017b).
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