Effects of Increased Dietary Fat from Distillers Grains on the Long-term Dairy Heifer Performance

Researchers at South Dakota State University have been looking into heifer performance and growth investigating the effects of feeding distillers dry grains with solubles to 33 young holstein heifers.
calendar icon 8 January 2013
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Over the last few years, we have been working on a long-term heifer feeding project, researching the effects of feeding distillers dried grains with solubles (DDGS) to pre-pubertal dairy heifers. Part of this work was to determine how the diet fed during the growth phase influences heifer performance after they enter the lactating herd.

During the pre-pubertal growth phase, 33 Holstein heifers (133 ± 18 d old) were fed one of three treatment diets for 24 weeks. Treatments included the following: 1) a control diet (C) containing ground corn (15.9 per cnet of DM) and soybean products (17.9 per cent), 2) a low-fat diet distillers grains diet (LFDG) containing 21.9 per cent low-fat, high-protein distillers dried grains and 11.9 per cent ground corn, and 3) a high-fat traditional distillers grains diet (HFDG) containing 33.8 per cent traditional distillers dried grains with solubles (DDGS).

The remaining portion of all of the diets contained 39.8 per cent grass hay, 24.8 per cent corn silage, and 1.5 per cent vitamins and minerals. The results demonstrated that growth performance was maintained, despite differences in metabolic profiles, such as greater plasma cholesterol and fatty acid concentrations in the heifers fed the HFDG diet compared to other treatments.

Previous results also indicated that puberty may be occurring earlier in the heifers fed the HFDG. It was hypothesized that differences among treatments in metabolic profile and puberty may influence reproductive and first-lactation performance.

Milk Yield

After heifers completed the feeding trial and returned to the regular herd at the SDSU Dairy Research and Training Facility, data on the heifers continued to be collected. Data on reproductive performance were collected from herd health records. Data on milk production and components, for the first four months of lactation, were collected for each heifer from DHIA records.

At 3 weeks pre-calving and at calving, we measured body weights, body condition scores, and frame size of the heifers. There were no differences (P > 0.05) among treatments for age at conception, or age at calving, although heifers fed the LFDG diet were numerically older compared to the heifers fed the C and HFDG diets. At calving, heifers fed the HFDG were slightly shorter in wither height (P= 0.03) compared to heifers fed the other diets.

Milk yields and components (see Figure) were similar or improved in heifers fed either distillers grains diets compared to heifers fed the C diet. Heifers fed the LFDG had greater milk production (P= 0.03) and a tendency (P = 0.06) for greater milk protein yields compared to the heifers fed the C diet. Energy-corrected milk yields were similar among treatments.

Feeding greater amounts of dietary fat from traditional DDGS during the prepubertal growth phase did not negatively impact milk production, despite earlier attainment of puberty compared to other treatments. Based on these findings, producers can feed either traditional DDGS or a low-fat DDGS in place of corn and soybean products to pre-pubertal heifers and maintain or enhance subsequent reproductive and lactation performance. Dietary fat from DDGS can replace starch from corn as an energy source for prepubertal heifers with no detriment on the long-term performance of the dairy heifers.

Further Reading

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January 2013

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