Short communication: Feeding distillers dried grains in replacement of forage in limit-fed dairy heifer rations: Effects on post-trial performance.

The objective of this study was to determine the effect of increasing the inclusion rate of distillers dried grains with solubles (DDGS) in replacement of forage in diets that were limit-fed during peripubertal growth on performance during the first 3 mo of first lactation. A secondary objective was to also characterize reproductive performance of the dairy heifers. A 16-wk randomized complete block design study was conducted using 48 Holstein heifers (199 ± 2 d of age) with 3 treatments. Treatments were (1) 30% DDGS, (2) 40% DDGS, and (3) 50% DDGS, with the remainder of the diet consisting of grass hay and 1.5% mineral mix. Heifers were individually limit-fed using Calan gates at 2.65, 2.50, and 2.35% of body weight on a dry matter basis for 30, 40, and 50% DDGS, respectively. After completing the feeding study, heifers were fed a common diet according to standard herd management. Data on reproductive performance and milk production for the first 3 mo of lactation were collected for each heifer from dairy herd records. At 3 wk prepartum and at calving, body weight, frame measurements, and body condition score were recorded. We found no differences in reproductive or frame measurements taken around parturition. However, due to relatively small numbers of heifers for evaluation of reproductive parameters, results should be viewed as qualitative rather than conclusive, and more research is necessary. We noted a treatment by month effect for somatic cell count; however, there were no other differences for any of the lactation parameters measured. Results demonstrate that up to 50% of diet can be fed in limit-fed rations as DDGS, compared with 30 or 40%, to peripubertal dairy heifers without negative consequences to first-lactation performance during the first 3 mo.