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Superintendent
David Davis
21262 Genoa Road
Linneus, MO 64653
Phone: 660 895-5121
FAX: 660 895=5122
Email: DavisDK@missouri.edu

Forage Systems Update
Vol 16, No. 4

Sixty five heifers ( 35 Gelbvieh x Red Angus heifers) and 30 commercial Angus heifers were randomly assigned to two supplemental feed treatments to evaluate the impact of corn distillers dried grains on reproductive performance. As shown in table 1, the treatments were: 1) corn distillers dried grains with solubles (DDGS) and 2) corn gluten feed, soybean meal and corn (CGF/SC). The heifers were divided into 3 replications per treatment with 11 animals per replication (one replicate of CGF/SC had 10 animals) and placed on 5 acre paddocks consisting of endophyte-infected tall fescue (approximately 50 % infected) and legumes. In addition to supplemental DDGS or CGF/SC at 0.55 % of BW, round bales of hay were provided from December to March and heifers had access to free choice trace mineral.

Heifers were weighed on consecutive days December 11 and 12, 2006 to determine their initial weight, and then weighed approximately every 28 days. On March 8, in addition to weighing heifers, measurements were taken for pelvic area and reproductive tract score. On March 23 and April 2, a blood sample was collected for progesterone determination. On April 2, CIDR's were placed in the reproductive tract of the heifers. On April 16, CIDR's were removed. On April 25 an injection of GNRH was given. On May 2, heifers received an injection of Lutalyze. Fixed-time AI was used in breeding the heifers 3 days after the last injection. Only the thirty commercial Angus heifers were turned out with a bull 13 days later.

As shown in Table 2, there were no significant differences in overall average daily gain (ADG) of heifers fed DDGS vs. those fed CGF/SC supplements. However, during the first 84 days of the study, the DDGS treatment had a greater (P = 0.05) ADG than the CGF/ SC treatment (1.9 vs. 1.6 lbs per day). During the last 54 days, heifers fed DDGS tended to loose (P = 0.07) more weight than the CGF /SC treatment (ADG of - 0.40 and -0.18 lbs per day. This loss in weight was attributed to the rapid growth of the tall fescue pasture in March which was limited in nutrient quality, along with switching from feeding hay. The reproductive tract score of the DDGS treatment tended to be greater (P = 0.06) for heifers fed supplemental DDGS as compared to those fed the CGF/CS supplement. The pelvic area of heifers were not different between supplemental feed treatments. As shown in table 3, progesterone concentrations revealed no differences between treatments for either blood sampling periods. Progesterone concentrations greater than 1.0 ng/ml is an indication of ovarian luteal activity, and suggests that the heifer has reached puberty. The average concentrations for both treatments at each blood collection were greater than this value. When comparing individual heifers, 9 and 14 of the animals on the DDGS and CGF/SC, respectively, for the first blood collection were below 1.0 ng / ml; for the second blood collection, 16 and 14 animals, respectively, were below 1.0 ng / ml concentration. This indicates that 46 % of heifers were not cycling at time of second sample collection. One benefit of the use of CIDR's to synchronize heat in heifers is that CIDR's can assist heifers in starting their estrus cycle.

As shown in table 4, the AI conception rates revealed 42 % and 53 % of the DDGS and the CGF/SC treatments, respectively, were AI bred. However, when AI conception rates were compared between the commercial Angus heifers from Greenley Center and the Gelbvieh x Red Angus heifers from FSRC, the commercial Angus had an average AI conception rate of 73.5 % (75 % for DDGS and 72 % for the CGF/SC); the Gelbvieh X Red Angus heifers had an average of 26.5 % (24 % for DDGS and 29 % for CGF/SC). One possibility for the low conception rates in Gelbvieh x Red Angus heifers was that many of these heifers came into heat within 24 hours rather than the expected 48 to 60 hours after injection. This suggests that these heifers did not achieve estrus synchrony and that the ideal time to breed some of these heifers may have been missed. Another possibility for the difference in conception rates between the two groups of heifers from FSRC and Greenley Center may be attributed to the use of semen from two different bulls. The bull used on the Gelbvieh x Red Angus heifers may not have been suitable for fixed-time artificial insemination. It is known that certain bulls, while very suitable for breeding using traditional heat detection, are not well suited for fixed-time artificial insemination.

From this study, one may conclude that supplementing heifers with DDGS increased weight gain and reproductive tract scores of heifers. Based on environmental factors impacting forage quality, and potential problems with achieving estrus synchrony and/or suitability of certain bulls being used for fixed-time AI, more studies are warranted to investigate the improvements in conception rate of heifers fed DDGS.

Table 1. Composition of supplemental diets on a % of DM fed to heifers.

Table 2. Performance and reproductive measurements of heifers fed supplemental diets.

Table 3.Plasma progesterone concentrations (ng/ml) of heifers fed supplemental diets.

Table 4. AI conception rates of heifers fed supplemental diets.

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