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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #199314
Title: HEIFERS FED SOYBEANS OR MILLING BY-PRODUCTS UTILIZATION OF SOYBEANS OR CORN MILLING BY-PRODUCTS IN BEEF HEIFER DEVELOPMENT DIETS

Author
item HARRIS, H - UNIV OF NEBRASKA-NORTH PL
item CUPP, A - UNIV NEBRASKA - LINCOLN
item Roberts, Andrew
item FUNSTON, R - UNIV NEBRASKA - NORTH PLA

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2007
Publication Date: 1/15/2008
Citation: Harris, H.L., Cupp, A.S., Roberts, A.J., Funston, R.N. 2008. Heifers fed soybeans or milling by-products utilization of soybeans or corn milling by-products in beef heifer development diets. Journal of Animal Science 86:476-482.

Interpretive Summary: Development of replacement heifers at sufficient rates of growth to ensure attainment of puberty prior to breeding is critical for efficient beef cattle production. Forage diets can be economically supplemented with high-energy sources of protein to provide sufficient nutrients to support adequate development for successful reproductive function. Three experiments were conducted to evaluate whole soybeans (SB), dried distillers grains (DDG) or wet corn gluten feed (WCGF) as protein and energy sources in beef heifer development diets. In Experiment 1,Crossbred heifers were fed diets containing 1.25 kg SB or 2.0 kg WCGF from 10 to 13.5 mo of age (wt are on a dry matter/d basis). Weight gain during trial did not differ between diets (0.69 kg/d), but heifers fed SB had a lower estrous synchronization rate (81 vs. 96%) and longer interval (P = 0.05) from PGF2' to estrus (3.2 vs. 2.9 d) compared to heifers fed WCGF. In Experiment 2, heifers were fed 1.25 kg SB or 1.25 kg DDG from 6 to 13.5 mo of age. Daily gain was greater in DDG fed than (0.71kg/d) than SB (0.65) fed heifers. Synchronization rate (86%) and timing of estrus after PGF2' (2.9 d) did not differ due to diet. For Exp 1 & 2, heifers fed SB maintained weight better on native pasture during the 90d period after AI. In Exp. 3, heifers were fed 1.25 kg SB beginning at either 7 or 10 mo of age. Age at which heifers were started on SB diets did not alter synchronization rate (79%) or timing of estrus after PGF2' (3.2 d). There were no differences due to diet within each experiment for AI conception (76.5, 68.5, and 60% for Exp. 1, 2, or 3, respectively), AI pregnancy (67, 59, and 46%), or final pregnancy rates (92, 90 and 90%). In summary, SB, DDG and WCGF all appear to be feasible protein and energy supplements in heifer development diets at the inclusion rates used in these studies.

Technical Abstract: Three experiments were conducted to evaluate whole soybeans (SB) and either dried distillers grains (DDG) or wet corn gluten feed (WCGF) as protein and energy sources in beef heifer development diets. Crossbred heifers were fed diets containing 1.25 kg (DM) SB or 2.0 kg WCGF beginning at 10 mo of age (Exp. 1; n=104), 1.25 kg SB or 1.25 kg DDG beginning at 6 mo of age (Exp. 2; n=100), and 1.25 kg SB beginning at 7 or 10 mo of age (Exp. 3; n=100). Heifers were fed melengestrol acetate for 14 d followed by an injection of prostaglandin F2' (PGF2') 19 d later to synchronize estrus. Heifers were artificially inseminated for 5 d after PGF2', and subsequently exposed to bulls for ~60 d beginning 10 d after the last day of AI. Pregnancy to AI was determined by ultrasound 45 d after the last day of AI. Heifers fed SB in Exp. 1 had a lower (P < 0.05) synchronization rate (81 vs. 96%) and longer interval (P = 0.05) from PGF2' to estrus (3.2 vs. 2.9 d) compared to heifers fed WCGF. In Exp. 2, synchronization rate (84 vs 88%) and timing of estrus after PGF2' (2.9 vs. 2.9 d) did not differ due to diet. In Exp. 3, age heifers were started on SB diets did not alter synchronization rate (79%) or timing of estrus after PGF2' (3.2 d) There were no differences due to diet (P > 0.10) for AI conception (76.5, 68.5, and 60%), AI pregnancy (67, 59, and 46%), or final pregnancy rates (92, 90 and 90%) in Exp. 1, 2, or 3, respectively. An HPLC analysis of extracted SB detected presence of three phytoestrogens. The interaction of phytoestrogens and age of heifers at the time of feeding may have resulted in the lower synchronization rate and delayed estrus response in Exp. 1 when compared to Exp. 2. In summary, SB, DDG and WCGF all appear to be feasible protein and energy supplements in heifer development diets at the inclusion rates used in these studies.