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Developmental And Reproductive Characteristics Of Beef Heifers Classified By Number Of Estrous Cycles Experienced By Start Of First Breeding, Andy Roberts, Jaclyn N. Ketchum, Richard N. Funston

West Central Research and Extension Center, North Platte

A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or >3 (n = 249). Heifers (P …

Heifer Development Systems: Dry-Lot Feeding Compared With Grazing Dormant Winter Forage, Richard N. Funston, D. M. Larson

West Central Research and Extension Center, North Platte

Two hundred ninety-nine Angusbased, nulliparous heifers (253 ± 2 kg initial BW) from 3 production years were utilized to compare traditional postweaning dry lot (DL) development with a more extensive winter grazing system utilizing a combination of corn residue and winter range (EXT). Heifers developed in the DL were offered a common diet after the weaning period for 208 d in yr 1, 194 d in yr 2, and 150 d in yr 3 until breeding. Heifers developed in EXT grazed corn residue for 135 d in yr 1, 106 d in yr 2, and 91 d in yr 3, …

The Effects Of Corn Coproduct Supplementation On Primiparous Cow Reproduction And Calf Performance, D. M. Larson, R. N. Funston

West Central Research and Extension Center, North Platte

An experiment was replicated over 2 yr to determine the effect of additional RUP and dietary fat from dried distillers grains plus solubles (DDGS; n = 2) or wet corn gluten feed (WCGF; n = 2) before breeding on primiparous cow reproduction and calf production. Over 2 yr, 134 postpartum, primiparous cows (429 ± 5 kg initial BW) were fed 1 of 2 isocaloric, approximately isonitrogenous diets in 1 pen/yr (n = 4) providing varying levels of RUP and dietary fat. Treatments were initiated 21 (yr 1) and 60 d (yr 2) postpartum and continued for 56 (yr 1) or …

Extending Interval From Seventeen To Nineteen Days In The Melengestrol Acetate - Prostaglandin Estrous Synchronization Program For Heifers, G. H. Deutscher

West Central Research and Extension Center, North Platte

Two experiments were conducted to determine whether extending the interval between removal of melengestrol acetate (MGA) from feed and injection of prostaglandin F_2α (PGF) from 17 to 19 d would affect synchronization of estrus, conception, and pregnancy rates of beef heifers. In both experiments, heifers were fed MGA for 14 d, and PGF was given at either 17 or 19 d after cessation of MGA feeding. Heifers were observed for estrus and artificially inseminated for 5 d after PGF injection.

In Exp. 1, 240 yearling heifers were randomly assigned to either a 17- or a 19-d …