Effect of Heifer Development System on Reproduction and Subsequent Gain as a Pregnant Heifer

Weaned heifers grazed corn residue, upland range, or were fed 1 of 2 drylot diets differing in energy. Heifer development diets did not impact their resulting AI or final pregnancy rates. Cost per pregnant heifer was similar among treatments. A subset of AI- pregnant heifers was placed in a Calan Broadbent individual feeding system during late gestation. As a pregnant heifer, feed efficiency was not impacted by development system. These results indicate producers may utilize their most readily available and/or cost- effective feed resources with no detriment to pregnancy rates or feed efficiency as first- calf heifers

Beef Cattle Management Systems for Estrus Synchronization and Heifer Development

Four experiments were conducted to evaluate estrus synchronization and heifer development systems. In the first experiment delaying AI 19 h following GnRH administration in a hybrid estrus detection and time AI protocol was evaluated. Final pregnancy rate was not different among heifers detected in estrus, AI at the time GnRH administration, or delayed AI. The second study compared the effect of melengestrol acetate (MGA) -PG and 14-d controlled internal drug release (CIDR) -PG estrus synchronization protocols on estrus response and pregnancy rates of 311 d old heifers. Final pregnancy rate was similar between CIDR and MGA treatment groups. The objective of the third study was to determine the impact of heifer development system on subsequent growth and reproductive performance in 2 breeding seasons. Heifers were offered ad libitum meadow hay (HAY) and 1.81 kg/d (29% CP, DM basis) supplement or allowed to graze meadow (MDW) and 0.45 kg/d supplement. Although ADG during the winter feeding period was greater for HAY heifers, BW was similar between treatments in the spring, summer, and at pregnancy diagnosis suggesting a compensatory growth effect for MDW heifers. Similarly, pubertal status or pregnancy rate was not different, indicating a lower input winter management system is viable to maintain heifer pubertal status and pregnancy rates in 2 breeding seasons. Finally, to determine the impact of heifer development system on pregnancy rates and feed efficiency as a pregnant first calf heifer a 3 yr study was conducted. In Yr 1, weaned heifers either grazed corn residue (CR) or were fed in a drylot (DLHI). In Yr 2 and 3 heifers either grazed CR, upland range (RANGE), or were fed diets differing in energy, high (DLHI) or low (DLLO), in a drylot setting. Pregnancy rates to AI were similar among treatments. A subset of AI-pregnant heifers from each treatment were placed in a Calan gate system. Intake did not differ among treatments, either as DMI or as a percentage of BW. Advisors: Rick N. Funston and Andrea S. Cup

Growth and Reproductive Performance of Yearling Beef Heifers Implanted with Revalor G in the Nebraska Sandhills

Th is study evaluated effects of a single stocker implant (Revalor G) on growth and reproductive performance of yearling beef heifers in the Nebraska Sandhills. Crossbred heifers, grazing native Sandhills range, were randomly assigned to either be implanted 82 ± 2 days prior to estrus synchronization, or not implanted, to determine the effects of growth implants on heifer performance. Heifers were bred via artificial insemination followed with clean- up bulls. Implanted heifers gained more and were heavier at the end of the trial, but had a reduced pregnancy rate than non- implanted heifers. Implanted heifers also had a lower pregnancy rate in their second breeding season. Implanting yearling beef heifers increased average daily gain; however, it decreased initial and subsequent pregnancy rate compared with heifers not implanted. When deciding to implant replacement females, the current (or expected) market conditions for pregnant and feeder heifers must be considered

Effect of Heifer Development System on Reproduction and Subsequent Gain as a Pregnant Heifer

Weaned heifers grazed corn residue, upland range, or were fed 1 of 2 drylot diets differing in energy. Heifer development diets did not impact their resulting AI or final pregnancy rates. Cost per pregnant heifer was similar among treatments. A subset of AI- pregnant heifers was placed in a Calan Broadbent individual feeding system during late gestation. As a pregnant heifer, feed efficiency was not impacted by development system. These results indicate producers may utilize their most readily available and/or cost- effective feed resources with no detriment to pregnancy rates or feed efficiency as first- calf heifers

Impact of Heifer Development System in Two Different Breeding Seasons

Replacement heifers from March and May calving herds were offered ad libitum meadow hay and 4 lb/d supplement or grazed meadow and offered 1 lb/d supplement from mid- January to mid- April. Heifers fed hay gained more during the treatment; however, heifers grazing meadow experienced compensatory gain, resulting in similar body weight at pregnancy diagnosis in both calving herds. Pregnancy rates were similar between treatment groups in March and May heifers. A reduced input winter management system is a viable option to maintain pregnancy rates in early and late summer breeding seasons