Effect of Injectable Trace Mineral on Reproductive Performance in Beef Heifers

Trace minerals serve an essential role in regulating reproduction. Free-choice trace mineral supplementation is often provided to grazing beef cattle. An injectable trace-mineral solution used with free-choice trace minerals may be beneficial before breeding to improve mineral status. Therefore, Red Angus-based, May-born heifers were utilized to determine the effects of an injectable trace mineral on reproductive performance. Pregnancy rates did not differ between heifers injected with a trace mineral and heifers that received no injection. Injectable trace mineral at CIDR insertion 33 d before artificial insemination did not influence reproductive performance in heifers with adequate trace mineral status

Effect of Injectable Trace Mineral on Reproductive Performance in Beef Heifers

Trace minerals serve an essential role in regulating reproduction. Free-choice trace mineral supplementation is often provided to grazing beef cattle. An injectable trace-mineral solution used with free-choice trace minerals may be beneficial before breeding to improve mineral status. Therefore, Red Angus-based, May-born heifers were utilized to determine the effects of an injectable trace mineral on reproductive performance. Pregnancy rates did not differ between heifers injected with a trace mineral and heifers that received no injection. Injectable trace mineral at CIDR insertion 33 d before artificial insemination did not influence reproductive performance in heifers with adequate trace mineral status

Impact of Winter Supplementation of May Calving Cows and Heifer Development System in Two Different Breeding Seasons on Subsequent Growth and Reproduction

In Exp. 1, May-calving cows were utilized to evaluate the effects of winter supplementation on heifer progeny. Cows grazed either dormant upland winter range with or without a protein supplement or grazed dormant meadow with or without a protein supplement. In Exp. 2, 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. Calf weaning BW and ADG from birth to weaning was less for calves from cows grazing winter range with no supplement compared with all other dam treatments. Heifer development system did not impact final pregnancy rates. Therefore, a reduced input winter heifer development system is a viable option in both early and late summer breeding seasons. However, winter supplementation of May-calving dams did influence heifer progeny ADG from birth to weaning

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

Vascular Endothelial Growth Factor A 165 rescues steroids, inflammation and follicle arrest in High Androstenedione cows

A population of cows with excess androstenedione (A4; High A4) in follicular fluid, with follicular arrest, granulosa cell dysfunction, and a 17% reduction in calving rate was previously identified. We hypothesized that excess A4 in the ovarian microenvironment caused the follicular arrest in High A4 cows and that vascular endothelial growth factor A would rescue the High A4 phenotype. In trial 1, prior to culture, High A4 ovarian cortex (n=9) had greater numbers of early stage follicles (primordial) and fewer later-stage follicles compared to controls (n=11). Culture for 7 days did not relieve this follicular arrest; instead, High A4 ovarian cortex had increased indicators of inflammation, anti-Mullerian hormone, and A4 secretion compared to controls. In trial 2, we tested if vascular endothelial growth factor A (VEGFA) angiogenic (165) and antiangiogenic (VEGFA165b) isoforms could rescue the High A4 phenotype. High A4 (n=5) and control (n=5) ovarian cortex was cultured with (1) PBS, (2) VEGFA165 (50 ng/mL), (3) VEGFA165b (50 ng/mL), or (4) VEGFA165+VEGFA165b (50 ng/mL each) for 7 days. Follicular progression increased with VEGFA165 in High A4 cows with greater early primary, primary, and secondary follicles than controls. Similar to trial 1, High A4 ovarian cortex secreted greater concentrations of A4 and other steroids and had greater indicators of inflammation compared to controls. However, VEGFA165 rescued steroidogenesis, oxidative stress, and fibrosis. Both VEGFA isoforms reduced specific pro-inflammatory cytokines in High A4 cows to control levels. Thus, VEGFA165 may be a potential therapeutic to restore the ovarian steroidogenic microenvironment to promote folliculogenesis

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

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 Winter Supplementation of May Calving Cows and Heifer Development System in Two Different Breeding Seasons on Subsequent Growth and Reproduction

In Exp. 1, May-calving cows were utilized to evaluate the effects of winter supplementation on heifer progeny. Cows grazed either dormant upland winter range with or without a protein supplement or grazed dormant meadow with or without a protein supplement. In Exp. 2, 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. Calf weaning BW and ADG from birth to weaning was less for calves from cows grazing winter range with no supplement compared with all other dam treatments. Heifer development system did not impact final pregnancy rates. Therefore, a reduced input winter heifer development system is a viable option in both early and late summer breeding seasons. However, winter supplementation of May-calving dams did influence heifer progeny ADG from birth to weaning