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

Nitrate Concentrations of Annual Forages Grown for Grazing in Nebraska

Annual forage samples sent by producers to Ward Laboratories Inc. for nitrate analysis were evaluated to determine which cover crop species in Nebraska are most likely to accumulate nitrates, and how often the accumulated nitrates are considered toxic by traditional recommendations. Additionally, nitrate levels of cover crop mixes grown in research trials were analyzed to ensure species differences were repeated when grown together in the same fields. Brassicas accumulate more nitrate than small grains, millet, sorghum/sudan grasses, or cover crop mixes. Brassicas accumulated levels of nitrate considered moderately to highly toxic in 48% of the samples. The other cover crop species accumulated potentially toxic nitrate levels in 20–28% of the samples. However, when cattle graze these forages, there are multiple factors that may mitigate toxicity. Cattle have grazed annual forages containing nitrate concentrations considered toxic, and no adverse health consequences were observed. More research is needed to reevaluate the risk of nitrate toxicity when grazing cover crops

Nitrate Concentrations of Annual Forages Grown for Grazing in Nebraska

Annual forage samples sent by producers to Ward Laboratories Inc. for nitrate analysis were evaluated to determine which cover crop species in Nebraska are most likely to accumulate nitrates, and how often the accumulated nitrates are considered toxic by traditional recommendations. Additionally, nitrate levels of cover crop mixes grown in research trials were analyzed to ensure species differences were repeated when grown together in the same fields. Brassicas accumulate more nitrate than small grains, millet, sorghum/sudan grasses, or cover crop mixes. Brassicas accumulated levels of nitrate considered moderately to highly toxic in 48% of the samples. The other cover crop species accumulated potentially toxic nitrate levels in 20–28% of the samples. However, when cattle graze these forages, there are multiple factors that may mitigate toxicity. Cattle have grazed annual forages containing nitrate concentrations considered toxic, and no adverse health consequences were observed. More research is needed to reevaluate the risk of nitrate toxicity when grazing cover crops

Effect of Long- Term Corn Residue Grazing on Soil Properties

An experiment was conducted to evaluate the effect of long- term (16 years) corn residue grazing with cattle on soil compaction, soil structure, soil organic matter, and nutrients. Three treatments: 1) fall grazing (November through January; 1.8 to 2.5 AUM/ac), 2) spring grazing (February to middle April; 2.3 to 3.1 AUM/ac), and 3) control (no grazing) under a no- till irrigated corn- soybean system in eastern Nebraska were studied. Crop yields were increased and soil bulk density and cone index (parameters of soil compaction), wet soil aggregate stability (parameter of soil structural quality), and organic matter content were not affected by grazing during the fall. Spring grazing slightly increased crop yields while wet soil aggregate stability, bulk density, and organic matter content were unaffected. During spring grazing, only cone index was increased, but not above threshold levels. Crop residue grazing in the fall has no effect on soil and any effect from spring grazing is biologically unimportant

Prediction of Energy Value (TDN) in Grazed and Hayed Forages

The goal of producers and nutritionists is to meet the nutritional needs of their cattle. Requirements are well established, but the diets of grazing cattle are difficult to predict. Selection by the animal, sample handling, lab analysis, and relating the lab analysis to the animal are issues that have been researched the last 20 years. Based on that research, data have been compiled to predict the energy and protein values of grazed Sandhills range, meadows, smooth brome, and corn residue. Additionally, equations used by commercial labs to predict the TDN of grass hays based on ADF were compared to TDN estimates based on in vivo digestion. Predictions of TDN values from ADF varied in accuracy and need to be used with caution

Late Summer Planted Oat-Brassica Forage Quality Changes during Winter Grazing

Oat, radish, and turnip samples were taken on pivots being grazed from November through January in Clay Center, Nebraska. The objective was to determine how the quality changed throughout the winter. The forage was observed to be high-quality (highly digestibility with moderate CP content). Digestibility did decline over this period but minimal changes in CP content were observed. From early November to early January, the digestibility of oats appeared to decline more (10% unit decline) than turnip and radish leaves (5% unit decrease). However, digestibility (67% IVOMD) and CP content (15%) of oats in early January were still as high as a good quality grass hay. Brassica (radish and turnip) leaves were more similar to a concentrate (81–83% IVOMD and 23–26% CP) even in January. Thus, even though the forage changed color from green to brown after hard freezes, the forage still had good feed value in January

Production cow-calf responses from perennial forage-based and integrated beef-cropping systems

An experiment was conducted to measure production responses of an alternative cow-calf production system integrated into a cropping system without access to perennial forage compared to a traditional cow-calf system utilizing perennial forage. Multiparous, cross-bred beef cows (n = 160; average age = 6.2 ± 2.8 yr) were utilized in a randomized complete block experimental design and unstructured treatment design. Upon initiation, cows were blocked by age and stratified by source, assigned randomly to one of two production systems, each with four replicates (n = 20 cows/replicate). Once allotted to their treatment groups, cows remained in their experimental units for the duration of the experiment. Treatments were: 1) a traditional system consisting of April to May calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to August calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). There were no differences (P ≥ 0.27) in calving rates (91.8 vs. 86.7 ± 2.92%), pregnancy rates (89.3 vs. 89.9 ± 2.66%), and weaning rates (87.2 vs. 82.3 ± 3.29%) for TRAD vs. ALT, respectively. However, there was an increase (P = 0.04) in the rate of twin offspring in ALT (2.9 vs. 9.4 ± 2.36% for TRAD vs. ALT, respectively). One calf from the set of twins was selected randomly at birth to be removed from the experiment, so the production data are only from single calves. There was no difference (P = 0.47) in calf body weight at birth (40 vs. 39 ± 0.7 kg for TRAD vs. ALT, respectively). At weaning, calves in the ALT system were lighter (P \u3c 0.01) at the same day of age (184 vs. 229 ± 5.5 kg) compared to TRAD calves. Cows from the ALT system had fewer (P \u3c 0.01) kg weaned per cow exposed to bull (150 vs. 199 ± 7.2 kg) compared to TRAD cows. Apart from the twinning rate, no differences in reproductive performance were observed among systems. However, reduced weaning weights and kilogram of weaned calf per cow exposed may negatively impact revenue to the cow-calf enterprise of the ALT system

Evaluation of growth performance, carcass characteristics, and methane and CO\u3csub\u3e2\u3c/sub\u3e emissions of growing and finishing cattle raised in extensive or partial-intensive cow-calf production systems

An experiment was conducted over 2 yr to measure performance and greenhouse gas (GHG) emissions of weaned calves from two cow-calf production systems. Crossbred steers and heifers (n = 270, initial body weight (BW) = 207 kg, SD = 35) were used in a randomized complete block design, with treatments applied to the cow-calf system. Treatments were: 1) a traditional system consisting of April to June calving with smooth bromegrass pasture and grazed corn residue as forage resources (TRAD); 2) an alternative system consisting of July to September calving utilizing partial-drylot feeding, summer-planted oats, and corn residue grazing (ALT). Calves from both production systems were weaned at the same age and grown (diet NEg = 1.05 Mcal kg–1) for approximately 117 d. The calves then transitioned to a high-grain finishing diet (year 1: NEg = 1.32 Mcal kg–1; year 2: NEg = 1.39 Mcal kg–1) and fed to a targeted 1.52 cm backfat. Growth performance in the grower phase resulted in greater (P \u3c 0.01) average daily gain (1.39 vs. 1.22 ± 0.02 kg), greater gain:feed (P \u3c 0.01; 0.157 vs. 0.137 ± 0.003) for ALT calves compared to TRAD calves, However, a lower initial BW (P \u3c 0.01; 185 vs. 229 ± 4.9 kg) resulted in a lower ending BW (P \u3c 0.01; 347 vs. 371 ± 2.9 kg) for ALT calves compared to TRAD calves in spite of improved growth performance. In the finisher phase, ALT calves gained less (1.52 vs. 1.81 ± 0.218 kg; P = 0.02), were less efficient (0.139 vs. 173 ± 0.0151; P = 0.01) but exhibited similar hot carcass weights (HCW) (388 vs. 381 ± 3.8 kg; P = 0.14) compared to TRAD calves. Each pen of calves was put into a large pen-scale chamber that continuously measured carbon dioxide (CO2 ) and methane (CH4 ) for 5 d during the grower and finisher phases. The average CH4 and CO2 production per unit of feed intake was used to calculate total GHG emissions over the entire grower and finisher phase. Overall, there were no differences (P ≥ 0.17) between treatments for CH4 per day and per kilogram dry matter intake (DMI). However, ALT calves tended to produce less (P ≤ 0.10) CO2 per day and per kilogram DMI than TRAD calves. Overall, methane emissions were greater in ALT calves (110.7 vs. 92.2 ± 8.3 g CH4 kg–1 HCW; P = 0.04) than TRAD calves. The ALT calves required 27 additional days on feed to market, which resulted in more total CH4 per animal across the entire feeding period (P = 0.02) than TRAD calves. Production systems that reduce days to market to achieve similar HCW may reduce GHG emissions