Using precision tools to manage and evaluate the effects of mineral and protein/energy supplements fed to grazing beef heifers.

Our objectives were to develop a Mobile Cow Command Center (MCCC) capable of precision monitoring of grazing heifers to 1) examine the relationship between supplement intake on concentrations of liver mineral and blood metabolites and 2) examine activity, reproductive, and health behavior. Yearling crossbred Angus heifers (N = 60; initial BW = 400.4 ± 6.2 kg) were fitted with radio frequency identification ear tags that allowed access to electronic feeders (SmartFeed system; C-Lock Inc., Rapid City, SD), and with activity monitoring tags (CowManager B.V., the Netherlands) that monitored reproductive, feeding, and health-associated behaviors. Heifers were assigned randomly to one of three treatments for a 57-day monitoring period: 1) no supplement (CON; N = 20), 2) free choice mineral (MIN; Purina Wind and Rain Storm [Land O'Lakes, Inc.], N = 20), or 3) free choice energy and mineral supplement (NRG; Purina Accuration Range Supplement 33 with added MIN [Land O'Lakes, Inc.], N = 20). Consecutive day body weights, blood, and liver biopsies were collected at pasture turnout and final day of monitoring. By design, mineral intake was greatest in MIN heifers (49 ± 37 g/d) and energy supplement intake was greatest in NRG heifers (1,257 ± 37 g/d). Final BW and ADG were similar among treatments (P > 0.42). Concentrations of glucose on day 57 were greater (P = 0.01) in NRG compared with CON and MIN heifers. Liver concentrations of Se and Fe on day 57 were greater (P < 0.05) in NRG heifers than CON, with MIN being intermediate. Activity tags reported NRG heifers spent less time eating (P < 0.0001) and more time (P < 0.0001) being "highly active" than MIN with CON heifers being intermediate. Data retrieved from activity tags identified 16 of 28 pregnant heifers exhibiting some type of estrus-associated behavior even after confirmation of established pregnancy. The activity monitoring system triggered a total of 146 health alerts from 34 of the 60 heifers monitored, but only 3 heifers of the heifers initiating an electronic health alert needed clinical treatment. However, animal care staff identified nine additional heifers that required treatment for which no electronic health alert was generated. The electronic feeders successfully controlled intake of individual heifers managed in groups pastures; however, the activity monitoring system misrepresented estrus and health events.

Utilizing an electronic feeder to measure individual mineral intake, feeding behavior, and growth performance of cow-calf pairs grazing native range.

Crossbred Angus cow-calf pairs (n = 28 pairs) at the Central Grasslands Research Extension Center (Streeter, ND) were used to evaluate an electronic feeder to monitor individual mineral intake and feeding behavior and their relationship with growth performance and liver mineral concentrations. Cows and calves were fitted with radio frequency identification ear tags that allowed access to an electronic feeder (SmartFeed system; C-Lock Inc., Rapid City, SD) and were provided ad libitum minerals (Purina Wind and Rain Storm, Land O'Lakes, Inc., Arden Hills, MN). Mineral intake, number of visits, and duration at the feeder were recorded over a 95-d monitoring period while pairs were grazing native range. Liver biopsies were collected from a subset of cows on the final day of monitoring and analyzed for mineral concentrations. Data were analyzed with the GLM procedure in SAS for mineral intake and feeding behavior with age class (cows vs. calves), intake category (high vs. low), and the interaction between class and category in the model. Correlations were calculated among cow feeding behavior and calf intake and growth performance with the CORR procedure, and a comparison of liver mineral concentrations among cows of high (>90 g/d; average 125.4 g/d) and low (<90 g/d; average 33.5 g/d) mineral intake was performed using the GLM procedure. High-intake calves (>50 g/d; average 72.2 g/d) consumed greater (P < 0.001) amounts of minerals than low-intake calves (<50 g/d; average 22.2 g/d) intake calves. Cows and calves attended the mineral feeder a similar (P = 0.71) proportion of the days during the experiment (overall mean of 20%, or once every 5 d). On days calves visited the feeder, they consumed less (P < 0.01) minerals than cows (222 ± 27 vs. 356 ± 26 g/d, respectively). Over the grazing period, calves gained 1.17 ± 0.02 kg/d, whereas cows lost 0.35 ± 0.02 kg/d. Calf mineral intake was correlated with cow duration at the mineral feeder (r = 0.403, P = 0.05). Cows with high mineral intake had greater (P < 0.01) concentrations of Se (2.92 vs. 2.41 ug/g), Cu (247 vs. 116 ug/g), and Co (0.51 vs. 0.27 ug/g) compared with low mineral intake cows, but liver concentrations of Fe, Zn, Mo, and Mn did not differ (P ≥ 0.22). We were able to successfully monitor individual mineral intake and feeding behavior with the electronic feeder evaluated, and the divergence in mineral intake observed with the feeder was corroborated by concentrations of minerals in the liver.

Influence of stocking rate and advancing season on forage intake, digestibility, and ruminal fermentation in steers supplemented with dried distillers grains with solubles while grazing northern Great Plains rangelands.

The objectives of this study were to evaluate the effects of stocking rate and advancing season on diet chemical composition, intake, digestibility, and ruminal fermentation in steers supplemented with distillers grains with solubles [0.3% of body weight (BW)] while grazing northern Great Plains rangelands. Angus cross beef steers (n = 188; 320 ± 30.3 kg initial BW) were used to establish targeted stocking rates, and 12 ruminal cannulated steers (272 ± 20.0 kg initial BW) were used for diet sampling while cograzing with the noncannulated animals on 12 pastures (n = 3 per treatment). Stocking rates were set to target 65%, 50%, 35%, and 20% of an average annual above-ground biomass remaining at the end of the grazing season (May-September). Five 10-d collection periods were conducted for May 13-22, June 10-19, July 8-17, August 5-14, and September 2-11. There was no difference in steer BWs or average daily gain during any of the collection periods or between stocking rate (P ≥ 0.10). Organic matter (OM), neutral detergent fiber, and acid detergent fiber of forage masticate samples were not affected (P ≥ 0.25) by stocking rate. Crude protein, and all N fractions of forage masticates also did not differ between stocking rate treatments (P ≥ 0.18). Forage OM intake (grams per kilogram of BW) increased cubically across the entire grazing season (P = 0.05). Organic matter digestibility decreased quadratically (P < 0.01) from May to September. Neutral detergent fiber digestibility showed a cubic effect (P < 0.01) across the grazing season, increasing from May to June, then decreasing till September. Crude protein digestibility decreased linearly (P < 0.01) as the season advanced. Ruminal ammonia and volatile fatty acid (VFA) concentrations were affected by stocking rate × period interactions (P ≤ 0.02). Ruminal pH, ammonia, and VFA concentrations were not affected by the stocking rate (P > 0.13) but were impacted by the advancing season (P < 0.01). Ruminal pH increased quadratically (P ≤ 0.01) with advancing season (6.3 to 6.6 ± 0.05 from May to September, respectively). The results of this study demonstrate that intake, fermentation, and digestibility of northern Great Plains forages were influenced more by seasonal factors associated with forage maturity than stocking rate under the conditions of this study.

Efficacy of needle-free injection on antibody production against Clostridium chauvoei in beef calves under field conditions.

This study compared needle-free and needle-based injection devices for vaccination of calves against Clostridium chauvoei in warm and cold conditions. Both devices elicited comparable antibody responses in calves. Needle-free injection devices can be used to vaccinate calves provided appropriate precautions are taken in cold weather.

Efficacité de l'injection sans seringue sur la production d'anticorps contreClostridium chauvoeichez les veaux de boucherie dans des conditions sur le terrain. Cette étude a comparé les dispositifs à injection sans seringue et avec seringue pour la vaccination des veaux contre Clostridium chauvoei dans des conditions par temps chaud et froid. Les deux dispositifs ont provoqué des réponses comparables des anticorps chez les veaux. Des dispositifs d'injection sans seringue peuvent être utilisés pour vacciner les veaux pourvu que des précautions appropriées soient prises par temps froid.(Traduit par Isabelle Vallières).

A study of the effectiveness of a needle-free injection device compared with a needle and syringe used to vaccinate calves against bovine viral diarrhea and infectious bovine rhinotracheitis viruses.

The aim of this study was to compare the effectiveness of a needle-free injection device (NF) with a needle and syringe (NS) when used to vaccinate calves against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV). The study was conducted in two independent phases. Ninety-six crossbred beef calves were vaccinated in the spring and 98 beef calves in the autumn. The calves were vaccinated using a NF or NS at 2 months of age (day 0) and again on day 119, with a modified-live virus vaccine containing IBRV, BVDV (types 1 and 2), parainfluenza-3 virus, and bovine respiratory syncytial virus. In each herd 10 calves were left unvaccinated to determine whether exposure to either BVDV or IBRV occurred. Visible vaccine residue at the surface of the skin/hair was apparent immediately following vaccination with NF in 30% of the spring-born calves following both the primary and booster vaccination. In the autumn, visible vaccine residues occurred in 19% and 8% of NF-vaccinated calves following the primary and booster vaccination. Post-vaccination skin reactions recorded on days 21, 42, 119 and 140 occurred with greater frequency in NF-vaccinated calves than NS-vaccinated ones. Blood samples were collected on days 0, 21, 42, 119, and 140 and tested for antibodies to BVDV and IBRV. Vaccination technique had no significant effect on BVDV or IBRV antibody concentrations at any time point. NF was as effective as NS vaccination in eliciting BVDV and IBRV antibody responses.