bluuebunny/crossref_metadata_2025 huggingface dataset:
113 Influence of cattle stress response to restraint method on artificial insemination pregnancy rates
Authors: Carrell Russell C , Smith William B , Kinman Lea A , Mercadante Vitor R G , Roper David
Published: July 2019

Activation of physiological stress responses have been associated with decreased pregnancy rates in beef cattle. Therefore, alternative cattle restraint methods have been developed to reduce this negative impact. However, little evidence exists comparing pregnancy outcomes of differing methods. Thus our objective was to determine if a difference was present in pregnancy rate to fixed-time artificial insemination in Bos taurus beef females when using a breeding box (b) versus a squeeze chute (c). Cows and heifers from two separate locations (Virginia Tech University, VT; and R.A. Brown Ranch, RAB) were exposed to FTAI protocols at location of origin while restrained in a squeeze chute (n = 169) or a breeding box (n = 162). Females were exposed to the 7 day Co-Sync + CIDR protocol pre-breeding. At day of breeding, females were randomly assigned to treatment. Immediately following breeding, blood was collected via coccygeal venipuncture for assessment of plasma cortisol concentration using an automated ELISA assay (Immulite 2000 XPi, Siemens). Chute and Exit Score (1–5) were assessed at the time of breeding by a trained technician at each location. Pregnancy was verified thirty days post-breeding via rectal ultrasonography. Pregnancy rate (PROC FREQ) and cortisol (PROC GLIMMIX) were analyzed using SAS version 9.4. Also, a Linear Regression Model (SAS version 9.4) was used to determine relationships between chute score, exit score, and cortisol. It was found that there was no difference in pregnancy rate between the breeding box and the squeeze chute (61.73% vs 64.71%, P = 0.31, respectively). Cortisol showed no difference between b and c (59.44±10.17 vs 58.61±10.16, P = 0.68, respectively). There was no linear relationship between cortisol, exit score, and chute score (P = 0.14). It can be concluded that stress responses are similar between the breeding box and squeeze chute. Therefore females will have similar pregnancy rates when exposed to FTAI in either restraint mechanism.
154 Evaluation of repeated exposure to lipopolysaccharide on vaginal temperature and complete blood count in two-year-old Brahman heifers
Authors: O’Daniel Sydney E , Riley David G , Neuendorff Don A , Dailey Jeffery W , Carroll Jeffery A , Randel Ronald D , Welsh Thomas H
Published: July 2019

The effects of escalating lipopolysaccharide (LPS) doses on vaginal temperature (VT) and complete blood count (CBC) were evaluated to develop a model of low-level inflammatory response in cattle. Brahman heifers (2-yr-old; 326 kg BW) paired by birthdate, sire, and weaning temperament score were fitted with self-contained, indwelling vaginal temperature probes 7 d before initiation of treatment (d 0) and randomly assigned to Control (n = 6) or LPS (n = 6) treatment. Heifers were maintained as a group with free choice access to Coastal bermudagrass hay and fed 3.6 kg of a 3:1 corn:corn gluten grain mix per head per day. Heifers were weighed, BCS recorded, and blood samples were collected weekly by jugular venapuncture before delivery of treatments. Treated heifers received LPS (from Escherichia coli) via subcutaneous injection in the neck (d 0: 0.25 μg / kg BW; d7: 0.50 μg /kg BW; d 14: 0.75 μg /kg BW) and Control heifers received saline. Sickness behavior score (SBS) was monitored at 30-min intervals for 12 hr after LPS. Treatment was the fixed effect of interest. Random effects included sire and day repeated with heifer as the subject. No dose-treatment interactions were detected. The SBS did not change after subcutaneous LPS or saline (P > 0.1). Neutrophil and lymphocyte numbers 7 d after each injection were not affected by LPS (P > 0.1). A febrile response began within 1 hr and persisted up to 14 hr after LPS injections. The febrile effect of the 0.25 μg LPS dose was less pronounced (P < 0.05) than that of the 0.50 μg and 0.75 μg LPS doses which were similar to one another. Lipopolysaccharide treatment increased maximum VT (P < 0.0001), hastened time to attain maximum VT (P = 0.0429), and increased the change in VT (P < 0.0001). Weekly subcutaneous injection of LPS facilitates the study of the effect of sub-clinical illness in beef cattle.
150 Administration of prostaglandin F2α 24 h prior to CIDR removal impacts reproductive performance of suckled beef cows assigned to the 7-d CO-Synch + CIDR protocol
Authors: Fontes Pedro , Cooke Reinaldo F , Oosthuizen Nicola , Timlin Claire L , Dias Nicholas , Currin John F , Clark Sherrie , Lamb Graham Cliff , Pohler Ky G , Mercadante Vitor R G
Published: July 2019

Angus-influenced cows received 100 µg of GnRH and a CIDR device containing 1.38 g of progesterone (P4) on d 0, and were randomly assigned to 25-mg injection of PGF2α on d 6 (PG6; n = 147) or d 7 (PG7; n = 162). The CIDR device was removed on d 7, and cows received 100 µg of GnRH and artificial insemination (AI) on d 10. An estrus detection patch was attached to the tailhed of each cow on d 7, and estrus expression assessed at AI (> 50% coating removal). Blood samples were collected on d 0 to determine the presence of a functional corpus luteum via plasma P4 (CL, P4 ≥ 1.0 ng/mL; NOCL P4< 1.0 ng/ mL). A subset of cows (70 cows/treatment) were assigned to ultrasonography at AI to verify dominant follicle diameter (DFD). Blood samples for plasma P4 analysis were collected (42 cows/treatment) on d 6, and on d 7 at CIDR removal and 1 h later. A similar proportion of PG6 and PG7 cows were classified as CL (P = 0.38). Plasma P4 at CIDR removal and 1 h later were less in PG6 vs. PG7 cows classified as CL (1.81 vs. 3.99 and 1.06 vs. 2.89 ng/mL), and did not differ (P ≥ 0.43) within NOCL. Estrus expression was greater in PG6 vs. PG7 cows classified as CL (72.8 vs. 48.3%), but similar (P = 0.96) within NOCL. Pregnancy rates did not differ between treatments (P = 0.53), despite a numerical difference (P = 0.15) between PG6 vs. PG7 cows classified as CL (65.5 vs. 55.0%). No other treatment effects were detected (P ≥ 0.20). Hence, PGF2α administration 24 h prior to CIDR removal appears to benefit reproductive performance of beef cows with a functional CL at the beginning of the 7-d CO-Synch + CIDR protocol
151 Timing of concentrate supplementation during late gestation impacts calf pre-weaning growth, but not reproductive performance of Bos indicus-influenced cows
Authors: Palmer Elizabeth , Vedovatto Marcelo , Ranches Juliana , Miranda Miguel , Gouvêa Vinícius , Arthington John , Vendramini João , Moriel Philipe
Published: July 2019

This study evaluated the effects of timing of dried distillers grains (DDG) supplementation during late-gestation on performance of Bos indicus-influenced cow-calf pairs. At about 84 d before calving (d 0), 84 mature Brangus cows were stratified by BW and BCS (422 ±42 kg; BCS = 5.0 ± 0.14) and assigned randomly to bahiagrass pastures (14 cows/pasture). Treatments were assigned randomly to pastures (2 pastures/treatment) and consisted of no prepartum supplementation (CON), 1 kg/d of DDG from d 0 to 84 (LATE84; 84 kg of DM/cow); or 2 kg/d of DDG from d 0 to 42 (LATE42; 84 kg of DM/cow). The respective weekly supplement amount was divided and offered into 3 feeding events (Monday, Wednesday, and Friday). Cow BCS were assessed on d 0, 45, 84 (calving), 140 and 224 (start and end of breeding season, respectively). Calf BW was collected at birth and weaning (d 346). Growth and reproductive data were analyzed using SAS MIXED and GLIMMIX procedures, respectively. Cow BCS from d 45 to 224 did not differ between LATE84 and LATE42 cows (P ≥ 0.20) but was always the least (P ≤ 0.05) for CON cows. Calving date, calf birth BW, and percentage of pregnant cows on d 283 did not differ (P ≥ 0.19) among treatments. Calf pre-weaning ADG and BW at weaning did not differ (P ≥ 0.58) between LATE42 and CON calves, but LATE84 calves tended to have the greatest pre-weaning ADG (P = 0.10; 0.88, 0.83 and 0.82 ± 0.02 kg/d, respectively) and BW at weaning (P = 0.10; 263, 254 and 252 ± 4.4 kg, respectively). Therefore, timing of prepartum DDG supplementation did not impact cow reproductive performance. However, calf pre-weaning growth tended to be enhanced when cows received longer vs. shorter or no periods of prepartum DDG supplementation
121 Non-invasive monitoring of hot-iron brands on growing cattle
Authors: Tolleson Douglas R , Campbell Erika , Garza Nick , Moen Robert
Published: July 2019

Hot-iron branding is a traditional form of permanent cattle identification that produces a scar. There is a need for science-based determination of cattle brand age through non-invasive monitoring of the healing process. Near infrared reflectance spectroscopy (NIRS) has been used by medical forensic scientists to obtain such information. Healing of cutaneous injury involves inflammatory (1 to 3 d), proliferative (4 to 21 d), and remodeling (22 to 365 d) phases. Collagen changes as burn scars mature, i.e. there is an increase in the Type I/ Type III collagen ratio compared to normal skin. The altered ratio is evident in a transformation of collagen from a basketweave arrangement to small parallel bundles. During the remodeling phase, due largely to the Type I/III collagen ratio, scar tissue becomes visibly different than un-injured skin. Previous research has examined the differences in hot-iron brands applied to nursing (~30 d old) Bos taurus cross calves at 0, 33, and 153 d post-branding. Our objective was to continue this research by obtaining near infrared spectra (11001700nm) on hot-iron brands applied to 15 weaned (~ 270 d old; 238 ± 7kg) Bos taurus cross steers at 21, 32, and 51 d post-branding. Spectra were obtained on branded (n = 3) and unbranded (n = 3) skin tissue from each animal, each date. Hair was clipped to < 5mm on unbranded skin. Spectra were analyzed as log 1/reflectance with 1st derivative and scatter correction applied. Linear discriminant analysis and regression procedures were applied to distinguish between brand treatment and date post-branding. Spectra from branded and unbranded skin were correctly (P < 0.05) identified at ~95%. Brand age was predicted successfully (P < 0.05) but not accurately enough for forensic application (RSQ = 0.50; RMSE = 9.75 d). The NIRS technique can discriminate differences in the age of cattle brand scars but numerical prediction requires further investigation.
115 Safety in numbers: Social isolation increases behavioral responses of cattle during startle tests
Authors: Mathias Amanda , Daigle Courtney L
Published: July 2019

Social isolation confounds cattle fear tests. Fear tests often require individuals to be isolated from the herd, possibly eliciting other emotions (i.e. panic and grief) outside of fear. To test this, steer (n = 32) behavior during an individual startle test (IST) and a group startle test (GST) were video recorded. During IST, one steer was placed in a solid sided pen and, after 60 seconds, two umbrellas opened simultaneously. Behavior was video recorded for an additional four minutes. For GST, the same procedures were followed, except 4 familiar steers were in the pen simultaneously. Within each test, steers were evaluated in a random order. IST retesting (IST_2) occurred five weeks after the first IST (IST_1). The GST took place one week after IST_2 testing completed. Video recordings of IST_1, IST_2, and GST were decoded for frequency and duration of behavior (steps, standing bouts, time spent standing, eliminations). Relationships among behavior, test, and minute of test were analyzed using Generalized Linear Mixed Model (PROC MIXED). Minute and test affected number of steps (P < 0.0001) and time spent standing (P < 0.0001). During GST, steers performed fewer steps than in the IST_1 (P < 0.0001) and IST_2 (P = 0.0003). There were no differences in step count between IST_1 and IST_2. Steers spent more time standing during GST than IST_1 (P < 0.0001) and IST_2 (P = 0.004). No differences in time-spent standing were seen between IST_1 and IST_2. Number of standing bouts were impacted by test (P = 0.0008). Steers stood more during GST than in IST_1 (P = 0.0007) and IST_2 (PP = 0.03) with no differences observed between IST_1 and IST_2. The IST is repeatable, yet the strength of the behavioral response is reduced during GST. This is the first quantifiable representation of the impact of social isolation on the fear response in beef cattle.
123 Effect of a hydrolyzed yeast product on cow behavior, body eeight, body condition score, and hair coat score in cows grazing pastures containing endophyte-infected tall fescue
Authors: Harrelson Patricia L , Rogers C Brent , Martin Rick , Scott Johnna , Banks Brandi , McMillin Taelor , Sellinger Emory , Harrelson Flint W
Published: July 2019

The objective of this study was to determine if the addition of a hydrolyzed yeast product would alleviate the symptoms of fescue toxicosis in beef cattle. Thirty-eight Angus cow-calf pairs were stratified by cow age and body weight then randomly allotted to one of two treatments; control mineral (CON) or hydrolyzed yeast mineral (HYM). Cattle in both groups were allowed access to mineral for 126 d while they grazed the same eight pastures (1.21 ha each) in a rotational pattern. Mineral was provided at a target rate of 113.4 g·hd-1·d-1 every 28 d. Each pasture was grazed by cattle groups for 7 d. Mixed grass pastures containing tall fescue were utilized and evaluated for endophyte level prior to the start of the project. Due to pasture endophyte level variability (44%-73% endophyte), both groups of cattle rotationally grazed each pasture at least 2 times starting in June. Prior to entering a new pasture weekly, cows were weighed and assigned a BCS and hair coat score (HC) by two independent, trained personnel. Cow behavior was measured every 15-min within a 2-h block weekly. Percentage of cows active or inactive, outside or inside was recorded. Data were analyzed using the MIXED procedure of SAS. Cow BW change was unaffected by treatment (P > 0.23). Cow BCS significantly increased in HYM vs. CON cows (0.4 vs. 0.1; P = 0.02; SEM = 0.1) through the 126 d project. No treatment effect was observed on HC (P > 0.19). Cow behavior was impacted by treatment, as HYM cows spent more time outside compared to CON cows (P < 0.01). Results of this trial suggest that HYM cows may have experienced less heat stress as a result of fescue toxicosis as they were willing to spend more time outside and increased BCS.
122 The efficacy of extended-release eprinomectin for the reduction of horn flies, face flies, and fecal egg counts of parasitic nematodes in replacement beef heifers
Authors: Landers Sophia F , Tucker Christopher , Powell Jeremy G , Wray Eva , Cauble Reagan , Lester Toby D
Published: July 2019

The purpose of this study was to evaluate the efficacy of extended-release eprinomectin against horn flies, face flies, and fecal egg counts of parasitic nematodes in crossbreed replacement beef heifers. Fifty-four heifers were randomly placed into three treatment groups (n = 18 heifers/treatment). Group 1 was administered the labeled dosage of extended-release eprinomectin at the onset of fly season (day 0). Group 2 acted as the negative control. Group 3 received the anthelmintic injection once a quarter of the heifers in the group reached the threshold treatment level for horn flies (n = 200 flies/animal; day 41). All cattle were separately pastured for the duration of the study. Throughout the study, nematode infections were measured via fecal egg counts while horn and face flies were visually monitored. Evaluation of pregnancy status was recorded at the conclusion of the study (day 144). Due to the high number of face flies, heifers were treated with insecticide dusts twice during the study (day 54 and 69). Group 1 averaged a fecal egg count of (2.3), group 2 (7.4), and group 3 (9.1) (day 111). Low egg counts for all treatment groups reflected minimal parasite burden which likely had little effect on treatment groups. Extended release eprinomectin had little influence on face flies given that all groups were above threshold at days 40, 48, and 54. At study conclusion, horn fly population was lower (P < 0.05) for group 1 (405.6) compared to group 2 (680.6) and group 3 (680.6). Conception rates were greater (P < 0.05) in group 1 (89%) compared to the control heifers (56%) and group 3 exhibited an intermediate rate (72%). Results indicate that although treatment with extended-release eprinomectin did not decrease the face fly burdens, it did have an effect on fecal egg counts, horn fly burdens, and subsequent pregnancy status at the conclusion of the study
124 Finishing beef cattle under cover reduces heat load and improves efficiency during the summer
Authors: Sims William M , Stewart Lawton , Segers Jacob R , McKee Robert W , Rigdon Macc , Thomas Chevise L , Stelzleni Alexander M
Published: July 2019

Heat-stress in finishing cattle presents a significant risk to efficiency and economic viability. The project objective was to quantify the effects of long-term heat-stress when finishing cattle during the summer in the southeastern United States. Forty-five Angus crossbred steers (446±23 kg) were blocked by weight and randomly assigned to environmental finishing treatments including: covered with fan (CWF), covered without fan (CNF), or outside without shade (OUT). For 92 d steers were individually fed a typical feedlot ration. Environmental data were continuously recorded including: black globe temperature (BG), heat load index (HLI), and accumulated heat load units (AHLU). Feed intake was recorded daily, and steers were weighed every 20–25 days. When the first treatment averaged 613-kg all steers were slaughtered, and carcass data were collected. Data were analyzed as a Mixed Model (JMP V13; SAS Inst.) and means were separated (Least Squares Means). Average maximal BG was lower for covered finishing than OUT (P < 0.01); however, for HLI CWFCNF>OUT, while G:F was similar (P = 0.22) between CWF and CNF which were greater (P < 0.01) than OUT. Hot carcass weights were heavier for CWF than OUT (P < 0.01) and CNF was similar to both (P ≥ 0.11). There was no difference for USDA Yield Grade (2.6; P = 0.44), or marbling score (Modest20; P = 0.76). Steers finished under cover were more efficient than steers finished in open dry-lots. The addition of cooling fans further improved steer gains over those that were covered without fans.
126 Detection of fecal chemistry changes in cattle infested with the Southern Cattle Tick, Rhipicephalus (Boophilus) microplus
Authors: Rich Brian T , Teel Pete D , Thomas Donald B , Angerer Jay , Tolleson Douglas R , de Leon Adalberto A Perez
Published: July 2019

Bovine babesiosis, a highly fatal tick-borne disease of cattle, was eliminated from the United States in the last century through tick eradication programs against 2 species of cattle fever ticks. The threat to the U.S. cattle industry continues through tick introductions from Mexico. The standard method of detecting Cattle Fever Ticks [Rhipicephalus (B.) annulatus and R. (B.) microplus] in the state-federal tick eradication program is physical examination of restrained cattle to find attached ticks. New methods of detecting tick-infested cattle could improve reliability and reduce animal stress. The objective of this study was to determine whether changes in fecal chemistry induced by tick infestation was detectable using near-infrared reflectance spectroscopy (NIRS). Fecal samples were collected daily from 6 stanchioned Bos taurus yearling heifers (initial mean weight 163.3 kg +/- 4.7 kg) at the USDA Cattle Fever Tick Research Laboratory, Edinburg, TX, before, during, and after an infestation of 5000 R. (B.) microplus larvae. Cluster analyses were conducted using GRAMS IQ for NIR spectra in the 576–1126 nm range to test for fecal chemistry changes different from pre-infestation condition, and coincident with the biological phases of the tick infestation. The first three factors of spectral variation accounted for 87.87% of spectral variation among all samples. Factors 1, 2, and 3 had F-Ratios for the Reduced Eigenvalues of 941.59, 387.44, and 221.79, respectively. Three-dimensional analysis for these 3 factors shows shifts in sample clusters away from pre-infestation and coincident with progressive tick blood-feeding and post-infestation recovery. We conclude that fecal NIRS may provide a tool for detection of tick-infested cattle; however, further testing is needed to determine the sensitivity of detection on cattle with varying levels of tick burden, and a protocol developed and evaluated for fecal sampling under field conditions
166 Moo-vie Snacks: Evaluation of waste popcorn as a feedstuff in comparison with known livestock feeds
Authors: Bielamowicz Lauren P , Garcia Taylor J , Cherry Nichole M , Muir James P , Smith William B
Published: July 2019

While the use of by- or co-products can help offset the costs of feeding cattle, these feeds often increase in price with increased adoption. Therefore, discovery and characterization of novel feedstuffs could benefit the producer. Our objective was to evaluate the viability of waste popcorn (Zea mays L.) as a feedstuff in ruminant diets. This objective was addressed through a series of two experiments. In Exp. 1, storage stability of popcorn was evaluated. Popcorn was collected on consecutive weekdays in 2 wk from a local cinema. Samples (n = 10) were subdivided into 9 aliquots and subjected to storage, uncovered, for 0, 1, 2, 3, 7, 35, 70, 105, and 140 d. Following the assigned storage time, samples were dried at 55°C to determine weight loss. Following open storage in a laboratory at approximately 24°C, popcorn gained (P < 0.05) between 2.6% (3 d) and 5.6% (105 d) of the original weight through moisture absorption. When dried, however, samples from any length of storage were within 1% of the original weight (P < 0.05). In Exp. 2, a composite sample of popcorn was used in comparison with cracked and steam-flaked corn (Zea mays L.), popped milo [Sorghum bicolor (L.) Moench ssp. bicolor], and rolled barley (Hordeum vulgare L.). Samples were dried at 55°C, ground to pass through a 2-mm screen, and subjected to a batch-culture in vitro assay for digestibility estimates. In vitro true digestibility of popcorn (77.8%) was less (P < 0.05) than estimates for cracked corn (94.8%), popped milo (93.6%), steam-flaked corn (92.6%), or rolled barley (90.3%). From these results, we may conclude that, while popcorn is not as digestible as other commercial energy sources, it may represent a viable option in the arsenal of feed formulation.
172 Effect of energy and lasalocid supplementation on stocker cattle performance grazing winter-wheat pasture
Authors: Pickett Autumn , Gunter Stacey
Published: July 2019

Wheat pasture is unique to the Southern Plains where income can be reaped from the grazed forage followed by a grain harvest. The performance by cattle grazing is excellent, but nitrogen intake is excessive, resulting in inefficient use. Highly digestible supplements that are low in protein have been shown to augment ADG and improve nitrogen utilization. At the Southern Plain Experimental Range near Fort Supply, OK, an experiment was conducted to examine a supplement high in digestible fiber at multiple level of intake with or without 66 g of lasalocid/tonne. Sixty-five steers (324 ± 0.52 kg) grazed 41-ha of irrigated wheat pasture for 64 d. The supplement (4-Square Stocker/Grower 14; 14% CP; Purina Animal Nutrition, Shoreview, MN) was placed in 1 of 2 SmartFeed Plus feeders (C-Lock, Inc., Rapid City, SD); 1 feeder with the control feed and the other contained lasalocid. Each feeder was programmed to allow maximum intakes of 1.2, 2.0, and 3.2 kg/d for 8 or 9 steers at each level. So, there were 24 non-supplemented, 21 energy supplemented, and 21 energy supplemented steers with lasalocid. Because steers had liberty to consume supplement at will and only limited by a maximum, actual supplement intakes were calculated for the grazing period and steer performances were regressed on supplement intakes. Each kilogram of supplement increased (P = 0.04) ADG by 73 g/d; however, lasalocid did not increase (P = 0.73) ADG (avg ADG = 1.7 kg). Total BW gain by each steer (kg) was increased (P = 0.04) 4.7 kg for each kilogram of supplement fed daily and again, lasalocid did not increase (P = 0.73) performance (avg total BW gain = 109 kg). Supplementation with a moderate CP feed increased the ADG of steers grazing winter-wheat pasture, but the addition of lasalocid showed no benefit in this experiment.
176 Weaning weight trends in the U.S. beef cattle industry
Authors: Andresen Claire , Lalman David , Goad Carla , Kriese-Anderson Lisa , Odde Kenneth , King Mike E
Published: July 2019

The objective of this study was to characterize the trend over time for weaning BW in commercial cow/ calf operations in the U.S. beef cattle industry. The first data set contained weaning BW data from four enterprise analysis programs from 1991 to 2015. The second data set included mean forecasted delivery BW of sale lots of beef calves sold through Superior Livestock Auction (SLA) from 1995 to 2016. The SLA data were evaluated for two regions, North Central/Rocky Mountain region (NC) and South Central region (SC) and were restricted to sale dates and projected delivery dates approximating those associated with spring-calving operations. The third data set included mean actual and adjusted weaning BW of commercial cow/calf operations participating in the Alabama Beef Cattle Improvement Association (BCIA) from 1983 to 2017. Adjusted annual weaning BW reported from the American Angus Association and American International Charolais Association were used to evaluate trend over time for bull calves from 1995 to 2016. There was a significant linear increase (0.5 kg per yr; P = 0.01) for weaning BW reported by the Kansas Farm Management Association. Projected delivery BW for NC implanted and non-implanted calves increased (P < 0.01) and plateaued in 2006 and 2007, respectively. In contrast, projected delivery BW for non-weaned SC implanted and non-implanted calves increased (P < 0.01) linearly over time. Adjusted and unadjusted weaning BW reported to the Alabama BCIA increased until 1998 and 1995, respectively. The phenotypic trend for Angus and Charolais bulls was a polynomial regression equation (P < 0.01) with declining rate of change in weaning BW. Substantial variation in the trend over time for weaning BW in commercial cow/ calf operations exists within region and record program. Furthermore, weaning BW is substantially more variable in Southern states. Environmental limitations to continued progress in this trait are evident
188 Comparison of two software methods of fitting one- and two-compartment age-dependent digesta kinetics models
Authors: Moffet Corey A , Gunter Stacey
Published: July 2019

Ruminant nutritionists fit digesta kinetics models to better understand processes in the gastrointestinal tract. Several software packages are available to fit one- and two-compartment, age-dependent digesta kinetics models to fecal marker concentration over time after giving a marker dose. We characterized repeatability and agreement for two programs (R and SAS) used to fit these models. We constructed 8100 datasets using a Monte-Carlo approach where errors were added to true marker concentrations for samples from 81 synthetic profiles representing different animal and diet combinations (100 datasets per profile). Datasets contained concentrations at 15 nominal times (from 0 to 120 hours after dosing). The two error sources were sampling time (uniform between -3 and 1 hours) and concentration measurement (normal with mean 0 and SD = 5 + 0.08CT, where CT is true concentration). The resulting datasets were fit to G2 and G2G1 models using both software and model parameters (K0, λ or λ1, K2, and τ) were used to calculate digesta kinetics parameters (particle passage rate, gastrointestinal DM fill, fecal DM output, gastrointestinal mean retention time, and rumen retention time). When fitting G2 models, all converged, but when fitting G2G1 model, 60 did not converge. The parameters were more repeatable from R than from SAS, but the ratios of repeatability to the mean was generally less than 10%. Bias and SD of differences between software packages were also small. The G2G1 models produced smaller bias and SD of differences than the G2 models. Bias and SD for digestion parameters between software were also small, however, G2G1 models had smaller biases and SD of differences than G2 models. Repeatability was better with R than with SAS, but mean differences were small; the G2G1 model was more repeatable than the G2 model, but differences between software were small for G2G1 models.
182 Environment enrichment reduces aggression and stereotypic behaviors in feedlot steers
Authors: Park Rachel M , Bova Rachel , Jennings Jenny S , Daigle Courtney L
Published: July 2019

Feedlots provide limited environmental complexity to cattle-a highly curious and social species. In the absence of adequate stimulation, cattle may engage in aggressive or abnormal behaviors. Implementation of biologically appropriate and species specific environmental enrichment (EE) has the potential to enhance welfare of feedlot steers. The objective of this study was to identify behavioral differences between cattle exposed to EE compared to those without. Composite steers (n = 54) were assigned to one of two treatments 1) No enrichment (CON; n = 3 at 9 head/pen) and 2) BRUSH (cattle brush; n = 3 at 9 head/pen). Video recordings were decoded utilizing continuous observation for the frequency and duration of headbutting, mounting, kicking, bar licking, tongue rolling, allogrooming, and brush usage from 0800 to 1730 on d -2, -1, 0, 1, 2, 4, 8, 16, 32, and 64 relative to brush implementation. Impact of day, treatment and their interaction on cattle behavior was evaluated using a Generalized Linear Mixed Model (PROC MIXED) in SAS. (BRUSH) steers spent less time bar licking (P = 0.023) and engaged in bar licking less frequency (P = 0.005) than CON throughout the duration of the study. Compared to CON, BRUSH steers performed fewer headbutts across the duration of the study (P = 0.004). Brush usage frequency (P = 0.0002) and duration (P = 0.008) was greatest on d 0 compared to all other research days. The frequency (P = 0.0006) and duration (P = 0.0002) of tongue rolling increased with research day. Similarly, the frequency (P = 0.0001) and duration (P = 0.002) of allogrooming increased over time, however, there was a decrease in allogrooming on d 64. Mounting frequency was impacted by research day and peaked at d 8 (P = 0.002). BRUSH cattle performed less stereotypic and aggressive behaviors suggesting that EE is beneficial for feedlot cattle welfare.
180 Impact of weaning strategy on calf performance, behavior, and activity
Authors: Ott Grace C , Freeman Sharon R , Poore Matthew H , Pickworth Carrie L
Published: July 2019

Weaning is known to be the most stressful time in a beef calf’s post-natal life. Weaning stress may have long-term impacts on cattle performance. This study was conducted to determine differences in calf stress under three weaning strategies. Two hundred twenty-nine Angus or Angus-Simmental cross pairs at two locations were assigned to one of three weaning treatments: abrupt removal of the calf on d 0 (Abrupt, n = 77), fenceline contact for 7 d prior to removal of the calf on d 7 (Fence, n = 79), and abrupt removal of the calf on d 84 (Late, n = 73). Behavioral observations were conducted pre- and post-weaning, and total activity was measured prior to and after weaning using accelerometers placed on collars on five calves per treatment. Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate calf performance post-weaning. Data were analyzed using PROC MIXED of SAS. Statistical significance was determined at P < 0.05 and a tendency at 0.05 0.10) by timing or strategy of weaning. Total activity was greater (P < 0.05) in Abrupt than Fence on d 1 and d 2 post-wean (Abrupt 26772 and 22346 and Fence 22235 and 16691 relative activity units/hour, respectively). Calf activity was elevated (P < 0.05) on day of weaning until d 2 post-wean then returned to pre-wean level by d 3 for all treatments. Short-term differences in calf performance warrant further exploration of the possible long-term effects on heifer development and steer feedlot performance.
37 Carry-over effects of health management through the production chain
Authors: Thomson Daniel U
Published: July 2019

The beef supply chain has many segments for live animals and beef products. Live cattle are sold from the ranch to the stocker to the feedlot and then to the packer. Animals get sick due to an overwhelming exposure to a pathogen or a suppressed immune system. Many times, disease infections can occur in one segment of the industry but not present clinically until the cattle are stressed during transfer to a subsequent beef production segment in the supply chain. These diseases can have an impact on cattle reproductive efficiency, performance efficiency, food safety, and economics due to decrease animal health. The lack of vaccination, biosecurity, and diagnostic surveillance can result in animals being exposed to disease causing pathogens on the ranch, during marketing, or after they arrive at the feedlot. New animals entering the herd can bring diseases into a cow/calf operation. Calves leaving a cow/calf operation can carry agents such as infectious bovine rhinotracheaitis, bovine viral diarrhea, Leptospira bacteria, bovine leukosis virus and other pathogens into the stocker, backgrounder, or feedlot operation. Commingling occurs routinely in auction markets and feedlots. We can decrease disease exposure through diagnostic monitoring, biosecurity, and proper vaccination programs. We can improve the functioning immune system through preparing cattle for market transfer through animal husbandry, nutrition, comfort, and more. Health management in the beef supply chain is dependent on decreasing disease exposure and decreasing stress in cattle.
39 Thoughts on the energetic efficiency of grazing cattle
Authors: Gunter Stacey , Moffet Corey A
Published: July 2019

Energetic efficiency of cattle is a significant issue in the beef industry. Ruminant nutritionists have made strides in improving production efficiency, but we still see significant variation among individuals. A popular method for evaluating the cattle efficiency is selection based on residual feed intake. This method has some limitations because of mounting evidence that it has a genotype x environment interaction. Individuals deemed most efficient being fed in confinement are not most efficient when their environment is grazing. Hence, cattle efficiencies need to be evaluated in appropriate environments. Because it is impossible to directly measure DMI by grazing cattle, we need to develop proxies to assess the animal’s efficiency. By using experimental methods such as breath cloud analysis to provide individual estimates of total heat of production and known constants for retained energy in BW gain, we can calculate ME energy intake. However, we still lack the ability to measure DMI without the true digestibility of the grazed diet. The greatest energy expenditure is basal metabolism and if we are to decrease it, we will need to examine their body composition and protein-turnover rates. The rates of protein and fat deposition in the carcass affects an animal’s efficiency and ADG chiefly because of the higher energy density of fat. However, with great protein deposition, there also is a higher ME requirement for its maintenance because of the high protein turn-over rate. Energy expensed for protein turnover is approximately 23% of the total energy intake by average cattle. Management that decreases body protein turn-over rate probably would result in a decreased basal metabolism. The research needed to truly improve the energetic efficiency of grazing cattle will be time consuming and expensive, but for progress to be made it will be required.
43 Improved grazing system productivity, efficiency and sustainability through novel approaches
Authors: Neel James P S
Published: July 2019

A grazing system includes unique soil, plant, and animal attributes. Interactions between these entities will necessarily invoke reactions by the other players in the system. History shows us that manipulation of any one component of the system may or may not have negative ramifications on the system’s overall productivity and health. Novel approaches to improve nutrient use efficiency and product output from forage based livestock production systems are essential if we hope to provide high quality, nutrient dense, and high biological value livestock food products to an ever increasing world population. Furthermore, to ensure grazing systems’ health and sustainability these novel approaches must be evaluated for merit in a scientific and multidisciplinary manner. The Appalachian region is noted for its beautiful mountains, with farms generally containing a higher percentage of wooded area than pasture. If farm livestock productivity were to be increased, a novel approach was needed to bring woodlots into forage production. A long term research project was conducted at the Appalachian Farming Systems Research Center, in Beaver, WV, to determine how wooded areas could be transitioned into forage production systems in a sustainable manner. A multidisciplinary team was utilized to determine the implications of silvopasture development on soil and water quality, plant community response, and livestock productivity. Silvopasture was found to be a viable option for improving an Appalachian farm’s livestock productivity in an aesthetically pleasing and sustainable manner. Research is currently being conducted in central Oklahoma which evaluates methods of improving livestock productivity in a sustainable manner within native prairie livestock systems. This research is also team oriented, multidisciplinary, and multi-institutional. Production oriented approaches include the use of novel management practices, and the determination of superior phenotypic and genotypic livestock traits. Findings and experiences related to both geographic locations are presented and discussed.
130 Growth and carcass characteristics of short-scrotum, ram, and wether lambs
Authors: Schoenian Susan , Semler Jeff , David Gordon , O’Brien Dahlia , Bennett Mary Beth , Anderson Chris
Published: July 2019

Sixty male lambs (East Friesian x Lacaune) from a commercial sheep dairy were used to compare growth and carcass characteristics of short-scrotum (SS), ram (R), and wether (W) lambs. By d 10, every third single, twin, and triplet male was left entire (ram, n = 19), castrated (n = 24), or made short-scrotum (n = 17). After weaning and transport to the Western Maryland Research & Education Center, lambs were maintained as a single group on pasture, with supplemental feeding at 2–3% of BW. Lambs were weighed biweekly. Ultrasonic measurements were determined at d 102. The lambs were slaughtered at d 110. Growth and carcass data were analyzed using PROC GLM and carcass data correlations with PROC CORR. SS lambs had heavier final BW (53.5±1.0 kg) and higher ADG (0.25±0.001 kg/d) than W lambs (50.2±0.6 kg and 0.22±0.001 kg/d, respectively). R lambs were intermediate (51.6±1.0 kg and 0.23±0.001 kg/d, respectively). Sex did not influence ultrasonic backfat (BF), but there was a tendency to influence rib eye area (REA), with W lambs REA smaller than both R and SS lambs (P = 0.07). There was no influence of sex on dressing percentage, body wall thickness, REA, percent kidney and heart fat, leg conformation, or percent boneless closely trimmed retail cuts. There was a tendency (P = 0.10) for SS lambs to have heavier HCW (26.3±0.6 kg) compared to R (24.8±0.6 kg) and W lambs (24.7±0.25 kg). W lambs were fatter (P < 0.02), having greater BF (3.8 ± 0.6 mm) and yield grade (1.9 ± 0.1) than SS (3.0±0.6 mm and 1.6±0.1, respectively) and R lambs (2.8±0.6 mm and 1.5±0.1, respectively). There was strong correlation between ultrasonic and actual carcass measurements (r = 0.7, P < 0.0001), except for REA in SS lambs (r = 0.4; P = 0.1). Compared to W lambs, SS lambs had superior growth and produced leaner carcasses. The short-scrotum procedure may offer a viable alternative to castration.
134 Vegetation characteristics and diurnal periods influenced the landscape-use pattern of goats and sheep in woodlands
Authors: Bhattrai Shailes , Karki Uma , Poudel Sanjok
Published: July 2019

Woodlands dominate the landcover in the Southeast and offer great opportunities for expanding small-ruminant grazing. However, unmanaged understory shrubs grown beyond animals’ access minimizes the utilization of such vegetation. Managing the understory shrubs and non-target trees to lower heights may increase animals’ access to woodland vegetation and alter the landscape-use patterns of animals. The study objective was to determine the effect of vegetation height on the behavior and distribution of Kiko wethers and Katahdin rams in woodlands. The study was conducted in six woodland plots (0.4-ha each) containing southern pine and hardwood trees and numerous understory vegetation. The non-pine species were either cut to one of the heights from the ground level (0 m, 0.91 m, 1.52 m) or left uncut (control). Once the cut vegetation grew back and attained the full canopy, Kiko wethers (8, 48–50 months old, 72.8 ± 2.29 kg live weight) and Katahdin rams (5, 29–32 months old, 95.5 ± 4.31 kg live weight) were rotationally stocked in separate plots (3 plots each species), and their diurnal (dawn-dusk) behaviors and distribution patterns monitored when they were in each plot during the summer of 2018. Data were analyzed in Kruskal-Wallis rank sum test in R. Both wethers and rams visited the control treatment the least, rams grazed mostly in areas with short vegetation (0 m), and wethers visited more to areas with higher vegetation (1.52 m) than rams for feeding (P < 0.001), which was predominant during the post-midday period (3:00-dusk) (P < 0.0001). Browsing was the dominant feeding behavior of wethers (39% browsing vs. 4% grazing), while rams’ feeding behavior was dominated with grazing (24% grazing vs. 12% browsing). Lying was the dominant diurnal behavior of both wethers (46%) and rams (35%), and predominant during the midday period (11 a.m.-3:00 p.m.) (P <0.05). Vegetation heights and diurnal period highly influenced animals’ behavior.
128 Relationship between anti-Mullerian hormone (AMH) and reproductive traits in ewes
Authors: Acharya Mohan , Howell Berlin , Burke Joan M , Rorie Rick
Published: July 2019

Objective was to determine correlations between serum AMH and reproductive traits in ewes. Blood was collected at breeding from Katahdin ewes between 0.7 and 9 yr age in 2015 (n = 158) and 2017 (n = 233) for the analysis of serum AMH concentrations using different immunoassays (Equine and Ovine AMH in 2015 and Ovine AMH in 2017; AnshLab). Relationships between AMH and first exposure pregnancy rate (PR) to spring or fall breeding, number of lambs born to first lambing, age at first lambing (using lifetime records), and estimated breeding values (EBVs) for number of lambs born (NLB), number of lambs weaned (NLW), maternal weaning weight (MWT), weaning weight (WWT), and maternal index were determined. Correlations were determined using PROC CORR (SAS), and PROC GLM used with AMH or AMH quartile as dependent or independent variables, and season in models. Serum AMH or quartiles did not correlate with any reproductive trait. In 2017 but not 2015, AMH concentrations (P = 0.02) and quartiles (P = 0.04) were greater in ewes that became pregnant than nonpregnant ewes to first breeding. Ewes that were pregnant at a younger age had a higher WWT (P = 0.002), NLW (P = 0.04) and Index (P = 0.02), and more prolific ewes at first lambing had a higher NLB (P < 0.001), NLW (P < 0.001), and Index (P < 0.001), regardless of season of first breeding. Mean PR was -4.6 ± 3.8% and 68.4 ± 3.8% for spring and fall breeding (P < 0.001), resulting in older spring compared with fall bred ewes at first lambing (2.04 ± 0.08 vs. 1.52 ± 0.05 yr, P < 0.001). While AMH did not appear to consistently predict fertility in ewes, higher EBVs (NLB, NLW, Index) were associated with younger ewes and greater prolificacy at first lambing.
191 The effects of a yeast fermentation product on the average daily gain and digestibility on a rye grass hay-based finishing diet for lambs
Authors: Burt Justin C , Boyd Jamie , Garcia Ivan , Splan Rebecca , Perron Brittany S
Published: July 2019

The purpose of this study was to determine if supplementation of a yeast fermentation product had an effect on the ADG, performance, and meat quality characteristics of Katahdin sheep fed a ryegrass hay based diet in drylot. Twenty-four Katahdin lambs were divided into two groups (male, n = 8; female n = 16) based on weight and gender: a control (CON) and treatment (TRT) used in a repeated block design. The lambs had a BW of 21.5 ± 2.5 kg, and concluded with a finishing weight of 36.3 ± 3.4 kg. Lambs were housed on dirt drylot with shade structures, and offered an ad libitum TMR diet was formulated to be isocaloric and isonitrogenous at 14% CP and was ryegrass hay based, and top dressed with ground corn as a carrier. The TRT received the yeast supplement at a rate of 4/g/h/d. The diet was offered at 2% of the group’s body weight ad libitum. A 1-wk standardization period was conducted before the start of the study to obtain a 5% refusal rate. Orts were collected and recorded, as well as weekly feed samples were collected twice a week, and compiled for a chemical analysis for NDF, ADF, ASH, CP, and ether extract. Temperature and humidity data was also collected throughout the study. Lambs were weighed weekly with a rolling weight being used for the ADG of the lambs. Proc mixed procedures of SAS was used for data analysis. We found no statistical significance in DMI (CON=11.14 ±3.36 kg/d and TRT= 10.89 ±3.55 kg/d per group), and no statistical significance by gender (P < 0.11). There was a statistical significance (P < 0.03), for ADG per group. This suggests that there is a tendency for greater performance and ADG for lambs supplemented with a yeast fermentation product.
201 Factors that limit out-of-season breeding success in ewes
Authors: Howell Berlin , Burke Joan M , Lee Charles , Wood Erin , Rosenkrans Charles , Rorie Rick
Published: July 2019

The American Sheep Industry recently stressed the importance of out-of-season breeding to meet year round demand for quality lamb. Because ewes naturally breed during short days, spring breeding is a challenge. The objective was to determine factors that reduce pregnancy rate in Katahdin ewes in Arkansas. In 2017, 95 ewes (1.6 - 9.4 yr of age; mean 2.6 ± 1.8) were bred between mid-April to mid-May. Between mid-August to mid-September, 82 ewes (1.0 - 8.2 yr of age; 2.6 ± 1.7) were bred. In spring, ewes grazed endophyte-infected tall fescue, but in fall, primarily bermudagrass was available. Body weight (BW) and body condition scores (BCS), and serum concentrations of anti-mullerian hormone (AMH), prolactin, and cytochrome P450 enzyme activity were determined before rams entered. Ewes were exposed to teasers 14 d before breeding. Data were analyzed by Proc GLM and CORR (SAS) with season of breeding in model and ewe age used as covariate. Pregnancy rate was greater in fall than spring bred ewes (89.3 ± 4.0 vs. 21.9 ± 3.3%, P < 0.001). Ewes that became pregnant compared with nonpregnant had a greater concentration of AMH regardless of season bred (3.3 ± 0.22 vs. 2.4 ± 0.41 ng/mL, P = 0.04; R = 0.22, P = 0.004), but tended to have a lower concentration of prolactin (20.2 ± 2.7 vs. 30.4 ± 4.8 ng/ mL, P = 0.06; R = -0.38, P < 0.001). The overall lower prolactin in spring suggests a reduction associated with fescue toxins, but further research is necessary. Cytochrome P450 activity was not significantly lower in ewes that became pregnant compared with nonpregnant (R = -0.28, P = 0.002), and was greater in younger ewes (R = -0.25, P = 0.03). Selecting ewes more tolerant to fescue toxins may improve success of out-of-season breeding in the Southeastern United States