Brangus Cow–Calf Performance Under Two Stocking Levels on Chihuahuan Desert Rangeland

Cow–calf productivity on 2 lightly (25%–30% use) and 2 conservatively grazed pastures (35%–40% use) were evaluated over a 5-year-period (1997 to 2001) in the Chihuahuan Desert of south-central New Mexico. Spring calving Brangus cows were randomly assigned to study pastures in January of each year. Experimental pastures were similar in area (1 098 ± 69 ha, mean ± SE) with similar terrain and distance to water. Use of primary forage species averaged 28.8% ± 4.3% in lightly stocked pastures and 41.8% ± 4.4% on conservatively grazed pastures. Perennial grass standing crop (168.8 ± 86 vs. 173.6 ±  kg·ha^-1) and adjusted 205-day calf weaning weights (279.1 ±  vs. 270.7 ±  kg) did not differ among lightly and conservatively grazed pastures. Cow body condition scores in autumn, winter, and spring were similar among grazing levels as were autumn and winter body weights. However, cow body weights tended to be heavier (P < 0.10) in lightly grazed pastures relative to conservatively grazed pastures (524 vs. 502 ± 9.7 kg) in spring. Lightly grazed pastures yielded greater (P < 0.05) kg of calf weaned·ha^-1 and calf crop percent than conservatively grazed pastures in 1998 due to destocking of conservatively grazed pastures during that year's drought. Conversely, pregnancy percent tended to be greater (P < 0.1) in conservatively relative to lightly grazed pastures (92.6% vs. 87.7%); however, this advantage is explained by herd management as cows in the conservatively grazed pastures were removed during drought of 1998, avoiding exposure to the drought stress experienced by cows in the lightly grazed pastures. Nonetheless, pregnancy percents from both grazing treatments would be acceptable for most range beef production systems. Results suggest that consistently applying light grazing use of forage is a practical approach for Chihuahuan Desert cow–calf operations to avoid herd liquidation during short term drought.     

Physical Characteristics,Shade Distribution,and Tall Fescue Effects on Cow Temporal/Spatial Distribution in Midwestern Pastures

Nonpoint source (NPS) pollution of water resources may occur from congregation of cattle near streams or ponds. Therefore, relationships of physical characteristics, shade distribution, and tall fescue (Festuca arundinacea Schreb.) prevalence in cool-season grass pastures to the temporal/spatial distribution of grazing cattle were evaluated in two studies on beef cow/calf farms. Global positioning system (GPS) collars recorded the location of 2–3 cows per pasture at 10-min intervals for 5–14 d in the spring, summer, and fall annually. Pasture botanical composition was visually assessed annually. In Study 1, cow location was recorded on five pastures ranging in size from 13 ha to 125 ha with 1.9–3.8% of the pasture area in a stream or pond (water source) and 2–30% of the pasture area within 30.5 m of the water source (waterside zone) for 3 yr. Shade covered 27–73% of the pasture area with 3–64% of shade located within waterside zone. In Study 2, cow location was recorded in three pastures with areas of 8 ha, 10 ha, and 15 ha with 17.8%, 43.4%, and 14.7% of the total area and 28%, 73%, and 68% of the total shade in the waterside zone for 1 yr. In Study 1, proportions of cow observations within the waterside zone increased with decreasing pasture area (r² = 0.61) and increasing proportions of the total pasture area (r² = 0.37) and shade (r² = 0.29) within the waterside zone. In Study 2, proportion of cow observations in the waterside zone increased as the proportion of total area (r² = 0.62) and shade (r² = 0.42) in the waterside zone increased. Results imply more restrictive measures to minimize the risks of NPS pollution of water resources may be most effective in smaller and narrow pastures.     

Grazing Method Effect on Topographical Vegetation Characteristics and Livestock Performance in the Nebraska Sandhills

A study was conducted on upland range in the Nebraska Sandhills to determine differences in plant species frequency of occurrence and standing crop at various topographic positions on pastures grazed with short-duration grazing (SDG) and deferred-rotation grazing (DRG). Pastures within each grazing treatment were grazed at comparable stocking rates (SDG = 1.84 animal unit months (AUM) · ha^?1; DRG = 1.94 AUM · ha^?1) by cow–calf pairs from 1999 to 2005 and cow–calf pairs and spayed heifers from 2006 to 2008. Plant frequency of occurrence data were collected from permanently marked transects prior to, midway through, and at the conclusion of the study (1998, 2003, and 2008, respectively) and standing crop data were collected annually from 2001 to 2008 at four topographic positions (dune top, interdune, north slope, and south slope). Livestock performance data were collected during the last 3 yr of the study (2006 to 2008). Positive change in frequency of occurrence of prairie sandreed (Calamovilfa longifolia [Hook.] Scribn.) was 42% greater on DRG pastures than SDG after 10 yr. Total live standing crop did not differ between DRG and SDG except in 2001 when standing crop was 23% greater on DRG pastures. Standing crop of forbs and sedge was variable between grazing methods on interdune topographic positions depending on year. Average daily gain of spayed heifers (0.84 ±  kg · d^?1 SE) did not differ between SDG and DRG. Overall, SDG was not superior to a less intensively managed grazing method (i.e., DRG) in terms of vegetation characteristics and livestock performance.     

Integrating Ranch Forage Production,Cattle Performance,and Economics in Ranch Management Systems for Southern Florida

The presence of grazing cattle near open waterways has created environmental concerns related to the potential for water contamination. In Florida the removal of cattle from grazing landscapes or decreasing stocking density is being investigated as one option to improve the quality of surface water runoff draining into Lake Okeechobee, Florida. The objective of this study was to determine the effects of stocking rate on cow-calf performance, forage availability and quality, and ranch economic performance. Experimental pastures were established on a southern Florida cow-calf operation with stocking rates of 0.58, 1.01, and 1.35 ha·cow^-1 on summer pastures and 0.93, 1.62, and 2.16 ha·cow^-1 on winter pastures, corresponding to high, medium, and low rates, respectively. The study was conducted over 4 consecutive production years. Cow body condition scores (BCS), pregnancy rate, and calf average daily gain were used as measures of animal performance. Forage utilization was estimated by measuring the difference between forage yield inside and outside grazing exclusion cages and forage quality by crude protein and in vitro organic matter digestibility. Forage yield, utilization, and quality were not significantly affected by stocking rate. Although statistically not significant (P = 0.17), cattle in the high stocking rate experienced a numerically greater loss of BCS following the winter grazing period, but stocking rate did not affect pregnancy rate or calf gains. Production (kg weaned calves·ha^-1) was increased (P < 0.01) for a high stocking rate compared with medium and low stocking rates. Overall ranch profitability will decrease as stocking rates decline. Ranch revenues decrease one-for-one as stocking rates decrease. At the same time, unit cow costs increase at an increasing rate as fewer brood cows are left to support the ranch's fixed cost structure.     

Weaning and post-weaning performance by fall-born beef calves weaned on different dates in the spring from Neotyphodium coenophialum-infected tall fescue pastures

Fall-born calves grazing Neotyphodium coenophialum-infected tall fescue [E+; Lolium arundinaceum (Schreb.) Darbysh.] pastures should benefit from early weaning because of reduced exposure to fungal toxins. However, fall-born calves that grazed E+ and were weaned in mid-April had reduced post-weaning performance compared with calves managed similarly but weaned in early June. Gelbvieh × Angus calves (n = 238) were used in a 3-year study to determine the optimal time to wean fall-born calves grazing E+. Cow/calf pairs were allocated randomly to one of four weaning date treatments: 1) March 16 (177 ± 4.7 days of age; MarW), 2) April 13 (204 ± 4.7 days of age; AprW), 3) May 11 (236 ± 4.7 days of age; MayW), and 4) June 8 (264 ± 4.8 days of age; JuneW). On their assigned weaning date, calves were weighed, vaccinated, blood samples were collected, and calves were moved to 3.2-ha pastures adjacent to their dams for 14 days. After the weaning period, calves were weighed, blood samples were collected, and then calves were moved to pastures containing non-toxic forages. Birth weight and calf weights on MarW, AprW, and MayW weaning dates did not differ (P ≥ 0.21) across weaning date treatments. However, calf weaning weights on their respective weaning dates, weight on JuneW and on June 22 (14 days following the JuneW), daily gain between birth and June 22, and weight change between MarW and JuneW increased linearly (P < 0.05) across weaning dates. Linear decreases (P < 0.05) across weaning dates were noted for antibody titers to bovine virus diarrhea (BVD) and infectious bovine rhinotracheitis (IBR), serum Cu, and platelets at the time of actual weaning. Linear increases (P < 0.05) across weaning dates were noted for: i) total antioxidant potential and eosinophils at weaning; ii) changes in antibody titers to BVD and IBR, total antioxidant potential, and serum Zn during the 14-day post-weaning period; and iii) and changes in BVD and BRSV titers and serum Cu between actual weaning date and June 22. Heifer weight at breeding increased (P < 0.05) and steer weight at shipping, hot carcass weight and backfat thickness tended (P ≤ 0.10) to increase linearly across weaning dates. Final feedlot weight and gain did not differ (P ≥ 0.18) among weaning dates. Therefore, delaying weaning of fall-born calves grazing E+ pastures until early June may be beneficial for calf weight and immune function at weaning, and heifer weight at breeding, but those benefits in steers may be mitigated through the feedlot period.     

Cow and calf performance on Coastal or Tifton 85 Bermudagrass pastures with aeschynomene creep-grazing paddocks

Cow and calf performance was determined in a 2-yr, 2 x 2 factorial, grazing experiment using Coastal or Tifton 85 (T85) replicated Bermudagrass pastures (4 pastures each; each pasture 4.86 ha), without or with aeschynomene creep-grazing paddocks (n = 4, 0.202 ha each, planted in May of each year, 13.44 kg/ha). On June 10, 2004, and June 8, 2005, 96 winter-calving beef "tester" cows and their calves were grouped by cow breed (9 Angus and 3 Polled Hereford/group), initial cow BW (592.9 +/- 70.1 kg, 2-yr mean), age of dam, calf breed (Angus, Polled Hereford, or Angus x Polled Hereford), calf sex, initial calf age (117 +/- 20.1 d, 2-yr mean), and initial calf BW (161.3 +/- 30.4 kg) and were randomly assigned to pastures. Additional cow-calf pairs and open cows were added as the forage increased during the season. Forage mass was similar for all treatment pastures (P > 0.70; 2-yr mean, 6,939 vs. 6,628 kg/ha, Coastal vs. T85; 6,664 vs. 6,896 kg/ha, no creep grazing vs. creep grazing). Main effect interactions did not occur for performance variables (P > 0.10; 2-yr means), and year affected only the initial and final BW of the calves and cows. The 91-d tester calf ADG was greater for calves grazing T85 than Coastal (0.94 vs. 0.79 kg; P < 0.01), and for calves creep grazing aeschynomene compared with calves without creep grazing (0.90 vs. 0.82 kg; P < 0.03). Calf 205-d adjusted weaning weights were increased for calves grazing T85 compared with Coastal (252.9 vs. 240.3 kg; P < 0.01) and for calves with access to creep grazing (249.9 vs. 243.3 kg; P < 0.05). The IVDMD of esophageal masticate from pastures had a forage x creep grazing interaction (P < 0.05; Coastal, no creep grazing = 57.4%; Coastal, creep grazing = 52.1%; T85, no creep grazing = 59.1%; T85, creep grazing = 60.0%), and IVDMD was greater (P < 0.05) for T85 than for Coastal pastures. Cows were milked in August 2004, and in June and August 2005, with variable milk yields on treatments, but increased milk protein (P < 0.05) for cows grazing T85 compared with Coastal pastures in August each year, contributing to increased calf gains on T85 pastures. These results complement previous research with T85 and indicate increased forage quality and performance of cattle grazing T85 pastures. Calf gains on T85 pastures and for calves on creep-grazed aeschynomene paddocks were high enough to influence the efficiency of cow-calf operations.     

Grazing Distribution and Diet Quality of Angus,Brangus, and Brahman Cows in the Chihuahuan Desert

Grazing distribution can be improved by using adapted cattle breeds that travel to distant areas of extensive pastures. A 2-yr study was conducted to evaluate grazing distribution and diet quality of Angus, Brangus, and Brahman cows (seven cows per breed group) in the Chihuahuan Desert during three seasons (winter, early summer, and late summer) using three pastures. Two GPS collars were randomly assigned to each breed group and cow positions were logged every 10 min for 10- to 14-d periods in each pasture (3 periods · season^-1). In 2008, breed groups were evaluated in separate pastures and data were analyzed as a 3 × 3 Latin square design. In 2009, all breed groups were evaluated at the same time in the same pastures. Fecal samples were collected in 2008 and analyzed using near infrared spectroscopy (NIRS) to estimate diet quality. If positions recorded when cows were resting were excluded, Brahman cows traveled greater distances per day than Angus cows throughout the study and greater (P ≤ 0.10) than Brangus cows in all but one season during 2009. No differences in average distance to water were detected (P &spigt; 0.10) among breed groups. During early summer in 2008 and early and late summer in 2009, Angus cows maintained a more linear grazing path (P ≤ 0.10) than Brangus or Brahman cows. Brahman cows displayed more sinuous grazing paths (P ≤ 0.10) than other breeds during early and late summer seasons in 2009. In 2008, no differences in crude protein content of diets were detected (P &spigt; 0.10) among breed groups during all seasons. Spatial movement patterns of Brahman cows appeared to differ from Angus and Brangus cows; however, there was no evidence to suggest that there was any advantage in use of areas far from water by any breed group.     

Factors influencing social organization in postpartum Angus cows under confinement. Effect on cow–calf weight change

The objective was to determine factors influencing social organization in postpartum Angus cows and its effect on variation of cow–calf weight after 90 d. Postpartum Angus cows (N=90) with no history of puerperal problems, a calf suckling, and body condition score (BCS) no less than 3 were allocated into 3 groups of 30 (A, B, and C) according to parity (P) and cow body frame (CF). Using the agonistic interactions recorded during the study, a raw dominance value with subsequent Arc-sin conversion (Arc-sin DV) was calculated to generate a linear social dominance order (DO) with 3 social categories (dominant—D-, intermediate—I-, and subordinate—S-cows). The effects of postpartum body weight (PPBW), BCS, CF, and P on Arc-sin DV were statistically analyzed using ANOVA. Similar procedure was applied to analyze the effects of group, P, CF, and DO on cow body weight at 90 d (CW90), and the effects of DO of dams, P, group, calf gender (CG), and sire within breed (SWB) on calf body weight at 90 d (CFW90). Cows with larger CF and heavier PPBW obtained greatest (P<0.0005) Arc-sin DV. The youngest and the oldest cows tended (P<0.10) to obtain the lowest Arc-sin DV. After 90 d of trial, D cows were heavier than I (P<0.002) and S cows (P<0.0001). Calf birth weight was influenced by SWB (P<0.03) and P (P<0.05), and D cows had heavier (P<0.05) calf at birth than S cows. At 90 d, calf body weight was influenced by P (P<0.03) and DO of dam (P<0.008). Thus, calf weight at 90 d increased with DO of dams. In conclusion, CF, PPBW, and to a less extent P, influenced DO. Parity and CF influenced PPBW. Variation of CW90 was influenced by DO. Calf birth weight was influenced by SWB, P, DO of cow, and CG. Meanwhile, CFW90 was influenced by P and DO of cow. Interactions among social organization, management strategies, calf growth, and reproductive aspects need more attention.     

Cool-season annual pastures with clovers to supplement wintering beef cows nursing calves

ABSTRACT: In December of 3 years, 87 beef cows with nursing calves (594 +/- 9.8 kg; calving season, September to November) at side were stratified by body condition score, body weight, cow age, and calf gender and divided randomly into 6 groups assigned to 1 of 6 cool-season annual pastures (0.45 ha/cow) that had been interseeded into a dormant common bermudagrass (Cynodon dactylon [L.] Pers.)/bahiagrass (Paspalum notatum Flugge) sod. Pastures contained 1 of the following 3 seeding mixtures (2 pastures/mixture): 1) wheat (Triticum aestivum L.) and ryegrass (Lolium multiflorum Lam., WRG), 2) wheat and ryegrass plus red clover (Trifolium pretense L., WRR), or 3) wheat and ryegrass plus white (Trifolium repens L.) and crimson clovers (Trifolium incarnatum L., WRW). All groups had ad libitum access to grass hay (12% crude protein; 58% total digestible nutrients). The second week in December, cow estrous cycles were synchronized and artificially inseminated. In late December, a bull was placed with each group for 60-d. Data were analyzed with an analysis of variance using a mixed model containing treatment as the fixed effect and year as the random effect. Body weight and condition scores did not differ (P > 0.27) among cows between February and June. Calf birth weights or average daily gain did not differ (P [greater than or equal to] 0.17) among treatments; however, calves grazing pastures with clovers did tend (P = 0.06) to weigh more than calves grazing grass only. Weaning weight per cow exposed to a bull was greater (P = 0.02) for WRR and WRW than WRG. Cows grazing winter-annual pastures containing clovers tended to wean more calf body weight per cow exposed to a bull than cows grazing the grass only pastures.     

Strategic deworming for spring-calving beef cow/calf herds

Strategic application of an anthelmintic was tested during the 1982 grazing season as part of the continued study of the epidemiology of beef cattle parasitism in central Missouri. Forty Hereford and Hereford X Simmental cow/calf pairs were assigned to 2 treatment groups. The 20 cow/calf pairs in group 1 were nonmedicated controls. After calving in mid-March, the 20 cows in group 2 were drenched with a 10% suspension of the anthelmintic fenbendazole (10 mg/kg of body weight). Ten cow/calf pairs were placed on each of four 20-acre fescue or orchard grass pastures in mid-May. Cows and calves in treatment group 2 were drenched with the 10% fenbendazole suspension (5 mg/kg) in mid-July. Body weights and fecal specimens were obtained monthly. Nematode egg counts in cow and calf fecal specimens collected monthly were significantly (P less than 0.05) lower in treatment group 2 than in treatment group 1. Numbers of larvae cultured for speciation revealed that Ostertagia ostertagi was the predominant nematode species. Developmental arrest of O ostertagi was found to be significantly (P less than 0.05) greater than zero from mid-May to mid-July. An important significant difference (P less than 0.01) was shown in body weights of calves, with the calves in treatment group 2 having a higher mean weight gain of 22.5 kg in adjusted 205-day weaning weights, and a higher mean daily gain of 0.11 kg. Weight maintenance of cows was not affected significantly by anthelmintic treatment. Nematode egg counts in monthly cow and calf fecal specimens were not significantly different between those animals on different pastures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pyric–Herbivory and Cattle Performance in Grassland Ecosystems

Achieving economically optimum livestock production on rangelands can conflict with conservation strategies that require lower stocking rate to maintain wildlife habitat. Combining the spatial and temporal interaction of fire and grazing (pyric–herbivory) is a conservation-based approach to management that increases rangeland biodiversity by creating heterogeneous vegetation structure and composition. However, livestock production under pyric–herbivory has not been reported. In both mixed-grass prairie and tallgrass prairie, we compared livestock production in pastures with traditional fire and grazing management (continuous grazing, with periodic fire on tallgrass prairie and without fire on mixed-grass prairie) and conservation-based management (pyric–herbivory applied through patch burning) at a moderate stocking rate. Stocker cattle weight gain, calf weight gain, and cow body condition score did not differ (P > 0.05) between traditional and conservation-based management at the tallgrass prairie site for the duration of the 8-yr study. At the mixed-grass prairie site, stocker cattle gain did not differ in the first 4 yr, but stocker cattle gained more (P ≤ 0.05) on conservation-based management and remained 27% greater for the duration of the 11-yr study. Moreover, variation among years in cattle performance was less on pastures under conservation management. Traditional management in mixed-grass prairie did not include fire, the process that likely was associated with increased stocker cattle performance under conservation management. We conclude that pyric–herbivory is a conservation-based rangeland management strategy that returns fire to the landscape without reduced stocking rate, deferment, or rest.     

Effects of Weaning Date and Prepartum Protein Supplementation on Cow Performance and Calf Growth

Two experiments evaluated effects of weaning date on cow body condition score (BCS) and calf growth. In Experiment 1, 134 March-calving cows were used in a four-year experiment. Calves were weaned 18 August or 7 November and cows were fed 0 or 0.45 kg protein supplement (42% crude protein) three days per week from 1 December to 28 February while grazing upland range in a 2 by 2 factorial arrangement of treatments. In Experiment 2, spring calving cows (year 1, n = 97; year 2, n = 104) were assigned randomly to one of eight weaning dates at 2-week intervals from 19 August to 25 November. In Experiment 1, weaning in August increased cow BCS precalving (P &spilt; 0.001) and prebreeding (P &spilt; 0.001), but not pregnancy rates (P = 0.56). Cows fed supplemental protein had greater BCS precalving (P &spilt; 0.001) and prebreeding (P = 0.001) than nonsupplemented cows, but pregnancy rates were similar (P = 0.27). Calves born to cows fed supplemental protein prepartum had greater weaning weight than calves born to nonsupplemented cows regardless of whether weaning occurred in August (P = 0.001) or November (P &spilt; 0.001). Effects of weaning date on feedlot performance interacted with supplementation treatment. Calves born to cows fed supplement that were weaned in November generated the greatest net returns. In Experiment 2, BCS decreased linearly (P &spilt; 0.001) as date of weaning was delayed from August to November. Nursing calf gain increased cubically (P &spilt; 0.0004) and weaned calf gain from August to November increased quadratically (P &spilt; 0.002). Protein supplementation did not affect cow pregnancy rate, but calves born to cows fed protein supplement had greater pre- and postweaning gains. Cow BCS decreased as weaning date was moved later in the year but cow pregnancy rate was not affected by weaning date.     

Association between cow reproduction and calf growth traits and ELISA scores for paratuberculosis in a multibreed herd of beef cattle

The objective of this research was to assess the association between 4 cow reproductive and weight traits, and 2 preweaning calf traits and ELISA scores for paratuberculosis (0 = negative, 1 = suspect, 2 = weak-positive, and 3 = positive) in a multibreed herd of cows ranging from 100% Angus (A) to 100% Brahman (B). Cow data were 624 gestation lengths (GL), 358 records of time open (TO), 605 calving intervals (CI), and 1240 weight changes from November to weaning in September (WC) from 502 purebred and crossbred cows. Calf data consisted of 956 birth weights (BWT), and 923 weaning weights adjusted to 205 d of age (WW205) from 956 purebred and crossbred calves. Traits were analyzed individually using multibreed mixed models that assumed homogeneity of variances across breed groups. Covariances among random effects were assumed to be zero. Fixed effects were year, age of cow, sex of calf, year × age of cow interaction (except WC), age of cow × sex of calf interaction (only for WC), and covariates for B fraction of sire and cow, heterosis of cow and calf, and ELISA score. Random effects were sire (except for TO and CI), dam, and residual. Regression estimates of cow and calf traits on ELISA scores indicated that lower cow fertility (longer TO), lower ability of cows to maintain weight (negative WC), lower calf BWT, and lower calf WW205 were associated with higher cow ELISA scores. Further research on the effects of subclinical paratuberculosis in beef cattle at regional and national levels seems advisable considering the large potential economic cost of this disease.     

Integrated Ecological and Economic Analysis of Ranch Management Systems: An Example From South Central Florida

Developing sustainable ranch management systems requires integrated research that examines interrelations among ecological and economic factors. In south central Florida, where phosphorus (P) loading is an overriding environmental concern, we established an interdisciplinary experiment to address the effects of cattle stocking density and pasture type on P loading and other ecological and economic factors in subtropical Florida ranchlands through a partnership including ecologists, agricultural faculty, agency personnel, and producers. Here we present an overview of all project components detailed in 3 accompanying papers in this issue of Rangeland Ecology & Management. We describe the experimental design, which included 2 replicates of 4 different cattle stocking density treatments (control, low, middle, and high [0, 15, 20, and 35 cow–calf pairs per pasture]) maintained on 8 improved summer pastures (∼ 20 ha each), and 8 seminative winter pastures (∼ 32 ha each) from 1998 to 2003. Stocking densities did not significantly affect P loads and concentrations in surface runoff, soil chemistry, or soil nematode communities, but did affect cattle production and economic performance. Cattle production was greater at the high than at the middle or low stocking density; economic performance declined significantly with decreasing stocking density (break-even was $1.89·kg^-1 for high and $2.66·kg^-1 for low density). Pasture type significantly affected environmental factors; average P runoff from improved summer pastures (1.71 kg P·ha^-1·y^-1) was much greater than from seminative winter pastures (0.25 kg P·ha^-1·y^-1), most likely because of past P fertilizer use in improved pastures. We integrate results from all the papers within the context of a conceptual model and a P budget, and emphasize that management practices targeted at specific environmental factors on beef cattle ranches, such as nutrient loading, must include consideration of economic impacts and broader ecosystem implications.     

Effects of Tuli,Senepol, Brahman,Angus, and Polled Hereford Sire Breeds on Birth and Weaning Traits of Offspring

Progeny (n = 861) of tropically adapted breeds [Tuli (TU), Senepol (SE), and Brahman (BR)] and temperate breeds [Angus (AN) and Polled Hereford (HP)] were evaluated for birth and weaning traits in each of 5 yr. Multiparous crossbred cows representing three genetic types [British (Bt), ½BR½Bt, and ¾Bt¼BR] were mated to AN, HP, TU, SE, and BR sires, with the exception that BR sires were not mated to ½BR½Bt cows. Calving season was January through early March. Following calving, cows were provided bermudagrass hay and bahiagrass hay and had limited access to rye and ryegrass pastures. Cow and calf pairs grazed bermudagrass and bahiagrass pastures as available until weaning without access to creep feed. Male calves were castrated at birth and were not implanted. Data included birth weight, cannon bone length at birth, weaning weight, weaning hip height, ADG from birth to weaning (ADGBW), ADG from birth to April (ADGBA), ADG from April to weaning (ADGAW), and weight per day of age (WDA). Data were analyzed by PROC Mixed using a model that included calf genetic type, calf sex, calf birth day of year, and calf genetic type × calf sex interaction. Random effects were cow age, birth year, and sire and dam of calf. Calf genetic type and calf sex were significant sources of variation for all characteristics. Linear contrasts revealed that BR-sired calves were heavier at birth, had longer cannon bones at birth, and were taller at weaning (P<0.01). Tuli- and SE-sired calves were similar to AN- and HP-sired calves for birth weight, cannon bone length at birth, and weaning hip height. Angus-, HP-, and BR-sired calves were heavier at weaning compared with TU-sired calves, and SE-sired calves were intermediate for weaning weight (P<0.01). In conclusion, the TU-sired calves were smaller at birth and at weaning when compared with BR-sired calves. The TU- and SE-sired calves appear to offer more moderate size and growth rate through weaning than do the BR-sired calves.     

Productivity and hay requirements of beef cattle in a Midwestern year-round grazing system

Our objective was to evaluate a replicated (n = 2) Midwestern year-round grazing system's hay needs and animal production compared with a replicated (n = 2) conventional (minimal land) system over 3 yr. Because extended grazing systems have decreased hay needs for the beef herd, it was hypothesized that this year-round system would decrease hay needs without penalizing animal production. In the minimal land (ML) system, two replicated 8.1-ha smooth bromegrass-orchardgrass-birdsfoot trefoil (SB-OG-BFT) pastures were rotationally stocked with six mature April-calving cows and calves and harvested as hay for winter feeding in a drylot. After weaning, calves were finished on a high-concentrate diet. Six mature April-calving cows, six mature August-calving cows, and their calves were used in the year-round (YR) grazing system. During the early and late summer, cattle grazed two replicated 8.1-ha SB-OG-BFT pastures by rotational stocking. In mid-summer and winter, April- and August-calving cows grazed two replicated 6.1-ha, endophyte-free tall fescue-red clover (TF-RC) and smooth bromegrass-red clover (SB-RC) pastures, respectively, by strip-stocking. In late autumn, spring-calving cows grazed 6.1-ha corn crop residue fields by strip-stocking. Calves were fed hay with corn gluten feed or corn grain over winter and used as stocker cattle to graze SB-OG-BFT pastures with cows until early August the following summer. First-harvest forage from the TF-RC and SB-RC pastures was harvested as hay. Body condition scores of April-calving cows did not differ between grazing systems, but were lower (P < or = 0.03) than those of August-calving cows from mid-gestation through breeding. Preweaning calf BW gains were 47 kg/ha of perennial pasture (P < 0.01) and 32 kg/cow (P = 0.01) lower in the YR grazing system than in the ML system. Total BW gains ofpreweaning calf and grazing stocker cattle were 12 kg/ha of perennial pasture less (P = 0.07), but 27 kg/cow greater (P = 0.02) in pastures in the YR grazing system than in the ML system. Amounts of hay fed to cows in the ML system were 1,701 kg DM/cow and 896 kg DM/cow-stocker pair greater (P < 0.05) than in the YR grazing system. Extended grazing systems in the Midwest that include grazing of stocker cattle to utilize excess forage growth will decrease stored feed needs, while maintaining growing animal production per cow in April- and August-calving herds.     

Prevalence of Fasciola hepatica in the intermediate host Lymnaea truncatula detected by real time TaqMan PCR in populations from 70 Swiss farms with cattle husbandry

Bovine fasciolosis is an economically important parasitic disease. Quantitative real time PCR was utilized to determine the prevalence of Fasciola hepatica in the snail intermediate host Lymnaea truncatula from 70 selected, infected Swiss cattle farms, and to gain information on the infection risk to the definitive host. Snails from 130 habitats (36 streams, 21 wells, 24 drainage ditches, 33 spring swamps, 14 reeds, 1 drainage shaft and 1 pond) originating from 71 dairy cow pastures, 39 pastures for young stock, 14 hay fields and 6 dry cow pastures were collected. Of these, 51 populations were found to be infected with F. hepatica. A total of 4733 snails were examined of which 331 were infected (7.0%). The numbers of snails collected from different sites ranged from 1 to 159 snails. Clustering of infection in snails was found on the farm of origin with a mixed logistic model with random effects. The risk of infection of L. truncatula with F. hepatica was significantly higher in populations originating from spring swamps, wells and reeds compared to populations from streams. In addition the risk of snail infection was significantly lower in populations collected in young stock and dry cow pastures compared to dairy cow pastures. The greater the population size collected from a habitat also increased the risk of an individual snail being infected.     

Effects of a short-term increase in the nutritional plane before the mating period on metabolic and endocrine parameters, hepatic gene expression and reproduction in primiparous beef cows on grazing conditions

Sixty-four spring-calved primiparous crossbred cows paired by calving date and body condition score (BCS) at calving were used to study the effect of a short-term increase in the nutritional plane before the mating period on cow and calf performance, changes in metabolic and endocrine parameters and hepatic gene expression. At 48 ± 10 days post-partum (onset of nutritional treatment = day 0), cows were assigned to two treatments during 23 days: control (grazing of native pastures; NP; n = 31) and increased nutritional plane (NP improved with Lotus subbiflorous cv Rincon; IP; n = 33). Cow body weight (BW), BCS and total protein and albumin concentrations increased while urea and non-esterified fatty acids levels decreased from the beginning of the nutritional treatment in both groups, indicating the animal positive energy balance as forage growth and availability of pastures increased during spring. In addition, cow BW and BCS, as well as calf average daily gain and BW, were greater in IP than in NP cows groups. Insulin concentrations were less in IP than in NP (1.37 vs. 2.25 ± 0.26 μU/ml) because insulin increased owing to nutritional treatment only in NP cows. Hepatic insulin receptor mRNA at day 23 tended to be 1.5-fold greater, while insulin growth factor binding protein-3 mRNA expression was 1.7-fold greater in NP than in IP cows. Reproductive responses were not affected by nutritional treatment, but days to initiation of ovarian ciclicity (108 ± 10 days) were positively correlated with insulin concentrations. Grazing of improved NP for 23 days before the mating period did not improve cow reproductive performance but modified metabolic, endocrine and gene expression parameters, in agreement with greater nutrient and energy partitioning towards milk production, reflected in better calf performance.     

Offstream water and trace mineral salt as management strategies for improved cattle distribution

The objective of this study was to test the combined effect of offstream water and trace mineral salt on cattle distribution in a riparian meadow and its adjacent uplands. From July 15 to August 26, 1996 and 1997, three treatments were each randomly assigned to one pasture in each of three blocks. Sixty cow/calf pairs were then randomly allotted to the grazed pastures. The treatments included 1) stream access and access to offstream water and trace-mineral salt (off-stream), 2) stream access and no access to offstream water or trace-mineral salt (no-offstream), and 3) ungrazed control. The response of cattle was measured through visual observations of cattle distribution, grazing activity and travel distance, cow/calf performance, and fecal deposit distribution. Distribution patterns of the cattle, measured as the distance of cattle from the stream, was characterized by a time of day x treatment x time in grazing period x year interaction (P < 0.05). No-offstream cattle began the day further from the stream than offstream cattle but consistently moved closer to the stream after the morning grazing period (0600 to 0900). Differences in distribution patterns between the two treatments were more pronounced early in the grazing period than late in the grazing period. Grazing activity, fecal deposit distribution, and travel distance of cattle were not affected by the presence of offstream water and trace-mineral salt. Cows and calves with offstream water and trace-mineral salt gained 11.5 kg and 0.14 kg/d more, respectively, than no-offstream cows and calves averaged across years (P < 0.05). Overall, cattle distribution patterns and cow/calf performance were influenced by the presence of offstream water and trace-mineral salt. Changes in distribution were most pronounced early in the grazing season.     

Mefluidide effects on smooth brome composition and grazing cow-calf performance

Mefluidide, a plant growth regulator, was evaluated in two cow-calf grazing trials and one herbage trial on smooth brome (Bromus inermis) pastures stocked at recommended densities in eastern Nebraska. Mefluidide-treated pasture increased cow and calf production during August of 1982 (P = .03) and calf production was greater during July of 1983 (P = .09). Mefluidide-treated smooth brome pastures increased calf production over the 1982 grazing season (P = .11) and cow gain over the 1982 (P = .12) and 1983 grazing seasons (P = .13). Mefluidide decreased neutral detergent fiber (NDF) content and increased crude protein content of smooth brome during both years (P less than .05), and increased in vitro dry matter disappearance (IVDMD) in 1982 (P less than .05). In ungrazed smooth brome, mefluidide treatment appeared to shift dry matter production to green leaves from green stem and brown leaf and stem fractions. Cell wall components [NDF, acid detergent fiber (ADF) and lignin] of green leaves were not affected significantly by mefluidide treatment, although green stems treated with mefluidide were lower in ADF and lignin (P less than .05).