Mixed Grass Pastures Research Articles

PSV-10 Supplementing Amino Acid Complexed or Inorganic Trace Minerals to Grazing Cattle Following a Receiving Phase Dietary Trace Mineral Comparison

Abstract The objective was to investigate the effects of inorganic or amino acid-complexed sources of trace minerals (zinc and copper) on performance of beef heifers during a grazing period following a receiving trial. Crossbred beef heifer calves (n = 287, initial body weight = 231 ± 0.49 kg) were used in a 42-day receiving trial. Any cattle that failed to gain at least 0.45 kg/d, and(or) received 3 doses of antibiotic therapy during the receiving trial were removed from the study. Remaining cattle were kept within their respective pen and treatment and were randomly retained for the grazing phase. If there were not enough eligible calves/pen, calves on the same treatment that had been randomly removed from other pens were added to achieve equal pen counts. Cattle (n = 204; initial body weight = 262 ± 1.44 kg) grazed at 2 different locations in Arkansas; in Fayetteville, cattle (12 pens; 6 pens/treatment) grazed 6-acre stockpiled mixed grass pastures (n = 8 calves/pasture); in Batesville, cattle (12 pens; 6 pens/treatment) grazed 5-acre stockpiled novel-endophyte fescue pastures (n = 9 calves/pasture). Treatments consisted of supplemental zinc (540 mg/d) and copper (90 mg/d) from complexed (Availa, Zinpro Corp. Eden Prairie, MN) or inorganic sources (sulfates). Cattle grazed for at least 114 days until reaching a weight goal of 341 kg. Cattle had ad libitum access to water and were offered bermudagrass hay when forage was limited. Body weights were measured on 28-day intervals. A subset of calves (3/pen) were liver biopsied at the end of receiving and grazing phases to compare liver mineral concentrations. Following grazing, calves were removed from treatments and sent to a Kansas feedlot (n = 198) where they were commingled and fed in a single pen for 141 days. Morbidity and mortality data were recorded, and after slaughter, carcass data were collected. Statistical analyses were performed using MIXED and GLIMMIX procedures of SAS 9.4 with location as a random effect and pen within location specified as subject. There was no treatment (P = 0.14) or treatment × day interaction (P = 0.92) for body weights during the grazing phase. Overall average daily gain was not different between treatments (P = 0.94; 0.69, SE = 0.04). Treatment did not affect liver mineral concentrations (P ≥ 0.17). There were no differences in feedlot morbidity, mortality, or carcass characteristics (P ≥ 0.28). In conclusion, although complexed sources of trace minerals (zinc, copper, manganese, and cobalt) improved body weight gain and decreased morbidity treatments during the receiving phase, there were no significant differences from grazing to slaughter when supplementing amino acid complexed versus inorganic mineral sources of zinc and copper during the grazing period.

Influence of irrigation and supplementation on performance and ingestive behavior of beef cattle on mixed grass pastures

Influence of irrigation and supplementation on performance and ingestive behavior of beef cattle on mixed grass pastures

112 Effects of storage-handling methods on nutrient analysis of mixed-grass pasture samples

Forage should be the basis of any equine diet, even for those with insulin dysregulation (ID). Fresh and preserved forage low in nonstructural carbohydrates (NSC) is recommended for ID animals, indicating the need for an accurate forage analysis. It remains to be fully understood how handling fresh forage samples pre-analysis impacts nutrient values. The objectives of this study were to compare 5 pasture sample storage-handling methods, analyzed after 24h and 1wk, on various nutrients including crude protein (CP), water soluble carbohydrates (WSC), ethanol soluble carbohydrates (ESC), starch and NSC. In October 2022, forage samples were manually harvested to ground height between 0800 and 0900 from a mixed-grass pasture after a rest period. Subsamples were mixed to create triplicate samples for analysis at both time periods (24h vs 1 wk) and the following 5 storage-handling methods: microwave-oven (70s then stored at −20°C; MO), room temperature (RT), 3°C, −20°C, and −80°C, totaling 30 samples. All forage samples were shipped on ice to a commercial laboratory for wet chemistry and NIR analysis (Equi-Analytical, Ithaca, NY). Data were analyzed using 2-way ANOVAs in JMP with fixed effects of storage method, time and storage by time interactions as well as storage-handling method by laboratory analysis method and method by storage interactions.Statistical significance was declared at P ≤ 0.05. All data reported are from wet chemistry analysis as there were no significant differences between the 2 analysis techniques. Storage by time interactions were statistically different for some nutrients measured from the mixed grass when stored at RT. Specifically, the WSC (9.2 ± 0.4% DM vs. 5.4 ± 0.9% DM; P = 0.009) and ESC (5.4 ± 0.4% DM vs. 3.6 ± 0.6% DM; P = 0.001) content decreased from 24h compared with 1wk. The remaining storage-handling methods of MO, 3°C, −20°C, and −80°C, however, showed no statistical differences across time for WSC, Starch or NSC indicating these methods were appropriate for storing forage for this time. A decrease in CP content from 24h compared with 1wk was, however, shown when stored at −80°C (12.7 ± 0.6% DM vs. 11.2 ± 0.3% DM; P = 0.02), yet no other statistical differences in CP were detected. These results demonstrate that samples kept at RT or −80°C for one week before nutrient analysis may not accurately represent the nutrient content of the forage. Storage-handling method and time did affect the nutrient content of fresh forage thus, samples should be either immediately dried, kept at 3°C, or frozen (−20°C) preceding analysis.

70 Ahiflower (Buglosoides Arvensis) oil supplementation alters whole blood and muscle fatty acid profile in mature horses

The omega-3 (n-3) profile of common plant-based ingredients are derived from α-linolenic acid (ALA). Previous research has indicated that horses lack the ability to convert ALA or other short-chain polyunsaturated fatty acids (SC-PUFA) into the biologically relevant docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Ahiflower (Buglossoides Arvensis) oil is a novel plant-based source of omega-3 fatty acids derived from n-3 stearidonic acid (SDA), and gamma-linolenic acid (GLA), an omega-6 fatty acid (see Table 1 for fatty acid profile). The objective of this trial was to evaluate how supplementation of Ahiflower oil to horses would alter whole blood and muscle fatty acid composition. Mature Quarter Horses (n = 20) were balanced by age, BW, and BCS and assigned to one of 4 treatment groups. LOW (n = 5; BW = 507.12 ± 2.3kg; BCS = 5.4 ± 0.3) was offered 30mL/day of Ahiflower oil. HIGH (n = 5; BW = 517.45 ± 4.5kg; BCS = 5.7 ± 0.1) was offered 60mL/day of Ahiflower oil. FLAX (n = 5; BW = 497.25 ± 3.5kg; BCS = 6.1 ± 0.7) was offered a flaxseed pellet (CP = 15.42%, Total omega-3 = 3.75%) formulated to provide the same amount of total omega-3′s as LOW was offered. PAST (n = 5; BW = 508.14 ± 3.6kg; BCS = 5.2 ± 0.6) was allowed free-choice access to mixed grass pasture (CP = 16.0%, Total omega-3 = 0.79%). All horses were offered 1.81kg/d of Purina® Strategy GX® (CP = 14.24%, Total omega-3 = 0.44%) daily. LOW, HIGH, and FLAX were housed in drylots by treatment group and were offered 2.0% BW as Timothy grass hay (CP = 10.10%, Total omega-3 = 0.35%). On d 0, 30, and 60 blood samples were collected along with a mid-gluteal muscle sample (∼1g). Samples were analyzed for fatty acid profile via LC-HPLC (UF ATCL).Data were analyzed via ANOVA (SAS 9.4). Horses in the LOW group had a 12.5% increase in total omega-3, while horses in HIGH had a 40.1% increase. Similar differences were observed for EPA (LOW = 19.2%; HIGH = 40.1%), and GLA (LOW = 60.1%; HIGH = 167%). Horses in HIGH had a greater increase from baseline in muscle EPA + DHA compared with all other groups (250%). All differences were significant at P < 0.05. Taken together these data indicate that horses had the ability to convert the PUFA's in Ahiflower oil into EPA. Increased EPA in whole blood and muscle tissue potentially allows for increased production of anti-inflammatory eicosanoids and prostaglandins. Further research is necessary to elucidate the mechanism by which this conversion occurs.

Economic feasibility of extruded dried distillers grains cube as a supplement for beef steers grazing introduced mixed-grass pastures

Our objectives were to evaluate the effects of dried distillers grains (DDG) cubes (MasterHand Milling) on performance, and to assess the economics of steers grazing introduced pastures (n = 9 pastures; 7.2 ± 2.90 ha) in summer 2020 (n = 155 d) and 2021 (n = 182 d). Each year, crossbred steers (n = 140) were assigned to pastures, and pastures were assigned to 1 of 3 treatments (n = 3 pastures per treatment): (1) fertilized control (FC)—no supplement was given to steers on N-fertilized pastures (112 kg of N/ha); (2) fertilized supplement (FS)—steers were supplemented DDG cubes at 1.2 kg/d prorated for 3-d/wk feeding on N-fertilized pastures; or (3) supplement (SP)—steers were supplemented DDG cubes at 0.75% of BW/d prorated for 5-d/wk feeding on unfertilized pastures. Economic feasibility was determined each year using an enterprise budget analysis. Both FS and SP had greater ( P ≤ 0.01) mid-summer and final BW than FC steers. However, FS steers had greater total season supplemental efficiency ( P = 0.03) than SP. Cost of gain was the least ( P < 0.01) for FC animals and the greatest for SP ( P < 0.01). Supplementation increased gross returns ( P < 0.01), but FC had the greatest net returns ( P < 0.01). Our results suggest that DDG cubes are a suitable supplement and can replace N fertilizer for steers grazing introduced pastures, but the producer must determine the management strategy most profitable to meet their production goals.

Diurnal Variation in Forage Nutrient Composition of Mixed Cool-Season Grass, Crabgrass, and Bermudagrass Pastures

Warm-season grasses have been suggested as alternative low non-structural carbohydrate (NSC) pasture forages. The purpose of this study was to evaluate nutrient composition and diurnal changes in soluble carbohydrates for the warm-season annual 'Quick-N-Big' crabgrass [CRB; Digitaria sanguinalis (L.) Scop.] and the warm-season perennial 'Wrangler' bermudagrass [BER; Cynodon dactylon (L.) Pers] in comparison to mixed cool-season grass [CSG; 'Inavale' orchardgrass (Dactylis glomerata [L.]), 'Tower' tall fescue (Lolium arundinaceum [Schreb.] Darbysh.), and 'Argyle' Kentucky bluegrass (Poa pratensis [L.])]. Samples were collected at 4-hour intervals over 3 d when each forage reached the boot stage of maturity. Digestible energy was greatest for CSG (2.29 ± 0.34 Mcal/kg) and lowest for BER (2.13 ± 0.34 Mcal/kg), while crude protein was lowest for CSG (16.1 ± 0.29%) and neutral detergent fiber was greatest for BER (60.0 ± 0.41; P ≤ .0008). Non-structural carbohydrates were greater for CSG (17.6% ± 0.26%) compared to BER (10.6% ± 0.26%) or CRB (10.9% ± 0.26%; P < .0001). Overall, NSC was greatest in the afternoon and evening (14.5–14.9 ± 0.60%) and lowest in the early morning (11.2–11.4 ± 0.60%; P ≤ .04), but diurnal variation was most pronounced in CSG versus either Warm-season grasses. Results of this study provide needed data on nutritional composition of CRB and BER and demonstrate that these grasses may serve as pasture forages for horses where NSC intake is of concern. Results also support recommendations for restricting grazing to early morning to limit NSC consumption, particularly in CSG pastures.

PSII-13 Impact of maternal phosphorus intake on colostrum quality, calf growth, and calf immunoglobulin concentrations in primiparous beef cows

Abstract The objective of this experiment was to evaluate the effect of maternal phosphorus intake on growth and health of their calves. Treatments were 1) a free-choice mineral containing no supplemental P or 2) a free-choice mineral with 4% supplement phosphorus. Primiparous crossbred Angus beef cows (n = 36) were stratified by body weight and pregnancy status (bred by artificial insemination or natural service) then assigned to pasture groups (4 groups, 2/treatment, 9 heifers/group). These bred heifers had been receiving these same dietary treatments from 30 days after weaning until confirmation of pregnancy. Eighteen bred heifers from each treatment were selected randomly to continue into this experiment. At calving, colostrum and blood samples were collected from a subset of 12 heifers/treatment (6/group) and evaluated. Body weights and calf viability scores were obtained for all cattle. Data were analyzed using the MIXED (for continuous data) and GLIMMIX (for scoring data) procedures of SAS using group as the experimental unit. Cows grazed mixed grass pastures; monthly forage samples ranged from 0.28 to 0.36% P. There were no differences (P &amp;gt; 0.10) for cow body weight during gestation, calf birth weight, calf viability scores at birth, or calf weight at an average age of 21 days. There were also no differences (P &amp;gt; 0.10) in colostrum components (fat, protein, lactose, and IgG), or in the serum IgG or plasma mineral concentrations for both cows and calves 48 hours after parturition. All calves were sampled at approximately 21 days of age and there were no treatment differences (P &amp;gt; 0.10) in serum IgG concentrations. There were no benefits to supplementing gestating heifers with phosphorus when they grazed pasture with a history of fertilization with livestock manure.

94 Impact of a Hydrolyzed Yeast Product on Performance, Hair Coat Shedding, and Behavior of Cows Grazing Pastures Containing Endophyte-Infected Tall Fescue

Abstract Endophyte-infected tall fescue creates a multitude of problems for many beef producers, with supplementation being one management strategy to decrease these problems. Our research objective was to determine if supplementation with a hydrolyzed yeast product could alleviate some symptoms of fescue toxicosis in mature cows. Across the 3-yr study, Angus cow-calf pairs (n = 34, 38, 34) 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 treatment groups grazed the same mixed grass pastures (n = 6, 8, 8; 1.21 ha each) which contained varying levels of endophyte (20 – 90%) as measured prior to each year, in a rotational pattern for 126, 133, or 140 d, depending upon year. 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 a barn was recorded. Data were analyzed using the MIXED procedure of SAS. Cow BW change was affected (P &amp;lt; 0.01) by a treatment×year interaction. Cow BCS increased in HYM vs. CON cows (0.34 vs. 0.06; P &amp;lt; 0.01; SEM = 0.08) across the entire trial. Cows consuming the HYM supplement also spent a greater percentage of time outside being active (P &amp;lt; 0.01) and a lower percentage of time inside being inactive (P &amp;lt; 0.01) compared to CON cows. Results from this trial indicate that the hydrolyzed yeast mineral may be an effective tool to aid in combating heat stress associated with fescue toxicosis.

108 Influence of Cow Body Weight Changes on Calf Growth during the Summer Grazing Period

Abstract In spring calving beef herds, the summer grazing period allows the mature cow to recuperate prior to the next calving season. Cow body weight changes during the summer can vary from minimal to extreme, which may also alter calf growth rates. The objective of this study was to determine the influence of cow body weight changes on calf growth during the summer grazing season. Cows and calves were weighed at the beginning, mid-point and end of the summer grazing season with the end-point being weaning. Based on these weights, cows were categorized into one of four groups: low (LO), medium (MED), high (HI), and extreme (EXT). Groups were determined based on the percent body weight gained across the season with LO being less than 4.99%; 5–9.99% as MED; 10–14.99% as HI, and above 15% as EXT. Data were collected over a 3-yr period utilizing a total of 52 mature Angus cows and 102 Angus calves. Cows were rotationally grazed on mixed grass pastures containing tall fescue and supplemented with corn silage for part of the grazing season. Cows were managed in two groups, but all pastures were grazed by all cows during the season. Calves were provided ad libitum access to creep feed for the entire grazing season. All calves were treated similarly and bulls were left intact until weaning. Data were analyzed in the MIXED procedure of SAS with year and group effects with age of dam as a covariate. Calves had the lowest early ADG in LO cows compared to all other groups (P = 0.01). Overall calf ADG tended to be different between groups as LO cows had slower growing calves compared to EXT or HI dams (P = 0.09). Generally, cows that gained the least amount of weight over the grazing season had slower growing calves.

29 Demonstrating the Effects of Deworming and Implanting Weaned Calves for Retained Ownership on Pasture in Eastern Oklahoma

Abstract The majority of cow-calf producers in Oklahoma sell their calves at weaning. Preconditioning and retained ownership through the stocker phase provides economic benefits to these operations. The objectives of this demonstration were to illustrate the benefits of growth promoting technologies for calves post-weaning. Calves (n = 39 heifers and 24 steers; BW = 229 ± 23.9 kg) from the OSU Eastern Research Station cowherd were weaned on day – 20 (April 15) and preconditioned. On day 0 (May 6), calves (n = 20 heifers and 12 steers) were treated for internal parasites (Dectomax, Zoetis Animal Health) and evenly allocated to 2 Bermudagrass/tall fescue pastures (9.5 ± 1.42 ha) for 143 days. The remaining calves (n = 19 heifers and 12 steers) were not treated for parasites and allocated to 2 pastures (9.1 ± 1.42 ha). In each pasture, ½ of the calves of each sex were implanted (Synovex-S or Synovex-H, Zoetis). Calves dewormed on day 0 and were dewormed again on day 70 (July 16). Data were analyzed as a split plot experimental design with dewormer treatment as the main plot and calf sex and implant treatment were the split plots. There were no interactions among calf sex, deworming, and implants (P ≥ 0.42). Steers were heavier (P &amp;lt; 0.01) than heifers throughout the summer, but did not have an advantage in gain performance (P ≥ 0.22). Deworming did not impact (P = 0.44) overall growth performance of calves, but did numerically (P = 0.18) increase ADG from day 71 to 143 by 0.15 kg/d. Growth promoting implants increased (P = 0.03) daily gains by 0.09 kg/day in the early summer and over the entire summer by 0.07 kg/day (P &amp;lt; 0.01). The combination of deworming and implants increased (P = 0.01) season long ADG by 0.11 kg/day over unimplanted controls. This demonstration was used to illustrate the potential that growth promoting implants and deworming provides for economically beneficial performance enhancement for retained stocker calves on mixed grass pasture.

112 Mineral supplement intake by weaned steers as affected by offering multiple salt sources

Abstract Pastured cattle are sometimes offered multiple separate salt (NaCl)-containing nutritional supplements. This study objective was to determine how range meal presence impacts mineral supplement intake when cattle choose between multiple salt source offerings. Weaned Bos taurus crossbred steers (n = 24) (initial BW = 263 ± 4.0 kg) were stratified by BW in a completely randomized design across 4 pens with 2 GrowSafe bunks per pen with ad libitum access to mixed-grass pasture and 1) one bunk supplied with a mineral supplement containing 15.0% salt (Grazer Hi/Se Hi/Cu CTC 2800; Multi-Kare, Inc., Tifton, GA) (MINERAL) or 2) one bunk containing a 2:1 range meal containing 30% salt and 13% CP (HI-GRAIN RANGE MEAL 1–2; Land O’Lakes Purina Feed LLC, Shoreview, MN) and the other bunk containing the mineral supplement (RM2) (Exp. 1). In Exp. 2 the 2:1 range meal was replaced with a 3:1 range meal containing 22.5% salt and 15% CP (HI-GRAIN RANGE MEAL 1–3; Land O’Lakes Purina Feed LLC, Shoreview, MN) (RM3). After a 14-d acclimation period intake was monitored for 42 days for Exp. 1 followed by a 7-d acclimation and Exp. 2 spanning 42 days. Mean daily DMI per steer were 104.6 ± 22.7 g and 525.8 ± 228.0 g of the 2:1 and 3:1 range meal, respectively. In Exp. 1 steer daily DMI was greater (P &amp;lt; 0.01) for MINERAL (31.9 ± 2.2 g) than for the mineral portion (4.3 ± 2.2 g) of RM2. Mean steer daily DMI in Exp. 2 was greater (P &amp;lt; 0.01) for MINERAL (57.2 ± 6.1 g) than the mineral portion (3.4 + 6.1 g) of RM3. Range meal offered separately and simultaneously with a salt-containing mineral supplement decreases mineral supplement consumption by severalfold with implications for potential inadequate daily intake of nutrients and medications mixed in these supplements.

Effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range Beijing-you chickens

There is an increasing interest in free-range poultry with the increasing focus on food safety and animal welfare. This study was conducted to evaluate the effects of grazing mixed-grass pastures on growth performance, immune responses, and intestinal microbiota in free-range laying chickens. Ten-week-old female Beijing-you chickens were blocked by the BW and randomly assigned to 3 free-range systems in poplar plantations for 120 d: forage-removed paddocks with a high stocking density of 5 m2/hen (control [CK]); mixed-grass pastures with a low stocking density of 6 m2/hen ;or mixed-grass pastures with a high stocking density of 5 m2/hen. Intestinal microbial community analysis was performed by 16S rRNA gene sequencing using Illumina MiSeq. The results revealed that no differences (P > 0.05) were found between the 3 raising systems for the BW and ADG. Chickens grazing mixed-grass pastures exhibited decreased (P > 0.05) mortality and improved immune responses as evidenced by increased T-lymphocyte proliferation (P > 0.05) and immunoglobulin A (P > 0.05) and immunoglobulin M concentrations (P < 0.05) compared with those raised in forage-removed paddocks. Metagenomic analysis indicated that grazing mixed-grass pastures regulated the intestinal microbiota by increasing the prevalence of beneficial bacteria, such as Lactobacillus, Bacteroides, and Faecalibacterium, and reducing potentially pathogenic bacteria population, such as the Rikenellaceae_RC9_gut_group compared with the CK. Therefore, this study indicated that grazing mixed-grass pastures could positively influence intestinal microbiota that may contribute to the overall growth and immunity of free-range chickens and that a low stocking density of 6 m2/hen was optimal to Beijing-you chickens grazing mixed-grass pastures.

Long-term pasture management impacts on eolian sand soils in the southern mixed-grass prairie

Mixed grass pastures which occupy the eolian sand dunes of the southern Great Plains provide stabilizing soil cover, soil carbon (C) storage, and are a critical resource for livestock production. Large areas of dunes cover the American Great Plains, were active 700–1000 years ago during periods of frequent drought and have the potential to reactivate under forecasted climate scenarios and poor management. This study determined the soil age and development of eolian sandy soils and evaluated long-term grazing of native and improved pasture on root carbon, soil organic C (SOC), stable isotopes of soil fractions, and other soil properties. Pasture treatments included grazed and ungrazed (50 + yrs), improved pastures (28–50 yrs), and winter wheat (Triticum aestivum) or go-back grass (for 28–30yrs). Improved pasture grass species included both native (switchgrass (Panicum virgatum L.), and sand bluestem (Andropogon hallii Hack.) and non-native (weeping lovegrass (Eragrostis curvula (Schrad.) Nees)), and caucasian bluestem (Bothriochloa bladhii (Retz.) S.T. Blake) species. The Eda soil age was very recent and ranged from present at the surface to <1200 to <1600 yr BP (by luminescent or 14C dating, respectively) at the bottom of the soil profile (~130 cm). Long-term moderate grazing had relatively little impact on soil properties compared to ungrazed pastures. Soil C was dependent on grass root biomass across all improved pasture treatments, but with few differences among individual grasses or long-term pastures. Most improved pasture treatments either increased or maintained indicators of soil health (SOC, soil organic nitrogen (SON), mineral-associated carbon (Cmin-C), particulate organic matter carbon (POM-C), and silt and clay content). However, soils under winter wheat and sand bluestem had a third the SOC and SON of pasture, indicating soil degradation. Long-term grazing is a resilient practice that can stabilize these sandy soils and increase soil health. Soil protection is necessary should global warming result in drought and/or high winds and increase the potential for reactivation of eolian sand movement.

Isoflavone supplementation, via red clover hay, alters the rumen microbial community and promotes weight gain of steers grazing mixed grass pastures.

Biochanin A, an isoflavone present in the pasture legume red clover (Trifloium pratense L.), alters fermentation in the rumen of cattle and other ruminants. Biochanin A inhibits hyper-ammonia-producing bacteria and promotes cellulolytic bacteria and fiber catalysis in vitro and ex vivo. Consequently, biochanin A supplementation improves weight gain in grazing steers. Red clover contains biologically active isoflavones that may act synergistically. Therefore, the objective was to evaluate the effect of two levels of red clover hay on growth performance and the microbial community in growing steers grazing mixed grass pastures. A grazing experiment was conducted over 2 early growing seasons (2016 and 2017) with 36 cross-bred steers and twelve rumen-fistulated, growing Holstein steers for evaluation of average daily gain and rumen microbiota, respectively. Steers were blocked by body weight and assigned to pastures with one of four treatments: 1) pasture only, 2) pasture + dry distillers’ grains (DDG), 3) pasture + DDG + low level of red clover hay (~15% red clover diet), or 4) pasture + DDG + high level of red clover hay (~30% red clover diet). DDG were added to treatments to meet protein requirements and to balance total protein supplementation between treatments. All supplementation strategies (DDG ± red clover hay) increased average daily gains in comparison to pasture-only controls (P < 0.05), with a low level of red clover supplementation being the most effective (+0.17 kg d-1 > DDG only controls; P < 0.05). Similarly, hyper-ammonia-producing bacteria inhibition (10–100-fold; P < 0.05), fiber catalysis (+10–25%; P < 0.05) and short chain fatty acid concentrations were greatest with the low red clover supplement (+~25%; P < 0.05). These results provide evidence that lower levels or red clover supplementation may be optimal for maximizing overall microbial community function and animal performance in grazing steers.

Lamb performance in hardwood silvopastures, I: animal gains and forage measures in summer.

The integration of trees into pasture systems can have variable effects on forage and animal growth. Some reports of these systems have indicated that animal gains are similar or better even when tree presence lowers forage yield. Forage production and animal performance were compared in black walnut (Juglans nigra L.)-based and honeylocust (Gleditisia triacanthose L.)-based silvopasture systems and open pastures in a randomized complete block design with three blocks over three summers. Cool season-based, mixed grass pastures were rotationally stocked with four to seven lambs depending on available forage. A rising plate meter was used to estimate pre- and post-graze forage mass. Forage samples of the mixed sward were collected and analyzed for nitrogen (N) and neutral detergent fiber (NDF) concentrations. Species percent cover was estimated using a modified Daubenmire approach at the same 12 points within each experimental unit every 4 wk during the study. Pre-graze herbage mass was similar (P = 0.0717) in honeylocust silvopastures (5020 ± 30 kg·ha−1) and open pastures (4930 ± 30 kg·ha−1) and lowest (P < 0.0001) in the black walnut silvopastures (3560 ± 30 kg·ha−1). Forages in the black walnut and honeylocust silvopastures had similar (P = 0.4867) N concentrations (23.3 ± 0.4 and 23.9 ± 0.4 g·kg−1, respectively), which was greater (P ≤ 0.0003) than that of the forages in the open pastures (21.0 ± 0.4 g·kg−1). Forages in the honeylocust silvopasture had lower (P ≤ 0.0042) NDF concentrations (507 ± 3 g·kg−1) than forages in the black walnut silvopasture and open pastures (mean = 525 ± 3 g·kg−1). Forage species present in the black walnut silvopastures differed from those present in the open and honeylocust systems, which had similar composition. Despite differences in stocking rates, total lamb weight gains per system did not differ (P ≥ 0.7592) among black walnut, honeylocust, and open pasture systems (10 ± 2, 12 ± 2, and 10 ± 2 kg·d−1, respectively). Silvopasture practices can improve land productivity when incorporated into cool season forage pastures.

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

Abstract 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 &gt; 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 &gt; 0.19). Cow behavior was impacted by treatment, as HYM cows spent more time outside compared to CON cows (P &lt; 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.

162 Assessment of daily intake by beef heifers of sweet potato storage roots under competitive limit-feeding conditions

Abstract Excess consumption of sweet potato storage roots (SWP) poses an acidosis risk to cattle that may be mitigated by limit-feeding strategies. Yet limit-feeding is often administered to achieve mean desired daily DMI in groups of cattle with little regard for DMI variation among individuals. The study objective was to assess variation in daily DMI of SWP by beef heifers in limit-fed, competitive feeding groups. Twenty-four 9- to 10-mo-old Bos taurus crossbred heifers were stratified by initial BW (261.9 ± 8.8 kg) to 4 paddocks (6 heifers/ paddock) and offered SWP (24.9% DM on an as-fed basis; 7.7% CP, 5.9% ADF and 80% TDN on a DM basis) supplementation daily at a rate of 3.4 kg DM/ paddock with ad libitum access to mixed-grass pasture. After a 7-d acclimation period in which all heifers were trained to use a GrowSafe system, daily SWP DMI was monitored for 39 days. Standard deviation estimates were calculated from DMI data and used to classify DMI into the following levels: low (2.0 kg, &gt;0.5 SD). Half of the heifers (mean SWP DMI = 0.0 ± 0.02 kg) never consumed SWP at the high DMI level, but 42% of the heifers (mean SWP DMI = 1.1 ± 0.02 kg) consumed SWP at the high DMI level for at least 18 days over the study duration. No heifers consumed at the moderate DMI level more than 16 days during the trial. This suggests that DMI of individual cattle offered SWP in limit-fed groups often either exceeds by approximately 2-fold per animal mean values of SWP offered per group or is at or near zero. Additional research is needed to elucidate optimal group feeding strategies to achieve individual DMI targets among cattle offered SWP.

161 Evaluation of cull sweet potato storage roots as a winter supplement to grazing for cow-calf pairs

Abstract Cull sweet potato storage roots that would otherwise be left unharvested in production fields or dumped as waste from excess supplies in storage may be available for use as livestock feed at competitive pricing relative to other feedstuffs. Given this potential economical source of nutrients for consumption by beef cattle, the objective of this study was to assess cow-calf performance using unprocessed sweetpotato storage roots as a winter supplement to grazing cow-calf pairs as compared to whole cottonseed or no supplement. Fall-calving multiparous Bos taurus crossbred cows in Prairie, MS, were allotted ad libitum access to mixed-grass pasture with tall fescue as the predominant forage species and randomly allocated to one of three as-fed basis supplement groups: 6.8 kg/cow/d of sweetpotato storage roots (SWP); 2.3 kg/ cow/d of whole cottonseed (WCS); or no supplement (NONE). Supplements were offered to cows on a group basis on every Monday, Wednesday, and Friday for 93 d each winter initiating December 5, 2016 (n = 81) and December 11, 2017 (n = 105). Cow BCS on a scale of 1 to 9 (1 = emaciated; 9 = obese) at supplementation initiation was 6.1 ± 0.1. From supplementation initiation until calf weaning in March, change in cow BCS (P &lt; 0.01) was greatest for NONE (-1.1 ± 0.1), intermediate for SWP (-0.7 ± 0.1), and least for WCS (-0.4 ± 0.1). Adjusted 205-d calf BW was 16.9 ± 3.8 kg heavier (P &lt; 0.01) in steers than heifers but did not differ (P = 0.41) among supplementation groups. Although nursing calf performance was not impacted by supplementation regime, results suggest that cull sweetpotato storage roots may be an effective feedstuff for winter supplementation intended to reduce BCS loss in lactating beef cows. Additional research to determine optimal frequency and quantity of SWP supplementation is warranted

Performance and carcass quality of crossbred beef x Holstein bull and heifer calves in comparison with purebred Holstein bull calves slaughtered at 17 months of age in an organic production system

When crossbreeding with beef breeds in organic dairy herds, the use of non-sexed semen will results in both male and female offspring to be used for beef production. The objective of the present study was to compare growth and carcass characteristics of 15 Danish Holstein bull (HB) calves, 15 beef x Danish Holstein crossbred bull (CB) calves and 15 beef x Danish Holstein crossbred heifer (CH) calves reared under organic settings. As beef bred sire a high-merit bull of the Limousine breed was used. Furthermore, the study should generate knowledge which can support future organic beef production. Forty-five Spring-born calves were purchased at 10 private farms at approximately 20 days of age with an average initial body weight of 52.9, 58.2 and 56.1 (s.e.m. 2.6) kg for HB, CB and CH, respectively. Calves were housed indoors in groups of five until weaning off cows’ milk at 3 months of age. Calves were gradually introduced to a grass-silage based ration from 3 to 4 months of age. From 4 to 7 months calves were kept on mixed grass pasture of ryegrass and white clover. From 7 to 13.5 months calves were housed indoor in groups of 5 and fed a mixed ration with low-moderate energy content. From 13.5 months of age, the established groups of 5 animals grazed in a rotational paddock system until slaughter at 17 months. There was no difference between HB, CB and CH in average daily gain (ADG) from birth to weaning, from weaning until turn-out and during pasture from 4 to 7 months. The ADG indoor from 7 to 13.5 months, and during pasture from 13.5 to 17 months differed between treatment groups. The CB had greater ADG than CH for both periods with HB being intermediate (P < 0.02–0.001). The ADG indoor from 7 to 13.5 months were 1.06, 1.10 and 0.97 (s.e.m. 0.02) kg d − 1, and ADG during pasture from 13.5 months until slaughter were 0.88, 1.11, and 0.64 (s.e.m. 0.07) kg d − 1 for HB, CB, and CH, respectively. Final body weights were heavier for CB, intermediate for HB, and lowest for CH (575, 534, and 480 (s.e.m. 12.1) kg, P < 0.01). Overall, ADG from arrival to slaughter was 21% higher for CB than CH (P < 0.001), and the average ADG of the combined heifer and bull crossbreds ((CB+CH)/2) was not different from that of HB. Crossbreeding improved EUROP conformation markedly in both CH (5.3) and CB (7.0) compared with HB (3.0) (P < 0.001), and carcass weight was 4% higher for crossbreds ((CB+CH)/2) compared with HB. There was no difference in EUROP fatness between HB and CB which was low (1.0–1.2), whereas CH had an acceptable fatness (2.9). Carcass lean:fat color (assessed using a Danish 1–5 scale) was high for the bulls (3.9–4.0) but acceptable for CH (3.3, P < 0.01). It is concluded that improvements in carcass conformation and carcass weight coupled with similar overall growth of the combined heifer and bull crossbreds support the efficiency of beef x Holstein crossbreds of both sexes compared with purebred Holstein bulls within an organic system with summer grazing. Furthermore, it proved difficult to finish intact bulls on pasture to fulfill a premium beef cut market that requires higher fatness and less dark meat color than obtained herein.

Soil health indicators as affected by diverse forage species and mixtures in semi-arid pastures

‘WW-B.Dahl’ Old World bluestem [OWB, Bothriochloa bladhii (Retz) S.T. Blake] is a persistent pasture grass in the semi-arid Texas High Plains. Some growers are transitioning their irrigated continuous cotton (Gossypium hirsutum L.) land to dryland or low-irrigation production of WW-B.Dahl owing to diminished water supply. This grass strongly deters soil-dwelling ants (Hymenoptera: Formicidae), presumably via release of unidentified phytochemical repellants in the soil. Our aim was to determine whether the inhibitory effects of OWB extend to soil microbial community structure and function in relation to other adapted forages. We compared soil chemical and microbial properties in a Pullman clay-loam soil for OWB relative to OWB-alfalfa (Medicago sativa L.), alfalfa, and native mixed-grass pastures at 0–5 cm and 10–15 cm depth in June and December of 2016. The pastures ranged in age from 7 to 17 yr. Most measurements of organic forms of C and N showed greatest amounts in OWB-alfalfa; however, not always significantly. Enzyme activities linked to C, N, and S transformations were greatest (P ≤ 0.03) with OWB-alfalfa. This trend was similar for alkaline phosphatase activity, involved in P cycling, but not always significantly. Soil organic C in OWB was 1.2–1.4 fold greater than in the native mix depending on soil depth and sampling date, whereas SOC in OWB-alfalfa was 1.4–1.6 fold greater than in the native mix. Enzyme activities and microbial biomass N (MBN) were likewise greater in OWB and OWB-alfalfa than in the native mix, likely because the latter received no irrigation or N inputs. The microbial community structure demonstrated greater total FAMEs, bacterial markers for Gram+, Gram−, and actinomycetes in OWB-alfalfa compared to OWB, alfalfa, and native mix. Similar results were found in fungal markers for arbuscular mycorrhizal fungi (AMF) and saprophytic fungi. Protozoan indicators were found only in December, of which the native mix had the highest levels in the 0–5 cm depth. In general, selected soil properties, soil microbial biomass, community and enzyme activities were greater in December than in June except AMF, which was greater in June. The stimulating effect of OWB growing with alfalfa on the soil microbial community suggested this forage combination as favorable for soil health in relation to OWB, alfalfa alone, and native mixed-grass pastures. The previously reported inhibitory effect of OWB on soil-dwelling ants did not carry over to a depressing effect on the soil microbial component.