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Sustainability is a 'buzzword' often used within and outside of the agriculture industry. Southeastern beef cow-calf and stocker operations often utilize management practices which embody the core definition of sustainability to improve land resource, economic, and social viability. In forage-based production systems, year-round management practices are generally viewed by the scientific community in terms of production and economic responses. However, the continual global shift in emphasis on sustainable practices creates an opportunity to view these practices through a different lens. Goals of grazing-based beef systems often include optimizing the number of grazing days per year, reducing hay and supplemental feeding period duration, and strategic supplementation during grazed forage availability gaps. Methods for increasing the grazing season length per year may include stockpiling, inclusion of multi-species mixtures, increasing species diversity on farm, and optimizing stocking strategies. Outside of associative effects of feed supplementation are potential ancillary benefits of supplementation on the plant-animal-soil interface. As an example, feed-through fertilization influences forage growth production responses and stocking density modulation in grazed beef cattle systems. The role of mineral supplementation and ionophore inclusion in beef cattle diets is well documented from an animal performance perspective, but to a lesser extent on how using these practices may influence forage or soil response variables. Stacking management practices may elicit positive animal performance responses, while potentially reducing outside inputs into the system. The question then becomes if this is economically viable compared with a more traditional forage-based system. From a research perspective, systems-level studies are more prevalent than in the past, but funding models require scientists to evolve and lead with the sustainability message rather than from a production viewpoint. Valuing management practices from an ecosystem services view is a potential area of opportunity for researchers, industry and farmers to highlight strengths of forage-based beef cattle production systems from a consumer perspective. [ABSTRACT FROM AUTHOR]

Creating ensiled forage on a laboratory-scale is a tedious and cumbersome process. One must ensure an anaerobic environment for the success of the fermentation while also striving to replicate field-scale conditions. The objective of this experiment was to determine the effect of laboratory-scale silo type on nutritive value and fermentation profiles of grass-legume silage. This experiment was conducted as a generalized complete block design. There was one treatment factor (silo type) with 11 levels: field-scale baleage control (CON), miniature wrapped baleage (MINI), large fermentation bucket (6GAL), small fermentation bucket (2GAL), miniature silo (PVC), pint-sized Mason-type jar with "BurpLid" (BURP), pint-sized Mason-type jar with Ball-brand fermentation lid (BALL), pint-sized Mason-type jar with an airlock lid (LOCK), single-layered vacuum-sealed bag using a chamber-style sealer (CHMB), double-layered vacuum-sealed bag using a chamber-style sealer (HCHMB), single-layered vacuum-sealed bag using a suction-style sealer (FOOD), or double-layered vacuum-sealed bag using a suction-style sealer (HFOOD). Harvest served as the random blocking factor. Forage was harvested from a single alfalfa-bermudagrass pastures at the Wiregrass Research and Extension Center in Headland, AL. Forage was cut 24 h before collection and allowed to sun-cure. After allocation to treatment, samples were allowed to ferment for 56 d. Following fermentation, samples were assayed for NDF, ADF, ADL, CP, pH, mold, and yeast. Dunnett's test revealed a difference (P < 0.05) from CON for NDF, ADF, and pH. Samples from PVC had 26% greater NDF and 45% greater ADF than CON (58 and 37%, respectively). Samples from BALL were 3 units greater and samples from LOCK were 2 units greater in pH than CON (4.8). When comparing alternative treatments exclusive of CON, there were differences (P ≤ 0.01) in NDF, ADF, ADL, pH, and mold counts among treatments. Results are interpreted to mean that BALL and LOCK are not effective representatives of field-scale silage production due to lack of pH drop, while PVC alters the fiber profiles. All other methods showed promise as prospects for laboratory silage procedures. [ABSTRACT FROM AUTHOR]

In the Deep South, one of the hardest times of year for cattle producers is the summer due to extreme temperatures and low-quality perennial forages. Incorporating a high-quality crop like alfalfa (Medicago sativa) into forage mixtures could be economically advantageous; however, there is not much alfalfa produced in the Deep South. Therefore, our objective was to evaluate the effects of forage type on in vivo digestibility and nutrient balance in beef cattle systems. There was also an interest in differing conserved forage types, so we analyzed digestion dynamics influenced by various conserved forage types. Three treatments including bermudagrass (Cynodon dactylon) hay, alfalfa baleage, and alfalfa-bermudagrass baleage were supplied to four fistulated steers (average 412.34 kg +/- 41.25 kg) with a calculated daily forage allowance based on intake, body weight, and feed refusals. Each diet was allocated to one of three periods in which all four animals received the same diet due to potential feed spoilage. Each period had a 21-d adaptation period followed by a 5-d collection period to analyze total fecal excretion, feed intake, feed refusal, total urine output, and rumen fluid dynamics. Data were analyzed using R Core Team (2023) and the GLIMMIX procedure of SAS version 9.4 (SAS Inst., Cary, NC). There were significant differences in dry matter digestibility (DMD) between diets (P < 0.0015). We found that alfalfa-bermudagrass baleage had a 9% (+/- 0.058, 95% C.I.) less DMD than bermudagrass hay (P < 0.0088) and alfalfa baleage had a 7% (+/- 0.058, 95% C.I.) greater DMD than bermudagrass hay (P < 0.025). Results indicate that alfalfa baleage provides the most nutrient use efficiency when comparing alfalfa-bermudagrass mixtures. There was no significant conserved forage effect potentially due to baleage quality and inadequate fermentation of the alfalfa-bermudagrass baleage. That said, there is still potential for beef cattle producers in the Deep South to diversify feeding strategies by using nutrient-rich forage additives like alfalfa and different conserved forage methods to increase digestibility, thus increasing returns in their operations. [ABSTRACT FROM AUTHOR]

Though much effort has been made to characterize the in vivo (IV) and in situ (IS) dry matter digestibility (DMD) of southeastern forages, there is a lack of information identifying methods that best represent the in vivo digestibility of these forages. Thus, the objective of our study was to compare IV and IS methods to determine which technique best represents the in vivo DMD of four bermudagrass (Cynodon dactylon [L.] Pers.) cul-tivars. In an IV experiment, ruminally fistulated heifers (n = 4) were randomly assigned to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods (21-d adaptation and 9-d collection) in a Latin square design. On d 28 of each period, rumen fluid was collected 4 h post-feeding for an accompanying IV experiment using a completely randomized design with a 4 x 2 factorial treatment structure. Factors in the IV experiment included bermudagrass cultivar (COS, RUS, T44, and T85) and digestibility method (Tilley and Terry [TT] or Goering and Van Soest [GVS]). On d 31 of in vivo periods 3 and 5, an accompanying IS experiment was conducted as a randomized complete block design with three treatment factors (in vivo diet [previous described], bermudagrass cultivar [previously described], and incubation timepoint [0, 0.25, 0.50, 0.75, 1, 2, 3, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144, and 168 h]). Correlations were computed between in vivo DM disappearance and each of the IV (TT and GVS) and IS (24, 48, and 72 h) methods. Regressions were calculated for each of the individual IV and IS measurements, and a stepwise regression was used to determine the predictive value of linear combinations of the measurements. None of the IV or IS DMD values were correlated with in vivo DMD (P ≥ 0.18). Individual IV and IS DMD values did not yield significant models through linear regression (P ≥ 0.18), though the best model (based on AIC) was TT IVDMD (r² = 0.09; P = 0.26). Stepwise regression revealed that there was no linear combination of IV or IS DMD that improved prediction beyond single predictor models. While both IV and IS experiments remain viable tools to screen forages and make relative comparisons, results from this experiment are interpreted to mean that neither of these methods is suitable for prediction of in vivo performance. [ABSTRACT FROM AUTHOR]

Dual-purpose wheat (Triticum aestivum L.) systems increase farm sustainability by diversifying on-farm income. While these systems are common in the Southern Great Plains of the U.S., they are not often utilized in the Southeast. This study aimed to evaluate pre- and post-grazing herbage mass (HM) of four winter wheat varieties managed under a dual-purpose grazing and grain production system. The wheat varieties evaluated were generic feed-type wheat (unknown variety blend, Feed), seed-type wheat 'GA Gore' (Seed) and two forage-type varieties, 'AGS 2024' (AGS) and 'Pioneer 26R41' (Pioneer). The experiment was a randomized complete block design (n = 4) conducted during the winter of 2021 and 2022. Three grazing frequencies were utilized: an ungrazed control (NG), low frequency (LF) and high frequency (HF) grazing schedule. Low frequency plots received monthly grazing in January and February while HF treatments received a third grazing in March. Plots were grazed with 20 cow-calf pairs (Bos taurus) until an even defoliation height of 10 cm was achieved. Herbage mass was determined using three 0.1m2-quadrats per plot and clipped to a 10 cm stubble height before (PreG) and after (PostG) each grazing event. Forage samples were then dried at 45°C for 72 h. Data were analyzed using PROC GLIMMIX of SAS (SAS Inst., Cary, NC) with forage sample date as a repeated measure. Differences were declared at P < 0.05. Final biomass, including stems, chaff, and grain, was greatest for Pioneer but was not different from AGS or Feed (4,112 kg/ha and 4,003 kg/ha; P = 0.94). Before grazing, AGS herbage mass (2,646 kg/ha) was greater (P = 0.03) than all other varieties. There was an interaction (P = 0.01) of variety and grazing frequency for Pre-G herbage mass. Compared with all other varieties, AGS had greater ADF (24.93%; P < 0.01) and least TDN (72.49%: P < 0.01). Forage nitrate-nitrogen was not different (P = 0.49) among all varieties or grazing frequencies (157.73 ppm). Across grazing frequencies, Pioneer had greater final grain yield (3,619.43 kg/ha; P < 0.01) with Seed having the least (1,272.12 kg/ha; P < 0.01). These results indicate that common Southeastern wheat varieties can be successfully utilized in a dual-purpose management system; however, grazing frequency should be monitored to prevent grain yield losses. [ABSTRACT FROM AUTHOR]

Whole cottonseed (WCS) has long been a viable supplement in southern beef production systems, but new cultivars and ginning innovations have renewed interest in its use. Ad libitum supplementation of WCS, however, leads to increased fat intake, potentially resulting in reduced fiber digestibility. However, gestating and lactating beef cows have been observed to have adequate or optimum performance under supplementation scenarios as much as 3.6 kg·animal-1·day-1. It has been hypothesized that WCS may pass through the gastrointestinal tract without being digested, thereby not interfering with whole diet digestibility. Thus, our objective was to conduct an observational screening of beef cattle offered near ad libitum levels of WCS for passage dynamics. In this case study, we sampled beef cattle (approximately 1,000 head) at a farm in central Alabama offered an average of 3.6 kg WCS·animal-1·day-1. Cattle were divided by age and stage of production across seven pastures varying in forage base. Fresh manure samples (n = 22) were collected at random from the herd. Fecal samples were sorted by wet sieving to recover undigested seed material. Counts were conducted to determine whole or fractional seed remaining. Data were analyzed using SAS v. 9.4. Across samples, recovered WCS were approximately normally distributed (W = 0.83) with a mean of 3.3 seed per sample and a range of 2 to 76. Fractional WCS recovered were normally distributed (W = 0.92) with a mean of 31.9 parts per sample and a range of 0 to4. On average, WCS recovered accounted for 0.34 g per sample, or 5.0% of the DM recovered. While caution should be used in broad interpretation of these observational results, there is sufficient evidence to suggest that high levels of WCS supplementation may seed to decreased digestive efficiency (evidenced by undigested seed in manure). These observations serve as a basis for further investigation in designed experiments to evaluate WCS digestion and passage dynamics. [ABSTRACT FROM AUTHOR]

For in vitro digestibility experiments addressing both horses and cattle, feces have long been thought to be an equivalent surrogate for ruminal or cecal inoculum that would eliminate the need for fistulated animals. However, this assumption requires similar microbial and chemical properties among inoculum sources. Validation of the relationship of fecal to ruminal metabolic properties would allow for more readily accessible information on fermentation across nutrition experiments. Thus, the purpose of this study was to compare ruminal and fecal VFA production from heifers fed four bermudagrass (Cynodon dactylon [L.] Pers.) cultivars. Ruminally-fistulated heifers (n = 4) were assigned randomly to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods (21-d adaptation and 9-d collection). On d 28, rumen fluid (RF) samples were collected at 13 timepoints (0, 0.25, 0.5, 0.75, 1, 2, 3, 4, 8, 12, 16, 20, 24 h) and rectal fecal samples were collected at 7 timepoints (0, 0.5, 1, 2, 4, 8, 12 h). Samples were acidified with meta-phosphoric acid, and 2-ethylbutyric acid was included as an internal standard. Samples were assayed for acetic (A), propionic (P), isobutyric (IB), butyric (B), isovaleric (IV), valeric (V), 4-methylvalteric (4MV), and caproic (C) acids by gas-liquid chromatography. Data were analyzed using SAS v. 9.4. Heifers receiving COS produced less (P < 0.05) RF concentrations of A (25.01 mM), P (5.21 mM), and total VFA (34.2 mM) than T85 (43.4, 8.9, and 58.0 mM, respectively), T44 (42.0, 9.0, and 57.3 mM, respectively), and RUS (39.8 8.9, and 55.3 mM, respectively), which were all similar. Ruminal B was greatest (P < 0.05) from RUS (5.4 mM) and least from COS (3.1 mmol/L), with T44 and T85 intermediate (4.9 and 4.4 mM, respectively). There was no effect of cultivar (P = 0.10) on RF IB, IV, V, or 4MV concentrations. Fecal IB was correlated (P < 0.05) with RF IV (r = 0.59) and tended to be correlated (P = 0.09) with RF A (r = 0.39), P (r = 0.39), C (r = 0.37), and total VFA (r = 0.38). Fecal P was correlated (P < 0.05) with RF IV (r = 0.51). No other fecal VFA were correlated with RF VFA. Results are interpreted to mean that COS results in decreased ruminal fermentation relative to the other cultivars tested. However, there is little indication that fecal VFA can serve as an indicator for ruminal fermentation. [ABSTRACT FROM AUTHOR]

Maintenance of pastures for grazing accounts for $132.50/animal in the United States (23% of operating costs), and pasture nutrient input represents the single greatest influence in productivity per unit area. Cultivar differences in the forage offered to cattle have the potential to manifest differences in digestive efficiency, resulting in different nutrient excretion profiles. The objective of this study was to assess the growth potential and incorporation of N, P, and K into forage material from manure from cattle fed one of four bermudagrass (Cynodon dactylon [L.] Pers.) cultivars. Ruminally fistulated heifers (n = 4) were assigned randomly to one of four bermudagrass cultivars (Coastal, Russell, Tifton 44, or Tifton 85) for four 30-d in vivo periods (21-d adaptation and 9-d collection). On d 23, total fecal collections were subsampled from each heifer. As a hierarchical addition, a controlled greenhouse experiment was conducted for each period [15 pots per period; 5 manure treatments (four bermudagrass diets plus a negative control) × 3 replications]. Manure was added to 4.58 L pots based on stocking rate estimates for Central Alabama (1,110 kg/ha). The pots were seeded with bermudagrass (cv. Giant) as an indicator for forage nutrient uptake. At harvest (d 70), herbage, root, and soil samples were collected. Herbage and root samples were assayed for CP. Soil samples were assayed for pH, N, P, K, Mg, and Ca. Data were analyzed using SAS v. 9.4. There was no effect of manure treatment on herbage (P = 0.88) or root DM yield (P =.00;.54 and.73 g/pot, respectively). Similarly, there was no effect of manure treatment on soil pH (P = 0.18; 5.5), P (P = 0.78; 24.2 kg/ha), or K (P = 0.42;56.7 kg/ha). Results are interpreted to mean that, regardless of the cultivar effects on ruminal digestive dynamics, there is little to no effect of the resulting manure on subsequent forage production and nutrient uptake. [ABSTRACT FROM AUTHOR]

While much effort has been devoted to both the characterization of ruminal fermentation dynamics and the evaluation of bermudagrass production, independently, there is a lack of information regarding ruminal digestive kinetics using beef cattle in southern forage systems. Thus, the objective of our study was to evaluate in situ digestive kinetics of four bermudagrass (Cynodon dactylon [L.] Pers.) cultivars in heifers consuming typical southern forages. (Coastal, Tifton 44, Tifton 85, and Russell). Ruminally fistulated heifers (n = 4) were assigned randomly to one of four bermudagrass cultivars (Coastal [COS], Russell [RUS], Tifton 44 [T44], or Tifton 85 [T85]) for four 30-d in vivo periods (21-d adaptation and 9-d collection). On d 31 of periods 2 and 3, an in-situ experiment was conducted as a randomized complete block design with a 3-factor factorial treatment structure. The first factor (n = 4) was diet consumed by the animal (described above). The second factor (n = 4) was the incubated forage (same cultivars as the in vivo experiment). The third factor was incubation timepoint (n = 19; 0, 0.25, 0.50, 0.75, 1, 2, 3, 4, 8, 12, 16, 20, 24, 48, 72, 96, 120, 144, and 168 h). Four in situ bags were incubated in each animal at each timepoint; two were used for NDF, ADF, and ADL, and two were used for CP determination. Data were analyzed using SAS v. 9.4. There was a decreased (P < 0.05) potentially degradable fraction from COS (30.0%) compared with T85 (55.1%), T44 (48.1%), or RUS (47.1%). Similarly, COS presented the greatest (P < 0.05) undegradable fraction (37.0%) and T85 the least (15.9%), with RUS and T44 intermediate (25.0 and 21.9%, respectively). There was no effect of bermudagrass cultivar, however, on the rate constant of digestion (0.94%/h; P = 0.26) or lag time (3.2 h; P = 0.38). A visual appraisal of the degradation curve suggests that the asymptote of digestion was not reached at the measured 168 h. Results are interpreted to mean that T44 is the preferable bermudagrass cultivar, followed by T85 and RUS, while COS is the least favorable. Further, given the lack of visible asymptote, we speculate that bermudagrass likely passes the rumen before full digestion is realized. [ABSTRACT FROM AUTHOR]

Research in the area of pastures, forages, and grazing livestock has a storied history within the realm of statistical analysis. Unlike traditional experiments in ruminant nutrition, in which an animal is fed individually and data are collected to assess the applied treatment, research on the grazing animal presents its own unique set of challenges. The collection of data on multiple scales (e.g., animal, pasture, landscape, time) brings into question the appropriate assignment of the experimental unit, and variance and covariance estimates must account for both the spatial and temporal effects of the environment. Oftentimes, the designs, assumptions, and rules-of-thumb taught to us in graduate school do not meet muster to adequately address the intricacies of this situation. This presentation will seek to address these complications and present statisticallysound solutions to obtain the maximum information from experimental data. First, a historical examination will be offered of how grazing experiments were originally handled. Next, conjecture will be offered as to why these methods may not remain valid and how advances in computing power and statistical theory allow us to obtain more information from the experiment. Finally, solutions to common scenarios will be offered whereby a more adequate or complete description of the experiment may be obtained. [ABSTRACT FROM AUTHOR]

The 2018 Farm Bill, with its groundbreaking hemp legislation, offered an alternative protein source to livestock producers. Hemp is the agricultural product of Cannabis sativa L. which must contain less than 0.3% tetrahydrocannabinol, the psychoactive component common to marijuana. Hemp oil, cold-pressed from C. sativa seed, has been gaining popularity over recent years for its use in cosmetics, pharmaceuticals, and human food products. Like most oilseeds, this leaves an oilseed meal with a potential for inclusion in livestock feeds. Thus, our objective was to quantify the sources of variation in the nutritive value of hempseed meal. Hempseed meal samples were obtained from commercial oil processing facilities (n = 4). Across these facilities, samples represented 15 independent hempseed meal batches. Our experimental design was a completely randomized design including the random effects of source, batch within source, and replicate within batch by source (laboratory replication). Samples were assayed for NDF, ADF, ADL, CP, and IVTD. Source had no contribution to variance for NDF, ADF, ADL, or CP (P ≥ 0.20). However, batch within source had a significant contribution to variation for NDF (μ = 50.1%; P = 0.01), ADF (μ = 36.8%; P = 0.01), ADL (μ = 12.9%; P < 0.01), and CP (μ = 30.9%; P < 0.01). Irrespective of the differences in nutritive value, there was no contribution to variation (P ≥ 0.23) of any measured effect on IVTD (μ = 53.0%). Results are interpreted to mean that, while variation exists among hempseed meal samples with respect to nutritive value, the viability of hempseed meal as a livestock feed source is strong. [ABSTRACT FROM AUTHOR]