Effects in air-exposed corn silage of medium chain fatty acids on select spoilage microbes, zoonotic pathogens, and in vitro rumen fermentation.

Medium chain fatty acid (MCFA) treatment (0.75% C6, hexanoic; C8, octanoic; C10, decanoic; or equal proportion mixtures of C6:C8:C10:C12 or C8:C10/g; C12 = dodecanoic acid) of aerobically-exposed corn silage on spoilage and pathogenic microbes and rumen fermentation were evaluated in vitro. After 24 h aerobic incubation (37 °C), microbial enumeration revealed 3 log10 colony-forming units (CFU)/g fewer (P = 0.03) wild-type yeast and molds in C8:C10-treated silage than controls. Compared with controls, wild-type enterococci decreased (P < 0.01) in all treatments except the C6:C8:C10:C12 mixture; lactic acid bacteria were decreased (P < 0.01) in all treatments except C6 and the C6:C8:C10:C12 mixture. Total aerobes and inoculated Staphylococcus aureus or Listeria monocytogenes were unaffected by treatment (P > 0.05). Anaerobic incubation (24 h at 39 °C) of ruminal fluid (10 mL) with 0.02 g overnight air-exposed MCFA-treated corn silage revealed higher hydrogen accumulations (P = 0.03) with the C8:C10 mixture than controls. Methane, acetate, propionate, butyrate, or estimates of fermented hexose were unaffected. Acetate:propionate ratios were higher (P < 0.01) and fermentation efficiencies were marginally lower (P < 0.01) with C8- or C8:C10-treated silage than controls. Further research is warranted to optimize treatments to target unwanted microbes without adversely affecting beneficial microbes.

Different fat sources in supplements for beef cattle at pasture.

We investigated the consequences of fat supplementation (free oil and rumen-protected oil) on the nutrient intake and digestion of beef cattle at pasture. Five rumen-cannulated Nelore bulls, with a median body weight (BW) of 467.8 ± 32.8 kg and an age of 26 months, were distributed in a Latin square design (5 × 5). The treatments were as follows: WF, no additional fat; PA, rumen-protected palm oil; PS, rumen-protected soybean oil; SO, soybean-free oil and CO, free corn oil. Nutrient intake and digestibility, ruminal pH and ammonia (NH3-N), serum urea and nitrogen balance were analysed. The supplements with different oil sources did not alter (P > 0.05) the intake and digestibility of dry matter (DM), forage DM intake (DM), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF), neutral detergent fibre-corrected ash and protein (apNDF), nonfibre carbohydrates (NFC) or total digestible nutrients (TDN) compared to WF. An increase (P < 0.05) in the intake and digestibility of EE was observed with the inclusion of fat, independent of the source. No differences were observed between WF and other supplements with regard to ruminal parameters (pH and NH3-N) (P > 0.05) and serum urea (P > 0.05). The nitrogen balance was not affected by the fat source (P > 0.05). Supplementation of grazing beef cattle (2 g/kg BW) with free oil (130 g/kg DM supplement) or rumen-protected oil (160 g/kg DM supplement) did not interfere with nutrient intake and digestibility.

Effects of energy-protein supplementation frequency on performance of primiparous grazing beef cows during pre and postpartum.

OBJECTIVE: Twenty-four pregnant Nellore primiparous grazing cows were used to evaluate the effects of energy-protein supplementation and supplementation frequency during pre (105 d before calving) and postpartum (105 d after calving) on performance and metabolic characteristics. METHODS: Experimental treatments consisted of a control (no supplementation), daily supplementation (1.5 kg/d of concentrate/animal) and infrequent supplementation (4.5 kg of concentrate/animal every three days). During the pre and postpartum periods, concentrations of blood metabolites and animal performance were evaluated. Ureagenesis and energy metabolism markers were evaluated at prepartum period. RESULTS: Supplementation frequency did not alter (p>0.10) body weight (BW), average daily gain (ADG), and carcass traits during pre and postpartum. The BW (p = 0.079), adjusted BW at day of parturition (p = 0.078), and ADG (p = 0.074) were greater for supplemented cows during the prepartum. The body condition score (BCS; p = 0.251), and carcass traits (p>0.10) were not affected by supplementation during prepartum. On postpartum, supplementation did not affect animal performance and carcass traits (p>0.10). The dry mater intake was not affected (p>0.10) by supplementation and supplementation frequency throughout the experimental period. Daily supplemented animals had greater (p<0.001) glucose levels than animals supplemented every three days. Supplementation and supplementation frequency did not alter (p>0.10) the levels of blood metabolites, neither the abundance of ureagenesis nor energy metabolism markers. CONCLUSION: In summary, our data show that the reduction of supplementation frequency does not cause negative impacts on performance and metabolic characteristics of primiparous grazing cows during the prepartum.

The influence of virginiamycin on digestion and ruminal parameters under feedlot conditions.

This experiment aimed to assess the impact of virginiamycin on in vitro gas production dynamics, rumen kinetics, and nutrient digestibility in beef steers fed a grain-based diet. Nine ruminally cannulated British-crossbred steers (596 ±â€…49 kg) were assigned to this experiment. Animals were housed in three pens (n = 3/pen) equipped with a Calan gate feed system and water troughs. Pens were enrolled in a 3 × 3 Latin square design containing three periods of 16 d, and a 5-d washout interval between periods. Dietary treatments consisted of virginiamycin (VM) administration at 0 (VM0), 180 (VM180), or 240 mg/d (VM240). During days 15 and 16 of each period, about 600 mL of rumen fluid and urine samples were collected before (0 h), and at 4, 8, 12, and 16 h after the morning feed (0730 hours), rumen inoculum was used to take pH and redox potential measurements immediately after collection using a portable pH and redox meter, and subsamples were taken for volatile fatty acids (VFA) and NH3-N analyses, and urine samples were composited daily and analyzed for creatinine and purine derivatives (PD) content to estimate microbial crude protein flow. During the 4-h post-morning feed rumen collection, rumen inoculum was utilized to perform in vitro gas production measurements. Fecal samples were collected on day 16 of each period to estimate nutrient digestibility using acid detergent insoluble ash as an internal marker. Animals were considered the experimental unit for the statistical analyses, and periods and squares were included as random variables. The total and rate of gas production were similar among treatments (P ≥ 0.17). The second-pool (i.e., fiber) gas production increased linearly as VM inclusion increased (P = 0.01), with VM240 being greater compared to VM180 and VM0 (7.84, 6.94, and 6.89 mL, respectively). Ruminal pH linearly increased as VM increased, with VM240 being greater than VM0 and VM180 intermediate (5.90, 5.82, and 5.86, respectively; P = 0.03). The VFA concentrations did not differ (P ≥ 0.13), but the acetate-to-propionate ratio was the highest in VM240 (P = 0.005). Branched-chain VFA increased (P ≤ 0.03) while lactate concentrations decreased (P = 0.005) linearly with VM. The ruminal NH3-N concentration was the lowest in the VM0 (P = 0.006). The estimated absorbed PD, purine derivative to creatinine index, and microbial N flow increased linearly with VM (P ≤ 0.07). The provision of VM influenced rumen dynamics in a dose-dependent manner.

Influence of previous plane of nutrition on molecular mechanisms regulating the expression of urea and water metabolism related genes in the rumen and kidney of finishing crossbred Angus steers.

This study aimed to understand how molecular mechanisms controlling water and urea metabolism at the finishing phase can be affected by previous plane of nutrition of crossbred Angus beef steers. Twenty-four (n = 24) animals were randomly distributed into either a moderate (MP) or high plane of nutrition during the background phase for 85 d. Animals were then blocked by their previous plane and were moved onto a 105-d finishing phase in a 2 × 2 factorial arrangement. The forage-finished group received only high-quality alfalfa hay, whereas the grain-fed group received a high grain diet (80% whole corn and 20% alfalfa hay). By the end of the finishing phase, animals were harvested and tissue samples from the rumen and kidney were collected. Changes in gene expression of aquaporins (AQP)-2, -3, -4, -7, ATP1A1, ATP1B1, SGK1, CLIC1 (kidney and rumen), UT-A1 (kidney only) and UT-B (rumen only), were assayed via real-time qPCR; 18S rRNA was used as an endogenous control. One-way ANOVA followed by Tukey's post hoc analysis was conducted. When animals were from MP, forage-finishing increased the relative abundance of AQP3 (P ≤ 0.05), AQP7 (P ≤ 0.05), ATP1B1 (P ≤ 0.05), and SGK1 (P ≤ 0.05) in the kidney when compared to grain-fed animals. In the rumen, for the MP group, AQP7 was differentially expressed in both treatments at the finishing phase (P ≤ 0.01), with forage-finished steers having the highest expression of AQP7. For the MP group, UT-B had a tendency of presenting a higher expression on grain-fed animals (P = 0.075). Overall, these results suggest that previous plane can impact expression of genes associated with water and urea metabolism during the finishing phase, namely AQP3, AQP7, ATP1B1, and SGK1 in the kidney, and AQP7 and UT-B in the rumen. The greatest impact observed on gene expression changes of investigated genes at the finishing phase was reflective of animals backgrounded on the moderate previous plane.

Establishing the relationship between wildfire smoke and performance metrics on finished beef cattle in Western Rangelands.

Identifying causal relationships is complicated. Researchers usually overlook causality behind relationships which can generate misleading associations. Herein, we carefully examine the parametric relationship and causality between wildfire smoke exposure and animal performance and behavior metrics over a period of 2 yr in Reno, Nevada. The animals in the 2020 smoke season were grain-finished (n = 12) and grass-finished (n = 12), whereas the animals during the 2021 season were fed under the same diet but finished with either a hormonal implant (n = 9), or without (n = 9). The dataset included daily records of feed intake (FI), body weight (BW), water intake (WI), average daily gain (ADG), and WI behavior (time spent drinking [TSD]; water intake events [WIE]; no-WIE [NWIE]). Variable tree length Bayesian additive regression trees (BART) were utilized to investigate the relationships between air quality index (AQI), particulate matter 2.5 µm (PM2.5) and 10 µm (PM10), NO2, SO2, Ozone, and CO levels in the air (sensors < 1.6 km from animals) with the animal data. Additionally, linear mixed models with a 7-d lag were used to evaluate parametric relationships among the same variables. All statistical analyses were performed on R Statistical Software (R Core Team 2023). Under the linear mixed model with a 7-d lag, significant positive and negative associations were found for all parameters examined (P < 0.05). Negative associations were found between FI, WI, ADG, BW, WIE, NWIE, TSD, and PM2.5 (P < 0.05) for at least one animal group. Positive linear associations between wildfire smoke parameters and the metrics evaluated were more variable and dependent on year, treatment, and smoke parameters. When examining the credible intervals and the variable importance in the BART, relationships were more difficult to identify. However, some associations were found for Ozone, AQI, NO2, CO, and PM10 (P < 0.05). Overall, our results carefully examine the relationship between smoke parameters and cattle performance and present interesting pathways previously unexplored that could guide early culling/finishing of animals to avoid economic losses associated with performance decrease in response to wildfire smoke exposure. Though interesting associations are found under linear mixed models, causality is difficult to establish, which highlights the need for controlled exposure experiments.

Effects of Hops Treatment on Nitrogen Retention, Volatile Fatty Acid Accumulations, and Select Microbial Populations of Composting Poultry Litter Intended for Use as a Ruminant Feedstuff.

Poultry litter is a valuable crude protein feedstuff for ruminants, but it must be treated to kill pathogens before feeding. Composting effectively kills pathogens, but it risks losing ammonia to volatilization or leaching during degradation of uric acid and urea. Hops bitter acids also exert antimicrobial activity against certain pathogenic and nitrogen-degrading microbes. Consequently, the present studies were conducted to test if adding bitter acid-rich hop preparations to simulated poultry litter composts may improve nitrogen retention while simultaneously improving pathogen killing. Results from an initial study, testing doses of Chinook or Galena hops preparations designed to each deliver 79 ppm hops ß-acid, revealed that, after nine days simulated composting of wood chip litter, ammonia concentrations were 14% lower (p < 0.05) in Chinook-treated composts than untreated composts (13.4 ± 1.06 µmol/g). Conversely, urea concentrations were 55% lower (p < 0.05) in Galena-treated than untreated composts (6.2 ± 1.72 µmol/g). Uric acid accumulations were unaffected by hops treatments in this study but were higher (p < 0.05) after three days than after zero, six, or nine days of composting. In follow-up studies, Chinook or Galena hops treatments (delivering 2042 or 6126 ppm of ß-acid, respectively) for simulated composts (14 days) of wood chip litter alone or mixed 3:1 with ground Bluestem hay (Andropogon gerardii) revealed that these higher dosages had little effect on ammonia, urea, or uric acid accumulations when compared to untreated composts. Volatile fatty acid accumulations measured in these later studies were affected by the hops treatments, with butyrate accumulations being lower after 14 days in hops-treated composts than in untreated compost. In all studies, beneficial effects of Galena or Chinook hops treatments were not observed on the antimicrobial activity of the simulated composts, with composting by itself decreasing (p < 0.05) counts of select microbial populations by more than 2.5 log10 colony forming units/g compost dry matter. Thus, while hops treatments had little effect on pathogen control or nitrogen retention within the composted litter, they did lessen accumulations of butyrate, which may prevent adverse effects of this fatty acid on palatability of litter fed to ruminants.

Effects of isoenergetic supplementation as water use mitigation strategy on water footprint and health of nursing bull calves.

Sustainable livestock systems focus on mitigating natural resource use such as water. Dietary management strategies can significantly reduce the water footprint of livestock animals; however, animal health is of concern when animals reduce water intake due to subacute dehydration. To evaluate potential consequences of this nutritional management intervention, a total of 23, 60 ±â€…3 days old nursing Holstein bull calves, weighing 94.7 ±â€…12.07 kg, were distributed in a completely randomized design and received one of three diets. Control was a basal diet composed of a non-medicated milk replacer (milk replacer; n = 7), and the additional two diets, were composed of the same non-medicated milk replacer in addition to either lipid [n = 8; milk replacer + menhaden fish oil (3 %)] or soluble carbohydrate [n = 8; milk replacer + corn starch (7%) isoenergetic to fat group] supplements. Animals were offered ad libitum mineral mix and water, as well as 120 g/day of a composite mix of dried microbrewery's spent grains. Data were analyzed as linear and generalized linear mixed models with diet as a fixed effect and animal as random utilizing R studio (R Core Team, 2021, Vienna, Austria; SAS Inst., Cary, NC). Within supplementation groups, lipid supplemented calves had the highest lymphocyte (63.24 vs 57.69 counts/100 lymphocytes; P < 0.033), and lowest neutrophil counts (29.3 vs 35.3 counts/100 lymphocytes; P < 0.047). Supplementation significantly increased total serum protein (P = 0.001) and skin moisture (P < 0.011), with carbohydrate group having the highest skin moisture (5.30 vs 3.99; P < 0.047). Supplementation also decreased fecal fluidity scores (P < 0.001) with no significant change in serum electrolytes (P > 0.256). No significant differences were found amongst treatments for the ingestive behavior (P > 0.338). The carbohydrate-supplemented calves significantly decreased all daily water footprints compared to the control and fat-supplemented groups: blue a 47.55 L decrease, (P < 0.001), green a 265.62 L decrease (P = 0.005), and gray a 55.87 L decrease (P = 0.009) water footprint, as well as total water footprint (369.04 L, P = 0.004). Our results indicate the potential to maintain animal performance while increasing water use efficiency through diet supplementation tailored to mitigate water use, without adverse effects on animal health.

Characterization of body composition and liver epigenetic markers during periods of negative energy balance and subsequent compensatory growth in postpubertal beef bulls.

This study aimed to characterize the effects of dietary restriction and subsequent re-alimentation on body composition and hepatic gene expression of epigenetic markers of DNA methylation, RNA m6A methylation, and histone acetylation in the liver of postpubertal beef bulls. Twelve Angus × Hereford crossbred bulls (n = 6, 23 ± 0.55 mo [young bulls], 558 ± 6.1 kg; and n = 6, 47 ± 1.2 mo [mature bulls], 740 ± 30.5 kg) were submitted to two dietary regimes per offering of the same hay: low plane of nutrition (90 d) and compensatory growth (90 d). Each animal acted as its own control and were fed Beardless wheat (Triticum aestivum) hay and mineral mix during the trial. Statistical analyses were performed using SAS 9.4 following a pre-post repeated measures design. Bulls in negative energy balance (NEB) decreased (P < 0.001) empty body weight (EBW; 23.1% [-139.1 kg]), empty body fat (EBF; 39.8% [-85.4 kg]), and empty body protein (EBP; 14.9% [-13.5 kg]) and fully recovered at the end of the trial. Body fat accounted for 77.1% of daily changes in body energy status, whereas body protein accounted for only 22.9% (P < 0.001). Relative abundance of epigenetic markers transcripts was analyzed via qPCR. Bulls at NEB tended (P ≤ 0.097) to increase gene expression of epigenetic markers of RNA m6A methylation (METTL14, VIRMA, and WTAP) and increased (P ≤ 0.050) the gene expression of epigenetic markers of DNA methylation (DNMT3A) and histone-acetylation (SIRT3 and SIRT7). Young bulls had a tendency (P ≤ 0.072) of higher RNA m6A methylation, VIRMA, and WTAP than mature bulls. Effect of diet × age interaction was not detected (P ≥ 0.137) for METTL14, VIRMA, WTAP, DNMT3A, SIRT3, or SIRT7. Younger bulls tended to have greater RNA m6A methylation levels than mature bulls, indicating that, while contemporaneously fed the same diet during periods of undernourishment followed by compensatory growth, age has an impact on this epigenetic mechanism. In conclusion, metabolic status seems to carry a greater impact on regulating bovine hepatic epigenetic mechanisms that modulate gene transcription, such as DNA methylation and histone acetylation, than on epigenetic mechanisms that regulate gene translation, such as RNA m6A methylation. During periods of undernourishment followed by compensatory growth, body fat pools appear to change more dynamically and are easily detected having a greater impact on epigenetic markers that modulate hepatic gene transcription rather than translation.

Epigenetics refers to heritable modifications that regulate gene expression without altering DNA sequence, hence, acting on top of the genes. Epigenetic markers change in response to stressors such as environmental factors, nutritional challenges, among other overlooked players that altogether could drastically impair animal performance. During periods of undernourishment followed by fast weight gain, dynamic changes in body composition, especially fat, appear to trigger an increased action of such physiological markers that modulate hepatic gene expression. Findings of this study unveil epigenetic metabolic pathways that deserve further investigation for proper quantification of potential consequences of metabolic stress on the liver of bovines that suffer significant loss of body weight followed by recovery. The alterations at the molecular level shown in this study provide a picture of silent metabolic changes that have not been detected previously in liver metabolism studies of cattle. Therefore, the impact of nutritional management and metabolic stress may be greater than previously expected and differently controlled than previously assumed.

Sperm DNA 5-methyl cytosine and RNA N6-methyladenosine methylation are differently affected during periods of body weight losses and body weight gain of young and mature breeding bulls.

Aiming to characterize the effects of nutritional status on epigenetic markers, such as DNA 5-methyl cytosine (mC) methylation and RNA N6-methyladenosine (m6A) methylation, of bovine sperm, 12 Angus × Hereford crossbred breeding bulls were submitted to nutritional changes for a period of 180 d: no change in body weight (BW) (phase 1 = 12 d), BW loss (phase 2 = 78 d), and BW gain (phase 3 = 90 d) in a repeated measures design. Animals were fed Beardless wheat (Triticum aestivum) hay and mineral mix. Statistical analyses were performed using SAS 9.4 (SAS Inst., Cary, NC). Higher levels of RNA m6A (P = 0.004) and DNA methylation (P = 0.007) of spermatic cells were observed at phase 2 compared with phase 1. In phase 3, sperm RNA m6A methylation levels continued to be higher (P = 0.004), whereas the DNA of sperm cells was similar (P = 0.426) compared with phase 1. Growing bulls had a tendency (P = 0.109) of higher RNA m6A methylation levels than mature bulls. Phase 2 altered scrotal circumference (P < 0.001), sperm volume (P = 0.007), sperm total motility (P = 0.004), sperm progressive motility (P = 0.004), total sperm count (P = 0.049), normal sperm (P < 0.001), abnormal sperm (P < 0.001), primary sperm defects (P = 0.039), and secondary sperm defects (P < 0.001). In phase 3, bulls had scrotal circumference, sperm volume, sperm motility, sperm progressive motility, total sperm count, normal and abnormal spermatozoa, and primary and secondary spermatozoa defects similar to phase 1 (P > 0.05). Serum concentrations of insulin-like growth factor-1 and leptin decreased during phase 2 (P = 0.010), while no differences (P > 0.05) were detected between phases 3 and 1; growing bulls tended (P = 0.102) to present higher leptin levels than mature bulls. Specific for mature bulls, DNA methylation was positively correlated with leptin concentration (0.569, P = 0.021), whereas for young bulls, DNA methylation was positively correlated with abnormal spermatozoa (0.824, P = 0.006), primary spermatozoa defect (0.711, P = 0.032), and secondary spermatozoa defect (0.661, P = 0.052) and negatively correlated with normal spermatozoa (-0.824, P = 0.006), total sperm count (-0.702, P = 0.035), and sperm concentration (-0.846, P = 0.004). There was no significant correlation (P > 0.05) between RNA m6A and hormones and semen traits. In conclusion, the nutritional status of breeding bulls alters epigenetic markers, such as DNA methylation and RNA m6A methylation, in sperm, and the impact of change seems to be age dependent. These markers may serve as biomarkers of sperm quality and fertility of bulls in the future. Detrimental effects on sperm production and seminal quality are observed at periods and places when and where environmental and nutritional limitations are a year-round reality and may carry hidden players that may influence a lifetime of underperformance.

The influence of extended supplementation of quebracho extract to beef steers consuming a hay diet on digestion, ruminal, and blood parameters.

The addition of natural plant secondary compounds to ruminant feed has been extensively studied because of their ability to modify digestive and metabolic functions, resulting in a potential reduction in greenhouse gas emissions, among other benefits. Condensed tannin (CT) supplementation may alter ruminal fermentation and mitigate methane (CH4) emissions. This study's objective was to determine the effect of quebracho CT extract [QT; Schinopsis quebracho-colorado (Schltdl.) F.A. Barkley & T. Meyer] within a roughage-based diet on ruminal digestibility and kinetic parameters by using the in situ and in vitro gas production techniques, in addition to blood urea nitrogen (BUN) and ruminal (volatile fatty acid [VFA], NH3-N, and protozoa count) parameters. Twenty rumen-cannulated steers were randomly assigned to four dietary treatments: QT at 0%, 1%, 2%, and 3% of dry matter (DM; QT0: 0% CT, QT1: 0.70% CT, QT2: 1.41% CT, and QT3: 2.13% CT). The in situ DM digestibility increased linearly (P = 0.048) as QT inclusion increased, whereas in situ neutral detergent fiber digestibility (NDFD) was not altered among treatments (P = 0.980). Neither total VFA concentration nor acetate-to-propionate ratio differed among dietary treatments (P = 0.470 and P = 0.873, respectively). However, QT3 had lower isovalerate and isobutyrate concentrations compared with QT0 (P ≤ 0.025). Ruminal NH3 and BUN tended to decline (P ≤ 0.075) in a linear fashion as QT inclusion increased, suggesting decreased deamination of feed protein. Ruminal protozoa count was reduced in quadratic fashion (P = 0.005) as QT inclusion increased, where QT1 and QT2 were lower compared with QT0 and QT3. Urinary N excretion tended to reduce in a linear fashion (P = 0.080) as QT increased. There was a treatment (TRT) × Day interaction for in vitro total gas production and fractional rate of gas production (P = 0.013 and P = 0.007, respectively), and in vitro NDFD tended to be greater for QT treatments compared with no QT inclusion (P = 0.077). There was a TRT × Day interaction (P = 0.001) on CH4 production, with QT3 having less CH4 production relative to QT0 on day 0 and QT2 on days 7 and 28. Feeding QT up to 3% of the dietary DM in a roughage-based diet did not sacrifice the overall DM digestibility and ruminal parameters over time. Still, it is unclear why QT2 did not follow the same pattern as in vitro gas parameters. Detailed evaluations of amino acid degradation might be required to fully define CT influences on ruminal fermentation parameters and CH4 production.

Effects of the Incorporation of Tannin Extract from Quebracho Colorado Wood on Color Parameters, Lipid Oxidation, and Sensory Attributes of Beef Patties.

The tannin extract of Quebracho Colorado wood (Schinopsis balansae and Schinopsis lorentzii) is rich in proanthocyanidins with demonstrated powerful scavenging activity against free radicals. Currently, this extract is used in the wine industry to improve sensory attributes, stabilize color, and act as a redox buffer. In this study, we hypothesized that condensed tannins from Quebracho Colorado wood could be incorporated into beef patties as a natural antioxidant source to improve shelf life. Patties formulated with tannin extract (0, 0.5%, 1%, and 1.5%) were evaluated for instrumental color, lipid oxidation, and sensory attributes. Patties were displayed under refrigerated aerobic conditions (PVC film) for 6 days for color and lipid oxidation analysis. For sensory analysis, patties were frozen immediately after formulation. Control (0%) samples were redder than samples formulated with 1.5% tannin during the first 4 days of display. For b*, samples formulated with 1.5% tannin were predominantly yellower during display. After day 4, chroma values were higher in samples formulated with 1.5% tannin. The inclusion of tannin extract improved lipid stability, however, levels above 0.5% decreased tenderness, softness, juiciness, and overall desirability of patties.

Inclusion of quebracho tannin extract in a high-roughage cattle diet alters digestibility, nitrogen balance, and energy partitioning.

Condensed tannins (CT) might improve animal and system-level efficiency due to enhanced protein efficiency and reduced CH4. This study evaluated the impact of quebracho tannin (QT) extract fed at 0%, 1.5%, 3%, and 4.5% of dry matter (DM), within a roughage-based diet on apparent digestibility of DM, organic matter (OM), fibrous fractions, and N retention and energy partitioning of growing steers (236 ± 16 kg BW). A Latin rectangle design with eight animals and four periods was used to determine the whole-animal exchange of CO2, O2, and CH4 as well as the collection of total feces and urine over a 48-h period, using two open-circuit, indirect calorimetry respiration chambers. Following the removal of steers from respiration chambers, rumen inoculum was collected to determine ruminal parameter, including volatile fatty acids (VFA) and ammonia. Animals were fed a 56.5% roughage diet at 1.7% BW (dry matter basis). Dry matter and gross energy intakes were influenced by the level of QT inclusion (P ≤ 0.036). Digestibility of DM, OM, and N was reduced with QT inclusion (P < 0.001), and fiber digestibility was slightly impacted (P > 0.123). QTs altered the N excretion route, average fecal N-to-total N ratio excreted increased 14%, and fecal N-to-urinary N ratio increased 38% (P < 0.001) without altering the retained N. Increased fecal energy with QT provision resulted in reduced dietary digestible energy (DE) concentration (Mcal/kg DM; P = 0.024). There were no differences in urinary energy (P = 0.491), but CH4 energy decreased drastically (P = 0.007) as QT inclusion increased. Total ruminal VFA concentration did not differ across treatments, but VFA concentration increased linearly with QT inclusion (P = 0.049). Metabolizable energy (ME) was not affected by the QT rate, and the conversion efficiency of DE-to-ME did not differ. Heat energy decreased (P = 0.013) with increased QT provision likely due to changes in the DE intake, but there was no difference in retained energy. There were no differences for retained energy or N per CO2 equivalent emission produced (P = 0.774 and 0.962, respectively), but improved efficiency for energy retention occurred for 3% QT. We concluded that QT provided up to 4.5% of dry matter intake (about 3.51% of CT, dry matter basis) does not affect N and energy retention within the current setting. Feeding QT reduced energy losses in the form of CH4 and heat, but the route of energy loss appears to be influenced by the rate of QT inclusion.

The assessment of supplementation requirements of grazing ruminants using nutrition models.

This paper was aimed to summarize known concepts needed to comprehend the intricate interface between the ruminant animal and the pasture when predicting animal performance, acknowledge current efforts in the mathematical modeling domain of grazing ruminants, and highlight current thinking and technologies that can guide the development of advanced mathematical modeling tools for grazing ruminants. The scientific knowledge of factors that affect intake of ruminants is broad and rich, and decision-support tools (DST) for modeling energy expenditure and feed intake of grazing animals abound in the literature but the adequate predictability of forage intake is still lacking, remaining a major challenge that has been deceiving at times. Despite the mathematical advancements in translating experimental research of grazing ruminants into DST, numerous shortages have been identified in current models designed to predict intake of forages by grazing ruminants. Many of which are mechanistic models that rely heavily on preceding mathematical constructions that were developed to predict energy and nutrient requirements and feed intake of confined animals. The data collection of grazing (forage selection, grazing behavior, pasture growth/regrowth, pasture quality) and animal (nutrient digestion and absorption, volatile fatty acids production and profile, energy requirement) components remains a critical bottleneck for adequate modeling of forage intake by ruminants. An unresolved question that has impeded DST is how to assess the quantity and quality, ideally simultaneously, of pasture forages given that ruminant animals can be selective. The inadequate assessment of quantity and quality has been a hindrance in assessing energy expenditure of grazing animals for physical activities such as walking, grazing, and forage selection of grazing animals. The advancement of sensors might provide some insights that will likely enhance our understanding and assist in determining key variables that control forage intake and animal activity. Sensors might provide additional insights to improve the quantification of individual animal variation as the sensor data are collected on each subject over time. As a group of scientists, however, despite many obstacles in animal and forage science research, we have thrived, and progress has been made. The scientific community may need to change the angle of which the problem has been attacked, and focus more on holistic approaches.

Evaluation of different inclusion levels of dry live yeast impacts on various rumen parameters and in situ digestibilities of dry matter and neutral detergent fiber in growing and finishing beef cattle.

This study evaluated the effects of supplementing dry live yeast (LY; Saccharomyces cerevisiae) on in vitro gas production (IVGP) fermentation dynamics, pH, and CH4 concentration at 48 h, and in situ rumen parameters and digestibility of DM (DMD) and NDF (NDFD) of growing cattle during 3 feeding phases: grower (GRW) for 17 d (38% steamed-flaked corn; SFC), transition (TRANS) for 15 d (55.5% SFC: 1.2 Mcal/kg NEg), and finisher (FIN) for 13 d (73% SFC: 1.23 Mcal/kg NEg). Twenty British-crossbred, ruminally cannulated steers (183 kg ± 44 kg) 6 mo of age were blocked by weight into 5 pens containing Calan gate feeders and received a control (CON) diet (17.2% CP, 35.8% NDF, 86.7% DM) without LY on days -12 to 0. After that, animals were randomly assigned to treatments (TRT), 5 animals per TRT: CON or LY at inclusion rates of 5 g/d (LY1), 10 g/d (LY2), or 15 g/d (LY3) top dressed every morning at 0800 for 45 d. The DMD and NDFD were assessed during 7 separate collection days using in situ nylon bags containing 5 g of GRW, TRANS, or FIN diets, incubated at 1200 for 48 h. Protozoa counts (PC) were determined during 5 collection periods. Data were analyzed as a repeated measure within a randomized complete block design, assuming a random effect of the pen. For GRW, TRT altered the total gas production of the nonfiber carbohydrate (NFC; P = 0.045) and the fractional rate of degradation (kd) of the fiber carbohydrate (FC) pool (P = 0.001) in a cubic pattern (P ≤ 0.05): LY2 had the most gas production and fastest kd. TRT also influenced DMD (P = 0.035) and NDFD (P = 0.012) with LY2 providing the greatest digestibility. For TRANS, TRT tended to affect the NFC kd (P = 0.078) and influenced pH (P = 0.04) and DMD (P < 0.001) in which LY2 yielded the fastest kd, highest pH, and greatest DMD. For FIN, there was an effect of TRT on total gas production (P < 0.001) and kd (P = 0.004) of the NFC pool, FC kd (P = 0.012), in vitro CH4 concentration (P < 0.001), PC (P < 0.001), DMD (P = 0.039), and NDFD (P = 0.008). LY1 had the highest PC and provided the greatest DMD and NDFD. LY2 had the fastest kd of both the NFC and FC pools and had the least CH4 concentration. LY3 had the greatest NFC gas production. No specific dose-response pattern was observed, but 10 g/d provided the most beneficial result for all diets. We concluded that supplementation with LY affected IVGP as well as ruminal parameters and digestibilities.

Does partial replacement of corn with glycerin in beef cattle diets affect in vitro ruminal fermentation, gas production kinetic, and enteric greenhouse gas emissions?

Five in vitro experiments were conducted with the following objectives: 1) To evaluate the ruminal fermentation of three different single ingredients: corn, glycerin, and starch (Exp. 1 and 2); 2) To assess effects of partially replacing corn with glycerin in beef cattle diets on ruminal fermentation pattern (Exp. 3 and 4); and 3) To evaluate the effects of glycerin inclusion on the extension of ruminal DM digestibility of feeds with high (orchard hay) and low (corn) fiber content (Exp. 5). For Exp. 1 and 2, two in vitro systems (24-bottle AnkomRF and 20-serum bottles) were used in four consecutive fermentation batches to evaluate gas production (GP), fermentation profiles, enteric methane (CH4), and carbon dioxide (CO2) of corn, glycerin, and starch. The 24 h total GP, acetate concentration, and acetate: propionate ratio decreased only when glycerin was added to the diet (P < 0.01). The 48-h total GP and metabolizable energy were greatest for corn (P < 0.01), and similar between glycerin and starch. The starch treatment had the lowest total volatile fatty acids concentration (P = 0.01). Glycerin had greatest CH4 production, lag time, and maximum gas volume of the first pool (P < 0.05). However, the maximum gas volume of the second pool was greatest for corn (P < 0.05), and similar between glycerin and starch. The starch treatment had the greatest specific rates of digestion for first and second pools (P < 0.05). Production of CO2 (mL/g) was greater for corn (P < 0.01), but similar for glycerin and starch. For Exp. 3 and 4, the same systems were used to evaluate four different levels of glycerin [0, 100, 200, and 300 g/kg of dry matter (DM)] replacing corn in beef cattle finishing diets. Glycerin levels did not affect 24 and 48 h total GP, CH4, and CO2 (P > 0.05). The inclusion of glycerin linearly decreased acetate concentration (P = 0.03) and acetate: propionate ratio (P = 0.04). For Exp. 5, two DaisyII incubators were used to evaluate the in vitro dry matter digestibility (IVDMD) of the following treatments: orchard hay; corn; orchard hay + glycerin; and corn + glycerin. Glycerin inclusion decreased orchard hay IVDMD (P < 0.01) but did not affect corn IVDMD (P > 0.05). We concluded that, under these experimental conditions, glycerin has similar energy efficiency when used in replacement of corn and included at up to 300 g/kg in beef cattle diets.