Determination of Particulate Matter Emissions from Cattle Feedlots Using Wind-Trax and the Flux-Gradient Technique

Large commercial cattle feedlots are significant sources of particulate matter (PM) emissions. This research compared WindTrax and the flux-gradient technique in estimating emissions of PM with aerodynamic diameter < 10 μm (PM10) from cattle feedlots. Meteorological conditions were measured and PM10 concentrations were profiled vertically (i.e., 2.0 to 7.62 m) at a large commercial beef cattle feedlot in Kansas from May through September 2011. Results show that between the two methods evaluated, WindTrax was least sensitive to changes in heights and number of heights used in the emission estimation, with calculated PM10 emission rates varying by up to 18% only. On the other hand, PM10 emission rates produced by the flux-gradient technique varied by almost 56% when changing either heights and/or number of heights in emission calculation. Both methods were sensitive to height settings, with their respective PM10 emission rates higher when the lowest height setting (2.0 m) was included. Calculating PM10 emission rates with the 7.62-m height led to lower estimates for the flux-gradient technique but no significant change in estimates was observed for WindTrax. As demonstrated in this study, for the flux-gradient technique, settings for the lowest and highest heights were the most critical in emission estimation;exclusion of other heights in between showed only to 2% to 6% change in calculated PM10 emission rates. In general, the higher PM10 emission rates were obtained with the flux-gradient technique. However, eliminating the lowest height (2.0 m) in the calculation and, at the same time, using a specific set of formulations for the flux-gradient technique made its calculated PM10 emission rates slightly lower (but not significantly different) than those from WindTrax.

The distribution of drinking water-to-cattle ratios in the summer across four feedlots in the Texas High Plains

In this short communication, we report the findings of a cross-sectional pilot study of the amount of water available per head of cattle (water-to-cattle ratio) and the associated feedlot and environmental factors across 26 pens in four Texas feedlots. The water-to-cattle ratio varied greatly among pens within and between feedlots. Mixed-effect linear regression modeling with feedlot as a random effect indicated that water in troughs with a higher water-to-cattle ratio was generally warmer when compared with water in troughs with a lower water-to-cattle ratio. This may have implications in the transmission and persistence of pathogens in feedlot cattle, such as Shiga toxin-producing Escherichia coli and Salmonella, because warmer water has been reported to favor the growth of these pathogens. Therefore, future field studies in feedlot cattle are warranted to assess whether the water-to-cattle ratio affects the prevalence of these pathogens in the water itself or in feces shed by the animals.

Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

Background Stocker cattle diet and management influence beef cattle performance during the finishing stage,but knowledge of the dynamics of the rumen microbiome associated with the host are lacking.A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota.During the stocker phase,either dry hay or wheat pasture were provided,and three levels of monensin were administrated.All calves were then transported to a feedlot and received similar finishing diets with or without monensin.Rumen microbial samples were collected on d 0,28,85 during the stocker stage(S0,S28 and S85)and d 0,14,28,56,30 d before slaughter and the end of the trial during the finishing stage(F0,F14,F28,F56,Pre-Ba,and Final).The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.Results Higher alpha diversity,including the number of observed bacterial features and the Shannon index,was observed in the stocker phase compared to the finishing phase.The bacterial amplicon sequence variants(ASVs)differentiating different sampling time points were identified.Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota.For example,shared bacteria,including Bacteroidales(ASV19)and Streptococcus infantarius(ASV94),were significantly higher in hay rumen on S28,S85,and F0,while Bacteroidaceae(ASV11)and Limivicinus(ASV15)were more abundant in wheat.Monensin affected rumen microbial composition at a specific time.Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves.Bacterial taxa associated with body weight were classified,and core microbiotas interacted with each other during the trial.Conclusions In summary,the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy.Diet at the stocker phase may temporarily affect the microbial composition during this stage.Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

Impact of Chromium Propionate Supplementation and Days of Adaptation on Energy Status in Newly Weaned Steer Calves*

The objective of this research was to evaluate the influences that supplemental dietary chromium propionate (CrP;0 or 0.4 mg·kg-1 added to the total diet on a DM basis) has on plasma indicators of energy status in newly weaned steers upon introduction to the feedlot. For this experiment single source, Angus steers (n = 28;BW = 289 ± 12.0 kg) from a ranch in Western South Dakota were weaned and immediately shipped 579 km to the Ruminant Nutrition Center (RNC) in Brookings, SD. Steers were allotted to one of four 7.6 m × 7.6 m pens (2 pens/diet;7 steers/pen) at 4 d post-arrival to the RNC and test diets were initiated. No anabolic implant was used in this study. Subsequent BW measurements were obtained at 1400 h, to accommodate a post-prandial timing for blood sampling. This was 4 h after initial access to feed, and immediately prior to the afternoon feed delivery. Weights and blood sampling occurred on d 5, 12, 19, and 33. Whole blood samples were collected from all steers via jugular venipuncture and separated as plasma. There were no diet x day interactions (P ≥ 0.51) for plasma glucose, insulin, or urea-N. Plasma glucose, insulin, and urea-n levels were similar between diets (P ≥ 0.35). Plasma glucose and urea-n levels were not different across days (P ≥ 0.59). Insulin levels differed as a result of days of adaptation and were greatest (P = 0.01) on d 12 regardless of diet. There tended (P = 0.12) to be a diet x day interaction for NEFA levels. Plasma NEFA levels tended to be lower (P = 0.13) for calves fed CrP on d 5, and were greater (P = 0.09) on d 12 in calves fed CrP. The shift in NEFA on d 12 coincided with the spike in insulin levels. Both events occurred at the time that NEg intake was approaching the acclimated plateau and neither event impacted glucose status. In non-ruminants, elevated insulin concentrations decrease circulating NEFA levels. We detected minimal differences in regard to plasma indicators of lipid metabolism in this study due to chromium supplementation. These data indicate that ruminants may differ from non-ruminants in the regulation and maintenance of glucose status and body fat catabolism during the post-absorptive state.

Metabolizable Amino Acid Requirements of Feedlot Calves

One hundred ninety-two crossbred steers (229 kg) were used to evaluate the influence of metabolizable amino acid intake on growth performance and health during the initial 42-d receiving period. Treatments consisted of four levels of metabolizable lysine (23, 24, 25 and 26 g/kg diet DM). Morbidity averaged 36%, and was not affected (P > 0.20) by treatments. No steers died during the study. Increasing the metabolizable lysine supply increased DMI, ADG, gain efficiency, and dietary NE (linear effect, P < 0.01). Metabolizable amino acid supply of the basal diet was determined using 6 steers (214 kg) with cannulas in the rumen and proximal duodenum. Metabolizable amino acid supply of the diet was in close agreement with expected (R2 = 0.99;P < 0.0001) based on NRC (2000) [12] Level 1 model. The metabolizable amino acid supplies for treatments in Trial 1 were estimated by adding tabular metabolizable amino acid values for the respective supplemental proteins (cottonseed meal and fish meal) to the observed metabolizable amino acid supply of the basal diet. Treatment effects on metabolizable lysine supply explained 99% of the variation (P < 0.01) in ADG, and 91% of the variation in observed versus expected dietary NE. The biological value for the intestinal chyme was determined based on chemical score technique, using bovine tissue as the reference protein. Accordingly, methionine and lysine were closely co-limiting amino acids having ratios of 77% and 79%, respectively. We conclude that current NRC standards reliably predict both requirements and supplies of metabolizable amino acids for feedlot calves. Diet formulations that do not meet the metabolizable amino acid requirements may depress both ADG and the partial efficiency of utilization of metabolizable energy for maintenance and gain.

Extruded Corn Meal as a Partial Replacement for Steam Flaked Corn in Finishing Diets for Feedlot Cattle: Growth Performance and Digestive Function of Feedlot Cattle

Sixty-four Holstein steers (247 ± 4 kg) were used in a 70-d experiment to evaluate the effects of partial replacement of steam flake corn (SFC) with extruded corn meal (EC) on growth performance and dietary net energy. Treatments consisted of a steam flaked corn-based finishing diet containing 0%, 10%, 20%, or 30% EC, where EC replaced 0%, 15%, 30%, or 45% of SFC (DM basis). Replacement of SFC with increasing levels of EC did not affect (P > 0.10) ADG, DMI, and gain efficiency. When EC replaced 15% to 30% of SFC, observed dietary NE was 99% of expected. Whereas, when EC replaced 45% of SFC, observed dietary NE was 94% of expected. Four Holstein steers (210 ± 7 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate treatment effects on characteristics of digestion. Partial replacement of SFC with EC did not affect (P > 0.10) flow of undegraded feed N and microbial N and to the small intestine, and ruminal microbial N efficiency (g microbial N/kg OM fermented). Likewise, there were no treatment effects (P > 0.10) on ruminal digestion of OM, NDF, starch and feed N. As expected, total tract digestion of starch for all treatments exceeded 99%. However, partial replacement of SFC with EC decreased total tract digestion of DM and OM (linear effect, P = 0.02), and dietary DE (linear effect, P = 0.03). These effects were more pronounced where EC replaced 45% of SFC. Partial replacement of SFC with EC did not affect (P > 0.10) ruminal pH, total VFA concentration, molar proportions of acetate, propionate, and butyrate, and estimated methane production. It is concluded that partial replacement of SFC with EC does not have a beneficial effect on ruminal microbial efficiency and digestive function. The feeding value of extruded corn for feedlot cattle is comparable to that of steam flaked corn provided the inclusion rate does not exceed 20% of diet dry matter.

Effect of Supplemental Calcium Levels on Feedlot Growth Performance and Dietary Net Energy Utilization during the Receiving Feeding Period of Calf-Fed Holstein Steers

Ninety-six calf-fed Holstein steer (127 kg) were used to evaluate the influence of supplemental dietary calcium (Ca) on growth-performance, and dietary net energy (NE) utilization during the initial 112-d of receiving period. Treatments consisted of steam flake corn-based growing-finishing diets supplemented with limestone to achieve 0.60%, 0.70%, 0.80%, or 0.90% dietary Ca (DM basis). Morbidity was low (6.3%) and it was not affected (P > 0.87) by dietary treatments. During the initial 84-d period (181 kg average BW), increasing dietary Ca did not influence (P > 0.10) DMI, ADG, gain efficiency or observed/expected DMI. Observed DMI was 19% greater than expected based on diet formulation and growth. Estimated metabolizable protein and methionine supply during the initial 84-d period averaged 92% and 79% of the required, respectively. The apparent decrease in efficiency of energy utilization in the present study is in close agreement with previous studies involving calf-fed Holstein steers in the early growing phase fed conventional growing-finishing diet that is otherwise deficient in metabolizable amino acids. Thus, it is considered that the anticipated growth-performance responses to dietary Ca treatments may have been masked by expected inefficiencies due to metabolizable amino acid deficiency. During the final 28-d period (256 kg of average BW), increasing supplemental Ca reduced feed intake (linear effect, P = 0.04) and enhanced gain efficiency (linear effect, P = 0.03). During this period, predicted ([1] Level 1) metabolizable protein and methionine supply were 110% and 94% of the required, respectively. Nevertheless, improvements in gain efficiency during the final 28-d period with increasing levels of supplemental Ca were not sufficient to influence (P > 0.10) overall 112-d growth-performance. It is concluded dietary Ca requirements of calf-fed Holstein steers during the initial 112-d feeding period appear to be secondary to deficiencies of conventional steam-flaked corn-based diets in meeting metabolizable amino acid requirements. However, when those requirements are met during the early growing phase, gain efficiency responses are optimized at approximately 0.90% dietary Ca.

Subcutaneous fatty acid composition of steers finished as weanlings or yearlings with and without growth promotants

Background： The current study evaluated the subcutaneous fatty acid （FA） composition of calf- and yearling-fed steer with or without growth promoting implants. Crossbred steers （n = 112; 267 ± 5.0 kg） of the same contemporary group were allocated to one of four production system and implant strategy based treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Results： There were no interactions （P 〉 0.05） between production systems and growth promoting implants for the total and individual subcutaneous FA. Yearling as opposed to calf finishing reduced （P 〈 0.05） subcutaneous proportions of C20：3n-6, trans （t）l 2-18：1, C14：0, several minor cis-monounsaturated FA （c-MUFA; c9-14：1, c11-16：1, cl 1-18：1, cl 2-18：1, cl 3-18：1, c9-20：1 and cl 1-20：1）, and increased （P 〈 0.05） subcutaneous proportions of tl 1 cl 5-18：2, total and individual branched-chain FA. Subcutaneous fat from steers implanted with growth promotants had higher （P 〈 0.05） proportions of total polyunsaturated FA （PUFA）, total n-6 PUFA, C18：2n-6 and individual t-18：1 isomers （t6 to tl0） compared to non-implanted steers. Conclusions： Overall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.

Impact of Feedlot on Soil Phosphorus Concentration

Raising cattle in feedlots is becoming more common in Argentina, but there is little information available about the effects of this practice on soil phosphorus (P) dynamics. In this study, concentrations of water and Bray -1 extractable soil P were quantified in a feedlot (upper and lower slope positions in the feedlot pen), runoff area and pasture during 2006 - 2008. The feedlot showed higher P concentrations in all P forms, soluble reactive P, soluble nonreactive, total soluble P, and Bray-P1 when compared to runoff area and pasture. Most of the total soluble P was soluble reactive P from the soil in the feedlot and the runoff area, while soluble nonreactive P predominated in the pasture. Concentrations of total soluble P were elevated in the feedlot at the soil surface, ranging on average from 158.71 to 245.86 mg?P?kg?1, and had a rapid decrease within the first 20 cm and remained relatively low, about 25.53 - 27.33 mg?P?kg?1. The evidence that total soluble P concentration in the feedlot was significantly (p < 0.05) higher than that registered in the pasture at 20 - 40 and 40 - 60 cm soil depth suggests a potential transfer of P through the soil from the surface. Although the feedlot had a moderate increase of 23.05 to 24.55 mg?P?kg?1 from the background concentration, it may represent a long-term source of increased nutrient loading to groundwater. Soil extractable Bray-1 P in the top 0 - 2.5 cm fluctuated from 659.26 to 45.36 mg?P?kg?1 in the feedlot and pasture, respectively. The relationship between soil P extracted by test and TSP was linear, and correlation coefficient was r2 = 0.95.

Wheat silage partially replacing oaten hay exhibited greater feed efficiency and fibre digestion despite low feed intake by feedlot lambs

This study aimed to investigate the feeding effect of wheat silage on growth performance,nutrient digestibility,rumen fermentation,and microbiota composition in feedlot lambs.Sixty-four male crossbred Chinese Han lambs(BW=27.8±0.67 kg,3 months of age)were randomly assigned to four ration groups with wheat silage replacing 0%(WS0),36%(WS36),64%(WS64),and 100%(WS100)of oaten hay on forage dry matter basis.The concentrate-to-forage ratio was 80:20 and the feeding trial lasted 52 d.Increasing wheat silage inclusion linearly decreased dry matter intake by 4%to 27%(P<0.01).However,increasing the wheat silage replacement of oaten hay by no more than 64%improved the feed efficiency by 14%as noted by the feed-to-gain ratio(P=0.04).Apparent digestibility of organic matter(P<0.01),neutral detergent fibre(P=0.04)and acid detergent fibre(P<0.01)quadratically increased.Ammonia nitrogen(P=0.01)decreased while microbial protein production(P<0.01)increased with the increase of wheat silage inclusion.Total volatile fatty acids concentration increased quadratically with the increase of wheat silage inclusion(P<0.01),and the highest occurred in WS64.The molar proportion of acetate(P<0.01)and acetate-to-propionate ratio(P=0.04)decreased while butyrate(P<0.01)and isovalerate(P=0.04)increased.Increasing wheat silage inclusion increased the Firmicutes-toBacteroidota ratio by 226%to 357%,resulting in Firmicutes instead of Bacteroidota being the most abundant phylum.The relative abundance of cellulolytic Ruminococcus numerically increased but that of amylolytic Prevotella(P<0.01)decreased as increasing wheat silage inclusion.Taken together,increasing wheat silage replacement of oaten hay by no more than 64%exhibited greater feed efficiency and fibre digestion despite low feed intake by feedlot lambs due to the change of Firmicutes-to-Bacteroidota ratio in the rumen.