Applied Animal Science最新文献

Objective

The objective of this study was to determine the effects of degree of steam flaking of corn (SFC) on energy metabolism of finishing cattle fed diets containing wet distillers grains with solubles (WDGS).

Materials and Methods

Crossbred steers (n = 4; initial BW = 308 ± 7.0 kg) were randomly assigned to 4 diets containing 0% or 20% WDGS and corn steam flaked to either 321 or 270 g/L bulk density (26 or 22 lb/bu, respectively) in a 2 × 2 factorial arrangement. Energy metabolism was measured in respiration chambers with a 4 × 4 Latin square design.

Results and Discussion

There were no interactions between WDGS concentration and SFC bulk density for nutrient digestion, nitrogen metabolism, or energy metabolism values. Digestibility of OM, NDF, and ether extract were not influenced by the degree of steam flaking of corn. Decreasing bulk density of SFC increased starch digestion, tended to increase the ratio of DE to digestible OM, and numerically decreased the plasma urea-N concentration, but did not significantly affect ME concentration or the DE:TDN ratio. Replacing SFC with 20% WDGS decreased fat digestion but did not affect digestion of other nutrients or dietary energy values.

Implications and Applications

Results suggest that increasing the degree of steam flaking of corn to less than 321 g/L does not improve diet digestibility or energy metabolism of cattle fed diets containing 0% or 20% WDGS.

Objective

Dual-purpose wheat (Triticum aestivum L.) systems are commonly used in the Great Plains of the United States but are not often used in the Southeast. This study aimed to evaluate the viability of dual-purpose wheat management in the Southeast.

Materials and Methods

Wheat varieties evaluated were generic feed type (unknown variety blend, Feed), seed type GA Gore (Seed), and 2 forage types, AGS 2024 (AGS) and Pioneer 26R41 (Pioneer). The experiment was a randomized complete block design (n = 4) conducted during the winters of 2021 and 2022. Three grazing frequencies were used: an ungrazed control (NG) and low-frequency (LF) or high-frequency (HF) grazing. Low- frequency plots received monthly grazing in January and February, whereas HF treatments received a third grazing in March. Destructive forage sampling occurred at monthly intervals. Data were analyzed using PROC GLIMMIX of SAS (v. 9.4, SAS Institute Inc., Cary, NC), with differences declared at P < 0.05. Ad hoc economic evaluation was performed for establishment costs and potential net returns.

Results and Discussion

Before grazing, AGS herbage mass (2,660 kg/ha) was greater than all other varieties. Compared with all other varieties, AGS had greater ADF (24.9%) and least TDN (72.5%). Across grazing frequencies, Pioneer had greater final grain yield (3,620 kg DM/ ha), with Seed having the least (1,270 kg DM/ha). Dual- purpose returns above costs were greatest for Pioneer.

Implications and Applications

Results indicate that common southeastern wheat varieties can be successfully used in a dual-purpose management system.

Objective

Livestock disease management is crucial for producers. To control and eradicate disease, the US gov- ernment has a duty to depopulate infected or potentially infected animals, and current indemnity policy dictates that producers must receive fair market compensation for depopulated animals. This study surveys producers’ pref- erences regarding livestock indemnity policy to better un- derstand ordered preferences for any changes in the future.

Materials and Methods

Through a ranked-ordered probit model, we analyzed producers’ rankings of 4 dif- ferent types of indemnity from an online producer survey.

Results and Discussion

Based on the responding producers, the most preferred method of livestock indem- nity is fair market value for the animal, and the second most preferred indemnity policy is government-subsidized livestock insurance.

Implications and Applications

The results indicate heterogeneity in preference rankings across producers and by producer characteristics. Our findings provide policy- makers with information on producers’ opinions for com- pensation after a disease outbreak. These insights allow legislators to consider producers’ preferences when updat- ing or creating new policies regarding livestock disease management in the future.

Objectives

The objective of this study was to evaluate the accuracy of Brix in predicting sugar concentrations in fresh alfalfa (ALF; Medicago sativa L.) and orchardgrass (OG; Dactylis glomerata L.) forages to be used as an inexpensive and rapid field-level assessment of relative energy in forages.

Materials and Methods

In a 2-yr study, fresh forages samples from ALF and OG monoculture pastures in central Pennsylvania, USA, were collected once monthly from May to September. Samples were immediately evaluated for Brix values with a hand-held digital refractometer, and the remaining biomass was frozen immediately with liquid N to halt cellular respiration. Samples were lyophilized and analyzed for individual sugars and wet chemistry nutritive analyses.

Results and Discussion

Brix was positively correlated with total and individual sugars in ALF during late spring and late summer (0.53–0.93), but correlations were nonexistent or negative in mid-summer. However, Brix values did not correlate with any notable sugar parameters in OG beyond the first sampling date. These findings were attributed to greater fibrous fraction contamination, lower sugar concentrations found in grasses and legumes compared with horticultural crops, and changes in seasonal growth of ALF and OG.

Implications and Applications

Brix values did not consistently predict sugar concentrations in fresh ALF and OG forages. Because Brix measures dissolved solids in solution (not just sugars), Brix readings collected from crushed ALF or OG samples may be confounded by fibrous fractions found in the solution. Brix accuracy may also be dependent on seasonal temperature patterns, plant growth stage, and daily weather patterns. Other solutions should be investigated that rapidly assess sugar profiles and nutritive values of fresh forages.

Objective

The objective of Exp. 1 was to evaluate the effects of adding urea to modified distillers grains with solubles (MDGS) when supplemented to growing steers and in Exp. 2 to evaluate whole corn as an alternative to dried distillers grains with solubles (DDGS) for growing steers grazing cornstalk residue.

Methods and Materials

In Exp. 1, 120 crossbred beef steers (initial BW = 244 kg, SD = 19 kg) grazed corn residue for 72 d. Treatments were a 2 × 2 factorial arrangement of MDGS inclusion (1.4 or 2.3 kg/d) and urea inclusion (0 or 0.05 kg/d). Residue diet samples were collected to determine CP, in vitro organic matter disap- pearance (IVOMD) and digestible organic matter (DOM). Steers were individually supplemented daily. Data were analyzed using the MIXED procedures of SAS. In Exp. 2, 75 crossbred steer calves (235 kg, SD = 3.5) grazed corn residue for 86 d. Treatments were arranged in a ran- domized complete block design, which included (1) a non- supplemented control, (2) whole corn, (3) whole corn with urea in a molasses carrier (corn/mol/urea), (4) DDGS, and (5) 60% SoyPass + 40% soybean meal (SoyPass/ SBM). Supplements were designed to be isocaloric. Data were analyzed using the GLIMMIX procedures of SAS. Results were considered significant at P ≤ 0.05.

Results and Discussion

No MDGS × urea inter- actions were observed for growth performance (Exp. 1). Steers supplemented with 2.3 kg MDGS had greater ADG than those supplemented with 1.4 kg MDGS (1.05 kg/d vs. 0.83 respectively). Urea level did not affect ending BW or ADG. The IVOMD and DOM of the grazed residue decreased linearly and quadratically, respectively, as the grazing progressed as expected, but CP was not different. In Exp. 2, nonsupplemented calves lost weight (0.08 kg/d) Calves receiving whole corn had greater gains (0.14 kg/d) than the nonsupplemented calves but less than corn/ mol/urea (0.24 kg/d). The DDGS and SoyPass/SBM had greater gains than the other treatments, but were not dif- ferent from each other (0.60 and 0.67 kg/d, respectively).

Implications and Applications

These data suggest adding RDP when supplementing MDGS is unnecessary and that feeding whole corn, even with a source of NPN to supply RDP does not result in similar performance as feeding DDGS or SoyPass/SBM.

Objective

The objective was to evaluate the effect of days on feed (DOF) on performance and carcass characteristics of crossbred beef × dairy heifers.

Materials and Methods

Beef × dairy heifers (n = 3,765; initial BW = 508 ± 8.55 kg) were blocked by arrival date and lot (n = 6 blocks at feedyard 1 and n = 7 blocks at feedyard 2) and randomly assigned to 1 of 4 DOF treatments of 323, 344, 362, or 385 when administered a Revalor-200 (200 mg of trenbolone acetate [TBA] and 20 mg of estradiol [E₂]) on d 265.

Results and Discussion

Dry matter intake was not affected by DOF, whereas final BW increased linearly from 593 to 655 kg. As DOF increased, ADG and gain: feed decreased quadratically. Hot carcass weight, LM area, calculated YG, and marbling score increased linearly as DOF increased. Across the 63-d serial slaughter period, hot carcass weight increased 0.67 kg/d. Dressing percentage and backfat thickness increased in a quadratic manner across DOF. Further, QG and YG distribution increased linearly as DOF increased. Liver abscess prevalence or severity did not increase with DOF.

Implications and Applications

Results of this study indicate that extending DOF by 63 d led to increased BW, hot carcass weight, LM area, marbling, YG, and QG but poorer ADG and feed conversion efficiency for beef × dairy crossbred heifers.

Objective

Our objective was to evaluate how a particular zeolite-based flow agent affected ergot alkaloid digestion and physiological markers associated with fescue toxicosis.

Materials and Methods

Twenty-four steers (226 ± 27.6 kg) were used to test effects of enhanced zeolite-based flow agent (KALLSIL, Kemin Industries, Des Moines, IA) on ergot-like alkaloid digestion. Treatments were control (E+) or enhanced zeolite inclusion (E+Z; 2 g/kg, DM basis). Steers were limit-fed diets (1.8% of BW, DM basis) containing 465 μg of ergovaline/kg of DM. Rectal temperature and respiration rate were recorded daily at 0700 and 1200 h from steers in a room kept at 18.5°C ± 0.33°C, 32.6% ± 2.19% relative humidity. Blood was collected on d 1, 7, 14, and 21 to measure prolactin. On d 21 prolactin stores were measured following infusion of thyrotropin- releasing hormone (TRH; 1 μg/kg BW). Feces and urine were collected every 8 h from d 17 to 20, with 2-h advancement daily for digestibility, N balance, and recovery of ergot-like alkaloids.

Results and Discussion

Digestion and N balance were not affected by treatment. Zeolite did not affect fecal recovery of ergovaline. Serum prolactin declined over time. Serum prolactin was greater in steers fed E+Z. Following TRH infusion, prolactin was numerically greater for E+Z. Rectal temperatures and respiration rates were not affected by E+Z.

Implications and Applications

Under the conditions of this experiment, addition of this particular zeolite-based feed additive had minimal impact on ergot alkaloid recovery and physiological markers associated with fescue toxicosis.

Purpose

This literature review explains current understanding of the mechanisms by which branched-chain volatile fatty acids (BCVFA), historically termed isoacids, can improve fiber digestibility, microbial protein production, and either milk production or production efficiency.

Sources

Peer-reviewed literature and ADSA abstracts were the primary course of information reviewed.

Synthesis

Although traditionally included in isoacid supplements with the 3 BCVFA, the straight-chain valerate does not warrant being included. Because of the high concentration of its precursor leucine in corn protein, isovalerate is less likely to be needed than 2-methylbutyrate and isobutyrate. If conditions are not amenable for BCVFA assimilation into microbes, particularly if ruminal ammonia is deficient, more supplemental BCVFA are available for postruminal metabolism. Isovalerate is likely metabolized primarily in the rumen epithelium, whereas isobutyrate and 2-methylbutyrate are likely metabolized in the liver or peripheral tissues. If BCVFA improve fiber degradability, typically by 3 to 5 percentage units, a more balanced consortium of ruminal microbes should improve efficiency of microbial protein production so long as ruminal nitrogenous precursors are adequate.

Conclusions and Applications

Increased acetate production from improved fiber digestibility is thought to increase milk fat production, particularly in multiparous cows. In primiparous cows, the acetate from improved fiber degradability might be diverted to body weight gain. Milk production efficiency responses of 5% to 10% have been recorded with optimum doses of BCVFA and adequate rumen-degraded protein supply.

Objective

This study evaluated the effects of feeding lubabegron fumarate compared with ractopamine hydrochloride in beef × dairy crossbred steers fed a corn-based diet in western Canada.

Materials and Methods

Beef × dairy (Limousin × Jersey) crossbred steers (n = 760, initial BW = 530.0 ± 34.7 kg) were randomly allocated 80 d before slaughter to 1 of 2 experimental groups. A total of 20 replicates were allocated to the study, with each replicate comprising 1 pen from each experimental group (for a total of 40 pens) and 19 steers per pen. Pen was the experimental unit. Experimental groups consisted of either lubabegron fumarate (Experior 10, Elanco Canada Limited, Mississauga, Canada) fed at a target level of 3.5 mg/kg diet DM for 56 d before slaughter (EXP) or ractopamine hydrochloride (Optaflexx 100, Elanco Canada Limited) fed at a target level of 250 mg/steer daily the last 28 d before slaughter (RAC).

Results and Discussion

Steers in the EXP group had lower DMI, greater carcass weight, and greater DP compared with steers in the RAC group. Steers in the EXP group had greater ADG and G:F on both a carcass weight and live weight basis compared with steers in the RAC group. Steers in the EXP group also had a greater proportion of YG Canada 1 carcasses, a lower proportion of QG Canada Prime carcasses, increased LM area, and a lower overall marbling score compared with steers in the RAC group.

Implications and Applications

Feeding lubabegron fumarate increased feedlot performance, the proportion of YG Canada 1 carcasses, and LM area, but decreased the proportion of QG Canada Prime carcasses and overall marbling score compared with feeding ractopamine hydrochloride. Magnitude of improvement in G:F was greater on a carcass weight basis than on a live weight basis.