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Journal of Animal Science - Animal Nutrition

Effects of dietary concentration of wet distillers grains on performance by newly received beef cattle, in vitro gas production and volatile fatty acid concentrations, and in vitro dry matter disappearance1

 

This article in JAS

  1. Vol. 91 No. 6, p. 2836-2845
     
    Received: July 2, 2012
    Accepted: Feb 27, 2013
    Published: November 25, 2014


    2 Corresponding author(s): dougs@ppl-usa.biz
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doi:10.2527/jas.2012-5619
  1. D. R. Smith 2,
  2. C. H. Ponce*,
  3. N. DiLorenzo*,
  4. M. J. Quinn*,
  5. M. L. May*,
  6. J. C. MacDonald†‡,
  7. M. K. Luebbe,
  8. R. G. Bondurant†‡ and
  9. M. L. Galyean*
  1. Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409
    Texas AgriLife Research, Amarillo 79106
    Department of Agricultural Sciences, West Texas A&M University, Canyon 79016

Abstract

Three studies were designed to evaluate effects of wet distillers grains with solubles (WDGS) on health and performance of newly received beef cattle, in vitro gas production, molar proportions and total concentrations of VFA, and IVDMD. In Exp. 1 and 2, 219 (BW = 209 kg, SE = 2.2 kg; Exp. 1) and 200 beef steers (BW = 186 kg, SE = 3.2 kg; Exp. 2) were used in randomized complete block design receiving studies. The 4 dietary treatments (DM basis) were a 65% concentrate, steam-flaked corn (SFC)-based receiving diet without WDGS (CON) or diets that contained 12.5, 25.0, or 37.5% WDGS. There were no differences among the 4 receiving diets in BW (P ≥ 0.61), ADG (P ≥ 0.75), DMI (P ≥ 0.27), and G:F (P ≥ 0.35), or in the proportion of cattle treated for morbidity from bovine respiratory disease in either of the 2 experiments. In Exp. 3, in vitro methods were used to determine the effects of WDGS on IVDMD, total gas production, and molar proportions and total concentrations of VFA. Substrates used for the incubations contained the same major components as the diets used in Exp. 1, with ruminal fluid obtained from steers fed a 60% concentrate diet. Total gas production was less (P = 0.03) for the average of the 3 WDGS substrates than for CON, with a linear decrease (P = 0.01) in total gas production as WDGS concentration increased in the substrates. In contrast to gas production, IVDMD was greater for the average of the 3 WDGS concentrations vs. CON (P ≤ 0.05) at 6 and 12 h and increased (P ≤ 0.02) with increasing WDGS concentration at 6 (linear and quadratic) and 12 h (linear) of incubation. At 48 h, there was a quadratic effect (P = 0.05) on IVDMD, with the greatest value for 25% WDGS. Molar proportion of butyrate increased linearly (P < 0.01) as the concentration of WDGS increased in the substrate, and the average of the 3 substrates containing WDGS had a greater proportion of butyrate (P = 0.03) than CON. Performance data from Exp. 1 and 2 indicate that including WDGS in the SFC-based diets for newly received cattle can be an effective at concentrations up to 37.5% of the DM. In vivo measurements are needed to corroborate the in vitro fermentation changes noted with addition of WDGS.



INTRODUCTION

Growth of the ethanol industry has increased the availability and use of wet distillers grains plus solubles (WDGS) in the southern High Plains. Extensive research has documented the value of WDGS at varying concentrations in beef cattle finishing diets containing steam-flaked corn (SFC), high-moisture corn (HMC), dry-rolled corn (DRC), and combinations of HMC and DRC. The majority of these data have been generated from research conducted in the northern Great Plains, in which the benefits of including WDGS in finishing diets based primarily on DRC and HMC are evident, as a source of both protein and energy in feedlot diets (Klopfenstein et al., 2008). In addition, recent research findings in the southern Great Plains have demonstrated the efficacy of including WDGS in diets based on SFC (May et al., 2009, 2010a, 2011). To our knowledge, however, there are no published data on the use of increasing concentrations of WDGS in the diets of newly received beef cattle, regardless of the dietary grain processing method. Receiving diets typically have much greater concentrations of roughage than finishing diets, and as such, responses to substitution of WDGS might differ from those in finishing diets. Similarly, there are no published data on the effects that WDGS on morbidity associated with bovine respiratory disease (BRD) in newly received cattle. Our objectives were to i) quantify the effects of increasing concentrations of WDGS compared with a receiving diet typical of those commonly used in the southern Great Plains on performance by newly received beef calves, and ii) use in vitro techniques to examine the effects of WDGS on fermentation of receiving diet substrates that included WDGS.


MATERIALS AND METHODS

All procedures involving live animals were approved by the Texas Tech University Animal Care and Use Committee (Exp. 1 and 3) and the Amarillo Area Cooperative Research, Education, and Extension Team Animal Care and Use Committee (Exp. 2).

Experimental Design and Procedures: Experiment 1

The WDGS was obtained from a commercial ethanol plant (Quality Distillers Grains, LLC) in Plainview, TX, and stored in a plastic silage bag before initiation of the experiment. The WDGS was made from a blend of approximately 70% corn and 30% sorghum, and had this average composition as reported by Quinn et al. (2011; DM basis): 30.0% CP, 15.2% ADF, 10.1% ether extract, 0.04% Ca, 0.65% P, 0.83% K, and 0.69% S.

The experimental design consisted of replicated truckloads of calves, with a randomized complete block structure within each load. The 4 dietary treatments (DM basis) were: 65% concentrate, SFC-based receiving diet without WDGS (CON); and 65% concentrate diets with 12.5, 25.0, or 37.5% WDGS. Diets were formulated to contain equal concentrations of ether extract and RDP (8.9% of DM based on National Research Council, 1996, tabular values; urea was used to balance RDP), and the SFC was flaked to a bulk density of approximately 360 g/L. To achieve these desired nutrient targets, in the 3 WDGS diets, SFC, cottonseed meal, molasses, and supplemental fat in the CON diet were replaced by WDGS.

Before arrival, the identification tags to be used for steers within each load were assigned randomly to 3 blocks (4 contiguous pens constituted 1 block), and the 4 treatments were assigned randomly to the pens within each block. Thus, for the 2 loads, a total of 24 soil-surfaced pens (4.9 m wide by 30.5 m deep; linear bunk space = 4.5 m) were used in the experiment, with 8 to 10 steers/pen.

The first truck load of 111 beef steers (British × Continental; average BW on arrival = 205 kg) obtained from auction barns in West Plains, MO, arrived on August 11, 2010. They were delivered to the Texas Tech University Burnett Center at approximately 0740 h (average pay weight = 217 kg; approximate shrink = 5.5%; approximate time in transit = 11.5 h). The second truck load of 108 beef steers (British × Continental; average BW on arrival = 200 kg) also were obtained from auction barns in West Plains, MO, and arrived on September 01, 2010. They were delivered at approximately 1400 h (average pay weight = 212 kg; approximate shrink = 5.6%; approximate time in transit = 14.5 h). After arrival of each load, the cattle were housed in 6 Burnett Center soil-surfaced pens (approximately 18 to 19 per pen) with access to approximately 1.8 kg/steer (as-fed basis) of long-stemmed sorghum sudangrass hay and water.

After resting overnight, the calves in each load were processed the next morning. At the time of initial processing, calves were weighed using a hydraulic squeeze chute (Silencer Squeeze Chute, Moly Mfg. Inc., Lorraine, KS) set on 4 Avery Weigh-Tronix (Fairmount, MN) load cells (readability ± 0.45 kg) and processed as follows: i) placement in the left ear of a numbered ear tag; ii) recording of coat color; iii) vaccination (subcutaneous injections) with bovine rhinotracheitis virus, bovine viral diarrhea virus (Types I and II), parainfluenza-3 virus, and bovine respiratory syncytial virus [Bovi-Sheild Gold 5 (Pfizer Inc., Overland Park, KS) and Clostridium chauvoei, septicum, novyi, sordellii, perfringens Types C and D bacterin toxoid (Vision 7 with SPUR, Intervet Inc., Millsboro, DE)]; iv) treatment for internal and external parasites with a s.c. injection of Dectomax (Pfizer, Inc.); and v) subcutaneous injection with Draxxin (tulathromycin; Pfizer, Inc). Horns were tipped as needed (3 steers in Load 1 and 3 steers in Load 2), resulting in the removal of approximately 2 cm of horn. All products used during initial processing were administered at the recommended dose of the manufacturer. After each block was processed, the steers in that block were housed in the soil-surfaced pens to which they had been previously assigned. Throughout the experiment, the scale used to measure BW was validated up to 453.6 kg using certified weights (Texas Department of Agriculture; 22.68 kg per weight) each time before the cattle were weighed.

During initial processing, 10 animals were identified as bulls (5 in each truckload). The bulls were sorted to a holding pen until all the cattle in the load had been processed, after which they were then returned to the processing facility, restrained in the squeeze chute, and surgically castrated. After castration, these calves were housed in a shaded pen for the remainder of morning and afternoon. At approximately 1530 h, these steers were removed from the shaded pen and housed in the soil-surfaced pens to which they had been assigned.

After processing and movement to pens, the cattle were offered their assigned 65% concentrate receiving diets. In addition to the treatment diets, a limited quantity of long-stemmed sorghum sudangrass hay [approximately 0.8 kg/steer (DM basis)] was offered for the first 7 d of the study. Diet composition and analyzed nutrient content of the diets are presented in Table 1.


View Full Table | Close Full ViewTable 1.

Ingredient composition (DM basis) and analyzed nutrient content of steam-flaked corn-based receiving diets with either 0, 12.5, 25.0, or 37.5% wet distillers grains with solubles (WDGS; DM basis) fed to beef steers during Exp. 1

 
Treatment1
Item CON 12.5% WDGS 25.0% WDGS 37.5% WDGS
Ingredient
    Steam-flaked corn 45.00 41.44 34.66 23.21
    WDGS - 12.50 25.00 37.50
    Alfalfa hay 17.50 17.50 17.50 17.50
    Cottonseed hulls 17.50 17.50 17.50 17.50
    Cottonseed meal 9.15 5.00
    Molasses 4.00
    Yellow grease 3.35 2.36 1.55 0.78
    Supplement2 2.00 2.00 2.00 2.00
    Limestone 1.00 1.15 1.15 1.15
    Urea 0.50 0.55 0.64 0.36
Analyzed composition,3 %
    DM 84.5 72.9 64.0 56.6
    CP 14.4 15.9 17.5 20.3
    ADF 22.0 24.1 24.6 23.1
    Ether extract 5.5 6.2 6.4 7.1
    Ca 0.69 0.68 0.69 0.61
    P 0.31 0.34 0.35 0.42
    K 1.33 1.15 1.17 1.10
    S 0.24 0.24 0.34 0.39
1CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.
2Diets were formulated to meet or exceed nutrient National Research Council (1996) requirements. Supplement for the CON diet consisted of (DM basis): 66.476% cottonseed meal; 0.500% Endox (Kemin Industries, Des Moines, IA); 0.648% dicalcium phosphate; 10.000% potassium chloride; 4.167% ammonium sulfate; 15.000% sodium chloride; 0.002% cobalt carbonate; 0.196% copper sulfate; 0.083% iron sulfate; 0.003% ethylenediamine dihydroiodide; 0.333% manganous oxide; 0.125% selenium premix (0.2% Se); 0.986% zinc sulfate; 0.010% vitamin A (1,000,000 IU/g; DSM Nutritional Products, Inc., Parsippany, NJ); 0.157% vitamin E (500 IU/g; DSM Nutritional Products, Inc.); 0.750% Rumensin (176.4 mg/kg; Elanco Animal Health, Greenfield, IN); and 0.563% Tylan (88.2 mg/kg; Elanco Animal Health). Supplement for the 12.5, 25.0, and 37.5% WDGS diets consisted of (DM basis): 54.883% cottonseed meal; 0.500% Endox (Kemin Industries); 0.648% dicalcium phosphate; 10.000% potassium chloride; 3.760% urea; 15.000% sodium chloride; 0.002% cobalt carbonate; 0.196% copper sulfate; 0.083% iron sulfate; 0.003% ethylenediamine dihydroiodide; 0.333% manganous oxide; 0.125% selenium premix (0.2% Se); 0.986% zinc sulfate; 0.010% vitamin A (1,000,000 IU/g; DSM Nutritional Products, Inc.); 0.157% vitamin E (500 IU/g; DSM Nutritional Products, Inc.); 0.750% Rumensin (176.4 mg/kg; Elanco Animal Health); and 0.563% Tylan (88.2 mg/kg; Elanco Animal Health).
3Analyzed composition from SDK Laboratories, Hutchinson, KS.

Treatment diets were mixed in a 1.3-m3 capacity paddle mixer (Marion Mixers, Inc., Marion, IA) and transferred by a drag chain conveyor to a tractor-pulled mixer/delivery unit (Roto-Mix 84-8, Dodge City, KS; scale readability of ± 0.45 kg), which was used to deliver feed to each pen. Diets were delivered to the feed bunk in the experimental pens once daily at approximately 0930 h. Estimates of the quantity of unconsumed feed remaining in the feed bunk were recorded between 0730 to 0800 h daily for each of the 3 pens per treatment within a load. Adjustments to the feed delivery for each pen were made to ensure ad libitum access to feed, with the target for feed bunk management being to leave from 0 to 0.45 kg of orts in the bunk each day. In addition, throughout the experiment, adjustments were made to the as-fed deliveries of feed to account for differences in the DM content of the diets. Water tanks in the experimental pens were cleaned twice weekly for the first 2 wk and once weekly during the remainder of the 35-d receiving study.

Diet and WDGS samples were taken from the feed bunks twice weekly to determine the DM content (dried in a forced-air oven at 100°C for approximately 24 h). Similarly, samples of sorghum sudangrass hay were taken twice during the first week of the experiment. Weights for DM determination were measured on an Ohaus (Pine Brook, NJ) electronic balance (readability of ± 0.1 g). Feed bunks were cleaned to remove orts on d 14 and 35 for both loads. In addition on d 28 for Load 2, feed refusals had accumulated in the bunks of 6 pens (1 for CON; 2 for 12.5% WDGS; 2 for 25.0% WDGS; and 1 for 37.5% WDGS) and needed to be removed. The DM content of orts was determined as described for diet samples. The DMI by each pen during various periods of the study was calculated by subtracting the quantity of dry orts at the end of each period plus any dry feed associated with orts that were removed from the total dietary DM delivered to each pen during that period. The number of animals housed per pen was multiplied by number of days in the period to determine animal days, which were divided into the corrected total DM delivered to the pen to obtain average DMI per steer. Twice-weekly diet samples were composited across the study period for the 4 diets, ground to pass a 2-mm screen in a Wiley mill, and analyzed for various chemical components by SDK Laboratories (Hutchinson, KS; Table 1).

On d 14 after arrival, the steers in each load were weighed to obtain a nonshrunk BW measurement and also were revaccinated against bovine rhinotracheitis virus and bovine viral diarrhea virus (Types I and II; Bovi-Shield Gold 5; Pfizer Inc.). To control for any potential differences in gut fill among the 4 treatments, a shrunk BW was obtained at the end of the 35-d receiving period for each load. On d 35, beginning at approximately 1200 h, the water supply to the tanks was turned off and any remaining water in the tanks was drained. Subsequently, all feed was removed from the bunk, weighed, and samples were taken for DM determination. The next morning, cattle were weighed to obtain a final shrunk BW measurement.

Because Draxxin was administered at the time of arrival processing, a 7-d moratorium was applied on treating animals for BRD. This moratorium reflects the length of time that therapeutic concentrations of antibiotic should be maintained in the tissues of the animal after Draxxin is administered (Elam et al., 2008). The cattle were evaluated visually at least once daily throughout the experiment, and animals showing symptoms of BRD (depression, anorexia, lethargic behavior, labored breathing, ocular and nasal discharge) were removed from their pen for further examination. Steers that showed signs of BRD and had a rectal temperature ≤ 37.7°C or ≥ 39.7°C received Resflor Gold (florfenicol and flunixin meglumine; 6.6 mL/50 kg of BW; Merck Animal Health, DeSoto, KS). Steers diagnosed with BRD for a second time were scheduled to be treated at the discretion of the attending personnel with a dose of Terra Vet-200 (oxytetracycline; 9.92 mL/100 kg of BW; Aspen Veterinary Resources, Ltd., Liberty, MO) plus Penicillin-G (Aspen Veterinary Resources, Ltd.; 8.82 mL/100 kg of BW). A waiting period of at least 3 d after initial treatment was followed before a retreatment was administered. An a priori decision was made that cattle that did not respond to 2 treatments would be classified as “chronic” and removed from the study.

Statistical Analyses.

Performance data (pen basis) were analyzed as a randomized complete block design using the Mixed procedure (SAS Inst. Inc., Cary, NC). The effects of treatment, load, and the treatment × load interaction were included in the model, with block nested within load as a random effect. Because there was little BRD morbidity in the experiment, morbidity data were not analyzed statistically. Preplanned contrasts were included to compare i) CON vs. the average of the 12.5, 25.0, and 37.5% WDGS treatments; ii) linear effect of WDGS; and iii) the quadratic effect of WDGS. Alpha values ≤ 0.05 were considered significant, with alpha values between 0.05 and 0.10 considered tendencies.

Experimental Design and Procedures: Experiment 2

The experimental design, dietary treatments (Table 2), and procedures in Exp. 2 were similar to those used in Exp. 1. The WDGS was obtained from a commercial ethanol plant (Quality Distillers Grains, LLC) in Hereford, TX, and stored in a plastic silage bag for the duration of the experiment. The WDGS was a made from a blend of approximately 85% corn and 15% sorghum, and had this analyzed composition (SDK Laboratories; DM basis): 34.3% CP, 17.3% ADF, 12.9% ether extract, 0.10% Ca, 0.86% P, 1.04% K, and 0.55% S.


View Full Table | Close Full ViewTable 2.

Ingredient composition (DM basis) and analyzed nutrient content of steam-flaked corn-based receiving diets with either 0, 12.5, 25.0, or 37.5% wet distillers grains with solubles (WDGS; DM basis) fed to beef steers during Exp. 2

 
Treatment1
Item CON 12.5% WDGS 25.0% WDGS 37.5% WDGS
Ingredient
    Steam-flaked corn 45.50 42.09 35.31 23.85
    WDGS 12.50 25.00 37.50
    Alfalfa hay 17.50 17.50 17.50 17.50
    Cottonseed hulls 17.50 17.50 17.50 17.50
    Cottonseed meal 9.15 5.00
    Molasses 4.00
    Yellow grease 3.35 2.38 1.57 0.81
    Supplement2 2.50 2.50 2.50 2.50
    Urea 0.50 0.53 0.62 0.34
Analyzed composition3
    DM, % 88.6 76.1 66.2 58.7
    CP, % 14.0 16.0 17.8 20.3
    ADF, % 21.2 22.5 23.5 25.3
    Ether extract, % 6.0 6.4 7.0 7.5
    Ca, % 0.88 0.83 0.82 0.83
    P, % 0.25 0.30 0.34 0.43
    K, % 1.11 1.01 1.04 1.13
    S, % 0.19 0.21 0.25 0.30
1CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25.0% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.
2Diets were formulated to meet or exceed nutrient National Research Council (1996) requirements. Supplement consisted of (DM basis): 25.000% wheat midds; 11.150% salt; 57.320% calcium carbonate; 0.664% ferrous sulfate; 1.000% soybean oil; 0.027 ethylenediamine dihydroiodide; 0.136% zinc sulfate; 0.031% manganese sulfate; 0.063% copper sulfate; 0.021 vitamin A-D3 (Cargill Animal Nutrition, Minneapolis, MN); 0.118% vitamin E (Cargill Animal Nutrition); 2.500% ROC technology premix (Cargill Animal Nutrition); 1.071% BeefMax (Cargill Animal Nutrition); 0.730% Rumensin (176.4 mg/kg; Elanco Animal Health, Greenfield, IN), and 0.180% Tylan (88.2 mg/kg; Elanco Animal Health).
3Analyzed composition from SDK Laboratories, Hutchinson, KS.

Two truckloads of 216 male beef calves (British × Continental; average BW on arrival = 186 kg) obtained from auction barns in South Texas arrived at the Texas AgriLife Research Feedlot (Bushland, TX) on July 18, 2011 (average pay weight = 190 kg; approximate shrink = 2.11%). After arrival, cattle from the 2 loads were commingled and allowed to rest for approximately 12 h before initial processing with ad libitum access to water without hay. Calves were blocked by the order they entered the processing chute (40 calves per block and 5 blocks). The final 16 calves to be processed were not used in the experiment. Before arrival, the identification tags to be used for steers were assigned randomly to 1 of 4 pens within each block (4 contiguous pens constituted 1 block), and the 4 treatments were assigned randomly to the pens within each block. For the 2 loads, a total of 20 fly ash-surfaced pens (6.1 m wide × 27.4 m deep; linear bunk space = 3.6 m) was used in the experiment with 10 steers per pen.

Processing, vaccination, and antibiotic therapy protocols were similar to Exp. 1. A large proportion (55.6%) of the calves was bulls, which were castrated at the time of processing and allocated to pen according to their preassigned ear tag. After all calves were processed and housed in their pens, they were offered 0.68 kg/steer long-stemmed prairie hay, with the experimental diet placed on top of the hay for the first 7 d of the experiment. Experimental diets were mixed and delivered with a tractor-pulled mixer and delivery unit (Roto-Mix 84-8, Dodge City, KS; scale readability of ± 0.45 kg). Feed bunks were evaluated daily at 0630 h, and feed was allotted such that approximately 0.30 kg remained in the bunk each morning. Diets were mixed and delivered once daily throughout the duration of the study. Steers were individually weighed and revaccinated (d 21) as described in Exp. 1. On d 42, a shrunk BW measurement was collected as described in Exp. 1.

Steam-flaked corn (bulk density = 348 g/L) was purchased 3 to 4 times a week from a local feedlot. Throughout the study, when wet, stale, or excessive feed remained in the bunk, orts were weighed and a subsample was collected for DM determination. Orts were subtracted from feed offered (DM basis) to calculate DMI. Ingredient samples were collected 3 times per week for SFC and WDGS, and once weekly for all other ingredients for DM determination. Ingredient DM was determined by drying in a 60°C oven for 48 h (AOAC, 1999) and was updated weekly for diet formulation. A composite sample was made for each ingredient using DM samples collected over the duration of the study and sent to SDK Laboratories (Hutchinson, KS) for analysis of chemical components.

Statistical Analyses.

Statistical analyses for morbidity data were conducted with the GLIMMIX procedure of SAS, with a binomial distribution and a logit link function. The proportion of cattle in each pen that were treated 1 or more times for BRD was the dependent variable. Performance data (pen basis) were analyzed as a randomized complete block design using the Mixed procedure of SAS. For both analyses, the fixed effect of treatment was included in the model, with block considered a random effect. As in Exp. 1, preplanned contrasts were included to compare i) CON vs. the average of the 12.5, 25.0, and 37.5% WDGS treatments; ii) linear effect of WDGS; and iii) the quadratic effect of WDGS. Alpha values ≤ 0.05 were considered significant, with alpha values between 0.05 and 0.10 considered tendencies.

Experimental Design and Procedures: Experiment 3

In vitro experiments were conducted to determine the effects of WDGS on gas production, IVDMD, and molar proportions and total concentrations of VFA. Substrates used for the in vitro incubations contained the same major components as the diets used in the receiving study (Table 1). All feedstuffs were collected at the Burnett Center. The SFC and WDGS were allowed to air dry for 48 h by placing the feedstuffs on a tabletop and blowing air over the surface of the feedstuff by means of an electric fan. After drying in this manner, samples of each feedstuff were ground in a Wiley mill to pass a 2-mm screen and then mixed to provide experimental substrates. Mixed substrate samples were sent to a commercial laboratory for nutrient analyses (SDK Laboratories; Table 3).


View Full Table | Close Full ViewTable 3.

Analyzed nutrient content (DM basis) of steam-flaked corn-based in vitro substrates with 0, 12.5, 25.0, or 37.5% wet distillers grains with solubles (WDGS; DM basis) used in Exp. 3

 
Treatment2
Item1 CON 12.5% WDGS 25% WDGS 37.5% WDGS
DM, % 89.9 90.6 90.3 90.3
CP, % 14.3 15.5 16.8 19.0
ADF, % 19.7 20.6 22.9 23.6
NDF, % 29.5 30.7 33.6 36.4
Ether extract, % 5.9 6.0 6.1 6.4
Ca, % 0.73 0.77 0.79 0.80
P, % 0.27 0.30 0.32 0.37
K, % 1.38 1.26 1.22 1.34
1Analyzed composition from SDK Laboratories, Hutchinson, KS.
2CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25.0% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.

For all in vitro measurements, ruminal fluid was collected approximately 4 h after feeding from 2 Jersey crossbred steers (BW = approximately 405 kg) fitted with 7.62-cm ruminal cannulas. The steers were housed in open-lot, soil-surfaced pens at the Burnett Center and fed a 60% concentrate diet based on SFC, with ground alfalfa hay, cottonseed meal, cottonseed hulls, and a supplement formulated to contain 33 mg/kg Rumensin and 11 mg/kg Tylan (DM basis; Elanco Animal Health, Greenfield, IN). After sampling, ruminal fluid from the 2 steers was blended together in equal proportions, immediately placed in a sealed thermos, and transported to the Texas Tech Ruminant Nutrition Laboratory for inoculation of batch cultures. Cultures were inoculated within approximately 30 to 45 min of collecting ruminal fluid. To provide statistical replication (blocking), all in vitro analyses were replicated on 2 separate days.

Total Gas Production.

To determine total gas production during a 24-h incubation period, triplicate samples containing approximately 0.63 g (DM basis) of ground substrate were weighed (Mettler AE 160; Mettler-Toledo, Inc., Columbus, OH) into 160-mL serum bottles. After the addition of 37.5 mL of McDougall’s buffer (McDougall, 1948), the bottles were placed in an oscillating incubator (Environ-Shaker; Lab-Line Industries, Melrose Park, IL). Bottles remained in the incubator as ruminal fluid was collected. Approximately 2 L of collected ruminal fluid was strained through 4 layers of cheesecloth. Strained ruminal fluid (12.5 mL) was added to each serum bottle, after which the serum bottles were flushed with CO2, crimp-sealed with butyl rubber stoppers, and oscillated (125 rpm) at 39°C for 24 h in the Environ-Shaker incubator. Gas production was measured using a water displacement method. A 14-gauge needle connected to a 250-mL inverted buret was used to puncture the butyl-rubber stopper of each 160-mL bottle, and gas production was calculated by measuring the volume (milliliters) of water displaced.

Volatile Fatty Acid Analysis.

The fluid contents of each 160-mL serum bottle from the gas production measurements were retained, and 0.5 mL of a 20% (vol/vol) H2SO4 solution was added to stop fermentation. These samples were frozen and subsequently analyzed by gas chromatography for VFA concentrations (Shimadzu GC-8A; Shimadzu Scientific Instruments Inc., Columbia, MD; Supelco SP-1200, 2 m × 5 mm × 2.6 mm glass column; Supelco/Sigma-Aldrich Inc. Bellefonte, PA). Sample preparation methods and analytical procedures were as described by Goetsch and Galyean (1983).

In Vitro Dry Matter Disappearance.

To measure IVDMD, approximately 0.45 g (DM basis) of substrate was weighed and placed in duplicate 50-mL centrifuge tubes combined with 36 mL of a 3:1 McDougall’s buffer (McDougall, 1948) and ruminal fluid solution, flushed with CO2, and sealed with No. 5 1/2 rubber stoppers with 16-gauge needles puncturing the top to allow for gas release. The tubes were then incubated for 6, 12, 18, 24, 36, and 48 h at 39°C with constant oscillation (125 rpm; Environ-Shaker, Lab-Line Instruments Inc.). After each incubation period, the IVDMD tubes were removed and fermentation was stopped by placing the tubes in an ice-water bath for 15 min. The tubes were then centrifuged at 2,000 × g for 15 min at 4°C. Pepsin solution was prepared by adding 7.92 g of pepsin (1:2,500 pepsin from porcine stomach mucosa; Sigma-Aldrich Inc., St. Louis, MO) and 100 mL of 1 N HCl and diluting to 1 L with distilled water. Approximately 35 mL of pepsin solution were added to each test tube, and tubes were incubated for 48 h at 39°C under constant oscillation (125 rpm; Environ-Shaker). After the pepsin incubation, samples were then filtered (Whatman No. 541 ashless; Whatman International Ltd., Maidstone, UK), rinsed with water, and dried in a forced-air oven at 100°C for 24 h to determine the residue dry weight. The substrate DM content was determined by drying at 100°C in a forced-air oven for 24 h, and the fraction of IVDMD for each tube was calculated by subtracting the dry residue weight (corrected for the blank) from the dry substrate weight and dividing by the dry weight of substrate.

Statistical Analyses.

Total gas production, IVDMD, and VFA measurements were replicated on 2 separate days. Within each day, serum bottles were incubated in triplicate, and IVDMD tubes were incubated in duplicate. Replicate samples within each run were averaged before statistical analyses. All in vitro variables were analyzed using the Mixed procedure of SAS, with day as a random effect and substrate treatment as the fixed effect. Preplanned contrasts were included to compare i) CON vs. the average of the 12.5, 25.0, and 37.5% WDGS treatments; ii) linear effect of WDGS; and iii) the quadratic effect of WDGS. Alpha values ≤ 0.05 were considered significant, and values between 0.05 and 0.10 were considered tendencies.


RESULTS AND DISCUSSION

Although the treatments were the same in the Exp. 1 and 2 and the basic experimental design was the same, the cattle in Exp. 2 had a greater proportion of intact males and a greater incidence of BRD morbidity, and the revaccination date and length of the received period differed between the 2 experiments. In addition, calves in Exp. 2 were received on the same day and commingled before processing, so load could not be used in the statistical analyses. Thus, the decision was made not to pool the data from the 2 experiments for statistical analyses.

Diet Composition—Experiments 1 and 2

Dietary chemical composition data (Tables 1 and 2 for Exp. 1 and 2, respectively) measured on grab samples taken from the feed bunks (Exp. 1) or ingredient samples collected throughout the study (Exp. 2) generally agreed with values expected from formulation. Diets were formulated for equivalent ether extract concentrations, and actual dietary composition of ether extract ranged from 5.5 to 7.1% of DM in Exp. 1 and 6.0 to 7.5% of DM in Exp. 2, with the CON treatment being least and the 37.5% WDGS treatment being the greatest. Diets also were formulated for equivalent RDP concentrations, although no laboratory measures of RDP were evaluated. Diets were not balanced for CP, which led to the 12.5, 25.0, and 37.5% WDGS diets having a greater CP concentration than the CON diet. Sample ADF concentrations ranged from 22.0 to 24.6% of DM in Exp. 1 and 21.2 to 25.3% of DM in Exp. 2. Diet formulation was based on chemical composition of samples analyzed during the initial unloading of the WDGS product (Exp. 1) or previous nutrient values from the same WDGS source (Exp. 2); thus, some variation in concentrations of nutrients might be expected as material was removed from the plastic silo bags.

Feedlot Performance—Experiments 1 and 2

Receiving period performance data from Exp. 1 are presented in Table 4. No differences (P ≥ 0.61) were detected in initial BW or final shrunk d 35 BW among treatments. As would be expected from the lack of differences in BW, no differences (P ≥ 0.75) in ADG from d 0 to 14 or d 0 to 35 were detected among treatments. Similar to ADG results, no treatment effects (P ≥ 0.75) were noted for DMI from d 0 to 14 or d 0 to 35. Consequently, no differences (P ≥ 0.35) in G:F from d 0 to 14 or d 0 to 35 were observed among the 4 treatments.


View Full Table | Close Full ViewTable 4.

Effects of steam-flaked corn-based receiving diets with 0, 12.5, 25.0, or 37.7% wet distillers grains with solubles (WDGS; DM basis) on performance by newly received steer calves in Exp. 1

 
Treatment1
Item CON 12.5% WDGS 25.0% WDGS 37.5% WDGS SE2 P-value3
No. of pens 6 6 6 6
Initial BW, kg 211 208 209 209 2.2 0.78
d 35 BW, kg 253 250 249 251 2.1 0.61
ADG, kg
    d 0 to 14 1.56 1.47 1.51 1.43 0.117 0.88
    d 0 to 35 1.20 1.21 1.15 1.20 0.047 0.75
DMI, kg/(steer∙d)
    Hay (d 0 to 7 only) 0.80 0.80 0.80 0.80
    Concentrate
        d 0 to 14 4.14 4.10 4.05 4.02 0.119 0.91
        d 0 to 35 6.05 5.87 5.91 5.86 0.138 0.75
G:F
    d 0 to 14 0.37 0.36 0.37 0.35 0.020 0.89
    d 0 to 35 0.20 0.21 0.19 0.21 0.005 0.35
1CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25.0% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.
2Pooled SE of the treatment means.
3Observed significance level for the F-test of treatment effects.

Despite the differences in length of the receiving period and source of feeder calves between the Exp. 1 and 2, results for receiving period performance between the 2 experiments were very similar. In Exp. 2, no differences (P ≥ 0.72) were detected in initial BW or final shrunk d 42 BW among treatments (Table 5). As a result, no differences (P ≥ 0.77) in ADG from d 0 to 21 and d 0 to 42 were detected, and similar to Exp. 1, no treatment effects (P ≥ 0.27) were noted for DMI from d 0 to 21 and d 0 to 42 or in G:F from d 0 to 21 and d 0 to 42.


View Full Table | Close Full ViewTable 5.

Effects of steam-flaked corn-based receiving diets with 0, 12.5, 25.0, or 37.7% wet distillers grains with solubles (WDGS; DM basis) on performance by newly received steer calves in Exp. 2

 
Treatment1
Item CON 12.5% WDGS 25.0% WDGS 37.5% WDGS SE2 P-value3
No. of pens 5 5 5 5 - -
Initial BW, kg 185 185 188 186 3.2 0.76
d 42 BW, kg 223 225 228 222 3.9 0.72
ADG, kg
    d 0 to 21 1.18 1.14 1.10 1.04 0.193 0.93
    d 0 to 42 0.90 0.97 0.94 0.87 0.102 0.77
DMI, kg/(steer∙d)
    Hay (d 0 to 7 only) 0.680 0.680 0.680 0.680 - -
    Concentrate
        d 0 to 21 3.87 3.77 4.03 3.81 0.137 0.57
        d 0 to 42 4.98 5.07 5.24 4.92 0.113 0.27
G:F
    d 0 to 21 0.30 0.30 0.27 0.27 0.047 0.88
    d 0 to 42 0.18 0.19 0.18 0.18 0.020 0.93
1CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25.0% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.
2Pooled SE of the treatment means.
3Observed significance level for the F-test of treatment effects.

In Exp. 1, only 5 steers (approximately 2% of all cattle) were treated for BRD-related morbidity, which included 2 steers fed the 12.5% WDGS treatment, 2 steers fed the 25.0% WDGS treatment, and 1 steer fed the 37.5% WDGS treatment. As noted previously, because of the very low incidence of BRD morbidity, these data were not statistically analyzed. Our results are similar to those of Elam et al. (2008), who also administered a prophylactic dose of Draxxin to newly received beef heifers. In their study, no heifers were removed from their pen or treated for BRD-related morbidity. In Exp. 2, 13.2% of cattle in the CON treatment were treated once for BRD-related morbidity, whereas only 3.7% of the cattle in treatments containing WDGS were treated; however, the linear effect of WDGS concentration was not significant (P = 0.14; data not shown). No cattle were classified as chronic in either experiment. Draxxin was chosen for use in both Exp. 1 and 2 as a means of decreasing BRD morbidity and thereby minimizing potential confounding effects that differences among treatments in the proportion of calves treated for BRD might have on receiving period performance. Thus, performance data from these 2 experiments should reflect effects of the dietary treatments per se and are not confounded by differences in BRD morbidity.

Results for our receiving period performance data are similar to those of May et al. (2009), in that no differences in ADG, DMI, or G:F were noted in steers fed 0 or 15% WDGS from corn. In addition, several other similarities between our experiments and the results of May et al. (2009) were noted. The authors reported exceptional animal health, with only 3 steers (1.4% of total) treated for BRD-related morbidity. The 0% WDGS treatment fed in their study was similar to the CON treatment fed in the present studies, and cattle were obtained from auction barns in Southwest, MO, as were the cattle in Exp. 1. Thus, present data and those of May et al. (2009) suggest that in the absence of BRD morbidity, inclusion of WDGS at concentrations up to 37.5% of the DM in SFC-based receiving diets provides an effective source of protein and energy. The lack of morbidity in the present study suggests that our results provide a clear picture of the effects of WDGS in receiving diets on performance.

Ham et al. (1994) conducted a growing trial with DRC-based diets to determine the efficacy of dry and wet corn distillers grains as a protein source for growing calves. They evaluated 3 sources of dry distillers grains (DDGS) and 1 source for WDGS. The 3 DDGS sources contained low, medium, and high levels of acid detergent insoluble N. In contrast to the results of the present study, steers fed distillers grains had greater ADG than controls. Overall, the results of Ham et al (1994) indicated that both dried and wet distillers grains were effective dietary components for growing feedlot calves fed DRC-based diets, which agrees with our results for SFC-based receiving diets.

In Vitro Fermentation Results—Experiment 3

Substrate Composition.

The analyzed substrate composition is shown in Table 3. Because the substrates were made from the same formulation used to derive the diet compositions in Exp. 1, the analyzed nutrient content of the substrates did not differ greatly from that of the diets fed in Exp. 1. The CP composition ranged from 14.3 to 19.0% of DM, whereas ADF and ether extract ranged from 19.7 to 23.6% and 5.9 to 6.4% of DM, respectively.

Total Gas Production.

The effects of inclusion level of WDGS in the in vitro substrates on total gas production are summarized in Table 6. There was a linear decrease in total gas production (P = 0.01) as WDGS concentrations increased, as well as a decrease in total gas production when WDGS was included in the diet relative to CON (P = 0.03). Our gas production results are similar to those of May et al. (2011). In vitro total gas production per gram of DM was greatest in their 0% WDGS substrate compared with 15 and 30% WDGS. In addition, as WDGS concentrations increased in the substrate, total gas production decreased. Although the observations of May et al. (2011) were taken with high-concentrate substrates, it seems that the effects of increasing WDGS concentrations in diets with a greater roughage concentration (e.g., receiving diets) on in vitro gas production are consistent with their findings. Quinn et al. (2010) reported that, with greater concentrations of either corn or sorghum WDGS (0, 15, or 30% WDGS), in vitro gas production decreased, which also agrees with the gas production data from the present study.


View Full Table | Close Full ViewTable 6.

Effects of steam-flaked corn-based receiving diets with 0, 12.5, 25.0, and 37.5% wet distillers grains with solubles (WDGS; DM basis) on in vitro total gas production, DM disappearance (IVDMD), molar proportions of VFA, and total VFA concentration, and the acetate:propionate ratio (A:P) in Exp. 3

 
Treatment1
Contrast P-value3
Item CON 12.5% WDGS 25.0% WDGS 37.5% WDGS SE2 CON vs. D Linear Quadratic
Gas production, mL/g of substrate DM 172 165 160 144 3.5 0.03 0.01 0.28
IVDMD, %
    6 h 38.8 37.7 40.1 44.9 0.47 0.03 0.01 0.01
    12 h 48.1 48.4 51.8 52.0 0.72 0.05 0.02 0.93
    18 h 57.7 58.3 61.3 60.0 1.44 0.29 0.23 0.54
    24 h 64.2 64.8 65.5 64.8 1.65 0.69 0.76 0.71
    36 h 69.0 70.3 71.2 70.1 0.47 0.06 0.14 0.08
    48 h 72.4 72.6 75.3 71.6 0.60 0.38 0.95 0.05
VFA, mol/100 mol
    Acetate 59.9 59.4 59.3 59.1 0.26 0.13 0.11 0.68
    Propionate 22.9 23.3 23.4 23.3 0.32 0.31 0.42 0.50
    Isobutyrate 0.7 0.7 0.7 0.7 0.03 0.36 0.50 0.73
    Butyrate 13.1 13.1 13.2 13.4 0.03 0.03 0.01 0.16
    Isovalerate 1.9 1.9 1.8 1.9 0.03 0.61 0.69 0.64
    Valerate 1.6 1.6 1.6 1.8 0.03 0.08 0.03 0.37
    Total VFA, mM 126.6 125.0 123.2 120.5 1.51 0.12 0.06 0.75
    A:P 2.6 2.5 2.5 2.5 0.05 0.25 0.31 0.56
1CON = steam-flaked corn-based receiving diet without WDGS; 12.5% WDGS = steam-flaked corn-based receiving diet with 12.5% WDGS; 25.0% WDGS = steam-flaked corn-based receiving diet with 25.0% WDGS; 37.5% WDGS = steam-flaked corn-based receiving diet with 37.5% WDGS.
2Pooled SE of the treatment means; n = 6 bottles per treatment (3 bottles on 2 separate d) for gas production and VFA data, and n = 4 tubes per treatment (2 tubes on 2 separate d) for IVDMD.
3P-values are the observed significance levels for contrasts: CON vs. 12.5, 25.0, and 37.5% WDGS inclusion (CON vs. D); and linear and quadratic effects of increasing concentrations of WDGS.

In Vitro Dry Matter Disappearance.

The results for IVDMD at various incubation times are summarized in Table 6. There was an increase in IVDMD for the average of the 3 WDGS concentrations vs. CON (P ≤ 0.05) at 6 and 12 h. In addition, at 6 and 12 h there was a linear increase in IVDMD as the concentration of WDGS increased in the substrate (P ≤ 0.02). Moreover, at 6 h there was a quadratic effect (P = 0.01) on IVDMD, with 37.5% WDGS having the greatest disappearance (44.9%) and 12.5% WDGS having the least disappearance (37.7%); the CON and 25.0% WDGS were intermediate. No differences were detected in IVDMD for the 18- and 24-h incubation periods (P ≥ 0.23). At 36 h, there was a tendency (P = 0.06) for CON to have less IVDMD than the average of the 3 WDGS treatments, as well as a quadratic tendency (P = 0.08) for increased IVDMD as the concentration of WDGS increased. The IVDMD was least for CON and greatest with 25.0% WDGS, whereas 12.5 and 37.5% WDGS were intermediate. At 48 h, there was also a tendency (P = 0.05) for a quadratic increase in IVDMD as the concentration of WDGS increased in the substrates, with IVDMD being greatest with 25.0% WDGS and least with 37.5% WDGS. The CON and 12.5% WDGS substrates were intermediate.

In contrast to our results, with high-concentrate substrates, May et al. (2010b) reported that as either WDGS from corn or sorghum increased from 0 to 15 to 30% (DM basis), IVDMD decreased. Similar to our results, however, Quinn et al. (2010) reported a tendency for a linear increase in IVDMD with WDGS from sorghum, but no effect on IVDMD with WDGS from corn. Nonetheless, May et al. (2011) reported a tendency for substrates containing 15% WDGS to have greater IVDMD than those containing 30% WDGS, which agrees with the quadratic effect of WDGS at 48 h that we noted; however, the difference in IVDMD between 12.5 and 37.5% WDGS at 48 h was relatively small, with the quadratic effect reflecting the increased IVDMD for 25.0% WDGS.

Volatile Fatty Acids.

Results for the in vitro molar proportions of VFA, total VFA concentration, and Acetate:Proprionate (A:P) ratio are presented in Table 6. No differences were observed in molar proportions of acetate, propionate, isobutyrate, isovalerate, or in the A:P ratio. There was a linear increase (P = 0.01) in the molar proportion of butyrate as the concentration of WDGS increased in the substrate. Similarly, the average of the 3 substrates containing WDGS had a greater proportion of butyrate (P = 0.03) than the CON substrate. There also was a linear increase in molar proportions of valerate (P = 0.03) as the concentration of WDGS increased in substrates and a tendency (P = 0.08) for valerate molar proportions to increase for the average of the WDGS substrates relative to CON. Finally, there was a tendency for a linear decrease (P = 0.06) in total VFA concentrations as WDGS increased in the substrates.

Leupp et al. (2009) used 5 ruminally cannulated steers to evaluate the effects of increasing concentrations of DDGS on ruminal fermentation. Steers were fed 70% concentrate, DRC-based diets with 0, 15, 30, 45, or 65% DDGS. As concentration of DDGS increased, molar proportions of acetate decreased, which does not agree with our results. In addition, molar proportions of propionate and butyrate were not affected by treatments, whereas in the present results, although propionate molar proportions were not affected by treatment, a linear increase in molar proportions of butyrate was noted. In agreement with the results of the present study, Leupp et al. (2009) reported a linear decrease in total VFA with increasing DDGS in DRC-based diets. The differences in ruminal fermentation measurements between our study and that of Leupp et al. (2009) likely reflect the use of WDGS in the present study vs. DDGS in their experiment and differences in grain processing method.

Overall, our in vitro fermentation data are somewhat perplexing, in that IVDMD increased at early incubation times but did not differ greatly at 24 h of incubation and beyond, whereas total gas production and total VFA concentration decreased with added WDGS. We interpret these findings to suggest that as the proportion of WDGS increased in these receiving diet substrates, components in WDGS were solubilized, thereby increasing IVDMD, particularly at early incubation times, but not fermented to the same extent as other non-WDGS dietary components, thereby decreasing 24-h gas production and total VFA concentration.

In sum, performance data from Exp. 1 and 2 indicate that including WDGS in SFC-based receiving diets up to a concentration of 37.5% of the DM can be an effective means of providing a source of protein and energy. The general lack of differences in animal performance as WDGS concentrations increased in the diet indicate that WDGS is a viable option compared with a standard SFC-based receiving diet typical of those fed in the southern Great Plains. Given that WDGS decreased in vitro total gas production without affecting IVDMD, further in vivo research is needed to verify these in vitro observations.

 

References

Footnotes


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