K. M. Koenig

Backgrounding and finishing diets are associated with inflammatory responses in feedlot steers

The objective of this investigation was to study the effects of feeding backgrounding and finishing diets on selected acute phase proteins in the plasma of feedlot steers. Two groups of 12 steers each, at the backgrounding and finishing stages, were offered either a backgrounding (45% barley grain-based concentrate and 55% barley silage on a DM basis) or a finishing (91% barley grain-based concentrate and 9% barley silage) diet for 12 and 15 wk, respectively. Steers at the backgrounding and finishing stages had initial BW of approximately 250 and 380 kg, respectively, at the beginning of the experiment. Blood samples were obtained from a jugular vein at 3-wk intervals during the experimental period beginning at wk 3 or 0 for the backgrounding and finishing periods, respectively. Plasma samples were analyzed for serum amyloid A (SAA), lipopolysaccharide-binding protein (LBP), haptoglobin, and alpha(1)-acid glycoprotein. Steers fed the finishing diet showed peak plasma SAA, LBP, and haptoglobin within 3 wk from the initiation of the diet (20, 23, and 1,940 microg/mL for SAA, LBP, and haptoglobin, respectively). Although plasma alpha(1)-acid glycoprotein reached a peak concentration (449 microg/mL) at the beginning of the finishing phase, no diet effect was obtained for this variable. Steers fed the backgrounding diet showed less variation in the concentrations of plasma acute phase proteins measured; plasma haptoglobin reached a peak concentration (1,720 microg/mL) 9 wk after the beginning of this diet. In conclusion, feeding feedlot steers the backgrounding or finishing diet was associated with increased peak concentrations of acute phase proteins in the plasma. More research is warranted to elucidate the mechanisms behind the inflammatory responses observed in feedlot steers and their implications for health issues and the production efficiency of feedlot operations.

Effects of encapsulated nitrate on enteric methane production and nitrogen and energy utilization in beef heifers

UNLABELLED The objective of this study was to investigate effects of encapsulated nitrate (EN) on enteric methane emission and N and energy utilization in beef heifers. Eight ruminally-cannulated beef heifers (451 ± 21 kg BW) were used in a replicated 4 × 4 Latin square design. Four experimental diets were prepared and fed once daily for ad libitum intake: control, 1%, 2%, and 3% EN (0.15, 0.9, 1.5, and 2.5% NO3(-) in dietary DM, respectively). The control diet (55% forage and 45% concentrate) included encapsulated urea, which was gradually replaced with EN for the EN diets (iso-nitrogenous; 12.5% CP). In each period, EN was increased stepwise by 1% every 4 d during adaptation. A 7-d washout period (control diet offered to all heifers) was provided between experimental periods. Dry matter intake tended to decrease (10.4 to 10.1 kg/d; linear, P = 0.06) with EN levels. Enteric methane yield was linearly decreased (21.3 to 17.4 g/kg DMI; P < 0.01) by EN, and methane production (g/d) recovered to the level from heifers fed the control diet on the first day when EN was withdrawn from the diet. Apparent total-tract digestibility of DM and OM increased (P = 0.03) or tended to increase (P = 0.06), respectively, with EN levels. Starch digestibility tended to be greater (P = 0.07) for EN vs. CONTROL The concentrations of rumen ammonia-N and plasma urea-N decreased linearly (P < 0.01) with EN. Total urinary N and urea-N excretion as proportions of N intake were linearly decreased (46.3 to 41.4%, = 0.09 and 37.1 to 29.9%, P = 0.01, respectively) with EN addition. However, NO3(-)-N excretion in urine increased linearly (P < 0.01) with EN levels. Fecal N excretion was not affected (P = 0.47) by EN, although fecal NO-N excretion increased linearly (P < 0.01) with inclusion of EN (0.09 to 0.88% of total N, P < 0.01). Retained N tended to be increased (percentage of N intake; 16.6 to 21.4%, = 0.08) by the EN. Supplementary EN lowered (6.64 to 5.46% of GE intake [GEI], P < 0.01) energy losses by enteric methane mitigation, which increased ME supply (calculated; 56.5 to 58.8% of GEI, P = 0.01) without changes in calculated heat production (P = 0.24). As a result, retained energy tended to increase (P = 0.07) with EN levels. In conclusion, feeding EN to beef heifers lowered enteric methane production in a dose-response manner, which slightly increased energy supply. Total urinary N excretion was lowered for EN due to lower urinary urea-N excretion.

Nitrogen metabolism and route of excretion in beef feedlot cattle fed barley-based backgrounding diets varying in protein concentration and rumen degradability

The objectives of the study were to characterize the effects of CP concentration and ruminal degradability of barley-based backgrounding diets on route and chemical form of N excretion, ruminal fermentation, microbial protein synthesis, and nutrient digestion in beef cattle. Four Angus heifers (479 ± 14.6 kg average BW) with ruminal and duodenal cannulas were used in an experiment designed as a 4 × 4 Latin square. The basal diet consisted of 54% barley silage and 46% barley grain-based concentrate (DM basis). Dietary treatments included the basal diet with no added protein (12% CP) or diets formulated to contain 14% CP by supplementation with urea (UREA), urea and canola meal (UREA+CM), or urea, corn gluten meal, and xylose-treated soybean meal (UREA+CGM+xSBM). The amount of feed offered was restricted to 95% of ad libitum intake. There was no effect of the diets on DMI (P = 0.38), and therefore, N intake was less (P < 0.05) in heifers fed the 12% CP diets than the 14% CP diets. Fecal N output was not affected by the diet (P = 0.15), but urine N (P < 0.10) and urea N output were greater (P < 0.05) in heifers fed the 14% CP than the 12% CP diets. There was no effect of CP degradability (P > 0.10) on the amount of urine N output. Urine N output was 38.9 and 45.1 ± 5.50% of N intake in heifers fed the 12% CP and 14% CP diets (P < 0.05), respectively. Urea N, the form of N most susceptible to NH3-N volatilization and loss, was the major form of N in urine (75.5% in heifers fed the 12% CP diet and 81.4 ± 1.7% in heifers fed the 14% CP diets; P < 0.05). Supplemental RDP (UREA+CM) and RUP combined with urea (UREA+CGM+xSBM) to provide 14% CP increased (P < 0.05) ruminal NH3-N but had no effect on ruminal peptide N (P = 0.62) and free AA N (P = 0.18) concentration, the flow of microbial (P = 0.34) and feed (P = 0.55) N, and ruminal (starch, P = 0.11; NDF, P = 0.78) and total tract nutrient digestibility (OM, P = 0.21; starch, P = 0.16). Supplementation of barley-based backgrounding diets containing 12% CP with NPN alone or combined with ruminally degradable and undegradable true protein to attain 14% CP had no effect on fecal N output, but urine N and urea N increased irrespective of protein source. In addition, the ruminal degradability of the protein sources did not influence the composition of protein flowing to the intestine and site and extent of nutrient digestibility.

Ammonia emissions and performance of backgrounding and finishing beef feedlot cattle fed barley-based diets varying in dietary crude protein concentration and rumen degradability.

Crossbred beef steers (n = 312) were used in an experiment with a completely randomized design during the growing (235 ± 1.6 kg initial BW) and finishing (363 ± 2.7 kg) phase to determine the effects of dietary CP concentration and rumen degradability on NH3-N emissions, growth performance, and carcass traits. Diets were barley based and consisted of 55% silage and 45% concentrate in the backgrounding phase and 9% silage and 91% concentrate in the finishing phase. For each phase, there were 4 dietary treatments (6 pens of 13 cattle per diet): the basal diet with no protein supplementation (12% CP backgrounding and 12.6% CP finishing) or supplemented (14% CP) with urea (UREA), urea and canola meal (UREA+CM), or urea, corn gluten meal, and xylose-treated soybean meal (UREA+CGM+xSBM). Feed intake and BW of cattle were measured at 3-wk intervals. One pen of steers fed the 12 or 12.6% CP and 1 pen fed 1 of the 14% CP diets were housed in 2 isolated pens to quantify NH3-N emissions using the integrated horizontal flux technique with passive NH3 samplers. In the backgrounding phase final BW, ADG, and G:F were less (P < 0.05) in cattle fed the 12% CP and UREA compared with the UREA+CM and UREA+CGM+xSBM diets. Nitrogen-use efficiency of cattle fed UREA+CM and UREA+CGM+xSBM was equal to that of cattle fed 12% CP and averaged 19.8%. In the finishing phase, there was no effect (P > 0.10) of CP supplementation on BW, DMI, ADG, G:F, N-use efficiency, and carcass traits. The NH3-N emissions from December to February during the backgrounding phase ranged from 4.3 to 25.6 g N/(steer•d) and 3.8 to 16.3% of N intake and from April to July during the finishing phase ranged from 9.7 to 76.4 g N/(steer•d) and 4.4 to 26.7% of N intake. Differences in NH3-N emissions between the pens of cattle fed the backgrounding diets with 12 and 14% CP were not detected. For cattle fed the 12.6 and 14% CP finishing diets, NH3-N emissions tended (P ≤ 0.16) to be less for 2 of the 5 periods and averaged 14.4 and 28.1 g N/(steer•d) and 7.7 and 12.7% of N intake, respectively. The NH3-N emitted as a % of N intake averaged 42% less for cattle fed 12.6% compared with 14% CP. Feeding the barley-based concentrate diet to finishing cattle with 12.6% compared with 14% CP diets reduced NH3-N emissions with no effect on performance. Feeding the barley-based forage diet to backgrounding cattle with 12% CP, however, reduced performance compared with growing cattle fed supplementary degradable and undegradable true protein.

Barley- versus protein-supplemented corn-based diets for feedlot cattle evaluated using the NRC and CNCPS beef models

A study was conducted to evaluate the effects of supplementing a corn-based finishing diet [10.0% crude protein (CP), 6.2% degradable intake protein (DIP), dry matter basis, no protein supplementation] with DIP in the form of urea (13.0% CP, 9.1% DIP) or canola meal and urea (12.8% CP, 8.6% DIP) on dry matter intake (DMI) and average daily gain (ADG). Animal performances were compared with those obtained by feeding a barley-based diet (13.9% CP, 9.6% DIP). Crossbred beef steers (398 ± 28 kg) were allocated to 24 pens and six pens were assigned to each diet. There were no differences (P > 0.05) in DMI and ADG between cattle fed the barley diet and those fed the corn diets supplemented to provide a concentration of DIP similar to that supplied by the barley diet. However, ADG was 10% lower and DMI was 8% lower for cattle fed the corn diet with no protein supplementation (P < 0.05). The NRC and CNCPS models predicted the substantially lower gain of cattle fed the corn diet with no protein supplementation, bu...

Effects of encapsulated nitrate on eating behavior, rumen fermentation, and blood profile of beef heifers fed restrictively or ad libitum.

A slow-release form of nitrate (encapsulated nitrate [EN]) was investigated for effects on risk of toxicity, feed consumption rates, and feed sorting behavior in 2 experiments. In Exp. 1, 5 beef heifers (806 ± 72 kg BW) were fed once daily at 75% of ad libitum intake. Supplementary EN (85.6% DM; 71.4% NO3(-) on a DM basis) was increased by 1% every 4 d from 0 to 1.0, 2.0, 2.9, 3.9, 4.8, and 5.8% of dietary DM (from 10.3 to 15.6% CP and 0.11 to 4.8% total NO3(-)). During the study, a heifer was removed due to nitrate poisoning with 59% blood methemoglobin (MetHb; % of total hemoglobin) at 2.9% EN and another due to refusal to eat the 2% EN diet. When dietary EN increased from 0 to 5.8%, DMI (8.8 to 7.6 kg/d; P < 0.001) and feed consumption from 0 to 3 h were decreased (70.3 to 48.6% of total feed offered on an as-is basis; P = 0.001) and feed consumption from 12 to 24 h was increased (0.6 to 22.6%; P < 0.001). Blood MetHb at 1% EN was negligible (<1.5% of total hemoglobin). However, MetHb levels were greater (average 9.8 vs. 3.1% and maximum 23.6 vs. 13.6% at 3 h) at 2.0 and 2.9% EN than at 3.9, 4.8, and 5.8% EN. In Exp. 2, 8 beef heifers (451 ± 21 kg BW) were used in a replicated 4 × 4 Latin square design and fed for ad libitum intake, once daily, diets containing 0, 1, 2, and 3% EN (isonitrogenous, 12.7% CP, and 0.15 to 2.5% total NO3(-) in dietary DM). Each period consisted of 14 d for adaption and 14 d for sampling followed by a 7-d washout. During adaptation, EN was provided to heifers in a stepwise manner (an increase by 1% every 4 d). In Exp. 2 with ad libitum feeding, feed consumption rates were not different (41.8% of total feed consumed from 0 to 3 h; P = 0.56) among EN levels, but DMI tended to decrease linearly (0 to 3% EN; 10.4 to 10.1 kg/d; P = 0.06) and feed was sorted (linear, P < 0.05) against concentrates (containing EN) with EN inclusion. Potential toxicity of nitrate based on blood MetHb was not observed (all samples <2.0% of total hemoglobin). In both studies, ruminal pH increased numerically (Exp. 1) and significantly (Exp. 2; linear, P = 0.04) with EN. In conclusion, studies indicated that the organoleptic properties of diets containing >3% EN may have caused lower feed intake, reduced feed consumption rates, and feed sorting. In addition, feed consumption rate, which was altered by restrictive or ad libitum feeding, was an important factor affecting the potential toxicity of nitrate (e.g., MetHb). Ad libitum feeding minimized risks of nitrate toxicity.

Feedlot cattle diets based on barley or corn supplemented with dry corn gluten feed evaluated using the NRC and CNCPS beef models

A study was conducted to evaluate the effects of supplementing feedlot finishing corn diets with dry corn gluten feed (CGF). Animal performance and carcass traits were compared with those obtained by feeding a barley-based diet typical of diets fed commercially in western Canadian feedlots. The second objective of the experiment was to evaluate the diets using the 1996 National Research Council (NRC) Beef (level 1 and 2) and Cornell Net Carbohydrate and Protein System (CNCPS, version 5.0) models to determine how well the models predict animal response. Crossbred beef steers (248) weighing 423 ± 20.5 kg were allocated to 24 pens and then six pens were assigned to each of four diets: (1) barley grain (13.8% crude protein, CP), (2) corn grain (9.2% CP), (3) corn grain supplemented with a low level (7%, DM basis) of CGF (CGF-low, 9.7% CP), and (4) corn grain supplemented with a high level (23%) of CGF (CGF-high, 11.7% CP). The barley grain was steam-rolled and the corn grain was dry-rolled. All diets containe...

Optimum extent of barley grain processing and barley silage proportion in feedlot cattle diets: Growth, feed efficiency, and fecal characteristics

Koenig, K. M. and Beauchemin, K. A. 2011. Optimum extent of barley grain processing and barley silage proportion in feedlot cattle diets: Growth, feed efficiency and fecal characteristics. Can. J. Anim. Sci. 91: 411-422. A study was conducted to evaluate the effects of forage proportion and extent of processing of barley grain on growth, intake, feed conversion efficiency, and fecal characteristics of feedlot cattle. Crossbred steers (120; 407±31 kg) were housed individually and assigned to 10 diets (n=12): two degrees of temper rolling of barley grain [processing index (PI) of 82% (standard) or 87% (coarse)] were combined with five levels of barley silage [3, 6, 9, 12, and 15% of dietary dry matter (DM)]. The PI was determined as the weight of grain after processing expressed as a percentage of the weight before processing. Cattle were slaughtered after 104-109 d on feed, at a final weight of 576 kg, SEM = 5.1. There were very few interactions between grain processing and silage proportion for the variables measured. Grain processing had no effect (P>0.05) on average daily gain (1.59 kg d-1, SEM = 0.057) or final weight. Feeding PI-87% barley tended to increase dry matter intake (DMI) over the experiment (7.63 vs. 7.34 kg d-1, SEM = 0.123, P=0.10) compared with feeding PI-82% barley. Higher DMI of cattle fed PI-87% barley corresponded to lower estimated starch digestibility, as a result of increased appearance of whole kernels and grain fragments in feces. Consequently, gain:feed ratio tended (0.210 vs. 0.219, SEM = 0.0035, P=0.06) to decrease by 4% with PI-87% versus PI-82% barley. Similarly, silage proportion had no effect on gain but DMI increased (P=0.05) linearly from 7.19 to 7.75 kg d-1 (SEM = 0.194) with increasing proportion of silage. Consequently, gain:feed ratio decreased linearly from 0.225 to 0.202 (SEM = 0.0056) with increasing silage proportion. Optimum proportion of barley silage to maximize feed conversion efficiency was 3 to 6% of DM. Decreasing the extent of barley processing or increasing the silage proportion may reduce the risk of acidosis, but feed conversion efficiency is lowered. Formulating diets to reduce the incidence of digestive disorders may decrease the cost of mortalities and treatment of sick animals, thereby improving animal health and welfare, but these costs are unlikely to offset the increased cost of gain in commercial feedlots.

Effect of protein source on microbial protein synthesis and nutrient digestion in beef cattle fed barley grain-based diets

Four British cross heifers fitted with ruminal and duodenal cannulas were used in an experiment designed as a 4 × 4 Latin square. The basal diet was composed of 90% barley grain concentrate and 10% barley silage (DM basis) with either no protein supplementation (13.6% CP), or an additional 1.2% CP (% of DM) in the form of urea, canola meal (CM) or blood meal (BM). Ruminal ammonia N concentration was highest (P 0.05). Ruminal pH averaged 5.78 and was not affected by protein source (P = 0.97). Canola meal and BM tended (P 0.10). Ruminal OM and starch digestion were not affected by the dietary treatments (P > 0.10). In conclusion, barley grain-...

Using organic acids to control subacute ruminal acidosis and fermentation in feedlot cattle fed a high-grain diet.

The objective of this study was to determine whether supplementing organic acids can prevent incidences of subacute ruminal acidosis (SARA) in beef heifers fed a diet consisting of 8% barley silage and 92% barley grain-based concentrate (DM basis). Ten ruminally cannulated Hereford crossbred heifers (484 ± 25 kg BW) were used in a replicated 5 × 5 Latin square design with 14-d periods including 10 d for dietary adaptation and 4 d for measurements. Dietary treatments included no supplementation (Control), low fumaric acid (61 g/d), high fumaric acid (125 g/d), low malic acid (59 g/d), and high malic acid (134 g/d). Organic acid supplementation had no effect on DMI ( = 0.77). Similarly, no effects were observed on mean ( = 0.74), minimum ( = 0.64), and maximum ( = 0.27) ruminal pH measured continuously for 48 h. Moreover, area under the curve for pH thresholds 6.2 ( = 0.97), 5.8 ( = 0.66), 5.5 ( = 0.55), and 5.2 ( = 0.93) was similar for all treatments. However, malic acid supplementation lowered the amount of time that ruminal pH was <6.2 compared with the Control ( = 0.02) and fumaric acid treatments ( < 0.01). No effects were observed on total VFA concentrations with organic acid supplementation ( = 0.98) compared with the Control, but greater total VFA concentrations were observed with fumaric acid compared with the malic acid treatments ( = 0.02). The population of total culturable bacteria 3 h after feeding was reduced with supplemental malic acid compared with the Control ( = 0.03) and fumaric acid treatments ( = 0.03). However, no effects were observed with organic acid supplementation on lactic acid-utilizing bacteria ( = 0.59). In conclusion, under the conditions of the present study, organic acid supplementation did not have any significant effects on ruminal fermentation parameters compared with the Control and were not effective in preventing SARA in beef cattle fed high-grain diets.