• Journal of Animal Science and Technology
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• v.56 no.4
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• pp.14.1-14.7
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• 2014

Two trials were conducted to evaluate the influence of supplemental urea withdrawal on characteristics of digestion (Trial 1) and growth performance (Trial 2) of feedlot cattle during the last 40 days on feed. Treatments consisted of a steam-flaked corn-based finishing diet supplemented with urea to provide urea fermentation potential (UFP) of 0, 0.6, and 1.2%. In Trial 1, six Holstein steers ($160{\pm}10kg$) with cannulas in the rumen and proximal duodenum were used in a replicated $3{\times}3$ Latin square experiment. Decreasing supplemental urea decreased (linear effect, $P{\leq}0.05$) ruminal OM digestion. This effect was mediated by decreases (linear effect, $P{\leq}0.05$) in ruminal digestibility of NDF and N. Passage of non-ammonia and microbial N (MN) to the small intestine decreased (linear effect, P = 0.04) with decreasing dietary urea level. Total tract digestion of OM (linear effect, P = 0.06), NDF (linear effect, P = 0.07), N (linear effect, P = 0.04) and dietary DE (linear effect, P = 0.05) decreased with decreasing urea level. Treatment effects on total tract starch digestion, although numerically small, likewise tended (linear effect, P = 0.11) to decrease with decreasing urea level. Decreased fiber digestion accounted for 51% of the variation in OM digestion. Ruminal pH was not affected by treatments averaging 5.82. Decreasing urea level decreased (linear effect, $P{\leq}0.05$) ruminal N-NH and blood urea nitrogen. In Trial 2, 90 crossbred steers ($468kg{\pm}8$), were used in a 40 d feeding trial (5 steers/pen, 6 pens/treatment) to evaluate treatment effects on final-phase growth performance. Decreasing urea level did not affect DMI, but decreased (linear effect, $P{\leq}0.03$) ADG, gain efficiency, and dietary NE. It is concluded that in addition to effects on metabolizable amino acid flow to the small intestine, depriving cattle of otherwise ruminally degradable N (RDP) during the late finishing phase may negatively impact site and extent of digestion of OM, depressing ADG, gain efficiency, and dietary NE.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.2
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• pp.187-193
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• 2014

As a result of the cost of grains, the replacement of grains by co-products (i.e. DDGS) in feedlot diets is a common practice. This change produces diets that contain a lower amount of starch and greater amount of fibre. Hypothetically, combining feed grade urea (U) with slow release urea (Optigen) in this type of diet should elicit a better synchrony between starch (high-rate of digestion) and fibre (low-rate of digestion) promoting a better microbial protein synthesis and ruminal digestion with increasing the digestible energy of the diet. Four cannulated Holstein steers ($213{\pm}4$ kg) were used in a $4{\times}4$ Latin square design to examine the combination of Optigen and U in a finishing diet containing different starch:acid detergent fibre ratios (S:F) on the characteristics of digestive function. Three S:F ratios (3.0, 4.5, and 6.0) were tested using a combination of U (0.80%) and Optigen (1.0%). Additionally, a treatment of 4.5 S:F ratio with urea (0.80% in ration) as the sole source of non-protein nitrogen was used to compare the effect of urea combination at same S:F ratio. The S:F ratio of the diet was manipulated by replacing the corn grain by dried distillers grain with solubles and roughage. Urea combination did not affect ruminal pH. The S:F ratio did not affect ruminal pH at 0 and 2 h post-feeding but, at 4 and 6 h, the ruminal pH decreased as the S:F ratio increased (linear, p<0.05). Ruminal digestion of OM, starch and feed N were not affected by urea combination or S:F ratio. The urea combination did not affect ADF ruminal digestion. ADF ruminal digestion decreased linearly (p = 0.02) as the S:F ratio increased. Compared to the urea treatment (p<0.05) and within the urea combination treatment (quadratic, p<0.01), the flow of microbial nitrogen (MN) to the small intestine and ruminal microbial efficiency were greater for the urea combination at a S:F ratio of 4.5. Irrespective of the S:F ratio, the urea combination improved (2.8%, p = 0.02) postruminal N digestion. As S:F ratio increased, OM digestion increased, but ADF total tract digestion decreased. The combination of urea at 4.5 S:F improved (2%, p = 0.04) the digestible energy (DE) more than expected. Combining urea and Optigen resulted in positive effects on the MN flow and DE of the diet, but apparently these advantages are observed only when there is a certain proportion of starch:ADF in the diet.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.7
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• pp.968-973
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• 2002

To evaluate the chewing activity of ruminant feeds, four Holstein steers (average body weight $742{\pm}15kg$) were employed. Experimental feeds were four roughages ($NH_3$-treated rice straw, alfalfa hay, corn silage, orchard grass hay) and four concentrate ingredients (cotton seed hull, beet pulp pellet, barley grain, oat grain). Regarding palatability for each experimental feeds which was overviewed during the adjustment period, animals were fed roughages alone, but with 50% $NH_3$-treated rice straw ($NH_3$-RS) for concentrate ingredients. Therefore, all the data for concentrate ingredients was derived by extracting the result per unit obtained from steers fed $NH_3$-RS alone. The experiment was conducted using a 4${\times}$4 Latin square designs for roughages and concentrate ingredients. Experimental feeds were fed during a 10 d adaptation and 2 d chewing data collection during each experimental period. Animals were gradually adjusted to the experimental diet. Dry matter intake (DMI) was restricted at a 1.4% of mean body weight (10.4 kg DM/d). Time spent eating and eating chews per kilogram of DMI were greatest for beet pulp pellet, and lowest for barley grain (p<0.05). Time spent rumination per kilogram of DMI was greatest for $NH_3$-RS, cotton seed hull and orchard grass, but rumination chews were greatest for cotton seed hull and orchard grass except $NH_3$-RS (p<0.05). Roughage index value (chewing time, minute/kg DMI) was 58.0 for cotton seed hull, 56.1 for beet pulp pellet, 55.5 for $NH_3$-RS, 53.1 for orchard grass hay, 45.9 for corn silage, 43.0 for alfalfa hay, 30.0 for oat grain, and 10.9 for barley grain. The ratio of rumination time to total chewing time (eating plus ruminating) was about 72% for the roughages except corn silage (66.9%), and followed by cotton seed hull (69.5%), and ranged from 49.5% to 52.9% for other feeds. Higher percentages of rumination in total chewing time may be evidently indicate the characteristics of roughage. Therefore, this indicate that the chewing activity of concentrate ingredients can be more fully reflects by the ruminating time than total chewing time (RVI), although it is reasonable to define the RVI for roughages.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.1
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• pp.126-136
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• 2019

Objective: This study was performed to compare fat content, reducing sugar contents, sensory traits, and fatty acid (FA) and volatile compound profiles in longissimus thoracis (LT) among Korean cattle (KC), Holstein (HO), and Angus (AN) steers. Methods: Twelve LT samples (about 500 g each) of KC with an average age of $31{\pm}0.42months$, an average carcass weight of $431{\pm}12.5kg$, and a quality grade (QG) of 1+ were obtained from the joint livestock products market. Twelve LT samples of HO cattle with an average age of $24{\pm}0.54months$, an average carcass weight of $402{\pm}7.81kg$, and a QG of 2 were also obtained from the same market. Twelve LT samples of AN steers with an average age of about 20 months and a QG of choice were purchased from a beef delivery company. After slaughter, samples were kept at $4^{\circ}C$ for 42 days and prepared for immediate analysis or stored at appropriate conditions. The chemical composition, color, pH, shear force, collagen content, reducing sugars, sensory evaluation, FA composition, and volatile compound content for each LT sample were analyzed. Results: The LT of KC had the highest (p<0.05) fat content, the highest reducing sugar content, and the highest scores in the sensory evaluation (flavor, tenderness, juiciness, and overall acceptance). All the sensory traits were positively correlated (p<0.001) with intramuscular fat and reducing sugar content. Several FAs and volatile compound profiles varied among the breeds. KC LT had the highest (p<0.05) concentrations of acetaldehyde, 3-methyl butanal, and 3-hydroxy-2-butanone, and these volatile compounds were positively correlated (p<0.05) with all the sensory traits. Conclusion: Variations in fat content and reducing sugar contents and FA and volatile compound profiles may contribute to differences in the sensory quality of LT among breeds.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.9
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• pp.1209-1215
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• 2001

We conducted this study to investigate 24 h leptin profiles and to ascertain whether leptin secretion occurs in a pulsatile manner in cattle. Plasma leptin concentrations were measured every 10 min for 24 h in five Holstein steers aged 10 months. Simultaneously, feeding behavior was recorded every 5 min during this experiment. In two of the five cattle, leptin showed diurnal rhythmicity, which could be described by a cosine, with peaks between 15:00 and 16:00 and nadirs at around midnight. Pulsatile leptin release was quantified by model-free Cluster analysis. Plasma leptin showed a pulsatile pattern in all cattle, with an average number of pulses at 15 peaks/24 h. The daily number of pulses was not related to total time spent eating, ruminating or chewing. However, when divided into six 4 h time intervals, time spent ruminating was positively related with pulse number (p=0.05) in cattle showing no diurnal plasma leptin variation. These results suggest that cattle may have unique diurnal variation and pulsatile patterns of plasma leptin, differing from those of monogastric animals.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.131-138
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• 2013

The present study was conducted with three ruminally cannulated non-lactating Holstein cattle in a $3{\times}3$ Latin square design to determine the fermentation characteristics and effective degradability (ED) in the rumen, as well as the whole tract digestibility of whole crop silage based total mixed ration (TMR) in comparison with conventional separate feeding of concentrate and rice straw for late fattening Hanwoo steers. The cattle in each group were fed separate feeding of concentrate and rice straw (control), whole crop barley silage based TMR (BS-TMR) or whole crop rye silage based TMR (RS-TMR). The ruminal fermentation characteristics such as pH, ammonia-N concentration and total volatile fatty acid were not affected by the experimental diet. The molar portion of acetate ($C_2$) was lowest in rumen fluid 1 h after feeding when cattle were fed BS-TMR (p<0.033). Molar proportions of propionate ($C_3$), butyrate and $C_2/C_3$ were not influenced by the experimental diet. There were no differences in effective degradability or whole tract digestibility of feed components among any of the experimental diets. The data obtained from the metabolism trial indicate that the feeding value of TMR with BS or RS is equal to that of a conventional separate feeding of concentrate and rice straw.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.4
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• pp.313-318
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• 2013

A study was conducted to determine if subacute ruminal acidosis (SARA) induced by feeding high level of non-structural carbohydrates results in increases in lipopolysaccharides (LPS) of peripheral blood in dairy cattle. In this experiment four Holstein steers, two of which having ruminal canulae with indwelling probes placed for measuring long term pH changes, were alloted into two dietary treatments in a cross-over design, where an acidogenic diet (AD) was formulated by including high amount of non-structural carbohydrates (NSC) based on corn silage and corn flake as TMR ingredients. Data for ruminal pH change and plasma LPS concentration were compared against normal diet (ND) which contained grass hay as forage and low NSC ingredients. Feeding AD for more than 14 days to animals brought about a pH change as low as less than 5.8 for more than 4 hours, which made good contrast to ND fed animals. Decreased ruminal pH also had an effect on LPS concentrations which showed significantly higher level for AD compared with ND. Therefore, plasma LPS concentration may be used as an effective indicator to verify acidosis whether it is acute or chronic. Na-bentonite and Propylene glycol, which are frequently included in dairy TMR as additives, helped decrease ruminal pH by buffering and then ultimately alleviates SARA. Therefore, it could also be helpful to lower the occurrence of laminitis which is often caused by increased blood endotoxin (LPS) concentration.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.11
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• pp.1619-1624
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• 2003

The effect of maize hybrid (Suco and Dekalb 765, DK 765), maturity stage (milk, $R_3$ and 1/2 milk line, $R_5$) and animal diet (Diet 1: 70% lucerne hay+30% maize silage; Diet 2: 50% maize silage+20% sunflower meal+30% maize grain) on ruminal stover dry matter (DM) degradability was studied. Additionally, morphological and chemical plant composition was evaluated. Fodder samples ground at 2 mm were incubated in three Holstein steers (400 kg body weight) using the in situ technique. Ruminal degradation kinetics was studied and the effective degradability (ED) was estimated for an assumed kp of 5%/h. The in situ data was analyzed in a complete randomized block design with the animals as blocks. Significant interactions between hybrid${\times}$diet and maturity${\times}$diet on kinetic digestion parameters were detected. In Diet 1, hybrids did not differ in degradable fraction, kd or ED, although a minor difference (p<0.05) in the soluble fraction was found (25.5 and 23.2% for Suco and DK 765, respectively). In Diet 2, the DK 765 had greater degradable fraction (p<0.001) but smaller (p<0.01) kd than Suco, without differences in the soluble fraction or in ED. Anticipating the harvest increased ED of stover from 37.5% in $R_5$ to 44.6% in $R_3$ (average values across hybrids and diets) due to the increase (p<0.001) in the soluble fraction ($R_5$: 22.6%, $R_3$: 28.8%). It is concluded that hybrids had similar stover in situ DM degradability and that soluble fraction represent the main proportion of degradable substrates. Advancing the date of harvesting may not improve the in situ DM degradability of whole maize plant silage since the increase in stover quality is counteracted by the depression in the grain-to-stover ratio. The diet of the animal consuming silage might not improve stover utilization either.

• Korean Journal of Agricultural Science
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• v.44 no.4
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• pp.541-548
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• 2017

This study was conducted to compare in vitro rumen fermentation characteristics among corn grains imported from America, Brazil, Argentina and Ukraine A and Ukraine B. Two Holstein steers, each surgically fitted with a ruminal cannula, consuming total mixed ration were used as rumen fluid donors. In vitro rumen fermentation experiments were performed in a completely random design which included a control (no corn) and treatments with 3.0 g of corn from different geographical origins, i.e., America, Brazil, Argentina, and Ukraine A and Ukraine B, respectively. Ruminal pH, ammonia-N, volatile fatty acid (VFA) and total gas production were measured at 0, 1, 3, 6, 12, 24 and 48 h post-incubation, respectively. No differences (p > 0.05) in mean ruminal pH appeared among the treated groups, however, ruminal pH patterns differed; i.e. corn treated groups had dramatically lower pH compared with control during the entire incubation period. Similarly, no different patterns between the groups in ammonia-N (p > 0.05) appeared until 6 h post-incubation. Unexpectedly, higher ammonia-N concentration for control than that for the corn treated groups appeared after 12 h post-incubation despite that for all groups increased. Total VFA was similar between the groups until 6 h post-incubation, but VFA after 12 h post-incubation was different (p < 0.05), i.e. VFA for corn from Argentina, Ukraine A, Ukraine B, and Brazil were comparatively higher than for America. Overall, data in this study showed that the corns of different origins may have different feed values to ruminants despite having similar chemical compositions.

• Korean Journal of Agricultural Science
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• v.45 no.3
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• pp.419-427
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• 2018

The present study was conducted to investigate the effect of different levels of Korean corn grain on in vitro ruminal fermentation with total mixed ration (TMR) as a basal feed. Three ruminal cannulated Holstein steers (Body Weight $479{\pm}33.0kg$) were used as rumen fluid donors. Treatments for in vitro fermentation were TMR only (control, 3.0 g), TMR substituted partially with high level (HC, TMR 1.5 and corn 1.5 g), and with low level of Korean corn grain (LC, TMR 2.25 and corn 0.75 g), respectively. To measure in vitro ruminal pH, gas production, ammonia N and volatile fatty acids (VFA), the in vitro fermentation incubation was triplicated at $39^{\circ}C$, 120 rpm for 0, 1, 3, 6, 12, 24 and 48 h, respectively. Mean ruminal pH was significantly lower (p < 0.05) for HC than control. Changes in rumen pH was rather similar between the groups till 6 h after incubation, but the lowest pH for HC (pH 5.10) appeared at 48 h compared with control and LC. Total gas production was tended (p < 0.09) to be higher and ammonia N was significantly lower (p < 0.05) for HC than control and LC. Total VFA was higher (p < 0.05) for HC and LC than control but no differences appeared between HC and LC. Overall, the present data indicate that feeding different levels of Korean domestic corn grain may lead to high and sustainable starch degradation in the rumen.