C.A. Löest

Effects of Supplement Strategy on Intake and Digestion of Prairie Hay by Beef Steers and Plasma Amino Acid Concentrations

Twelve steers (373 kg initial BW) were used in three simultaneous 4 × 3 incomplete Latin squares to evaluate the effects of supplemental corn (1.8 kg/d, 0.14 kg CP/d), cooked molasses block (0.45 kg/d, 0.14 kg CP/d), and rumen-protected methionine (RPM; 3.5 g DL-methionine/d) on intake and digestion of prairie hay (5.7% CP, 72.3% NDF on DM basis). Steers that consumed the cooked molasses block ate more (P<0.05) forage OM (7.0 kg/d) and those fed supplemental corn ate less (P<0.05) forage OM (5.5 kg/d) than control steers (6.2 kg/d). Total OM intake was higher (P<0.05) for steers consuming the corn (7.0 kg/d) and cooked molasses block (7.3 kg/d) than for control animals (6.2 kg/d). Digestible OM intake was lower (P<0.05) for steers assigned to the control treatment (3.1 kg/d) than for steers consuming the cooked molasses block (3.9 kg/d) or corn (3.6 kg/d). Digestible NDF intake was higher (P<0.05) for steers assigned to the molasses block treatment (2.9 kg/d) and lower (P<0.05) for steers assigned to supplemental corn (2.0 kg/d) than for those steers assigned to the control treatment (2.4 kg/d). Although RPM increased plasma methionine concentrations (P<0.05), it was ineffective in stimulating forage intake or digestion. In summary, supplementation with a cooked molasses block increased digestible OM intake by increasing forage intake and digestion, whereas corn supplementation depressed forage intake but nonetheless increased total digestible OM intake.

Betaine as a dietary supplement for finishing cattle

One hundred seventy five steers (902 lb feedlot cattle fed finishing diets may respond initial body weight) were used in a finishing positively to supplemental choline. However, study to determine the effect of betaine, choline is degraded extensively by ruminal provided either as feed-grade betaine bacteria, so it must be protected from ruminal (Betafin-S6, Finnsugar Bioproducts) or as fermentation. One function of choline is concentrated separator by-product (CSB; methyl donation via betaine. Ruminal degradesugared beet molasses), on animal perfordation of betaine may be somewhat slower mance and carcass characteristics. Steers than that of choline; thus, betaine may yield were fed a finishing diet based on steamresults similar to those with rumen protected flaked and dry-rolled corn. Treatments choline. In addition, betaine may possibly included 10.5 or 21 g/steer daily supplemenalter ruminal fermentation by serving as a tal feed-grade betaine or 250 g (15.5 betaine) source of either ruminally available nitrogen or 500 g (31 g betaine) of CSB per steer or methyl groups. Our objective was to daily. Dry matter intakes increased (linear, investigate the effect of betaine, provided P<0.1) for steers supplemented with feedeither as feed-grade betaine (Betafin-S6, grade betaine. Average daily gains and feed Finnsugar Bioproducts) or as a concentrated efficiencies were not affected by treatments. separator by-product (CSB), on animal perDressing percent and twelfth rib back fat formance and carcass characteristics. increased (P<0.1) for steers that received feed-grade betaine. Rib-eye area decreased (P<0.1) when steers were supplemented with either feed-grade betaine or CSB. Yield One hundred seventy five steers (902 lb grades were significantly higher (linear, initial body weight) were used in a randomP<0.1) for cattle receiving supplemental CSB ized complete block design. Steers were or feed-grade betaine (quadratic, P<.05). allotted to one of five blocks based on weight Hot carcass weights, KPH, marbling scores, and stratified by breed and weight to one of and percentage of carcasses grading USDA five pens within each block. The three Choice were not affected by supplemental heaviest blocks had five steers per pen (open betaine. In this study, betaine supplementfront barn), whereas the remaining two ation did not markedly alter growth perforhoused 10 steers per pen (uncovered). All mance, but carcass fatness tended to increase steers were implanted with Revalor -S and for both supplements. treated for external parasites using Boss

Effect of hydrogen peroxide on protein degradation of feather meal

Protein degradation of feather meal treated with hydrogen peroxide was evaluated using the in situ bag technique. Bags containing untreated feather meal or feather meal treated with 1.4, 2.5, 2.7, 5.0, or 7.0% hydrogen peroxide (g/100 g feather meal, as fed basis) at various pH and times of heating (55C) were suspended in the rumen of a cannulated steer for 12 hours. Protein degradabilities of feather meal treated with 2.5 and 2.7% peroxide were only 12 to 19% greater than untreated feather meal, but feather meal treated with 5% peroxide had protein degradabilities 56 to 67% greater than untreated feather meal. Treatment of feather meal with 7% peroxide did not increase protein degradation further. Altering pH and heating (55C) peroxidetreated feather meal for 30 or 120 minutes had only minor effects on protein degradability.

Effects of carnitine on performance of finishing steers

Ninety-five crossbred steers (787 lb initial body weight) were fed finishing diets (14.5% crude protein) for 129 days. Diets were based on steam-flaked corn and contained 6% alfalfa and 4% tallow. Steers were supplemented with 2 g per day of L-carnitine, or not supplemented (control). Feed intakes, gains, and feed efficiencies were not impacted by carnitine supplementation. However, steers receiving L-carnitine had fatter carcasses as indicated by tendencies (P<.2) for more subcutaneous fat, higher marbling scores, and higher yield grades. Carnitine supplementation may increase fat deposition and alter carcass quality of finishing cattle.

Role of methionine as a methyl group donor in cattle

Holstein steers were used in two 5 × 5 Latin square experiments to evaluate the sparing of methionine by alternative sources of methyl groups (betaine or choline). Steers were housed in metabolism crates and limit fed a diet high in rumen degradable protein. To increase energy supply, volatile fatty acids were infused into the rumens, and glucose was infused into the abomasum. An amino acid mixture, limiting in methionine, was infused abomasally to ensure that non-sulfur amino acids did not limit protein synthesis. Treatments for Exp. 1 were abomasal infusion of 1) water (control), 2) 2 g/day additional L-methionine, 3) 1.7 g/day Lcysteine, 4) 1.6 g/day betaine, and 5) 1.7 g/day L-cysteine + 1.6 g/day betaine. Treatments for Exp. 2 were abomasal infusion of 1) water (control), 2) 2 g/day additional L-methionine, 3) 8 g/day betaine, 4) 16 g/day betaine, and 5) 8 g/day choline. In both experiments, nitrogen retention increased (P<.05) in response to methionine, demonstrating a deficiency of sulfur amino acids. Responses to cysteine, betaine and choline were small. The low response to cysteine indicates that either the response to methionine is not due to transsulfuration to cysteine, or that cysteine supply does not alter the flux of methionine through transsulfuration. The small responses to betaine and choline suggest that they do not substitute for methionine. Thus, under our experimental conditions, responses to methionine likely were due to a correction of a deficiency of methionine per se rather than of methyl group donors.

Soybean hulls in roughage-free diets for limit-fed growing cattle

Three hundred heifers (573 lb initial body better (P=0.11) for the cattle receiving soyweight) were used in a growing study to bean hulls because less feed was consumed. compare growth performance of cattle fed The roughage-fed cattle gained 23% less roughage-free diets comprised mainly of (P<.01) than cattle fed corn at 2.25% of body soybean hulls with that of cattle receiving weight and were 34% less efficient. roughageand corn-based diets and to determine if cattle fed soybean hull-based diets (

Effect of glycine supplementation onsulfur amino acid use in growing cattle

Previous research has suggested the possibility that the supply of glycine, a nonessential amino acid, might affect how efficiently cattle use methionine. This study was conducted to determine the role of glycine on methionine utilization in growing steers as well as how glycine might impact utilization of cysteine, an amino acid produced in the body from methionine. In Exp. 1, treatments were abomasal infusion of 2 or 5 g/day Lmethionine and 0 or 50 g/day glycine in a factorial arrangement. Efficiency of methionine use was 27% in the absence of supplemental glycine, but 66% in its presence. Glycine supplementation by itself had little effect on protein deposition. In Exp. 2, treatments were abomasal infusions of 0 or 2.4 g/day L-cysteine and 0 or 40 g/day glycine in a factorial arrangement. Supplementation with cysteine in the absence of supplemental glycine did not change nitrogen balance. In fact, when glycine was supplemented alone, nitrogen retention decreased. However, when glycine and cysteine were supplemented together, nitrogen retention was increased. Thus, in the presence of supplemental glycine, it appears that cysteine can improve protein deposition, presumably by sparing methionine. Comparison of this and earlier studies suggests that B-vitamin status may play an important role in this response.

Effect of methionine supplementation on methionine metabolism in growing cattle

Methionine is often the first limiting amino acid for growing cattle. This study was conducted to determine how methionine metabolism is regulated in the liver of growing steers. Six ruminally cannulated steers were used in a replicated 3 × 3 Latin square experiment. Either 0, 5, or 10 g/day L-methionine was infused into the abomasum. These treatments were designed to be deficient, adequate, and in excess of the steers’ requirements for methionine. Methionine supplementation linearly increased protein deposition and decreased the activity of methionine synthase (a methionine conserving enzyme). However, it had little effect on activity of cystathionine synthase (an enzyme that produces cysteine from methionine). Our results suggest that methionine metabolism and regulation in cattle may vary from that in monogastrics.

Peroxide treatment of feather meal for finishing cattle

Heifers (756 lb, 312 head) were used in a finishing study to evaluate the effects of peroxide-treated feather meal on animal performance and carcass characteristics. Diets contained 3.0% of peroxide-treated or untreated feather meal, and were fed ad libitum. Treatment of feather meal with hydrogen peroxide increased in situ protein degradabilities by 56%, but did not significantly alter feed intake or feed efficiencies. Although not statistically different, gains were 2.1% greater for heifers fed peroxide-treated feather meal. Hot carcass weights also averaged 6 pounds heavier for heifers fed diets containing peroxide-treated feather meal. Marbling tended to be lower, but carcasses grading USDA Choice tended to be higher for heifers fed diets containing peroxidetreated feather meal.

Improving the utilization of soybean hulls by cattle with digestive enzyme and dietary buffer supplementation

Four ruminally cannulated Holstein steers (749 lb) were used in a 4 × 4 Latin square experiment to evaluate the benefits of supplementing digestive enzymes and dietary buffers to a soybean hull-based diet fed to steers once daily at 15.4 lb/day (as fed basis). Treatments were arranged as a 2 × 2 factorial with factors being two levels (0 and 3 grams/day) of digestive enzymes and two levels (0 and 93 grams/day) of dietary buffers. Buffers and enzymes were thoroughly mixed with the soybean hullbased diet to provide a completely mixed ration. Digestive enzyme or buffer supplementation increased (P≤0.06) diet digestibilities of dry matter, organic matter, neutral detergent fiber, and acid detergent fiber. Addition of buffer also increased (P≤0.06) digestibilities of glucose, mannose, arabinose, xylose and galactose, whereas enzyme supplementation increased (P=0.03) xylose digestibilities and tended to increase (P=0.10) arabinose digestibilities. The addition of enzymes and buffer to the soybean hull-based diet did not alter passage of liquid or solids from the rumen and therefore cannot account for any of the responses in digestion. Also, ruminal pH was not altered when steers were supplemented with digestive enzyme and(or) buffer. The lack of response in pH to buffer was surprising, because the observed effect of buffer on fiber digestibilities would have been expected to be a result of a moderation of the ruminal pH. Results from this experiment demonstrated that both digestive enzyme and buffer supplementation improved the digestibility of soybean hull-based diet, and responses were greatest when both additives were supplemented together.