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These studies evaluated the effects of betaine, provided either as feed-grade betaine or as concentrated separator by-product (CSB; desugared beet molasses), on performance and carcass characteristics of finishing cattle. In Exp. 1, 175 steers (410 kg initial BW) were fed a finishing diet based on steam-flaked and dry-rolled corn, and treatments included 10.5 and 21 g/d feed-grade betaine and 250 and 500 g/d CSB (supplying 15.5 and 31 g/d of betaine, respectively). Steers fed feed-grade betaine had greater (linear and quadratic effects, P < 0.1) DMI than control steers, but ADG and gain efficiencies were not affected by treatment. Dressing percent and backfat thickness was greater (P < 0.1) for steers that received feed-grade betaine than for controls. Longissimus muscle area was lower (P < 0.1) for steers supplemented with either feed-grade betaine or CSB than for control steers. Yield grades were higher for cattle receiving feed-grade betaine (quadratic effect, P < 0.1) than for control steers. Marbling scores were not affected by supplemental betaine, but the percentage of carcasses grading USDA Select was lower (linear and quadratic effects, P < 0.1) for steers fed feed-grade betaine than for control steers, predominantly due to a greater percentage grading USDA Choice. In Exp. 2,312 heifers (343 kg initial BW) were used in a finishing study to evaluate the effects of graded levels of feed-grade betaine and peroxide-treated feather meal on performance and carcass characteristics. Treatments included two finishing diets (containing peroxide-treated or untreated feather meal) and four levels (0, 4, 8, and 12 g/d) of feed-grade betaine arranged in a 2 x 4 factorial. No significant interactions occurred between treatment of feather meal and betaine. Treatment of feather meal with hydrogen peroxide (5% wt/wt) increased in situ protein degradability but did not alter DMI, ADG, gain efficiencies, or carcass characteristics of heifers when it replaced untreated feather meal in the diet. Top-dressing feed-grade betaine to the diets had no effect on DMI, ADG, and gain efficiencies. Marbling scores were greater (cubic effect, P < 0.05) for heifers fed diets top-dressed with 4 and 12 g/d of feed-grade betaine, but other carcass characteristics were not altered significantly. Overall, feed-grade betaine and CSB did not alter growth performance, but did have minor effects on carcass characteristics. Key Words: Betaine, Cattle, Feather Meal, Feedlots, Performance

Because Gly is a precursor for Ser synthesis and is involved in metabolism of the one-carbon pool, we hypothesized that absorbable Gly supply might impact sulfur amino acid (AA) use in cattle. In Exp. 1, four ruminally cannulated Holstein steers (132 kg) were used in a 4 x 4 Latin square to evaluate effects of Gly supply on Met use. Steers were fed 2.2 kg DM/d of a diet containing 83% soybean hulls and 8% wheat straw. Ruminal infusions of 180 g/d acetate, 180 g/d propionate, 45 g/d butyrate, and abomasal infusion of 300 g/d dextrose provided energy. An AA mixture (352 g/d) limiting in Met (2 g/d) was infused abomasally to ensure that nonsulfur AA did not limit growth. Steers received a daily supplement of 10 mg folate, 10 mg vitamin B-6, and 100 [micro]g vitamin B-12 because they serve as cofactors in Met metabolism. Periods were 7 d with 3 d adaptations and 4 d of excreta collection. Treatments, infused abomasally, were 1) control, 2) 3 g/d added L-Met, 3) 50 g/d Gly, and 4) 3 g/d L-Met + 50 g/d Gly. Retained N (34.4, 40.9, 33.6, and 49.5 g/d for control, Met, Gly, and Met+Gly, respectively) increased (P < 0.05) in response to Met. A numerically (P = 0.23) greater N retention response to Met when Gly was supplemented suggests that Gly supply impacted Met use. Basal conditions for Exp. 2 were similar to Exp. 1 except the basal AA mixture was decreased to 260 g/d. Treatments, infused abomasally, were: 1) control, 2) 2.4 g/d L-Cys, 3) 40 g/d Gly, and 4) 2.4 g/d L-Cys + 40 g/d Gly. Retained N (21.7, 21.8, 18.4, and 24.8 g/d for control, Cys, Gly, and Cys+Gly, respectively) was not affected by Cys in the absence of Gly, but was increased by Cys when Gly was supplemented (Cys x Gly interaction, P = 0.01). This is in contrast to previous results from our laboratory where Cys did not alter N retention in the presence of Gly, although B-vitamins were not supplemented in previous studies. Thus, B-vitamin status may impact sparing of Met by Cys. Supplemental Gly numerically improved Met use and increased retained N when given with Cys. Key Words: Cattle, Methionine, Glycine

Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain amino acids (BCAA) on N retention and plasma amino acid concentrations of steers. Steers were limit-fed (3.0 kg DM daily) twice daily diets high in rumen degradable protein (72% soybean hulls, 19% alfalfa, 5% molasses, 4% minerals and vitamins). Acetate (400 g/d) was continuously infused into the rumen. Treatments were continuous abomasal infusions of 1) 115 g/d of a mixture of 10 essential amino acids (10AA), 2) 10AA with Leu removed (-LEU), 3) 10AA with Ile removed (-ILE), 4) 10AA with Val removed (-VAL), and .5) 10AA with all three BCAA removed (BCAA). Periods were 7 d with 3 d for adaptation to treatments and 4 d for total fecal and urinary collections for N balance. Blood samples were collected 5 h post-feeding on d 7. Retained N decreased (P < 0.06) in response to removal of Leu, Val, or all three BCAA. Plasma Leu concentrations decreased (P < 0.05) in response to removal of Leu and all three BCAA; plasma Ile concentrations decreased (P < 0.05) in response to removal of Ile and all three BCAA, but increased (P < 0.05) in response to removal of Leu; and plasma Val concentrations decreased (P < (0.05) in response to removal of Val and all three BCAA, but increased (P < 0.05) in response to removal of Leu. Responses in N balance and plasma amino acid concentrations of growing cattle limit-fed soybean hull-based diets demonstrate limitations in the basal supply of Leu and Val, but not Ile. Item 10AA -LEU -ILE -VAL N retention, g/d 25.7 23.1 (b) 24.8 22.4 (a) Plasma Leu, [micro]M 200 60 (a) 190 217 Plasma Ile, [micro]M 148 296 (a) 55 (a) 154 Plasma Val, [micro]M 298 530 (a) 289 123 (a) -BCAA SEM N retention, g/d 21.2 (a) 0.79 Plasma Leu, [micro]M 60 (a) 7.8 Plasma Ile, [micro]M 88 (a) 15 Plasma Val, [micro]M 162 (a) 21 Key Words: Leucine, Valine, Cattle

Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain AA supplementation on N retention and plasma AA concentrations of steers. Steers were limit-fed (3.0 kg/d of DM) twice daily diets low in ruminally undegradable protein (72% soybean hulls, 19% alfalfa, 5% molasses, and 4% vitamins and minerals). Acetate (400 g/d) was continuously infused into the rumen. Treatments were continuous abomasal infusions of 1) 115 g/d of a mixture of 10 essential AA designed to exceed the steers' requirements (10AA), 2) 10AA with Leu removed, 3) 10AA with Ile removed, 4) 10AA with Val removed, and 5) 10AA with all three branched-chain AA removed. Experimental periods were 7 d, with 3 d for adaptation to treatments and 4 d for total fecal and urinary collections for N balance. Blood samples were collected 5 h after feeding on d 7. Retained N decreased in response to removal of Leu (P < 0.06), Val (P < 0.05), or all three branched-chain AA (P < 0.05). Plasma Leu concentrations decreased (P < 0.05) in response to removal of Leu and all three branched-chain AA. Plasma Ile concentrations decreased (P < 0.05) in response to removal of Ile and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Plasma Val concentrations decreased (P < 0.05) in response to removal of Val and all three branched-chain AA but increased (P < 0.05) in response to removal of Leu. Responses in N balance and plasma AA concentrations of growing cattle limit-fed soybean hull-based diets demonstrate limitations in the basal supply of Leu and Val but not Ile provided that supplies of all other essential AA are met. Key Words: Cattle, Isoleucine, Leucine, Valine

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A study was conducted to determine how total phenolic (TP), protein precipitable phenolic (PPP), C, and N concentrations, and amount of protein bound (PB) by PPP in leaves of Desmodium paniculatum (panicled tick-clover; PTC) and Lespedeza cuneata (sericea lespedeza; SL) were affected by simulated herbivory and plant ontogeny. All PTC treatments resulted in a decrease (P ≤ 0.05) in TP, PPP, C, and N concentrations and PB between vegetative and seed set stages. All SL treatments resulted in increased (P ≤ 0.05) or stable TP and PPP concentrations from vegetative stage to seed set. The amount of PB was greatest (P ≤ 0.05) in SL plants submitted to 25% defoliation, and flowering and seed set stages had greater (P ≤ 0.05) PB than the vegetative stage. Ontogenesis and defoliation did not (P > 0.05) affect SL N and C concentrations. The protein binding characteristics of PPP from PTC, but not that of SL, appear to be altered in response to stress. Results might correspond with seed dispersal strategies of the two species, with PTC's epizoochory making increased palatability at seed set beneficial. [ABSTRACT FROM AUTHOR]

The beneficial effects of forages containing condensed tannins (CTs) on ruminants are well documented, but the chemical features of CT that yield benefits have not been defined. Some evaluations of limited numbers of highly purified compounds have resulted in positive correlations between CT molecular weight (MW) and biological activity, while others have failed to show a correlation. The objectives of this study were to determine if MW of CT could predict biological activity relative to protein precipitability. MW of condensed tannin, proteinprecipitable phenolics (PPP), and the amount of protein bound (PB) were determined for nine species of warmseason perennial legumes. There was no correlation between PPP or PB and MW (R² 0.11 and R² 0.02, respectively). However, CT concentration did correlate with PPP and PB (R² 0.81 and R² 0.69, respectively). It was concluded that CT MW does not explain the variation in protein precipitation by CT from the forage legumes surveyed. [ABSTRACT FROM AUTHOR]

Presents a study which evaluated the optimal level of alfalfa inclusion in soybean hull-based diets in cattle. Materials and methods; Results; Discussion.