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To improve profitability of newly arrived stressed feeder cattle, it is essential to minimize feed costs and health issues while optimizing growth performance. Effects of nucleotides (NA; PSB Complex; DSS Global LLC, McCormick, SC) in diets containing corn germ meal (CGM) or dried corn distillers grains with solubles (DDGS) on the health and performance of receiving and growing cattle were analyzed in 3 experiments. In Exp. 1, 213 crossbred heifers (BW 262 ± 67 kg) were used to compare CGM- and DDGS-containing diets and to determine the effects of NA in an 84-d trial. Treatments were a 2 × 3 factorial arrangement: 2 by-product–containing diets (CGM and DDGS) and 3 amounts of NA (0, 2, and 4 g/d). There were no effects of NA, corn by-product, or their interaction on growth performance (P≥ 0.15). Experiment 2 evaluated performance and immunity effects of NA using 240 crossbred heifers (BW 268 ± 34 kg) in a 56-d trial. The diet contained DDGS, and treatments were 0, 2, and 4 g/d of NA. There were no effects of NA on growth performance (P≥ 0.18) or fecal IgA concentration (P= 0.15). Experiment 3 used 4 ruminally cannulated Holstein heifers in a 4 × 4 Latin square design. Treatments were arranged as a 2 × 2 factorial: 2 by-product–containing diets (GCM and DDGS) and 2 amounts of NA (0 and 3 g/d). No treatment effects were observed for digestion. Ruminal pH was greater when NA was included (P< 0.05). Based on our results, diets can be formulated to contain 24.5% CGM (DM basis) in place of DDGS and maintain animal performance and digestibility. In our experiments, there was no benefit of supplementing NA in growing diets.

Two experiments were conducted to determine the effects of including ammoniated wheat straw in diets for beef cattle on growth performance and digestibility. Treatments consisted of diets containing 70% (DM basis) concentrate containing 40% (DM basis) wet corn gluten feed with 30% (DM basis) roughage from wheat straw (STRW), anhydrous ammonia–treated wheat straw (AMMN), or a 50:50 prairie hay and alfalfa hay blend (CONT). Experiment 1 used 288 crossbred steer calves (271 ± 28 kg) in a randomized complete block design in which steers were fed their experimental diets for 56 d. Final BW, ADG, and G:F were greater for calves fed CONT than for those fed either STRW or AMMN (P< 0.05). Experiment 2 used 6 ruminally fistulated Holstein heifers (288 kg) in a 3 × 3 Latin square design. Heifers fed CONT consumed less (P< 0.05) DM, OM, and ADF compared with those fed AMMN and STRW. Feeding heifers CONT improved (P< 0.05) digestibility of DM and OM but decreased (P< 0.05) digestibility of ADF. Ruminal pH was lowest (P< 0.05) for heifers fed CONT. The results of this experiment suggest that wheat straw and ammoniated wheat straw are equivalent roughage sources but inferior to a 50:50 blend of alfalfa hay and prairie hay when fed to growing calves at 30% of the dietary DM.

An experiment was conducted to evaluate the effect of a pelleted combination of raw soyhulls and condensed corn steep liquor on performance and plasma metabolites when fed to replace a portion of the grain and forage in diets for lactating dairy cows. The raw soybean hull-corn steep liquor pellet (SHSL) contained 24.2% crude protein, 8.7% rumen undegradable protein, 28.9% acid detergent fiber, 36.7% neutral detergent fiber, and 2.5% ether extract (% of dry matter, [DM]). Eighteen multiparous Holstein cows were assigned to one of three diets in a replicated 3×3 Latin square design with 28-d periods. Cows were blocked by pretreatment body weight and energy-corrected milk (ECM) and assigned to control, SHSL (20.7% of diet DM), or pelleted raw soybean hulls ([PSH] 14.3% of diet DM). The SHSL product replaced 6.2% alfalfa hay, 3.7% corn silage, 6.6% corn, and 3.3% soybean meal (SBM), and 1.7% expeller SBM replaced solvent SBM in order to maintain dietary levels of rumen undegradable protein. PSH replaced 6.2% alfalfa hay, 3.7% corn silage, and 5.1% corn. Diet crude protein (%) and energy density (Mcal/kg NEL) were 16.6 and 1.64, 16.3 and 1.65, 17.1 and 1.63 for control, SHSL, and PSH, respectively. Cows fed PSH consumed more DM than cows fed control, with the intake of cows fed SHSL being intermediate. SHSL and PSH increased ECM, milk protein, and solids-notfat and showed higher concentrations of milk and plasma urea N and total alpha-amino N in plasma than the control diet. Furthermore, feeding SHSL tended to improve the ratio of ECM to DM intake. There was no effect of diet on concentrations of total essential and nonessential amino acids in plasma. These production data suggest SHSL can replace a portion of the forage, grain, and SBM in diets for lactating dairy cows without decreasing lactational performance.

We used four ruminally cannulated, multiparous Holstein cows (690kg; 21 kg/d milk) in a 2-period crossover design to determine the impact of feeding a raw soybean hull-corn steep liquor pellet (SHSL) on induced subacute ruminal acidosis (SARA) in lactating cows. Cows were fed control [30% alfalfa hay, 15% corn silage, 34% corn, 9% whole cottonseed, 5% soybean meal (SBM)] or SHSL (20% of diet DM) diets as TMR. SHSL replaced 6.2% alfalfa hay, 3.7% corn silage, 6.6% corn, and 3.3% SBM. Periods were 15 d (10 d adaptation, 2 d for prechallenge measures, and 3 d of SARA challenge). Cows were fed once daily at a common DMI dictated by the cow consuming the least. Cows were fasted 12h before the first SARA challenge. For each of the three SARA challenges, cows were offered 75% of their daily diet at 0600h. The remaining 25% of diet DM was replaced by ground corn, which was mixed with the orts that remained 2h after feeding and placed into the rumen. Ruminal pH declined linearly with time after feeding, and this decrease was greater during the SARA challenges. Ruminal lactate increased linearly with repeated SARA challenges. Concentrations of total ruminal VFA increased linearly after feeding, and increases were greater when cows were challenged. No differences were observed due to SHSL inclusion. The model induced SARA, but partial replacement of alfalfa, corn silage, corn, and SBM by SHSL did not influence responses to SARA challenges.

Multigravid Holstein cows (n = 75) were used in a randomized block design to evaluate the effect of prepartum diets formulated to supply surplus energy and incremental concentrations of protein on the nutritional status of dairy cows at parturition. Cows were blocked according to expected calving date and assigned to one of five diets: 9.7, 11.7, 13.7, 14.7, and 16.2% crude protein (CP). Dietary treatments were initiated 28 d before expected calving date and fed until parturition. A common diet was fed postpartum. Dry matter intake and milk yield were recorded daily through 90 d postpartum. Increasing the protein concentration from 9.7 to 14.7% of dry matter during the last 28 d of gestation improved responses of cows during lactation. Increasing dietary protein up to 14.7% also increased milk yield response to recombinant bovine somatotropin (rbST) during the ninth week of lactation and yields of 305-d 2× mature equivalent milk, milk protein, and milk fat. Plasma aspartate aminotransferase tended to be highest in cows fed 13.7 and 14.7% CP prepartum, but decreased linearly postpartum in response to dietary protein levels. There were no treatment differences for plasma insulin-like growth factor-1 (IGF-1) at d 60 postpartum (before rbST provision), but IGF-1 on d 90 (after rbST provision) was higher in plasma of cows fed 14.7% CP than the other diets except 13.7% CP. Close-up diets containing 13.7% CP and surplus energy produced the most beneficial outcomes during the subsequent lactation.

In experiment 1, 24 midlactation, multiparous Holstein cows were used in six 4 × 4 Latin squares to evaluate extruded-expelled cottonseed (EEC) as a source of ruminally undegradable protein (RUP). Diets were formulated to contain: 16% crude protein (CP), 35% RUP (SBM16); 18% CP, 35% RUP (SBM18); 16% CP, 40% RUP using EEC (EC16); and 16% CP, 40% RUP using a fishmeal-blood meal blend (FBM16). Milk yields (37.2 kg/d) and percentages of milk fat, protein, casein, and SNF were similar across diets. Cows fed FBM16 consumed less dry matter (DM) (28.0 kg/d) than those consuming other diets (29.4 kg/d). In experiment 2, 18 midlactation, multiparous Holstein cows were used in six 3 x 3 Latin squares to determine the value of EEC as a replacement for whole cottonseed in lactating cow diets. Diets contained whole cottonseed (CS), EEC plus tallow (ECT), or EEC (EC). Diets were formulated to be similar in energy, N, and RUP. Milk yields (35.5 kg/d), DM intake (27.0 kg/d), and milk fat percent were similar across diets. Percentages of milk protein and SNF were higher for EC than CS or ECT. These production data suggest that EEC can replace whole cottonseed in isocaloric diets and can be partially substituted for soybean meal or a fishmeal-blood meal blend without affecting lactational performance. In situ ruminal degradation and in vitro ammonia N release indicate that processing of EEC was inadequate to protect the protein from ruminal degradation and EEC would not be a source of RUP.

Two experiments were conducted to evaluate responses of primiparous and multiparous Holstein cows to diets containing wet corn gluten feed (WCGF). In both experiments, WCGF replaced a mix of alfalfa hay, corn silage, and corn grain. In experiment 1, 32 primiparous Holstein cows (four pens with eight cows/pen) were used in two 2 × 2 Latin squares with 28-d periods. Cows were housed in free stalls and fed diets containing 0 or 20% WCGF dry matter (DM) basis. Cows fed WCGF consumed more DM and produced more energy-corrected milk (ECM) than controls. Production efficiency (ECM/DM intake) was not affected, but yield of milk components was improved by WCGF. In experiment 2, 24 multiparous Holstein cows were used in six 4 × 4 Latin squares with 28-d periods to determine the optimal dietary inclusion rate for WCGF. Cows were housed in a tie-stall barn and fed a total mixed ration twice daily. Treatments were 0, 20, 27.5, and 35% WCGF (DM basis). Cows fed WCGF produced more ECM than controls, but ECM did not differ among cows fed WCGF diets. Cows fed 20 and 27.5% WCGF consumed more DM as a percentage of body weight than those fed either 0 or 35% WCGF. Cows fed WCGF produced ECM more efficiently than controls. Percent milk fat was lower, but fat yield was not different when WCGF was added to diets. Milk protein and lactose yields were higher when WCGF was fed. Plasma glucose, α-amino N, and triglyceride concentrations were similar among diets in both experiments, but plasma urea N was higher for cows fed WCGF in experiment 2.

Twelve steers (373kg initial BW) were used in three simultaneous 4 × 3 incomplete Latin squares to evaluate the effects of supplemental corn (1.8 kg/d, 0.14kg CP/d), cooked molasses block (0.45 kg/d, 0.14kg CP/d), and rumen-protected methionine (RPM; 3.5g 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.

Five ruminally and duodenally cannulated Holstein steers (305kg) were used in a switchback experiment with three periods to evaluate two experimental treatments: a basal diet with or without 45ppm of lasalocid. The basal diet contained approximately 43% rolled corn, 45% alfalfa hay, and 10% soybean meal (DM basis). Lasalocid did not affect feed intake or ruminal digestion of OM and NDF. Ruminal digestion of ADF tended to increase with supplemental lasalocid. Total tract digestion of OM, NDF, ADF, and N and intestinal flow of amino acids were not affected by lasalocid. Also, the ratio of microbial to nonmicrobial N fractions at the duodenum remained unchanged. Ruminal pH and concentrations of NH3, VFA, peptides, and amino acids were not affected by lasalocid. Ruminal protease activity decreased with supplemental lasalocid, but this decrease was not reflected in other variables, such as ruminal concentrations of peptides and amino acids. Ruminal deaminase activity remained unchanged. Thus, we concluded that dietary lasalocid did not alter ruminal protein degradation or postruminal flow of amino acids.

Newborn Holstein heifers (n = 32) and bulls (n = 12) were used to investigate the use of dry feed intake as a percentage of birth weight as a weaning criterion. Three different percentages (1, 1.5, and 2%) were used. Calves in the 1% treatment group met the weaning criterion earlier than did those in the 1.5 and 2% treatment groups; no difference was detected between the latter two groups. Total dry feed intake at 8 wk was higher for calves in the 1% treatment group than for calves in the other treatment groups; no difference was detected between the 1.5 and 2% treatment groups. Weights for all calves at 8 wk and weights of heifer calves at 12, 16, and 20 wk were not different among groups. Using dry feed intake at 1% of birth weight as a weaning criterion reduced days to weaning, increased dry feed intake from birth to 8 wk, decreased variation in weaning age, and had no apparent negative effect on growth at 20 wk of age. Using dry feed intake as a percentage of birth weight appears to be a suitable criterion to determine when to wean dairy calves.

Twelve newborn Holstein bull calves were used to evaluate the effects of dietary abrasiveness, determined by a new method, on ruminal development. Calves were blocked by age and body weight and were assigned to one of three different diets. Each diet had the same ingredients but different particle sizes, which resulted in different abrasive values. No differences were detected in molar percentages of volatile fatty acids in ruminal fluid or in plasma concentrations of urea, glucose, or β-hydroxybutyrate. The pH of ruminal fluid was lower for calves fed the fine and intermediate diets than for those fed the coarse diet. Digesta-free weights of the stomach and stomach compartments were similar among calves fed the three diets, except that omasum weights were heavier for calves fed the fine diet. Length of the ruminal papillae increased as the abrasive value of the diet decreased. Measurements of ruminal tissue layers from the ventral floor of the cranial sac were not different among diets, but the keratin portion represented more of the epithelial layer for calves fed the diet with the lowest abrasive value, thus decreasing the percentage of metabolically active tissue for those calves.

We evaluated the effect of centrifuging rumen fluid prior to analysis on concentrations of α-amino N (AAN) and peptides. Rumen fluid was collected from steers fed grain-based diets at either various times after feeding or after dosing the rumens with solubilized casein. Fluid was either directly processed for peptide analysis by acidifying 10ml of rumen fluid with 0.5ml of 70% (wt/wt) perchloric acid, or first centrifuged at 500×g for 20min to remove protozoa and then at 30,000×g for 15min to remove bacterial cells prior to further processing. By removing microbial cells, intracellular AAN and peptides were not included in subsequent analyses. Concentrations of AAN were determined using an automated trinitrobenzene sulfonic acid assay, and peptides were determined as the increase in AAN following acid hydrolysis of the samples. When casein was not dosed, removal of microbial cells prior to analysis decreased concentrations of both AAN and peptides, and the decrease was greater for AAN (2.2mM) than for peptides (1.2mM). Dosing with casein led to much higher concentrations of ruminal peptides and AAN. After casein dosing, decreases in AAN and peptide concentrations due to prior centrifugation (2.1mMand 1.0mMfor AAN and peptides, respectively) were similar to the decreases observed before the casein dosing. Results suggest that the contribution of intracellular AAN and peptides to the concentrations in ruminal fluid are relatively constant across broad ranges of dietary protein supply for cattle fed corn-based diets.