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The objective of the study was to evaluate the effect of forage and non-flber carbohydrate content on duodenal and fecal P flow. Eight Holstein cows (4 primiparous) fitted with ruminal and duodenal cannulae were fed diets containing either 60 or 35% forage and either 30 or 40% NFC in a 2x2 factorial with a replicated 4x4 Latin square design. Dietary P content (% DM) was 0.0.36, 0.36, 0.35, and 0.36 for 60:30, 60:40, 35:30 and 35:40 respectively. Duodenal digesta and feces were collected for 3 d at the beginning of wk 3, every 3 h, advanced 1 h/d. Samples were composited by cow within period and analyzed for total P. Increasing dietary forage content decreased P intake and fecal P excretion, and salivary P flow (daily duodenal P - P intake) tended to increase with increased forage (49.9 vs. 55.8 g/d, P < 0.11). Duodenal P flow and apparent P digestibility were unaffected by forage content. Increasing dietary NFC content increased P intake and increased apparent P digestibility (32.8 vs. 41.5%; P < 0.02). Cows were in negative P balance but cows fed high NFC diets had less negative P balance. In a subset of samples (4 cows fed diets with 40% NFC and 60 or 35% forage in sequential 3 wk periods), P compounds were extracted with 0.1M NaOH-EDTA and quantified by NMR spectroscopy. Duodenal digesta was higher in orthophosphate, pyrophosphate and lipid phosphate concentration than were feces. Concentration of myo-inositol hexakisphosphate (IHP, or phytic acid) was higher in feces, but duodenal and feces IHP flows were similar. Concentration and flow of "other" P (primarily degradation products of IHP) was higher in duodenal digesta than in feces, indicating post-ruminal degradation. Increasing dietary forage increased orthophosphate concentration in both duodenal digesta and feces, but flow of ortho-P was unaffected by diet. Increased understanding of form and amount of P flow through the digestive tract will support refinements to more accurately match absorbable P supply to P requirements of the lactating cow. [ABSTRACT FROM AUTHOR]

Only 25 to 35 % of the crude protein (CP) consumed by dairy cows is converted into milk. Such poor use of dietary CP may be due to inefficiencies associated with forage nitrogen (N) capture and metabolism. Manure N excreted in feces and urine, and the transformation of manure N in air, soil and crops are highly influenced by what dairy cows consume. For example, reducing dietary CP resulted in less total manure N, especially urine N excretion. Ammonia loss from manure from a low CP diet (13.6%) was lower than from a high CP diet (19.4%), representing 9 and 25% of applied manure N, respectively. Increasing condensed tannin content of dietary forage legumes also reduced urine N excretion. Ammonia emissions from barn floors were greater from manure derived from alfalfa silage (AS)-based diets than either birdsfoot trefoil with low or high tannin levels. After application to soil, feces from cows AS-based diets generally lead to higher soil inorganic N (IN) levels than soils amended with feces from corn silage-based diets; feces from AS-based diets increased plant yield and N uptake; feces from high CP diets resulted in greater soil IN levels than feces from low CP diets; and feces from low CP diets did not increase soil IN but decreased plant yield and N uptake. Only a small increase in N efficiency is necessary to make substantial reductions in the dairy industry's contribution to the environmental N load. There appears to be a range of dietary options that satisfy the nutritional requirements of high-producing dairy cows, yet produce manure that has differential effects on post-excretion transformations and environmental losses. Dairy production efficiencies may be gained and manure N losses reduced by incorporating moderate levels of tannins or other protein protection compounds into forages to enhance CP use and reduce dietary CP concentrations, and by developing perennial forages that tolerate manure applications, have improved ammonia absorption and assimilation potential, and are able to assimilate excess soil nitrates. [ABSTRACT FROM AUTHOR]

The objective of the study was to evaluate the effect of increasing dietary beet pulp (BP) content on duodenal and fecal flow of total phosphorus (P) and phytic-acid (PA) P. Eight multiparous Holstein cows fitted with ruminal and duodenal cannulae were fed diets containing 40% forage (corn silage and alfalfa silage) and 0, 6.1, 12.1 or 24.3% unmolassed, pelleted BP (replacing high moisture corn grain on a DM basis) in a replicated 4x4 Latin square design with 21-d periods. The nutrient content of BP averaged 39.9% NDF, 8.9% CP, 8.0% indigestible NDF, 3.9% starch, and 0.29% free glucose on a DM basis. Duodenal digesta and feces were collected every 9 h on d 12-14, and rumens were evacuated and subsampled 4 h after feeding on d 20 and 2 h before feeding on d 21. Samples were composited by cow within period and analyzed for P (nitric/perchloric digestion) and PA-P (anion-exchange method). Linear and quadratic effects of increasing BP content were analyzed using Proc Mixed of SAS. Dietary P and PA content were reduced linearly with increasing percent BP (0.59, 0.58, 0.57, 0.56 %P and 0.15, 0.14, 0.13, 0.11 %PA, respectively). With increasing BP content, P intake, ruminal P content, and rumen P pool size decreased. Digestion, duodenal flow and fecal excretion of P were not affected. With increasing dietary BP content, PA intake was reduced, ruminal pool size was reduced, and rumen turnover time (h) was increased. Apparent ruminal digestibility of PA was decreased linearly with increasing BP (36.5, 31.8, 24.6, 13.6 %; P < 0.02), and apparent total tract PA digestibility was similarly affected (85.3, 82.7, 82.1, 79.1%; P < 0.01). As previously reported, increasing BP was associated with reduced ruminal starch digestion and increased post-ruminal starch digestion. Fecal excretion of PA-P averaged 5.2 g/d. Replacing starchy grains with BP reduced digestion of PA-P, and the majority of the disappearance of PA-P occurred post-ruminally. [ABSTRACT FROM AUTHOR]

Data were collected for one year from a working manure system consisting of a mechanical screen separator, gravitational settling basin (SB), and three aerated storage tanks in series. The manure from 140 lactating dairy cows was flushed with ~ 40,000 L recycled wastewater four times per day. The blend was separated to solid and liquid portions by a mechanical solid-liquid manure separator consisting of two concave screens, pore size 0.79 mm (screen 1) and 3.18 mm (screen 2). The liquid portion flowed into a SB and by gravity into the first aerated tank (pump power: 5 kg O2/h). The wastewater was pumped into sequential aerated tanks, with the third tank supplying the flush water. Composite samples of flushed slurry and effluents from the separator, SB, and tanks 1, 2, and 3 were taken every other week (n=14) and then monthly (n=7). Weighted results were analyzed using Proc Mixed with site and date in the model and date as a repeated measure. Mechanical separation of the blend, including the solids and nutrients from the flushwater, reduced total (TS) and volatile solids (VS) by 19 and 25%, total Kjehldahl N (TKN) by 9%, total P (TP) by 18%, and chemical oxygen demand (COD) by 17%. The SB reduced TS by 11%, VS by 12%, and TKN and TP by 10%. The combined effect of aeration and settling in tanks 2 and 3 decreased TS and VS by 22% and 24%, respectively. Nitrates, TKN, and TP were reduced by 49%, 14%, and 13%. Ortho-P and nitrite concentrations remained steady. The combined tanks reduced COD by 21%, while dissolved oxygen increased from 0.4 to 1.1 mg/l, and the oxidation-reduction potential rose from -230 to 16 mV. Separation of flushed dairy manure with subsequent settling and aeration effectively removed particles and nutrients from the wastewater. Aeration improved dissolved oxygen content and oxidation-reduction potential. [ABSTRACT FROM AUTHOR]

The objectives were to monitor for one year final irrigation water after separation of solids, and settling and aeration in three tanks on a 140-cow flushed freestall dairy with sawdust bedding. The flushed slurry was separated (screen sizes 0.79 and 3.18 mm). The liquid flowed into a 400 m3 settling basin, then via gravity into a tank (2.3 Dm3), and was pumped into the next two successive tanks (2.3 and 4.3 Dm3). The third tank provided the flush and irrigation water. An aerator (pump volume: 5 kg O2/h) supplied air at a surface depth of 45 cm in each tank. On 21 dates volumes and constituents of the flushwater were determined, and the effects of period (Nov. to Apr. 2005, Apr. to July 2005, Aug. to Dec. 2005) on its composition were analyzed using Proc GLM in SAS. The manure system was primed with 5 Dm3 fresh water at startup (July 2004). Daily fresh water input ranged from 34 to 56 m3. Concentrations of solids and nutrients were lowest in the first period. The tanks were pumped down dramatically in Apr. Total, total suspended, volatile, and volatile suspended solids concentrations rose 3, 9, 4, and 8-fold in period two (13.7, 10.9, 9.4, and 8.5 g/l), and dropped in period three (7.0, 3.6, 3.9, and 3.0 g/l, respectively). Total P (63, 253, 147 mg/l), total Kjeldahl N (425, 986, 594 mg/l), and chemical oxygen demand (2.5, 13.5, and 5.4 g/l) were lowest in period one, and highest in period two. Nitrate (0.62 mg/l), nitrite (6.73 μg/l), and pH (8.0) did not change. Dissolved O2 (1.40, 0.35 and 2.05 mg/l) and oxidation-reduction potential (84, -110, and 47 mV) were lowest in period two. Low initial concentrations were likely due to dilution. After perturbation it took four months for solid and nutrient concentrations to decline and stabilize. Continued sampling will be used to assess whether the values observed since Aug, 2005 are sustainable values for this system. [ABSTRACT FROM AUTHOR]

Manure and its nutrient concentrations are important in meeting environmental regulations. This project determined the daily production of manure at the Virginia Tech Dairy in 2005. The herd consisted of 140 Jerseys, Holsteins, and crossbreds, with a mean bodyweight of 560 kg, and averaged 30.1 kg/d milk with 3.16% true protein. The intake of N and P was estimated from the formulated TMR, allowing for a 3% feed refusal. Approximately 103 kg/d of sawdust were used as bedding. The alleys in the freestall barn were flushed every 6 h with recycled wastewater and the slurry was collected. On 17 dates the volumes and constituents of the flushwater and the flushed manure were determined during a 6 h flush cycle. One sampling showed outlying results and was eliminated from the analysis. Net daily accumulations of solids and nutrients from the manure were calculated as the differences between masses in flushed slurry and flushwater. These results were compared with ASAE Standards for "Manure Production and Characteristics" with the Students t-test. Total (TS) and volatile solids (VS) per cow were 6.4 and 5.3 kg/d with bedding, and 5.7 and 4.6 kg/d without bedding. Production of TS and VS without bedding differed from the standards, but VS as a percentage of TS (84%) did not. Daily chemical oxygen demand was similar to the ASAE prediction of 6.2 kg/cow. Total Kjeldahl N (289 g/d), ammonia-N (144 g/d; n=12), and P (77 g/d) accumulations per cow were higher than predicted. Recovery in slurry of the P in feed and bedding minus P in milk was 93%. Recovery of N averaged 59%. Assuming a constant N loss from manure, N loss was 4.3%/h. Assuming that 60% of the manure N was in urine, the urinary N volatilization rate was 15.5%/h. These results showed less than predicted production of TS and VS in the manure of lactating dairy cows and provide a practical estimate of N volatilization and P recovery. [ABSTRACT FROM AUTHOR]

The effect of exogenous phytase + cellulase (CattleAse P™) on nutrient digestibility and excretion was evaluated in 46 Holstein cows (n=23 per trt). Cows were fed corn silage and alfalfa silage based diets with or without a cellulase-phytase blend for 31 days in a CRD. Treatment groups were balanced for parity, days in milk and M.E. projected milk yield (mean = 2.2, 100 and 25,574, respectively). Diets were 37% forage, 18.3% CP, 35.4% NDF, 18% ADF, and 0.42% P (no supplemental P). Cows were fed 1X in Calan doors and milked 2X. Body weight and milk yield were recorded at each milking. Milk samples were collected on d 28 to 31 at 8 consecutive milkings. On d 28 to 31, fecal grab samples were collected from 24 cows (12 per treatment) every 8 h, with sampling times advanced by 2 h each day. Feces samples were pooled by cow. Feed and feces samples were analyzed for sulfuric acid lignin (used as an internal marker) and for N, P, ADF, and NDF. Effect of diet on milk yield and components, body weight, and feed intake was analyzed using PROC Mixed with day as a repeated measure. The effect of treatment on nutrient digestibility and excretion were analyzed with PROC GLM. The phytase + cellulase tended to increase milk yield efflciency (1.68 vs. 1.77 kg milk/kg feed) and milk urea N content was lower in cows fed the enzyme. DMI tended to be lower in cows fed the enzyme (24.4 vs. 22.8 kg/d; P < 0.10), and body weight and milk yield were unaffected by treatment. During the feces collection period (d 28-31) DMI was similar between treatments (25.5 kg/d), and cows fed the enzyme formulation had reduced feces DM excretion (9.55 vs. 7.66 kg/d; P < 0.01) and reduced fecal excretion of N (252 vs. 203 g/d; P < 0.01) and P (66.9 vs. 55.2 g/d; P < 0.01). Apparent digestibility of DM, ADF, NDF, and N tended to increase with the enzyme formulation. Utilization of an exogenous phytase + cellulase formulation reduced fecal nutrient excretion by lactating cows. [ABSTRACT FROM AUTHOR]

Twenty-four newborn Holstein heifer calves (n=6) were fed one of four diets: CON (20/20 fed at 450 g/d, 24%CP, 0.53%P); HP (28/20 fed at 970 g/d, 32%CP, 0.55%P); HFHP- (28/28 fed at 970 g/d, 32%CP, 0.46%P); and HFHP+ (28/28 fed at 1460 g/d, 32%CP, 0.46%P). Calves were grouped by age and treatments were assigned randomly within group. Calves were fed 3.4 L of colostrum twice within 16h of birth. Upon arrival at the research farm, calves were fed a 20/20 milk replacer for the first two feedings. On d 3, treatments were imposed and calf starter (20% CP, 0.48%P) comprised of corn (40%), soybean meal (40%) and cottonseed hulls (20%) was offered free choice. Calves were on study for ~63 d. Total collection of feed refusals, feces and urine were initiated on d 59 ± 2d. Body weight and body size measures were taken weekly. Feces, urine, milk replacers, and starter samples were pooled (25% of each daily sample) by calf or diet, respectively, across collection period and analyzed for total Kjeldhal N and total P. All calves were slaughtered at 63 d to evaluate additional tissues (reported elsewhere). Preplanned contrasts were used to compare CON to all, HP to HFHP-, and CON to HFHP-. Total DMI was not different as calves fed CON consumed more starter than those fed greater amounts of milk replacer. Apparent DMD was lower for calves fed CON. Fecal output (kg DM/d) and fecal N excretion were highest in calves fed CON while urine output (kg/d) and urine N excretion were lowest. Nitrogen intake and urine N excretion were highest for calves fed HFHP+ but were not affected by fat content (HFHP- vs. HP). Nitrogen retention was not improved by increasing energy intake (mean = 34.9%), however, it was improved by increasing N intake (CON vs. HP; 20.5 vs. 38.2%). Phosphorus digestibility, total excretion, partitioning, and retention were not impacted by treatment. Calves fed HP tended to have higher P retention compared to those fed CON. Milk replacer composition influenced nutrient excretion in pre-weaned calves. [ABSTRACT FROM AUTHOR]