Exogenous Phytase Plus Cellulase and Phosphorus Excretion in Lactating Dairy Cows

The Professional Animal Scientist 06/2005; 21(3):212-216. DOI: 10.15232/S1080-7446(15)31205-5


The objectives were to assess the ef-fects of exogenous phytase plus cellulase on P excretion in lactating cows. The ef-fects of an exogenous phytase plus cellu-lase mixture and dietary P content on P partitioning and excretion were evaluated in nine early lactation cows (mean = 27 d in milk); six of the cows were rumi-nally cannulated. Cows were assigned to treatments in replicated (three) 3 × 3 Latin squares, and each cow received each treatment sequentially in three, 21-d periods. Diets were 45% forage (all corn silage) and included supplemental P (high P; 0.47%), no supplemental P (low P; 0.32%), or no supplemental P with ex-ogenous phytase (low P-enzyme; 0.32%). Total collection of milk, urine, and feces was conducted on d 19 to 21 of each pe-riod. There were no effects of dietary P or exogenous phytase plus cellulase on DMI, milk yield, or milk composition. Ex-cretion of feces was unaffected by diet, but urine excretion was less by cows fed the low P diets than by cows fed the high P diets (16.5 vs 21.3 kg/d). Com-pared with cows fed high P diets, cows fed the low P diets had reduced P intake (68.1 vs 103.9 g/d), reduced fecal (34.4 vs 51.3 g/d) and urinary P excretion (2.8 1 To whom correspondence should be ad-dressed: vs 9.2 g/d), and lesser P balance (−8.0 vs. 4.4 g/d). The addition of exogenous phytase plus cellulase did not affect P in-take, milk P, fecal P, or urinary P excre-tion, but apparent P digestibility tended to be greater in cows fed diets supple-mented with the enzyme formulations (50.1% vs 40.5% for low P-enzyme and low P, respectively).

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    • "Even in early-lactation cows, however, effects of phytase on production have not been observed. Knowlton et al. (2005) "
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    ABSTRACT: Accurate estimates of phosphorus (P) availability from feed are needed to allow P requirements to be met with reduced P intake, thus reducing P excretion by livestock. Exogenous phytase supplementation in poultry and swine diets improves bioavailability of P, and limited research suggests that this strategy may have some application in dairy cattle rations. The effects of exogenous phytase and forage particle length on site and extent of P digestion were evaluated with 5 ruminally and ileally cannulated lactating cows (188 ± 35 d in milk). Cows were assigned in a 2 × 2 factorial arrangement of treatments in 2 incomplete Latin squares with four 21-d periods. Diets contained P slightly in excess of National Research Council requirements with all P from feed sources. During the last 4 d of each period, total mixed ration, refusals, omasal, ileal, and fecal samples were collected and analyzed for total P, inorganic P (Pi), and phytate (Pp). Total P intake was not influenced by dietary treatments but Pp intake decreased and Pi intake increased with supplemental phytase, suggesting rapid action of the enzyme in the total mixed ration after mixing. Omasal flow of Pi decreased with phytase supplementation, but we observed no effect of diet in ileal flow or small intestinal digestibility of any P fraction. Fecal excretion of total P was slightly higher and Pp excretion was lower for cows receiving diets supplemented with phytase. Milk yield and composition were unaffected by diets. When phytase was added to the mixed ration, dietary Pp was rapidly degraded before intake and total-tract Pp digestion was increased. The lack of effect of phytase supplementation on dietary P utilization was probably because these late-lactation cows had a low P requirement and were fed P-adequate diets.
    Full-text · Article · Nov 2013 · Journal of Dairy Science
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    • "Reduced fecal excretion of P is consistent with recent reports. Knowlton et al. (2005) observed that addition of a blend of phytase and cellulase (same formulation as in the current study) to the diets of lactating cows tended to increase apparent P digestibility (50.1 vs. 40.5%). Kincaid et al. (2005) reported that hydrolysis of phytate P was increased by exogenous phytase, and total P digestibility tended to be increased. "
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    ABSTRACT: The effect of an exogenous phytase and cellulase-containing enzyme formulation on nutrient digestibility and excretion was evaluated in 24 Holstein cows. Cows were fed corn silage- and alfalfa silage-based diets with or without a cellulase-phytase blend for 31 d in a continuous random design. Treatment groups were balanced for parity, days in milk, and mature-equivalent projected milk yield. Diets contained 37% forage, 18.3% crude protein, 35.4% neutral detergent fiber, 18% acid detergent fiber, and 0.42% P (no supplemental P). Cows were fed once daily in Calan doors and milked 2 times daily. 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 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 acid detergent lignin (used as an internal marker) and for N, P, neutral detergent fiber, and acid detergent fiber. Days in milk were similar between treatments, and body weight and milk yield were unaffected by treatment. Cows fed the enzyme formulation had reduced fecal dry matter, neutral detergent fiber, and acid detergent fiber excretion and reduced fecal excretion of N and P. Apparent digestibility of dry matter, acid detergent fiber, neutral detergent fiber, and N tended to increase with the enzyme formulation. Addition of an exogenous phytase and cellulase enzyme formulation to diets for lactating cows reduced fecal nutrient excretion.
    Preview · Article · Oct 2007 · Journal of Dairy Science
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    ABSTRACT: One approach to reduce nutrient losses from livestock farms is to apply biological waste treatment systems such as biological nitrogen (N) removal or enhanced biological phosphorus (P) removal (EBPR) to reduce the nutrient content of land-applied waste. The EBPR process takes advantage of the ability of P-accumulating organisms (PAOs) to sequester excess P as polyphosphate granules in their cytoplasms, yielding a P-depleted liquid effluent and a P-enriched biomass. Biological N removal systems result in the conversion of organic or ammonia-N to innocuous N 2 gas. Understanding the variation in parameters such as chemical oxygen demand (COD), total and volatile suspended solids (TSS and VSS), and ammonia-N (NH 3 -N) is necessary to design these systems. Our objectives were to evaluate the effects of diet and manure separation on parameters important to reactor design. Waste was collected from nine cows fed a high P diet (0.47% P), a low P diet (0.32% P), or low P with exogenous phytase plus cellulase (0.32% P), in a replicated Latin square design (three 3 × 3 squares). Total collection of milk, urine, and feces was conducted on days 19 to 21 of each period, a mixed slurry (urine, feces, and water) was created, and slurry was separated mechanically to generate liquid effluent. Slurry contained more COD, solids, N, and P than liquid effluent, but the COD:P ratio was similar in the two wastes. The ratio of COD:N was higher in slurry than in separator effluent, but the ratio in both wastes was sufficient to support biological N removal. The P content of slurry, liquid effluent, and manure solids from cows fed low P was lower than from cows fed high P, and the COD content of effluent was higher with the low P diet. The COD:P ratio of all wastes was sufficient to support EBPR and biological N removal, but variation was observed with diet. Waste from cows fed low P had a higher COD:P ratio than that of cows fed high P, and waste from cows fed the enzyme-supplemented diet had a lower COD:N ration than that of cows fed the control diet. Dairy manure slurry and effluent will support EBPR and biological N removal. Dietary effects on parameters important to the design of advanced waste treatment systems were observed, but were not of a magnitude that would affect reactor design. Keywords. Lactating cows, Manure treatment, Research-scale manure separation. he development of strategies to reduce the nitrogen (N) and phosphorus (P) content of land-applied livestock manure is an important aspect of long-term efforts to reduce nutrient pollution of water re-sources. Reducing the nutrient content of land-applied waste reduces potential nutrient losses, allows livestock producers to increase the rate of manure application to a fixed land base, and/or reduces the amount of land needed for spreading ma-nure. Approaches to reducing the nutrient content of waste include dietary nutrient management (refining diets to maxi-mize efficiency of utilization of consumed nutrients) and physical or biological nutrient removal systems. Physical separation of manure solids and liquids via gravity or screening reduces organic loading to the liquid treatment system, removes large particles that could plug or damage nozzles in the irrigation system used in land Article was submitted for review in September 2004; approved for publication by the Structures & Environment Division of ASAE in March 2005.
    Preview · Article · May 2005
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