[show abstract][hide abstract] 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.
Journal of Dairy Science 10/2007; 90(9):4356-60. · 2.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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: Knowlton@vt.edu 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).
The Professional Animal Scientist. 01/2005; 21:212-216.