Milk production and nutrient digestibility by dairy cows when fed exogenous amylase with coarsely ground dry corn
ABSTRACT The digestibility of starch provided by coarsely ground corn is often low, which reduces the digestible energy (DE) concentration of the diet. We hypothesized that adding exogenous amylase to diets based on coarsely ground dent corn would increase dietary DE resulting in greater milk production. Total-tract nutrient digestibility was measured in a partially replicated Latin square experiment (6 cows and 4 periods) with a 2 × 2 factorial arrangement of treatments. Diets had 26 or 31% starch with or without exogenous amylase (amylase was added to the concentrate mixes at the feed mill). In the low and high starch diets, coarsely ground dry corn (mean particle size=1.42 mm) provided 43 and 62% of total dietary starch (corn silage provided most of the remaining starch). No treatment interactions were observed. High starch diets had greater dry matter (DM), organic matter, and energy digestibility than low starch diets, and diets with amylase had greater neutral detergent fiber digestibility than diets without amylase. Digestibility of starch averaged 88% and was not affected by treatment. A long-term (98-d) lactation study with 48 Holstein cows (74 d in milk) was conducted using 3 of the diets (low starch diets with and without amylase and the high starch diet without amylase). Addition of amylase to a diet with 26% starch did not affect intake, milk yield, milk composition, body weight, or body condition. Cows fed the diet with 31% starch had greater DM and DE intakes; yields of milk, fat, and protein; and feed efficiency than those fed diets with 26% starch. Milk composition was not affected by starch concentration. Adding exogenous amylase to a lower starch diet did not make the diet nutritionally equivalent to a higher starch diet.
- SourceAvailable from: German D MendozaANIMAL NUTRITION AND FEED TECHNOLOGY 01/2013; 13(3):391. · 0.36 Impact Factor
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ABSTRACT: A meta-analysis was performed to determine the influence of cereal grain type and corn grain harvesting and processing methods, dietary starch, rumen-digestible starch, and forage NDF concentrations on intake, digestion, and lactation performance by dairy cows using a data set comprising 414 treatment means from 102 peer-reviewed journal reports from 2000 to 2011. Categories for corn processing were dry ground, cracked or rolled corn (DRY), high-moisture shelled or ear corn (ENS), and steam-flaked or -rolled corn (STM); categories for kernel mean particle size were 500 to 1,000, 1,000 to 1,500, 1,500 to 2,000, 3,000 to 3,500, and 3,500 to 4,000 µm for dry corn and <2,000 and ≥2,000 µm for ensiled corn. Dietary starch and forage NDF concentrations were used as continuous variables. Data were analyzed using PROC MIXED in SAS (SAS Institute Inc., Cary, NC), with treatment as fixed and trial as random effects. Total-tract starch digestibility was reduced and milk fat content was greater for DRY compared with ENS or STM. Total-tract digestibility of dietary starch was reduced for both DRY and ENS as particle size increased. Increased dietary starch concentrations increased milk yield and protein content, but decreased ruminal and total-tract NDF digestibilities and milk fat content. Dry matter intake, total-tract starch digestibility, and milk protein concentration decreased as forage NDF in the diet increased. Total-tract starch digestibility was positively related to ruminal (percentage of starch intake) and postruminal (percentage of duodenal flow) starch digestibilities.Journal of Dairy Science 11/2012; 96(1). DOI:10.3168/jds.2012-5932 · 2.55 Impact Factor
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ABSTRACT: We performed a meta-analysis to evaluate the effect of the addition of exogenous enzymes in ruminant feeding on milk production and chemical composition. We analysed the observations of 29 experiments, which included 52 treatments, 9 enzymes, and 1187 animals; with this information, we arranged a comprehensive database. The dose and study were used as experimental approaches. We observed that the addition of enzyme has no effect on the increment in milk yield production (P=0.16), fat content (P=0.88), lactose (P=0.39) or protein (P=0.95). The study showed that the variable milk yield is not a good parameter for determining with respect to the administration of exogenous enzymes (R2=0.001). As a conclusion, it is necessary to reconsider the use of exogenous enzymes in domestic ruminants when the focus is to improve milk production and their chemical composition.ANIMAL NUTRITION AND FEED TECHNOLOGY 01/2013; 13:399-409. · 0.36 Impact Factor