V.A. Ishler

Effect on production of replacing dietary starch with sucrose in lactating dairy cows.

Replacing dietary starch with sugar has been reported to improve production in dairy cows. Two sets of 24 Holstein cows averaging 41 kg/d of milk were fed a covariate diet, blocked by days in milk, and randomly assigned in 2 phases to 4 groups of 6 cows each. Cows were fed experimental diets containing [dry matter (DM) basis]: 39% alfalfa silage, 21% corn silage, 21% rolled high-moisture shelled corn, 9% soybean meal, 2% fat, 1% vitamin-mineral supplement, 7.5% supplemental nonstructural carbohydrate, 16.7% crude protein, and 30% neutral detergent fiber. Nonstructural carbohydrates added to the 4 diets were 1) 7.5% corn starch, 0% sucrose; 2) 5.0% starch, 2.5% sucrose; 3) 2.5% starch, 5.0% sucrose; or 4) 0% starch, 7.5% sucrose. Cows were fed the experimental diets for 8 wk. There were linear increases in DM intake and milk fat content and yield, and linear decreases in ruminal concentrations of ammonia and branched-chain volatile fatty acids, and urinary excretion of urea-N and total N, and urinary urea-N as a proportion of total N, as sucrose replaced corn starch in the diet. Despite these changes, there was no effect of diet on microbial protein formation, estimated from total purine flow at the omasum or purine derivative excretion in the urine, and there were linear decreases in both milk/DM intake and milk N/N-intake when sucrose replaced dietary starch. However, expressing efficiency as fat-corrected milk/DM intake or solids-corrected milk/DM intake indicated that there was no effect of sucrose addition on nutrient utilization. Replacing dietary starch with sucrose increased fat secretion, apparently via increased energy supply because of greater intake. Positive responses normally correlated with improved ruminal N efficiency that were altered by sucrose feeding were not associated with increased protein secretion in this trial.

Ammonia and Greenhouse Gas Flux from Manure in Freestall Barn with Dairy Cows on Precision Fed Rations

Two lactating cow trials were conducted to evaluate the impact of diets differing in silage source (alfalfa/maize vs. grass/maize or maize/hay) and maize grain particle size (fine vs. coarse) on ammonia (NH3), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from a freestall barn floor with two groups of 60 cows each. In addition, the effects of environment (temperature, humidity) and management (manure depth, time since manure removal) factors were evaluated. Manure (feces and urine), spilled feed, bedding, and spilled drinking water were allowed to collect on the solid concrete, sloped barn alleys and were scraped twice a day. Gas fluxes from the freestall floor were measured at 64 locations over a 12 h period using a fast-response, non-steady-state flux chamber and an infrared photoacoustic gas analyzer during 18 trial days over a 9-month period. Fluxes of ammonia from manure on the barn floor were within average reported values for these 165 g kg-1 crude protein diets. All gas fluxes were similar (p = 0.253 to 0.977) regardless of silage source and maize grain particle size. The highest average ammonia emissions coincided with higher environmental temperature at 30 NH3 g AU-1 d-1, while the highest average greenhouse gas emissions from the manure on the floor were 10 g AU-1 d-1 for CH4 and 580 g AU-1 d-1 for CO2. Time in hours since scraping the floor had little impact on the production of ammonia, but greenhouse gas loss from the barn floor was reduced after scraping. Air and manure temperatures were positively correlated with emissions of NH3, CO2, and CH4 (p = <0.0001). NH3 (g AU-1 d-1) = (R2 = 0.38) for indoor air temperatures (Tair, °C) over the range from -5°C to 32°C (AU = 500 kg animal unit). Ammonia emissions were positively correlated with CO2 and CH4 gas emissions, suggesting that NH3 release from the manure was controlled to some extent by microbial activity and similar environmental factors. Nitrous oxide emissions remained <0.1 g AU-1 d-1 and were relatively constant for all diets and trials.

Evaluating the effect of ration composition on income over feed cost and milk yield.

Feed is generally the greatest expense for milk production. With volatility in feed and milk markets, income over feed cost (IOFC) is a more advantageous measure of profit than simply feed cost per cow. The objective of this study was to evaluate the effects of ration cost and ingredient composition on IOFC and milk yield. The Pennsylvania State Extension Dairy Team IOFC tool (http://extension.psu.edu/animals/dairy/business-management/financial-tools/income-over-feed-cost/introduction-to-iofc) was used to collect data from 95 Pennsylvania lactating dairy cow herds from 2009 to 2012 and to determine the IOFC per cow per day. The data collected included average milk yield, milk income, purchased feed cost, ration ingredients, ingredient cost per ton, and amount of each ingredient fed. Feed costs for home-raised feeds for each ration were based on market values rather than on-farm cost. Actual costs were used for purchased feed for each ration. Mean lactating herd size was 170 ± 10.5 and daily milk yield per cow was 31.7 ± 0.19 kg. The mean IOFC was

Amendments for mitigation of dairy manure ammonia and greenhouse gas emissions: Preliminary screening

7.71 ±

Effects of dietary forage level and monensin on lactation performance, digestibility and fecal excretion of nutrients, and efficiency of feed nitrogen utilization of Holstein dairy cows

1.01 cost per cow, ranging from -

Amendments for mitigation of odor emissions from dairy manure: Preliminary screening

0.33 in March 2009 to

Amendments For Short- And Medium-Term Mitigation Of Odor Emissions From Dairy Manure

16.60 in September 2011. Data were analyzed using a one-way ANOVA in SPSS (IBM Corp., Armonk, NY). Values were grouped by quartiles and analyzed with all years combined as well as by individual year. Purchased feed cost per cow per day averaged

The Use of Fiber Concentrations for Ration Formulation

3.16 ±

Utilization of phosphorus in lactating cows fed varying amounts of phosphorus and forage

1.07 for 2009 to 2012. For 2009 to 2012 combined, milk yield and IOFC did not differ with purchased feed cost. Intermediate levels (quartiles 2 and 3) of forage cost per cow per day between

Effects of Sucrose Supplementation on Dry Matter Intake, Milk Yield, and Blood Metabolites of Periparturient Holstein Dairy Cows

1.45 and