Economic and environmental effects of double cropping winter annuals and corn using the Integrated Farm System Model.

Dairy farms have been under pressure to reduce negative environmental impacts while remaining profitable during times with volatile milk and commodity prices. Double cropping has been promoted to reduce negative environmental impacts and increase total dry matter yield per hectare. Three dairy farms that double cropped winter annuals and corn were selected from northern and western Pennsylvania. Data were collected from recorded crop and dairy records and financial data for 2016 and 2017. Farms ranged in size from 336 to 511 ha with 233 to 663 cows. Data were used to set parameters for the Integrated Farm System Model, which was then used to simulate 8 scenarios for each farm: current operation; 0, 50, and 100% of corn hectares double cropped; 30% feed price increase with and without double cropping; and 30% feed price decrease with and without double cropping at the farm's current level of double cropping. A 20-yr time period, using weather data that was representative of the actual farms, was used in the Integrated Farm System Model simulation to produce both financial and environmental outputs. Double cropping winter annuals and corn silage increased dry matter yield per hectare by 19%, when comparing 0 to 100% of the corn area double cropped. With all corn land double cropped, net return to management per hundredweight (45.36 kg) of milk increased by 1.8%, N leached per hectare per year decreased by an average of 4.5%, and phosphorus loss was reduced by an average of 9.2% across farms. When feed prices increased by 30%, double cropping increased net return over feed cost and net return to management by 1.6 and 2.2%, respectively, across farms. When feed prices decreased by 30%, double cropping decreased net return over feed cost and net return to management by smaller amounts of 0.13% and 0.11%, respectively, across farms. Modeling indicated that double cropping winter annuals with corn silage can have both environmental and economic benefits when winter-annual silage yields are enough to cover expenses.

Supplemental carbohydrate sources for lactating dairy cows on pasture.

Two experiments were conducted to evaluate steam-flaked corn and nonforage fiber sources as supplemental carbohydrates for lactating dairy cows on pasture. Cows were allotted to a new paddock of an orchardgrass (Dactylis glomerata L.) pasture twice daily in one group in both trials. In experiment 1, 28 Holstein cows, averaging 216 d in milk, were randomly assigned to either a cracked-corn (CC) or a steam-flaked (SFC) supplement in a split plot design. The supplement contained 66.7% of corn and a protein/mineral pellet. In experiment 2, 28 Holstein cows, averaging 182 d in milk, were randomly assigned to either a ground corn (GC) or a nonforage fiber (NFF)-based supplemented in a single reversal design. The GC supplement contained 85% ground corn plus protein, mineral, and vitamins. The NFF supplement contained 35% ground corn, 18% beet pulp, 18% soyhulls, 8% wheat middlings plus protein, mineral, and vitamins. In both experiments, cows were fed the grain supplement twice daily after each milking at 1 kg/4 kg milk. In experiment 1, milk production (24.3 kg/d) and composition did not differ between treatments; however, plasma and milk urea N were lower with the SFC supplement. In experiment 2, milk production (27.5 kg/d) was not affected by treatments, which may be related to the medium quality of pasture grazed. The GC supplement tended to reduce plasma and milk urea N and increased milk protein percentage (3.23 vs. 3.19%). Pasture dry matter intake, measured using Cr2O3, did not differ between treatments in either experiment 1 (15.1 kg/d) or experiment 2 (12.2 kg/d). Milk production did not differ when mid-late lactation cows on pasture were supplemented with SFC or NFF instead of dry corn.

Lymphocyte proliferation response of lactating dairy cows fed varying concentrations of rumen-protected methionine.

Six midlactation Holstein cows were used in a replicated 3 x 3 Latin square design to characterize the influence of dietary concentration of Mepron 85 (Degussa Corp., Allendale, NJ) on isolated mononuclear cell composition and lymphocyte proliferation. Cows were fed a common total mixed ration containing corn silage, legume silage, chopped legume hay, and a grain and mineral pellet that was top-dressed with one of three treatments. Treatments consisted of 1) 0 g/d of Mepron 85, 2) 15 g/d of Mepron 85 (11 g of rumen-protected Met), or 3) 30 g/d of Mepron 85 (22 g of rumen-protected Met). Cows were housed in a tie-stall barn, had continuous access to fresh water, and were fed once daily at 0900 h for ad libitum intake. Dry matter intake (DMI), orts, and milk yields were recorded daily, and weekly milk samples were collected for analyses of fat, protein, SCC, and milk urea nitrogen. Blood and milk samples were collected before the beginning of the experiment and during wk 2 and 4 of each 28-d treatment period. Blood was analyzed for serum methionine, lymphocyte proliferation, and phenotypic composition of isolated mononuclear cells. Milk samples were analyzed for phenotypic composition of isolated mononuclear cells. Least square means for DMI, milk yield, milk composition, and phenotypic mononuclear cell composition of blood and milk were not affected by treatment. Proliferative ability of peripheral blood T lymphocytes increased for cows consuming 30 g/d of Mepron 85.

Comparison of methods of in vitro dry matter digestibility for ten feeds.

The objectives were to determine if the in vitro dry matter (DM) digestibility was similar by using a traditional method compared to the new DAISYII system and to determine if in vitro DM digestibility was similar for sources of inoculum from two different donor cow diets, all forage or total mixed ration. Ten feeds were digested by the traditional method, the DAISYII method with same feeds in a digestion vessel, and the DAISYII method with different feeds in a digestion vessel. The study used a 2 x 3 factorial arrangement of treatments with two sources of inoculum and three methods. The study was replicated. Source of inoculum affected in vitro DM digestibility; the grass hay donor cow diet resulted in lower digestibility values in six of the 10 feeds tested. Method did not significantly affect the digestibility values, and there were no significant source by method interactions. The DAISYII method can be used to increase labor efficiency in the in vitro DM digestibility analysis, and forages and grains can be analyzed together in a single digestion vessel.

Effect of corn silage supplementation on intake and milk production in cows grazing grass pasture.

The objective was to determine the effects on milk production and DMI of 2.3 kg/d of corn silage DM fed to lactating cows grazing grass pasture and fed supplemental grain. Thirty Holstein cows, averaging 32 kg of milk at the start of the trial, intensively grazed grass pasture for 8 wk. One-half of the cows received 2.3 kg/d of corn silage DM in two equal feedings, and one-half of the cows were used as controls (no corn silage). All cows were fed grain at 1 kg of grain DM/4 kg of milk. Corn silage had no effect on milk production or milk composition. Cows fed corn silage did not have improved BW gain or body condition score. Each unit of corn silage consumed replaced 1.2 units of pasture, but total DMI was not different because of supplementation with corn silage. Blood urea N concentrations were lower for cows fed corn silage. Supplementation of high producing Holsteins grazing grass pastures with 2.3 kg/d of corn silage DM had no effect on milk production, milk composition, or total DMI.

Ruminal digestion and duodenal nutrient flows in dairy cows consuming grass as pasture, hay, or silage.

The objective of this experiment was to quantitate ruminal digestion and flow of nutrients to the small intestine of Holstein cows grazing grass pasture or fed grass hay or silage. Three dry, nonpregnant Holstein cows fitted with ruminal and duodenal (Y-type) cannulas grazed or were given free choice access to hay or silage during three consecutive 19-d periods. Pasture intake was estimated using chromic oxide; hay and silage intakes were both measured and estimated. Intakes were similar among forages. Ruminal samples had higher VFA and ammonia when cows grazed than when cows were fed hay or silage. Ruminal pH did not differ. Based on duodenal spot sampling, cows on pasture had lower DM flows to the small intestine. Bacterial N flow, as a percentage of total N flow, was higher for cows that grazed. Most flows of AA to the small intestine were similar among forages, but Pro and Phe were lower for grazing cows. Supplementation strategies for cows on pasture should be designed to synchronize protein and carbohydrate in the rumen and to increase the supply of nutrients available in the small intestine.