Urea-treated Corn Silage Research Articles

Effect of Feeding Urea on Reproductive Efficiency in Michigan Dairy Herd Improvement Association Herds

Information on feeding practices in Michigan Dairy Herd Improvement Association (DHIA) herds to determine if feeding urea affected reproductive efficiency in dairy cattle was obtained through a survey form distributed by county extension personnel. Calving interval (days) was from DHIA records. Adjusted calving interval (ACI) was calculated by subtracting from the calving interval the number of days the dairy man waited from calving to first breeding as a herd policy. Percent of cows sold for sterility was also from DHIA records. A total of 3,157 herd-year observations representing 85,281 calving intervals was from the 5 years 1965 to 1969. Of the 3,157 herd-year observations, 1,709 were in herds fed urea. In herds which used urea, daily urea intake averaged 80.6g (range 9 to 370g). Approximately 50% of this came from urea-treated corn silage and the remainder from concentrate. The mean ACI for herds fed no urea was 314.4 days compared to 315.7 days for herds fed urea. The ACI for herds fed 1 to 60g urea was 313.4; 61 to 120g, 317.8; 121 to 180g, 316.5; and over 181g, 313.7 days. These differences were not significant. Cows sold for sterility in nonurea herds was 2.15% versus 2.40% for all urea. This small difference is of no practical significance.

Urea-Treated Corn Silage in Low Protein Rations for Lactating Cows

Corn silages (34 to 37% dry matter) ensiled with 1) no additive; 2) 0.5% urea; 3) 0.75% urea; and 4) 0.75% urea+0.17% CaSO4 were fed as the only forage to lactating cows averaging 29.3kg milk per day when treatment began. Concentrates containing 8, 12 or 18% crude protein also were fed at 1kg per 3kg milk. Treatments (six groups of 10 cows each), designated by silage number and per cent crude protein in the concentrate were: A) 1, 8;B) 2,8; C) 3, 8; D) 4, 8; E) 2, 12 and F) 1, 18. Experimental rations were fed for 70 days. Nitrogen balances were determined on five cows per group at the end of the feeding period. Intakes of total and silage dry matter (kg per 100kg body weight) averaged, respectively, 2.4, 1.2; 2.7, 1.4; 2.7, 1.5; 2.8, 1.5; 3.1, 1.6; and 2.8, 1.6. Silage intake of A was lower (P<0.05) than of E and F. Milk yields (kg per day) and persistencies (%) were significantly affected by dietary nitrogen and, for the respective treatments, averaged 19.2, 67; 23.7, 81; 23.8, 82; 23.9, 84; 26.4, 91; and 25.7, 88. Added sulfate did not affect milk yields. Crude protein and dry matter digestibilities were directly related to ration protein. Negative controls (A) excreted equivalent to 143% of their digested nitrogen as milk and urine while averages for other groups ranged from 89 to 109%.

Effect of Nitrogen Source, Stage of Maturity, and Fermentation Time on pH and Organic Acid Production in Corn Silage

Two hundred and ninety-four plastic bag silos were prepared to determine the effect of adding urea or soybean meal on the corn plant fermentation process. Urea was added at 0.5, 0.75, and 1.0% of fresh silage weight at ensiling. Equivalent amounts of nitrogen from soybean meal were added for a comparative treatment. The corn was harvested at three stages of maturity, 25.6, 30.4, and 52.0% dry matter. Only the lowest level of urea and soybean meal was added to the silage containing 52.0% dry matter. Triplicate silages were prepared and analyzed after 0, 0.5, 1, 3, 7, 21, and 42 days of storage.Over all treatments the average pH of urea-treated corn silage (4.85) was higher than that of soybean meal-treated corn silage (4.69). Differences between treatments after 42 days of fermentation were greater with either low or high dry matter silages than with medium dry matter. Total organic acid concentration declined from 11.94% of dry matter in low dry matter samples after 42 days of storage to 3.14% of dry matter in high dry matter samples averaged over all treatments. The concentration of these acids increased (P<.01) with storage time and was higher in the urea-treated samples. Contrary to what was observed with lactic acid, volatile fatty acids were higher with the lower nitrogen supplementation. Acetic acid comprised 90% of the total volatile fatty acids.

Further Evaluation of Milk Production Responses from Urea-Treated Corn Silage

In the first experiment, lactating Holstein cows produced significantly less milk (P<.10) when receiving urea in concentrate (1.0%) and in high-dry matter corn silage (0.5%), instead of soybean meal, as the only nitrogen supplement. For the soybean meal-and urea-supplemented cows, respectively (kilogram per cow daily), preliminary period milk yields were: 26.9, 26.4; experimental period milk yields: 23.2, 20.5; silage intakes: 19.8, 21.7; concentrate intakes: 11.1, 10.6; hay intakes: 2.0, 2.1, and body weight gains: 0.44, 0.39. The control silage was 45.1% and the urea-silage 43.6% dry matter.In the second experiment, using feeding programs identical with the urea treatment in Experiment 1, milk production from Holstein cows receiving 31.9% dry matter urea-silage was significantly higher (P<.10) than from cows receiving 46.2% dry matter urea-silage. for the 31.9% and 46.2% dry matter urea-silage-fed cows, respectively (kilogram per cow daily), preliminary period milk yields were: 26.7, 26.8; experimental period milk yields were: 26.7, 26.8; experimental period milk yields: 22.7, 20.6; silage intakes: 27.7, 17.7; concentrate intakes: 10.5, 10.5; hay intakes: 2.1, 2.2; and body weight gains: 0.16, 0.30. We conclude that high-dry matter urea-silage is not as satisfactory as lower dry matter urea-silage for lactating dairy cows.

Response of Lactating Cows Fed Urea-Treated Corn Silage Harvested at Varying Stages of Maturity1,2

Corn harvested for silage at 30, 36, and 44% dry matter was treated with 0 or 0.5% urea at ensiling time. Yields of dry matter for the respective maturities were 10.4, 12.2, and 10.2 ton/ha. Losses of dry matter in the silo were highest for the high-dry matter silage (15.1%) compared to the medium (6.4%) and low-dry matter silages (7.0%). Urea-treated silage lost more dry matter than control silages (12.8 vs. 6.1%). Silages were fed to nine groups of lactating cows (six per group) as the only forage during an 80-day treatment period. Six groups were fed untreated silages; three received a 13.8% crude protein concentrate and three an 18.7% crude protein mix. The groups fed urea-treated silages received a 13.8% concentrate. Silages were fed ad libitum and concentrates at 1 kg/2.5kg of milk for all milk over 11.4 kg/day. Milk yields were not affected by urea-treatment of silage, but were decreased (P<.05) with increasing maturity of silage. A significant interaction (P<.05) between urea-treatment of silages and maturity was shown with milk persistencies higher for urea-treated than control silages at the early and medium maturities, but markedly lower for the late-maturity silage. Silage dry matter intake was significantly higher (P<.01) for urea-treated than for control silages. There was a trend towards lower intakes on the 45% silage compared to 37 and 30%, but differences were not significant.

Urea-Treated Corn Silage as the Only Forage for Lactating Cows

Two experiments were conducted to determine the feeding value of corn silage to which from 0.5 to 0.85% urea was added at the time of ensiling. The per cent of total ration nitrogen furnished by added urea averaged 0, 14.8 and 26.8 in Experiment 1 and 0, 25.2 and 38.0 in Experiment 2. Treatment periods for the respective experiments were 70 and 63 days. Concentrates were formulated so that rations within each experiment were isonitrogenous and isocaloric. Milk production was not significantly affected by consumption of urea-treated corn silage. However, in both experiments per cent milk protein was lowest (P<.05) at the highest level of urea. Neither silage dry matter nor total dry matter intakes were affected by urea treatment. Difference between treatments in several volatile fatty acids were observed in Experiment 1 but not in Experiment 2. Blood serum urea and rumen ammonia were generally increased as urea in the ration increased. In Experiment 2 crude protein digestibility was least (P<.01) and urinary nitrogen excretion greatest (P<.01) at the highest level of urea; thus resulting in considerable negative nitrogen balance for cows on this treatment (P<.01).

Effects of Multiple Feeding upon Performance of Guernsey Heifers Fed Urea-Treated Corn Silage

The effects of feeding grain and urea-corn silage (0.5% urea) two and four times daily were studied in a 74-day trial utilizing 40 Guernsey heifers in a 2×2 factorial design. Urea-corn silage fed 4× daily resulted in a nonsignificant (at P<.05) 18.4% greater gain than 2× daily feeding. No significant effect (at P<.05) on growth was observed for 2× vs. 4× daily feeding of both grain and urea-treated corn silage. However, feeding urea-treated corn silage 4× daily resulted in a significant (at P<.05) 13.7% decrease in estimated kg of TDN required per kg of weight gain when compared to 2× daily feeding. When grain was fed 2× and 4× and silage 2× daily, 14.4% less TDN was required per kg of gain in the group receiving grain 4× than among those fed grain 2× daily. Blood urea nitrogen and rumen volatile fatty acids (VFA) were not significantly affected by treatments. However, their trends favored more frequent feeding of silage.