|Institution:||South Dakota State University|
|Keywords:||corn silage; forage blends; forage quality; forage soybean; intercropping; water quality; Dairy Science|
|Full text PDF:||http://openprairie.sdstate.edu/etd/990|
The overall objectives of the six studies were to increase the feed efficiency in lactating dairy cows. The first study evaluated the efficacy of different water sources and treatment systems on ruminal parameters using an in vitro gas production system. Outcomes of the study suggested that the source and nutrient quality of water can affect rate of ruminal fermentation. Thus, use of real farm water being offered to the cow to conduct in vitro gas production measurements may accurately predict the ruminal fermentation, digestibility and total gas production. The second study evaluated two recently developed leafy-floury corn silage hybrids against conventional starchy corn silage hybrid on performance of early lactating dairy cows. The results showed that all three corn silage hybrids are similar in terms of DMI, milk yield, milk components and 3% fat corrected milk FE. Starchy corn silage hybrid was lower in CP, higher in starch, lower in sugar content, lower in starch digestibility and lower in fiber digestibility compared to both leafy-floury corn silage hybrids. This study demonstrates that a lower starch, higher digestible fiber corn silage diet can support similar milk production compared to a higher starch, lower digestible fiber diet. The third study evaluated intercropping of Vining soybean and BMR grazing corn with different seeding ratios on forage yield, nutrients composition and digestibility. The results showed that monocropping of Vining soybean produced lower DM yield, lower DDM yield, lower NFC yield and lower milk yield (T/ha) compared to intercropping of Vining soybean and BMR grazing corn with monocropping of BMR grazing corn being intermediate. The optimal seeding ratio of Vining soybean to BMR grazing corn is between 67:33 and 50:50 based on yield of DDM and Milk (T/ha). The fourth study evaluated late season row cropping of mixed seeds of corn and soybean with different seeding ratios on forage yield, nutrient yields and digestibility. The result showed that the combinations and seeding ratios of corn and soybean affect the forage and nutrient yields. The greatest yield of nutrients occurred with BMR grazing corn and Big Buck 6 soybean combination at 65:35 seeding ratio. A minimum of 90 d is required to complete the ensiling process of forage before feeding to the cow. The fifth study evaluated the effect of intercropping of MC 5300 corn with Viking 2265 soybean or Vining soybean at different seeding ratios on biomass and nutrient yields under organic condition. The results showed that seeding ratio of MC 5300 corn and Vining soybean or Viking 2265 at 67:33 produced higher fresh biomass yield and dry matter yield. Land equivalent ratio was greater for MC 5300 corn and Viking 2265 soybean combination at 67:33 or 50:50 seeding ratios. The sixth study evaluated the effect of row cropping of mixed seeds of corn and soybean with different seeding ratios on forage and nutrient yields grown under organic condition. The main effect of corn on fresh, DM, DDM, CP, NDF, NFC and starch yield was higher… Advisors/Committee Members: David P. Casper.