Location: Dairy Forage Research
2020 Annual Report
Objectives
Objective 1: Develop and evaluate strategies that optimize growth and development; maximize feed nutrient use efficiency; increase milk production potential; and increase the lifetime productivity, health, and well-being of dairy heifers.
Objective 2: Develop and evaluate dietary feed formulation strategies that increase the utilization of conventional feeds/forages and alternative feeds/forages that reduce competition with human food consumption, enhance nutrient use efficiency, and increase milk production.
• Sub-objective 2.A. Evaluate effects of forage type, amount, and quality on animal performance, nutrient digestibility, and feed conversion efficiency.
• Sub-objective 2.B. Evaluate effects of alternative/byproduct feeds that replace or reduce grain in the diet on animal performance, nutrient digestibility, and feed conversion efficiency.
Objective 3: Develop and evaluate dairy diets that enhance milk production and quality, reduce manure nutrient excretions, and reduce environmental impacts of dairy farms.
Approach
Objective 1. Dry matter intake, body weight, and growth measurements at prepubertal (6 months of age) and postpubertal (12 months of age) stages of dairy heifers growth will be determined as part of a study that will help us determine whether efficiency of growth changes during the lifetime of the dairy animal. Growth measurements for prepubertal and postpubertal dairy heifers will be combined with calfhood and mature cow measurements to evaluate if growth efficiency is correlated through the lifespan of a dairy animal.
Objective 2. A series of lactating dairy cow studies will be conducted to evaluate the effect of forage type, forage amount, and forage quality on animal performance, nutrient digestibility, and feed conversion efficiency. In addition, alternative forages and byproduct feedstuffs will be evaluated as replacements for traditional feedstuffs used in dairy cow diets. We will collect production measurements, gaseous emissions, digesta, and feces to determine the effects of altering fiber digestibility on ruminal fermentation, lactation performance, and environmental output.
Objective 3. Several studies will be conducted to evaluate dairy diets that enhance milk production, reduce nutrient excretion, and reduce the environmental impacts of dairy production systems. Cows will be fed diets with differing ratios of alfalfa silage and corn silage at high and low forage inclusions and at different dietary crude protein concentrations to evaluate the effect of diet formulation on production measures, gas emissions, and nutrient excretion. Manure collected from these experiments will further studied in laboratory emission chambers to determine effect of manure chemistry on gaseous emission during storage. Stored manure will then be applied to a field to determine plant nutrient uptake during a growing season. Gas measurements will be taken to evaluate the impact of manure application on carbon dioxide, ammonia, and nitrous oxide emissions.
Progress Report
The impact of dosing newborn and pre-weaned calves with rumen fluid from cows with different milk production efficiency status on intake, structural growth, and feed efficiency at different stages of growth is being evaluated in a long term, collaborative study (Objective 1). Calves were inoculated with one of three types of rumen fluid: 1) from a cow with high milk production efficiency, 2) from a cow with low milk production efficiency, and 3) a control treatment containing a sterilized mixture of the two rumen fluids. This portion of the study will evaluate how the dosing of different rumen inoculums may impact feed intake, body weight, and structural growth of the calves from weaning until calving at approximately three years of age. Recording measurements at calving and near the end of first lactation was added this past year to provide a better understanding of the effect of treatments on long-term growth of each animal.
A study was conducted to evaluate the ability of lactating dairy cows to maintain their feed efficiency when the nutrient composition of the diet was altered (Objective 2.A). Improving feed efficiency of dairy cows is a key component for dairy farmers to maintain milk production when using fewer resources, and in particular, when using less feeds that are in direct competition with human and non-ruminant animal consumption. In this study, cows were fed either a traditional control diet formulated with corn grain (high starch diet) or a higher forage diet formulated without corn grain (low starch diet). Lactation performance, nutrient digestibility, and feed efficiency were evaluated for cows fed either the high starch or low starch diet. In addition, fecal samples, rumen microbiome samples, blood samples, and liver and mammary biopsies were taken on a subset of these cows to evaluate the relationship of diet on feed efficiency of individual dairy cows. A manuscript evaluating the effect of the diet’s starch concentration on the repeatability and reproducibility of feed efficiency has been submitted. A second manuscript evaluating whether different epithelial sites in the rumen would be associated with their own distinct and unique sites was submitted and published. Data from this study were also included in a third submitted manuscript evaluating the viability of using buccal swabs as a proxy of the rumen microbial contents. Additional manuscripts evaluating the impact of diet on feed efficiency using data from this experiment are currently being written.
A study was conducted to evaluate the inclusion of high-quality alfalfa silage as a replacement for concentrate feeds on the lactation performance and digestibility of high producing lactating dairy cows (Objective 2.A). Laboratory analysis has been completed except for the in vivo digestibility of diets and evaluation of its relationship to in vitro digestibility methods. A manuscript related to production responses of cows fed increasing levels of high-quality alfalfa silage is currently in preparation and will be submitted once digestibility data is completed.
A study was conducted to evaluate the inclusion of brown-mid rib (BMR) sorghum silage as an alternative to BMR corn silage in lactating dairy cow diets (Objective 2.A). Laboratory analysis is currently underway. Additional analysis will be completed before a manuscript can be written.
Accomplishments
1. Feed efficiency repeatability and reproducibility across different diets in lactating dairy cows. Improving feed efficiency is a key component for dairy farmers to maintain or improve production while using fewer resources, especially by decreasing feedstuffs that are directly edible for human or non-ruminant consumption. The determination of whether dairy cows are efficient on a high forage diet compared to a high starch diet or vice versa, would help producers select cows for specific types of dairy feeding systems. Research by ARS researchers at Madison, Wisconsin, demonstrated that lactating dairy cows were more able to maintain their feed efficiency when they were fed the same diet than when their diet was changed. These findings demonstrate to dairy producers and the scientific community that feed efficiencies should be considered within the same diet to avoid any misidentification of cows as most or least efficient.
Review Publications
Cardoso, F.C., Kalscheur, K., Drackley, J.K. 2020. Nutrition strategies for improved health, production, and fertility during the transition period. Journal of Dairy Science. 103(6):5684-56931. https://doi.org/10.3168/jds.2019-17271.
Erickson, P.S., Anderson, J.L., Kalscheur, K., Lascano, G.J., Akins, M.S., Heinrichs, A.J. 2020. Strategies to improve the efficiency and profitability of heifer raising. Journal of Dairy Science. 103(6):5700-5708. https://doi.org/10.3168/jds.2019-17419.
Sbardellati, D., Fischer, A., Cox, M.S., Li, W., Kalscheur, K., Suen, G. 2020. The bovine epimural microbiota displays compositional and structural heterogeneity across different ruminal locations. Journal of Dairy Science. 103(4):3636–3647. https://doi.org/10.3168/jds.2019-17649.
Ranathunga, S.D., Kalscheur, K., Herrick, K.J. 2019. Ruminal fermentation, kinetics, and total-tract digestibility of lactating dairy cows fed distillers dried grains with solubles in low-and high-forage diets. Journal of Dairy Science. 102(9):7980–7996. https://doi.org/10.3168/jds.2018-15771.
Sanchez-Duarte, J.I., Kalscheur, K., Casper, D.P., Garcia, A.D. 2019. Performance of dairy cows fed diets formulated at 2 starch concentrations with either canola meal or soybean meal as the protein supplement. Journal of Dairy Science. 102(9):7970–7979. https://doi.org/10.3168/jds.2018-15760.
Erickson, P.S., Kalscheur, K.F. 2019. Nutrition and feeding of dairy cattle. In: F.W. Bazer, G.C. Lamb, and G. Wu, eds. Animal Agriculture: Sustainability, Challenges and Innovations. London United Kingdom: Academic Press. p.157-180. https://doi.org/10.1016/B978-0-12-817052-6.00009-4
