Brown Midrib (BMR) dwarf pearl millet may provide northeastern dairy farmers with an alternative forage source for lactating dairy cows to increase annual forage yield, add crop diversity and enhance nutrient utilization. Pearl millet is a summer annual with a shorter growing season than corn and therefore increases the growing season for winter annuals in a double cropping system. Pearl millet grows well in heat and performs well with inconsistent moisture. It offers more summer opportunities to spread manure at a more appropriate time when growing crops can rapidly utilize nutrients before they are lost to the environment. Pearl millet has to be shown to adequately support milk production in order to replace a portion of the corn silage acres on northeast dairy farms. Our hypothesis is that the BMR dwarf variety of pearl millet proposed in this project would support milk production in high-producing dairy cows due to its higher fiber digestibility and higher leaf to stem ratio than regular pearl millet. To test this hypothesis, we proposed a crossover feeding trial with 16 lactating cows. The effect of partial replacement of corn silage in the diet with BMR dwarf pearl millet on feed intake, milk production, digestibility, nitrogen utilization, rumination, enteric methane emissions and farm profitability is being evaluated.
The purpose of this project is to evaluate BMR dwarf pearl millet as forage for lactating dairy cows. Dairy farmers in the northeast U.S. increasingly need to harvest more forage off the same acreage to support more and higher producing cows. Corn silage is excellent forage for dairy cows with good nutritional quality, yet its long growing season limits its suitability for double cropping strategies. Additionally, continuously growing corn increases the risk for disease and pest damage. Pearl millet is a warm season grass like corn but with a shorter growing season. It can be planted later and harvested earlier thereby increasing the growing window for winter annual double crops, such as annual ryegrass or triticale. A longer growing season for winter annuals is of particular benefit to farmers where the total growing season is short. Double cropping has more benefits than just increasing yield per acre. Other benefits include: reduced soil loss, increased soil organic matter, improved soil structure, increased soil microbial life, and increased nutrient utilization. The later planting date for pearl millet shifts field work to reduce the peak spring planting rush for corn, and the earlier pearl millet harvest can reduce the heavy corn silage harvest workload. This might allow for more efficient use of planting and harvesting equipment and labor, and may enhance farmer’s quality of life. Pearl millet for silage can yield two cuttings and offer better times to spread manure on a growing crop than corn silage production provides. Spreading manure on growing crops makes better utilization of nutrients and further protects the environment from nutrient overloads. Planting pearl millet breaks the continuous corn-after-corn cycle and can help reduce corn root worm pressure. This may promote beneficial soil biological activity by reducing the amount of pesticides applied to the crops. The addition of pearl millet in the cropping rotation adds diversity for protection against disease outbreaks. It grows well with limited and inconsistent rainfall and has higher water use efficiency than sorghum. This could lead to more consistent yields even in the face of changing weather patterns. Pearl millet can also be safely fed to horses with no risk of prussic acid poisoning as with sorghum and sudangrass.
Dairy farmers need to produce highly digestible forage to maintain high milk production of their herds. Corn silage meets this expectation and supports high milk yields. Regular pearl millet has been fed as silages to lactating dairy cows with mixed results when compared to corn silage control diets. The pearl millet proposed in this study is a dwarf Brown Midrib (BMR) variety not previously studied. The dwarfing increases the more digestible leaves in relation to the stems by shortening the stem internode length. The BMR trait reduces the amount of fiber, particularly the lignin component of the fiber fraction, and increases plant digestibility. It is also recommended to harvest pearl millet for silage in a vegetative state as it increases digestibility even though it reduces yield per cutting. The harvested pearl millet will be ensiled to minimize harvest losses. By partially replacing corn silage in the diet with this type of BMR pearl millet silage, it is expected that high milk yields will be sustained and BMR pearl millet silage will be shown as a viable addition to the crop rotation of dairy farms in the northeast U.S. As the expectation is that dairy farmers would only partially replace corn silage acres with BMR pearl millet, we have not proposed a complete substitution of corn silage by BMR pearl millet in the experimental diet.
Increasingly animal agriculture is being challenged for its effects on the environment. Nitrogen is a nutrient of concern for water and air quality as well as an expensive component of animal diets. Therefore, we will be assessing the effect BMR pearl millet silage inclusion has on nitrogen utilization. Methane is a major greenhouse gas from livestock production of global importance, so enteric methane emissions will also be measured from each cow on trial. Additionally, we will look at resting, rumination, and activity times as these have both nutritional and animal welfare importance.
A farming practice must be profitable for it to be sustainable; therefore an economic analysis of BMR pearl millet as forage for lactating dairy cows will be conducted. Dairy farmers make cropping decisions based on many variables including yield, planting costs, and the ability of a crop to produce milk. The proposed research will focus on clarifying the milk yield level that BMR pearl millet inclusion in a diet can support. Then the income over feed costs of BMR pearl millet versus corn silage will be investigated. This approach may not factor in secondary benefits of growing pearl millet, such as reduced disease and pest crop damage, but it is a fairly straightforward method that farmers can use.
- To evaluate the effect of including BMR dwarf pearl millet silage in a high producing dairy cow ration on dry matter intake and milk production .
- To investigate the effect of diet inclusion of BMR dwarf pearl millet silage on milk components and fatty acid profile.
- To evaluate the total tract nutrient digestibility and nitrogen utilization of a dairy cow diet containing BMR dwarf pearl millet silage.
- To examine the effect of BMR dwarf pearl millet silage inclusion in the diet of high producing dairy cows on enteric methane emissions, resting time, rumination time, and activity.
- To elucidate the economic impacts on farm profitability of growing BMR dwarf pearl millet silage in partial substitution of corn silage.
We are on tract to accomplish these objectives and will begin to look at our results in light of these objectives at the completion of the second and final period of our experiment at the end of January 2017.
Brown midrib brachytic dwarf pearl millet, Pennisetum glaucum, forage harvested at the flag leaf visible stage and subsequentially ensiled, was investigated as a partial replacement of corn silage in the diet of high producing dairy cows. Seventeen lactating Holstein cows were fed 2 diets in a crossover design experiment with 2 periods of 28 d each. Both diets had forage to concentrate ratios of 60:40. The control diet (CSD) was based on corn silage and alfalfa haylage and in the treatment diet, 20% of the corn silage dry matter (corresponding to 10% of the dietary dry matter) was replaced with pearl millet silage (PMD). The effects of partial substitution of corn silage with pearl millet silage on dry matter intake, milk yield, milk components, and fatty acid profile, apparent total-tract digestibility of nutrients, N utilization, and enteric methane emissions were analyzed.
The pearl millet silage was higher in crude protein and neutral detergent fiber and lower in lignin and starch than the corn silage. Diet did not affect dry matter intake or energy corrected milk yield which averaged 46.7 ± 1.92 kg/d. The PMD diet tended to increase milk fat concentration, had no effect on milk fat yield, and increased milk urea N. Concentrations and yields of milk protein and lactose were not affected by diet. Apparent total-tract digestibility of dry matter decreased from 66.5% in CSD to 64.5% in PMD. Similarly, organic matter and crude protein digestibility was decreased by PMD, whereas neutral- and acid-detergent fiber digestibility was increased. Total milk trans fatty acid concentration was decreased by PMD with a particular decrease in trans-10 18:1. Urinary urea and fecal N excretion increased with PMD compared with CSD. Milk N efficiency decreased with PMD. Carbon dioxide emission was not different between the diets, but PMD increased enteric methane emission from 396 to 454 g/d and increased methane yield and intensity.
Substituting corn silage with brown midrib dwarf pearl millet silage at 10% of the diet dry matter supported high milk production in dairy cows. Brown midrib pearl millet silage was a highly digestible fiber replacement for corn silage; however, it lacked the level of starch in the corn silage, which caused decreased organic matter digestibility in the current study. In practical dairy farm rations, incorporating flag leaf stage brown midrib pearl millet silage may require the balancing of starch to maintain milk yield. When planning on farm forage production strategies, brown midrib dwarf pearl millet should be considered as a viable fiber source.
The fiber is rapidly degraded compared to corn silage fiber based on a ruminal in situ comparison.
Education & Outreach Activities and Participation Summary
We submitted an abstract to the American Dairy Science Association (ADSA) to give an oral presentation during the 2017 ADSA annual meeting in Pittsburg. This abstract was accepted and the oral presentation was given. A manuscript detailing the experiment was also sent to the Journal of Dairy Science. We received revisions on that manuscript and resubmitted it. We are currently waiting to hear back from the journal and expect to have our manuscript accepted. Harper.-BMR-Dwarf-Pearl-Millet-Silage-JAM-2017.6.20.17
Our project has shown that lactating dairy cow forage can include forage sources beside corn silage and alfalfa haylage. The more critical decision is what crops grow best on a particular farm in a sustainable way. Our research support the idea of using BMR pearl millet as an option for a crop rotation away from corn. This may have benefits for reduce pest and disease pressure on the other corn fields for the farm and region.
Sustainable agriculture is a challenge particularly in production agriculture because sustainable practices compete for profitability against unsustainable practices in the short term. For example, eroded soil may not immediately affect yields but the costs of planting a cover crop are immediate.
Sustainable agriculture is also system based which makes scientific inquiry difficult because variables need to be controlled in a designed experiment. Regardless of these challenges, I still think sustainable agriculture is the future. In my future career as a practicing livestock nutritionist, I will include elements of the sustainable mindset so that the farms that I service will continue for many more generations.