Preliminary Results of the Penn State Extension Feed Assessment

The Penn State Extension Dairy Team has recently implemented a new program to evaluate dairy farm feed efficiency and determine opportunities for improved feeding management and production. The feed assessment evaluates multiple areas of farm feed management, including crop quality, feed storage, feeding protocols, cow comfort, and production records.

Crop Quality and Feed Storage:

Corn silage harvest and packing have both shown opportunities for improvement. Visible mold (Figure 1) has been present on corn silage taken from an ag bag currently being fed to the milking herd. It is well established that achieving a dense pack during harvest can help with oxygen exclusion and improve the fermentation and stability of corn silage. Additionally, ensuring that the silage face is well matched to the herd size to ensure that the feed-out rate is fast enough to prevent spoilage is critical to maintaining silage and crop quality during warmer months. The University of Florida recommends feeding at least 8 to 12 inches during cooler weather and 18 inches during warmer weather, while Penn State University recommends 4 to 6 inches be removed from silos.^1,3 Muck et. al. 2003, states that farmers in the northern US should remove 2 to 10 inches from tower silos, 4 to 6 inches from bunker silos, and 12 inches from ag bags. The University of Florida likely has higher requirements for removal rates due to warm, humid conditions. When feeding improperly packed or spoiled silage, adverse effects such as reduced dry matter intake, reduced milk yield, and increased risk of health problems can occur. Production of small grain silage also demonstrated potential improvements. For small grains, moisture exceeding 72 to 75% can lead to poor fermentation due to butyric acid production and seepage. Seepage can lead to a reduced nutrient value of harvested feeds. Ensuring harvested small grains maintain quality throughout the ensiling process is tricky due to the necessary dry-down period between harvest and ensiling. Repeated tedding of small grains before ensiling can help obtain the desired moisture for this crop.

In addition to the evaluation of crop quality, the total mixed ration (TMR) delivered to the cows was collected and analyzed. Total mixed ration samples were collected from along the feed bunk, shortly after delivery from the mixing wagon. Therefore, these samples represent freshly mixed and delivered feed. When the collected TMR sample was analyzed, some herds had butyric acid present in the TMR. Butyric acid ranged from 0.22 to 0.30% dry matter (DM) in these herds. Total mixed ration samples that had butyric acid present, could have even higher levels in the refusals. The majority of herds evaluated did not have any butyric acid present in the TMR sample, which is desirable. Typically, in corn silage, butyric acid levels at or greater than 0.5% DM is indicative of spoilage.³ In properly fermented corn silage, butyric acid levels are near zero.³ On one farm, ensiled small grains were allowed to sit open for about 24 hours until they were used for the next feeding. While using the right amount of ensiled forage is difficult, especially when using baleage, finding another purpose for unused feed can help ensure that cows are fed fresh feed at every feeding. It is typical to scrape feed refusals once daily; however, increasing the frequency in which refusals are removed in the hot summer months can help remove unappealing or potentially spoiled feed from the bunk.

Feeding Protocols:

During the feed assessment, feeding protocols were evaluated. Evaluation included looking at mixing order, mixing time, feeding time, and feed-out strategies. Baleage fed herds tended to have a longer particle length than recommended, according to the Penn State Particle Separator (PSPS) guidelines. The PSPS guidelines recommend that 2 to 8% of the TMR particles remain on the top sieve. Baleage-fed herds typically had anywhere from 20 to 40% captured on the top sieve. Figure 2 demonstrates the PSPS with too much forage remaining on the top sieve. Figure 3 is a visual of the PSPS from a herd with approximately 3% of forage particles remaining in the top sieve. The photo in Figure 3 was from a herd using pre-chopped small grain silage stored in a silo rather than as baleage. 

Frequently sharpening and replacing knives and using the proper mixing order can help improve baleage processing during mixing. For farms including baleage in their rations, adding the baleage into the mixer wagon first, followed by grains and concentrates, and allowing time for chopping and mixing should improve processing and reduce the percentage of longer particles captured on the top sieve of the PSPS. 

To demonstrate this concept, the two images below in Figure 4 show the same mix before and during mixing. It is clear in both images that the baleage is not being effectively chopped or mixed into the TMR.

While many farms have had difficulty chopping forages to adequate lengths, some have fallen below recommended levels of physically effective neutral detergent fiber (peNDF). Physically effective NDF is important for maintaining rumen function, rumen environment, and animal health. Too low of peNDF (i.e., >19% DM) can lead to metabolic diseases. One farm, with a particularly low peNDF (i.e., ~16%), had poor total track apparent starch digestibility and had visible corn kernels in the manure.

Additionally, calibrating mixing wagon scales frequently will offer further accuracy in mixing. The University of Minnesota recommends that farmers calibrate scales once every three months.²

Feeding right after milking should encourage animals to stand for 30 minutes to eat and allow time for post-dip on teats to become effective. In free stall systems, feed should be delivered before cows return from the milking parlor and should be pushed-up once every 30 minutes for two hours after milking. In tie stall systems, feeding before milking and pushing up feed during milking should help keep cows standing and encourage standing after milking is complete. Like free stall systems, frequent feed push-ups in tie-stall systems after milking can help encourage animals to stand and eat for longer.

Some of the producers have implemented excellent feed management practices. The two pictures above depict farmers that use a stopwatch to maintain consistency in mixing time (Figure 5) and mixing on a flat surface before delivering feed (Figure 6).

Figure 8: Deep water bowls with splash guard.

Additionally, to keep feed bunks and waterers clean, farms were using various materials to provide a smooth rounded edge between the feed bunk and curb (Figure 7) and deep-water bowls with a splash guard and drain to facilitate easy clean-out (Figure 8).

Cow Comfort:

This evaluation program focuses mostly on feed management; however, feed efficiency can be impacted by many other management factors - including cow comfort.

Across many of the farms evaluated minimal or no bedding was provided. Providing enough bedding for cows can be challenging on some dairy farms, especially those utilizing gravity flow systems for manure. When not enough bedding is offered to prevent or reduce hock-related injuries to the cows, the natural behavior of cows is to stand more often due to the uncomfortable lying surface. Comfort during these events is important to dry matter intake, water intake, and milk letdown. Comfort while lying down is additionally important to the time spent ruminating in dairy cows. Healthy feet and legs and a comfortable lying surface should be prioritized on dairy farms to avoid restricting dairy cows' natural eating, drinking, ruminating, or milking behaviors. Cows should be provided with 3 to 4 inches of bedding material on top of mattresses to provide adequate comfort for the animal.

Hoof health opportunities were found on many of the evaluated farms. Hoof health can be a challenge for smaller dairies, given the small number of animals that need hoof trimming at varying times throughout the year. However, focusing on hoof health could improve feed efficiency. In addition to hock injuries, hoof health could limit cow comfort while eating and drinking. Similar to leg and hock health, hooves play an important role in whether an animal is willing to stand to eat and drink. Hooves should be trimmed twice a year, ideally at 100 days in milk and at dry off. The goal of hoof trimming is to provide a flat surface for the animal to evenly distribute weight when standing.

Water management on many of the evaluated farms provided an area of improvement. It is well known that heat stress can impact milk production and cow comfort. While implementing technologies such as fans and sprinklers is common, farmers can further aid in heat abatement by ensuring cows have access to clean drinking water at all times. Additionally, water plays an important role in thermoregulation in periods of heat stress. Water bowls or troughs covered by feed should be frequently scooped out to encourage water intake. Water bowls and troughs should be cleaned at least twice a month using a weak chlorine solution and rinsed well. Water troughs should be dumped and refilled between cleanings at least once weekly to prevent mold and feed build-up.

Many farmers pay close attention to feed cost and actively seek out ways to reduce feed-related expenses. While evaluating feed cost and reducing the need for purchased feeds is important, feeding management and ensuring the formulated ration is delivered and consumed by dairy cows should also be an important consideration for Pennsylvania dairy farms. Evaluating crop quality, mixing order, the physical form of rations, mixer maintenance, and cow comfort could help improve feed efficiency on dairy farms. 

References:

1. Adesogan, A.T., and Newman, Y.C. 2021. Silage Harvesting, Storing, and Feeding. University of Florida Extension.
2. Feeding Total Mixed Rations. University of Minnesota Extension.
3. Ishler, V., Jones, C., Heinrichs, J., and Roth, G. 2017. From Harvest to Feed: Understanding Silage Management. Pennsylvania State Extension.
4. Muck, R. E., Moser, L.E., Pitt, R.E. 2003. Postharvest Factors Affecting Ensiling. Silage Science and Technology. 42:251-304.