--- title: What is 305AA and how does it differ from 305ME? slug: help/en-us/pulse/305AA docTags: createdAt: 2026-05-22T18:16:11.642Z --- ## Summary The Council on Dairy Cattle Breeding (CDCB) and USDA introduced a new standardized milk yield metric called 305-AA in 2024 to better reflect modern cows and farming practices. This update improves accuracy by standardizing production to a cow at 36 months of age instead of the older mature equivalent (ME) model. - 305AA uses updated adjustment factors based on recent research covering age, breed, seasonality, and region. The factor is updated for each lactation, and the 305AA is updated for each testday. - You can view 305AA values in both DairyComp and PULSE to compare them against traditional 305ME data. While DairyComp continues to use 305ME for CowVAL and RELV calculations for now, having both metrics side-by-side allows you to see how modern adjustment factors affect your herd's projected yields. - Researchers analyzed over 100 million lactation records and the new metric reflects advances in genetics, climate, and management since the 1990s. ## Distinctions | **Factor** | **305ME** | **305AA ** | | ------------------------ | --------------------------------------------------------------- | -------------------------------------------------------------------- | | **Standardization Age** | Mature equivalent (61-86 months depending on breed) | 36 months (fixed age) | | **Climate Regions** | 3 geographical regions (East to West across U.S.) | 5 climate-based regions | | **Breed Adjustments** | Calculated with season-region; heavily influenced by Holsteins | Breed-specific age-parity adjustments using broader dataset | | **Last Updated** | 1994 | 2024 (based on 1960-2022 data) | | **Dataset Size** | Limited by 1990s computing | 101.5 million milk, 100.5 million fat, 81.2 million protein records | | **Milking Frequency** | Adjusted to 2X milking | Adjusted to 2X milking (unchanged) | | **Days Open Adjustment** | Included | Included (unchanged) | :::hint{type="warning"} ⚠️ **IMPORTANT: ** - 305AA is calculated/displayed dynamically in PULSE and is not physically stored in the testday record. - 305AA can only be applied to PULSE-connected herds that receive testday reports from a DRPC. A PULSE DRPC partner integration is not required. - DairyComp CowVAL and RELV calculations were not updated; they continue to use 305ME. - If an animal is missing an AAFAC value, the system defaults the 305AA to the 305M value (no adjustment applied). See [Troubleshoot missing AAFAC values](docId\:yA4ssE7qJIxfsLsTykxKY) below to verify the animal's data. - If animals are restored in DairyComp, their AAFAC values may need to be repopulated. [Contact Us](docId:4ghs_95g97Ps-fCkKm8sU) to create a service desk ticket to have the values reloaded from PULSE. ::: ## Where can I check 305AA details? - **Testdays: **If your dairy imports testday data to PULSE, you can check 305AA results as the following items: - **305AA:** Projected 305-day yield based on **testday** data - **AA305: **Projected 305-day yield based on **daily milk** - ~~**PULSE ONLY**~~** 305AA Fat: **Age-adjusted fat production - ~~**PULSE ONLY**~~** 305AA Protein: **Age-adjusted protein production See [Testdays](docId\:eZdiewyReXXLQVuAI8k_2) to learn more about viewing mature equivalent data in PULSE. - **CowCards:** Customize your CowCards to view the new AA items alongside traditional ME values. See [View Animal Details on CowCards](docId\:z4i4tJLWgG4x5bNEms-6_) to learn more about working with CowCards in PULSE. - **DairyComp: **Go to [ALTER10: CowCard Definition](docId\:MX-W0_rojbf_tkitdbPql) and [TestDays Tab](docId\:P3JJ9kJdEE0buqHtC_0J9) to add 305AA to your CowCards and testdays table. DairyComp will automatically upgrade your cowfile to version 10 if extra space is needed. ## Troubleshoot missing AAFAC values If an animal is missing an AAFAC value, verify the following conditions in the animal's record: - **Lactation**: The animal must have a lactation number greater than 0. PULSE does not calculate factors for heifers or male animals. - **FRESH Date**: PULSE only includes animals with a FRESH date on or after January 1, 2024. Also, FRESH date cannot be a future date. - **Active**: The animal cannot be marked as SOLD or DIED. - **Birth Date**: The birth date must occur before the fresh date. If the animal's AAFAC value is still missing after confirming these conditions, [Contact Us](docId:4ghs_95g97Ps-fCkKm8sU). ## AAFAC for restored animals and lactations When an animal or lactation is restored in DairyComp (on-premise), PULSE AAFAC values may be cleared or overwritten. If necessary, you can manually reset the value in PULSE from the animal's cowcard. ## How is 305AA calculated? PULSE calculates 305AA by applying an Age-Adjusted Factor (AAFAC) to a cow's actual milk yield. This factor is derived from the latest CDCB/USDA methodology, which considers the cow's age, parity, breed, and the specific climate region of your dairy. For on-premise DairyComp to include 305AA items, you must first have PULSE connected to your herd and be actively receiving testday reports from a DRPC. [Contact Us](docId:4ghs_95g97Ps-fCkKm8sU) if you are using DairyComp, but are not yet connected to PULSE. After the connection is confirmed, DairyComp processes 305AA by integrating three AA items and calculation logic that mirror the existing 305ME structure but utilize the updated CDCB factors. ### Calculation details - **AAFAC**: Age-adjusted factor based on CDCB/USDA methodology - ~~**PULSE ONLY**~~** AAFAT**: Age-adjusted fat factor - ~~**PULSE ONLY**~~** AAPRO: **Age-adjusted protein factor - **305AA **= 305M × AAFAC - **AA305** = daily milk × AAFAC - ~~**PULSE ONLY**~~** 305AA Fat** = 305FAT × AAFAT - ~~**PULSE ONLY**~~** 305AA Protein** = 305PRO × AAPRO ## How is 305AA applied to regions outside of the US? The USDA’s climate region assignments were developed for US states. To extend the new age-adjustment factors to international customers, VAS applied the same climate analysis method to non-US locations. The approach is based on the concept of Average Degree Days (Heating Degree Days (HDD) and Cooling Degree Days (CDD), which is a representation of outside temperature data. See [eia.gov](https://www.eia.gov/energyexplained/units-and-calculators/degree-days.php) to learn more about degree days. ## What if I already have 305AA or AAFAC items in my dairy? If an item with the name "305AA" or "AAFAC" already exists in your cowfile, DairyComp will log a message in the **Activity Log** rather than overwriting it. In these cases, [Contact Us](docId:4ghs_95g97Ps-fCkKm8sU) to ensure the items are mapped correctly to the new standard definitions. ## Want to learn more about 305AA? See the VAS article [Understanding 305‑AA](https://vas.com/blog/305aa-standardized-yield-metric-in-dairycomp/) and CDCB's article[ Introducing 305-AA](https://uscdcb.com/introducing-305-aa-the-new-standardized-yield-measurement/).