| What is your opinion on the importance of cow longevity vs feed efficiency, in The Netherlands for example, farmers are lowering the number of replacement heifers and have more cows that reach 3, 4 or 5 lactations? |
It is a win-win situation, once cows reach their maturity, you don’t pay “growth tax” anymore, and also, the feed efficiency of a mature cow is better compared to a heifer. It also allows you to use part of the herd to breed hybrid bulls. Raising a heifer costs 2,000 USD, but the price of a heifer on the market is 1,300 USD only. Also, you spread the environmental impact of calf rearing over more lactations, which lowers the methane emission per kg of milk produced during the lifetime of a cow. |
| How do we deal with dairy cows that produce 30-35 liter when less than 17 days in milk and that have a feed efficiency >2? |
The good news is that these cows rapidly increase milk production, but their DMI lags behind. As a result, they will lose bodyweight. If they have to mobilise too much body reserves, they will develop metabolic disorders. The key to resolve this is managing the dry cow period properly. In the US, low energy diets during the dry cow period are commonly used. |
| How can dairy farmers increase feed efficiency on their farms? |
A number of factors that have an impact on feed efficiency of dairy cattle were listed during the presentation. Out of those, the most important are digestibility of feed, days in milk, somatic cell count and sub-acute rumen acidosis. |
| Is there a correlation between digestibility of fibre and milk production? |
Research by Oba et al. in dairy cows has shown that each one point difference in NDF digestibility represents 0.25 to 0.3 kg of daily Energy Corrected milk production. |
| If the milk protein level of dairy cattle is already 3.55 %, will it increase if you feed extra amino acids? |
Not really, it seems that a dairy cow that produces protein at that level has reached her genetic potential already, it is the cows that are low in protein that usually respond with an increase in milk production. |
| Can adding protected amino acids result in an increase of dry matter intake in dairy cows? |
We know that an increase in RDP or RUP will lead to an increase of dry matter intake of dairy cows. It is questionable if adding protected amino acids also will. |
| Will the use of amino acid supplements help to reduce the carbon footprint per kg of milk produced? |
The use of amino acid supplements in dairy cows will result in an increase in Energy Corrected Milk yield. If a cow can get such an increase via the protein fraction, it will reduce the amount of methane per kg of milk produced. |
| Do you know what the r2 of dairy cows for feed efficiency and methane emissions is? |
The r2 for feed efficiency of dairy cows lies between 10 and 15%, for methane emission it is a little bit higher, 25 to 30%. For health treats this is usually below 10%, whereas for production it is around 15%. Breeding for feed efficiency and methane emission is therefore very well possible. |
| Can the large dry matter intakes of Canadian dairy cows be related to cow size? |
Bigger and heavier dairy cows need more energy for maintenance and as a result have a somewhat lower feed efficiency. |
| From the nutritional point of view, what would you do to improve feed efficiency of dairy cows in late lactation? |
These cows present a big challenge, particularly if there is no precision feeding programme used on the farm. The Body Condition Score of these cows needs to be monitored and they need to be moved into a separate group. The ration needs to be bulked up with more forage with a lower energy density, e.g. straw. Cows with a BCS of > 3.5 are high risk cows, you might even want to restrict their feed intake. |
| If we want to compare feed efficiency between farms, should we not, next to taking into account the kg of FCM produced, the energy and protein value of the diet and the DMI, also take the amount of concentrate into account? |
Comparing feed efficiency between dairy farms would need to take into account the factors you listed. The power of feed efficiency is to calculate feed efficiency on the target farm and monitor changes in feeding or management. You can compare feed efficiency to the Ohio State standards for dairy cows with given levels of ECM yield. If feed costs are too high with the associated feed efficiency, explore reasons why (pregnancy status, forage quality, days in milk, mastitis, transition diet, etc.). |
| Do you have commercially available rumen protected histidine in the US? |
I am not aware of a commercially available rumen protected histidine currently marketed. Penn State reported a study in the January 2022, Journal of Dairy Science with varying levels of histidine using a Japanese experimentally fat coated product as rumen protected histidine. With the NRC Dairy 2021 listing of grams of metabolizable amino acid, more types and sources of rumen protected amines will emerge. |
| What kind of ration should be used to calculate correct levels of RDP and RUP for dairy cows? |
All lactating dairy cow rations should have correct RDP levels (if too high the farm will be wasting nitrogen and have higher MUN) and RUP levels (if too high, feed costs will be high and excess RUP can be used as an expensive energy source). If RDP and/or RUP are low, an economic opportunity exists. MP should be calculated along with amino acid profiles. |
