Farming Magazine - September, 2012
Dairy Nutrition: Feed Intakes (Still) Drive Milk Production
Which statement is correct? "The more a cow eats the more she will milk" or "the more a cow milks, the more she will eat."
Actually, both statements are accurate. However, I would suggest that the first statement causes a dairy farmer to be more proactive in his approach to milk cow feeding strategies, and the second would make him more reactive to milk cow feeding strategies.
So often we are told to monitor the feed intakes of our cows for budgetary reasons and on-farm mixing purposes. What we don't hear very often, though, is that we need to be monitoring our cows' intakes because feed intakes are what really drive milk production. More specifically, understanding the importance of dry matter intake (feed intake with the moisture removed) is foundational to attaining high milk production in a herd of dairy cows. You can't have high milk production without comparatively high feed intakes. The milk producer who understands that for a cow to produce lots of milk she's got to eat lots of high-quality feed will have half the battle won as he strives to create and maintain a high-producing herd of cows.
We've known for a long time that the most difficult area of nutrition to balance for high milk production is energy. The challenge continues to be, "how does one get a cow to consume upwards of 50 megacalories (Mcals) per day when she's producing over 100 pounds of milk and still maintain a healthy rumen?"
A properly formulated feed ration that is geared toward high milk production should maximize feed intakes and optimize the nutrient density of the ration.
To maximize feed intakes the ration should not have overly high neutral density fiber (NDF) levels, which will restrict the cow's consumption of the feed. At the same time, the ration must still contain enough effective fiber to maintain proper rumen health. The ration also needs to be kept fresh to keep cows coming back to the feed bunk. Cows will quickly sort feed if there is a lot of stemmy forage in a total mixed ration (TMR).
Optimizing nutrient density of the ration involves squeezing as many calories, protein, vitamins and minerals into a pound of feed as possible. Careful consideration needs to be given to the types of feedstuffs chosen for milk cow rations. As we gain a better understanding of specific digestibility fractions in different feedstuffs and the amino acid profiles of those feeds, we are able to better estimate energy values and metabolizable proteins in the lower digestive tract. We must know the types and the amounts of fats that are in a feed as well as the starch level.
High milk production starts in the dry period. We now know that cows that receive a properly formulated and well-managed close-up ration can produce from 1,000 to 2,000 more pounds of milk during the course of the following lactation. This is largely a result of increased feed intakes at the time of calving, which prepares the rumen for the lactation diet.
Once the cow has freshened, the energy density of the ration needs to be kept as high as possible. Feed intakes of fresh cows always lag behind milk production and this usually results in a negative energy balance for several weeks during early lactation. Feed management should include a fresh cow group in which energy densities of the formulated ration should be close to 1 Mcal per pound of dry matter. This level of caloric intake is difficult to attain without compromising the effective fiber in the ration unless rumen inert fats are used.
Even with energy densities near 1 Mcal per pound, a fresh cow that might consume only 45 pounds of dry matter in the first days postpartum will only consume 45 Mcals per day; we'd like to see 50 Mcals per day. A negative energy balance is unavoidable in cows producing over 100 pounds of milk per day during the first few weeks of lactation. Body conditions will decrease a point of body score.
Along with keeping energy levels up in the ration, there must be plenty of rumen degradable protein (RDP) for the rumen bugs to live on and plenty of high-quality, highly digestible forages to keep rumen papillae healthy along with appropriate vitamins and minerals.
Many milk producers mistakenly believe that attempting to bring their herd averages up to 25,000 pounds of milk or more is not cost-effective. I disagree. Dairy farmers should not be afraid to push their herds as hard as possible - you've been working on the genetics to improve milk production for decades. Every gallon that is produced over cost will generate profit. Only in those extreme cases when milk prices are very low and the total milk production on the farm can't cover the fixed cost of the business does it become questionable to push cows to the maximum of their production potentials.
In early lactation, the more a cow eats the more she will milk if the ration is properly formulated for the necessary energy and protein levels and careful attention is paid to rumen health. Most of the time the extra production will pay for itself many times over. With a proactive approach to your feeding strategies a cow will have a higher lactation peak and sustain that peak for a more profitable lactation, which will add dollars to the bottom line of your dairy business.
Ration formulation recommendations:
- Provide a close-up dry cow ration that keeps starch levels around 25 percent of dry matter and non-fiber carbohydrate (NFC) levels below 40 percent of dry matter.
- Fresh cow rations should be as energy dense as possible - close to 1 Mcal per pound of feed at the time of freshening.
- Effective fiber should be no less than 20 percent of dry matter intakes.
- Balance for the metabolizable amino acids, lysine and methionine, with the help of a computerized ration balancing model.
- Once a cow is fresh, keep the dietary cation-anion balance (DCAD) well into the cationic range. To accomplish this, keep potassium and magnesium levels up, especially during the hot summer months.
- Provide high-quality forages and always monitor feed intakes both during the close-up dry period as well as during the lactation.
The author is a dairy nutritional consultant and works for Central Connecticut Farmer's Cooperative in Manchester, Conn.