By
Donna M. Amaral-Phillips
I have often made the statement, ?the more feed an early lactation cow eats, the more milk she can produce, and the more profit she can potentially make for her owner. This statement emphasizes the importance of managing dairy cows to optimize feed intake, especially in early lactation and during the pre-fresh period. Why is this? After meeting the needs for maintenance, every extra pound of dry matter (feed with the water removed) that an early lactation cow eats provides enough energy to support 2 pounds of milk. In addition, cows which peak higher in early lactation produce more milk over the entire lactation. Thus, it behooves all dairy farmers to manage dairy cows so that feed intake is not compromised. Keeping a consistent source of feed composed of high quality forages in front of your dairy cows 22 hours a day (an additional 2-3 hours spent daily in the holding pen) is a high priority. Getting this feed into your cows is under your control and often times separates those herds that can get cows to milk well, stay healthy, and rebreed from herds which are lower producing and performing.
Feed intake determines nutrient concentration in diets
| Table 1. Energy density needed at two different amounts of feed intake to support the same amount of milk production. |
| | Need 35 Mcal
Energy (NEL) |
| 45 lbs dry matter | 0.77 Mcal/lb DM |
| 50 lbs dry matter | 0.69 Mcal/lb DM |
Dairy cows require a certain amount of each nutrient. The concentration of each nutrient is thus determined by feed intake on a dry matter basis. As shown in Table 1, when feed intake increases from 45 lbs of dry matter to 50 lbs of dry matter, the energy density or concentration of energy in the diet can be decreased dramatically and still provide the same amount of energy to the lactating dairy cow assuming constant amount of milk production. When nutritionists balance rations, feed intake for a group of cows is estimated based on body weight and expected milk production. The nutrient density of the diet then is set based on this expected intake and performance of the cows fed this diet.
| Table 2. Effect of decreased feed intake on energy intake. |
| | Energy density of the
total diet—
0.74 Mcal/lb DM |
| 45 lbs dry matter | 33 Mcal NEL |
| 50 lbs dry matter | 37 Mcal NEL |
| Difference- 4 Mcal NEl = 12 lbs of milk |
What happens when feed intake is not as expected? The short answer is....Cows do not get the nutrients needed and production can suffer, cows withdraw body stores or reserves and get too thin, or a combination of these two effects. Bottom line---cows do not milk as well as expected. These decreases might not be seen this lactation but are seen the next lactation when cows lack the body stores to support higher production in early lactation.
This concept is illustrated in Table 2. If dry matter intake drops 5 lbs, the amount of energy consumed from a TMR drops by 4 Mcal NEL which is equal to the amount of energy needed to produce 12 lbs of milk. Fresh cows and timid first-calf heifers are often the most affected by limited feed intake. These cows often represent the future/current profit.
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Source: University of Kentucky