Fresh green grass is a welcome sight come spring. However, early spring grass with limited growth or volume should be approached with caution when it’s used as the sole source of nutrition for recently calved cows.
With limited grass volume, cows can expend more protein and energy than they are taking in and lose body condition.
Cows are also coming out of gestation and into their time of highest nutritional requirement. While it can be lucrative to turn cows out on pasture at the first sign of grass, short grass won’t supply the nutrients a cow needs to perform her best.
When feeding cows in the spring, it’s vital to provide adequate nutrition to help cows maintain ideal body condition and get rebred. Your herd’s rebreeding success will determine the number of calves you’ll have the following year and how much those calves weigh.
Needs by the numbers
Nutritional requirements for cattle climb upward from gestation to the last trimester of pregnancy and are at their highest during lactation.
As a cow begins lactation, her protein and phosphorus requirements go up about 60 to 70 percent compared to requirements during the last trimester. Requirements for total digestible nutrients (TDN), or energy, increase by an additional 15 to 25 percent.
These nutrients impact milk production, a cow’s ability to get bred back quickly and, ultimately, the resulting calf crop.
If you only maintain your feeding rate from gestation to lactation, you may start shorting your cows of adequate protein and energy. This gap in nutrition can result in lost body condition and performance.
What’s at stake?
Research shows that body condition score (BCS) at calving impacts how quickly cows begin cycling and become pregnant. For cows that calved in at a body condition score of 6 (ideal), 98 percent showed estrus by day 40 of the breeding season, and 90 percent were confirmed pregnant by day 40. Comparatively, a drop to a BCS 5 resulted in just 80 percent in estrus and 65 percent confirmed pregnant.1
For every 100 cows, a single point drop from a BCS 6 to a 5 at breeding could equate to roughly 25 calves that are either born later or are not born at all because nutrition slipped post-calving.1 Calves born later result in less weaning weight.
The amount of energy provided to a cow also influences her milk production and lactation length, which impacts nutrition available for her calf.
Research has shown that a cow consuming 170 Kcal per metabolic body weight will maintain peak milk production for approximately 8.3 weeks at 20.2 pounds of milk per day, and will produce 2,726 pounds of milk over the course of 210 days. Providing additional energy, at a level of 290 Kcal per metabolic body weight, resulted in maintaining peak milk production for 10.9 weeks, at 24.2 pounds of milk per day and a total 210-day production of 3,742 pounds.2
Set up for spring success
It’s easy to get excited about a little bit of green grass, but there may not be enough volume to support a cow’s increasing requirements. Cows will run for green grass and burn more energy searching for grass than what they’ll consume. The energy deficit can result in lost body condition.
A visual loss in condition often means you’ve already left some performance on the table. Supplements can help regain condition, but playing catch-up typically means feeding large amounts of supplement at a higher cost.
Provide free-choice hay and supplement early until grass is lush and plentiful. Offer hay early and continue feeding it long enough for cows to achieve a BCS 6 at calving and no less than a BCS 5.5 at breeding.
Hay can be complemented with a self-fed solution like Accuration® supplement with Intake Modifying Technology®, which allows cattle to decide if they need additional energy and protein. Cows won’t consume much Accuration® supplement if forage is meeting their requirements, but will consume more supplement if forage is not meeting requirements.
Supplementation can help keep an ideal cattle body condition score through all seasons and optimize cow performance with existing forage.
Cover the spring nutrient gap, and set your cows up for greatness.
Talk to your local Purina representative to learn more, or visit ProofPays.com to start your feeding trial.
Article taken from Purina Animal Nutrion at
1Spitzer, J.C., Morrison, D.G., Wettemann, R.P. & Faulkner, L.C. (1995). Reproductive responses and calf birth and weaning weights as affected by body condition at parturition and postpartum weight gain in primiparous beef cows. Journal of Animal Science, 1995, 73:1251−1257.
2Jenkins, T.G. & Ferrell, C.L. (1992). Lactation characteristics of nine breeds of cattle fed various quantities of dietary energy. Journal of Animal Science, 1992, 70:1652−1660.