Many producers have been asking questions about supplementing their beef cattle herd.  There are three things people need to know when deciding how they are going to feed the beef herd this year.  These questions are:

1. What are the requirements of my cows?
2. What do I have on hand to feed my cows?
3. Where are my cows lacking and how can I supplement what is lacking for my cows?

Table 1 shows the nutrient requirements for a 1,200 pound beef cow of moderate milking ability.  This should represent the average beef cow in Virginia.  Spring calving herds have the lowest nutrient requirements during early winter while fall calving herds are at or near peak nutritional needs.  The nutrient requirements of beef cattle presented have been well established through research but do not account for any environmental factors.  There are many environmental factors that affect the nutrient requirements of a beef cow being wintered in Virginia.  Mud, wet hair coats, and very low temperatures can add significantly to the energy requirements of the beef cow.  Total Digestible Nutrients (TDN) is a common measure of the energy density of various feedstuffs.

Table 1. Requirements of a 1200 pound beef cow of average milking ability

The next thing you have to look at is what you have on hand to feed your cows.  This includes both the quantity and quality of what is available.  The level of fiber in the hay can decrease the amount of hay that a cow will eat.  Neutral Detergent Fiber (NDF) is a measure of the “bulkiness” of the hay.  Research indicates that beef cows will intake a maximum of 1.2% of their bodyweight in forage NDF.  Acid Detergent Fiber (ADF) is a measure of the digestibility of the hay.  If the ADF of the hay is high, less of the hay will be utilized by the cow and more will pass through the cow undigested.  Figure 1 shows the relationship between harvest stage and fiber content.

In the samples in Table 2, the forage quality can be best described as less than ideal.  The timing of the rainfall made producing quality hay in Virginia a challenge this year.  Many producers have commented that the hay was “actually much greener and better than they thought it would be due to all the undergrowth”.  The hay samples below demonstrate that on a whole that statement is probably not true and we need to take care when feeding this year’s hay crop.  When feeding very poor quality hay high fiber levels serve as a double whammy.  Not only are cows consuming hay with less energy and protein content, but because they will fill up their rumen faster they will eat less total pounds and take in even less total pounds of nutrients.  Hay that is stored outside unprotected or baled when it is too green may have significant areas of mold.  Moldy hay may limit intake as well.  These issues explain why we commonly have problems maintaining weight on beef cows even when we are providing them with all the hay they want (can) eat.  Table 2 contains the Total Digestible Nutrients (TDN), Crude protein, and NDF analysis from 61 hay samples from farms across the state of Virginia

 Table 2.  Nutrient analysis of 61 hay samples from Virginia beef cattle farms

Graph 1 shows what how many of the hay samples will meet the nutrient requirements of beef cows at three different stages of production.  The samples show that energy is the primary nutrient deficiency in cows in late gestation and early/peak lactation.  Energy demands are very high for beef cows during these 2 stages of production any supplement strategy needs to be designed around meeting the energy demand of these cows.

The effect of fiber on actual protein and energy intake in beef cows

In 51 out of 61 (83.5%) hay samples, the beef cows will run out of room in her rumen before she eats as much as she wants to eat.  High fiber levels in the hay cause the cows to eat less than normal.  While we talk about percentages of protein and TDN, it is important to remember that what is really vital is how many pounds of each nutrient each cow actually consumes.  Graph 2 shows the percent of samples meeting the protein and energy requirements of beef cows when the hay intake level is adjusted for the fiber content of the hay.

There is a common saying in business school that if you can’t measure it you can’t manage it.  Farmers must run their farms like business if they want to maximize animal well being and profit.  Feeding of beef cows generally makes up more than 60% of the costs of keeping a beef cow.  Hay samples can be analyzed for $15.50 per sample and you can body condition score cows while you are running them through the chute this fall.  The chart above shows that it is near impossible to meet the energy needs of cows after they calve on hay alone.  In order to ensure that cows are in adequate body condition so they will breed back in a timely manner producers have 3 choices.

1. Producers can have cows in a body condition score of 6+ so they can afford to lose 1 BCS
2. Cows can have access to grazing during this time frame
3. Producers can supplement cows to meet their needs

Coming next month:

Evaluating the hay feeding on individual farms and planning a supplementation program

This Issue:

• Livestock Update - November 2009

Other resources in:

• Beef Cattle

Other resources by:

• John Currin
• Mark A. McCann

Other resources from:

• Virginia-Maryland Regional College of Veterinary Medicine
• Animal and Poultry Sciences