commercial laboratory that is equipped to test hay. The laboratory submittal form should be completed and submitted with the samples. Although forage laborato- ries can analyze for a variety of substances, request an analysis of crude protein, TDN, minerals and vitamins. A list of testing labs can be found on page 5 of The
Cattleman Range and Pasture Management Manual, supported by DuPont. This manual is available free from DuPont or from TSCRA. Just contact The Cattle- man staff or your DuPont professional for a copy.
Know what your cattle need After learning the nutrient value of your hay, de-
termine the nutritional requirements of the animals to be fed. Many references contain tables adapted from data
presented by the National Research Council’s (NRC) publication on nutrient requirements of beef cattle published in 2000. An easy-to-use reference is Nutri- ent Requirements for Beef Cattle compiled by Edward Rayburn, West Virginia University Extension Service. Go to
wvu.edu, and type “Nutrient Requirements Beef Cattle” in the search box in the upper right corner of the web page. Click on Nutrient Requirements for Beef Cattle. Tables 1 and 2 with this article are taken from Ray-
burn’s publication and contain nutrient requirements for bred cows and heifers. Rayburn also presents National Research Council nutritional data on cows and heifers nursing calves and for growing medium-frame steers. A separate table in the publication contains suggested mineral and vitamin requirements of beef cattle. In various seminars across Texas, Dr. Jason Cleere,
Texas AgriLife Extension Service, demonstrates how to use forage analysis and animal nutrient requirements
Body Weight) (pounds
1000 1100 1200 1300 1400
Last third of pregnancy 900
1000 1100 1200 1300 1400
Avg. Daily Gain (pounds)
Middle third of pregnancy 900
0.0 0.0 0.0 0.0 0.0 0.0
0.9 0.9 0.9 0.9 0.9 0.9
Dry Matter Intake (pounds)
16.7 18.1 19.5 20.8 22.0 23.3
18.2 19.6 21.0 22.3 23.6 24.9
to calculate the needed amount of supplements. Using data similar to that shown in Table 1, Cleere says an 1,100-pound cow in the last third of her pregnancy gaining about a pound per day will consume 21 pounds of dry matter per day. She needs about 1.6 pounds of crude protein and 11 pounds of total digestible nutri- ents (TDN). “Assume hay analysis showed 8 percent crude protein
and 52 percent TDN,” states Cleere. “If you multiply the 8 percent protein times the 21 pounds of dry mat- ter consumption, you fi nd that the late-gestation cow is eating 1.68 pounds of crude protein daily. Since she only requires 1.6 pounds of crude protein, the animal’s requirements are being met with the hay. “If you multiply the 52 percent TDN in the hay times
the 21 pounds daily consumption, you learn that the cow is consuming 10.92 pounds of TDN. Since a dry cow requires 11 pounds of TDN daily, these requirements are being met. If the animal has good body condition, there is no need to feed anything but the hay.” During severe drought, we might be forced to buy
low quality hay. How will that change our supplement needs? Let’s assume we analyzed purchased hay and found that it contains 5 percent crude protein and 45 percent TDN. If we are feeding that same 1,100-pound pregnant cow, she will get 1 pound of protein daily and 9.45 pounds of TDN. From the hay, the cow will get approximately 0.6 pound less crude protein than she needs and 1.5 pounds less TDN. It will require 3 pounds of a 20 percent protein
feed in addition to the hay to supply the cow’s protein needs (0.6 pound ÷ 20 percent = 3.0 pounds). The daily protein required can also be supplied with 1.5 pounds of a 40 percent protein feed in addition to the hay (0.6 pound ÷ 40 percent = 1.5). Before buying
Table 1. Nutrient requirements for dry pregnant mature cows1
Crude Protein (pounds)
1.2 1.3 1.4 1.4 1.5 1.6
1.5 1.6 1.6 1.7 1.8 1.9
TDN (pounds)
8.2 8.8 9.5
10.1 10.8 11.4
9.8
10.5 11.2 11.8 12.5 13.1
Calcium (pounds)
0.18 0.18 0.19 0.19 0.20 0.20
0.27 0.26 0.26 0.26 0.26 0.26
1Adapted from the National Research Council’s Nutrient Requirement of Beef Cattle, 2000. 86 The Cattleman September 2014
thecattlemanmagazine.com
Phosphorous (percent)
0.18 0.18 0.19 0.19 0.20 0.20
0.21 0.21 0.21 0.21 0.21 0.21
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