Serving Society through Food Animal Agriculture
January 2001
FEED AND ANIMAL MANAGEMENT FOR BEEF CATTLE[*]
Beef cattle feeding operations typically include weaned calves that are fed to market weight or stocker cattle finished in feedlots. For short time periods, beef cows may also be fed in confinement. Distinctly different diets, generally differing in the relative amount of roughage to concentrate levels, are required for the different weights or stages of the life cycle. This results in great differences in the volumes of manure produced and the nutrient compositions of manure from the different life stages. This fact sheet briefly highlights some factors affecting nutrient excretion with potential dietary adjustments that can be used to minimize excess nutrient excretion. Selected nutrient requirements for beef cattle that could have environmental impact are listed in Tables 1 and 2. Reference to the NRC (1996) is imperative for a thorough evaluation of beef cattle diets on a commercial operation.
Table 1. Protein,
calcium and phosphorus requirements for growing and finishing beef cattle1
Body Weight,
lb.
525 650 775 900 1025 1150
Dry Matter Intake,
lb/d 14 17 19.5 21.5 23.5 25.5
Crude Protein, lb/d
Daily Gain, lb.
1.0 1.22 1.36 1.49 1.57 1.65 1.72
1.8 1.55 1.69 1.82 1.86 1.91 1.95
2.5 1.87 2.01 2.13 2.14 2.15 2.16
3.3 2.18 2.32 2.43 2.40 2.38 2.36
4.0 2.49 2.62 2.73 2.66 2.60 2.54
Calcium, lb/d
1.0 0.04 0.04 0.05 0.05 0.00 0.05
1.8 0.06 0.06 0.06 0.06 0.06 0.06
2.5 0.08 0.08 0.08 0.07 0.07 0.07
3.3 0.10 0.09 0.09 0.09 0.08 0.08
4.0 0.11 0.11 0.10 0.10 0.09 0.09
Phosphorus, lb/d
1.0 0.02 0.02 0.03 0.03 0.03 0.03
1.8 0.03 0.03 0.03 0.03 0.04 0.04
2.5 0.04 0.04 0.04 0.04 0.04 0.04
3.3 0.04 0.04 0.04 0.05 0.05 0.05
4.0 0.05
0.05 0.05 0.05 0.05 0.05
1Weight at small marbling, 1200 lbs. Adapted from Nutrient Requirements of Beef Cattle 7th Edition, 1996. National Research Council, National Academy of Science, National Academy Press, 2101 Constitution Ave., Washington, D.C. 20318
Avoid overfeeding nutrients. This is the first
step in feed management. By properly
balancing protein, phosphorus (P), and the other nutrients of the diet to meet
animal performance expectations, unnecessary excretion of potentially
environmentally damaging nutrients can be minimized. Because by-products are often utilized in cattle diets, one
should note the digestibility (availability) of nutrients from each feed
ingredient source, as well as significant nutrient excesses. Balancing nutrient levels can be challenging
when by-products are used. The availability
and levels of nitrogen (N) and P are especially important. Rumen metabolism of different protein
sources and retention varies considerably, potentially resulting in
significantly high levels of N excretion.
In addition, P has been routinely added into mineral mixes for
cattle. However, the normal level of P
in most concentrate (grains) ingredients in cattle feedlot rations exceeds the
P requirements of cattle. Recent research
has shown that P excretion can be reduced by 20 to 30% by not adding supplemental
P to the diet. With forage based diets,
the addition of supplemental P may be needed to meet animal requirements.
In semi-arid and arid climates where salinity
problems can exist and sodium accumulation can adversely affect crop
production, one should minimize dietary salt intake. In addition, beware of potassium accumulation in forages
receiving high levels of manure application.
This can potentially cause grass tetany problems with cattle consuming
such forages.
Table 2. Protein, calcium and phosphorus requirements for beef cows1.
Months
Since Body Dry Matter Crude
Calving Weight Intake Protein Calcium Phosphorus
lb. lb. ¾¾¾¾ lb/d
¾¾¾¾
0 (Calving) 1340 24.6 2.20 0.06 0.04
1 1200 26.8 2.71 0.08 0.05
2 (Peak Milk) 1200 27.8 2.97 0.09 0.06
3 1205 28.4 2.82 0.08 0.06
4 1205 27.4 2.54 0.07 0.05
5 1205 26.5 2.26 0.06 0.04
6 1210 25.7 2.04 0.06 0.04
7 (Weaning) 1215 24.2 1.45 0.04 0.03
8 1225 24.1 1.49 0.04 0.03
9 1240 24.0 1.57 0.04 0.03
10 1260 23.9 1.69 0.06 0.04
11 1290 24.1
1.89 0.06 0.04
1Mature weight at body condition 5, 1200 lb; peak milk, 20 lb; calf birth weight 85 lb; calving interval 12 months. Adapted from Nutrient Requirements of Beef Cattle 7th Edition, 1996. National Research Council, National Academy of Science, National Academy Press, 2101 Constitution Ave., Washington, D.C. 20418.
Feeding and Animal
Management
Penning and grouping strategies may also be used to
more nearly meet the nutritional needs of cattle of a common age, sex or
size. Homogenous groups (by weight and
stage of production) allow the producer to utilize diets that more closely
match the actual needs of all animals in the group, since there is less
variation between animals. Overfeeding
of nutrients within a group can thus be significantly reduced.
Good bunk management is imperative to reduce feed
wastage. This involves checking feed
intake levels and adjusting intake to closely meet the requirements of the size
of cattle involved. Consideration
should also be given to how much feed is being wasted in the feedlot
operation. In some operations,
leftovers may be scraped up and re-fed to a second group of cattle; oftentimes
they are fed to animals requiring less
nutrients. In other cases
refused feed is scraped from the feeding area and is not re-fed. In this situation, waste removed from the
lot will include both the wasted feed and the manure nutrients.
Another
aspect of feed management takes into account nutrient losses during feed
storage. Depending upon how feed
ingredients are stored, nutrients may be directly lost to the environment as a
result of poor feed storage conditions or as a result of rainfall on uncovered
feed. Fermented feeds, such as silage,
can produce a leachate. Containment of
silage leachate, and good management of all feed storage areas and feed
transport is advised so that feed-based nutrients will not be lost directly to
the environment.
The mineral content of the water supply should be
considered with regard to the total intake of dietary minerals. Depending on the quality of water supply
available, water intake may make a substantial contribution to daily mineral
intake, particularly with regard to sulfur, and in some areas of the country,
salt. Routine water sampling can help
the nutritionist formulate properly for the amount of minerals that need to be
added to the diet to meet the animal’s actual requirements.
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