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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[*] Prepared by the FASS Environment, Waste Management and Ecosystems Committee.