In recent years, providing low intake (less than 3lbs. per day), nutrient dense supplements such as cooked molasses tubs and liquid feeds have become popular in Louisiana for winter supplementation of cattle consuming hay. Protein supplementation has been shown to improve intake and digestibility of forages. However, before you conclude that protein supplementation will take care of your herd; take time to investigate how much protein is in the hay being fed by forage testing.
Companies that advertise the benefits of protein on intake and digestibility are usually presenting data for herds consuming low quality grass or hay that is less than 8% protein. Inadequate amounts of protein, degradable in the rumen, results in a reduction in the microbial population. Since the ruminant relies on these microbes to digest forages, a reduction in the microbial population will likewise result in a depression in fiber digestion. If the rate of digestion is reduced, nutrients will leave the rumen more slowly. If you think of the rumen as a tank with two pipes (an inlet and outlet), once the tank reaches its maximum volume, and the amount of flow exiting the outlet pipe is reduced, the amount of flow coming into the tank will decrease as well. Therefore, forage intake, digestibility and animal performance are reduced all because of low dietary protein.
In a review by two ruminant nutritionists, McCollum and Horn (1989 American Society of Animal Science meeting symposium paper), the authors noted that intake response to protein supplementation was not enhanced once the amount of protein in the forage was greater than 10% and total dietary protein (forage plus) supplement) was greater than 14%. In addition, an optimal balance between protein and energy is important, and a ration less than 7:1 (TDN:CP) has been suggested by researchers.
The only way to truly determine if protein supplementation is warranted is to forage test. Producers that practice good fertility management, fertilizing according to soil test recommendations, and harvest forages for hay before they become mature will likely produce hay that is sufficient in protein. Under these management conditions in Louisiana, protein supplementation will likely not enhance forage intake as observed which may be in part due to the fact that most natural protein sources will be higher in energy content than hay and energy may be the limiting factor. In this case, supplying a low protein, high energy supplement will be more economical.
On the back is a cost comparison of stored hay of adequate quality, liquid feed, cooked molasses tub, and concentrate. These calculations are done with common sense "cowboy arithmetic" and are intended for providing a snap shot of what it potentially could cost to feed a 1200 lb. cow through the winter months prior to the ryegrass grazing season. If you do not plant ryegrass for late winter/early spring grazing, then the estimated 135 day feeding period would need to be extended; in turn increasing your cow maintenance costs.
90% dry matter
Recommended rate of 5 to 6 lbs/per head/per day. However, it is difficult to limit hay consumption when feeding large round bales. Therefore, consumption rates can be as high as 25 lbs/per her/per day for a 1200 lb cow.
• Average of $.03556/lb.
º 25 lbs./per head/per day X $.03556 = $.889/cow/day
º 135 feeding days X $0889 = $120.00 per cow
• Alternative feeding methods for hay can save $$. The hay can be unrolled and offered at a predetermined amount. Another way would be to put an adequate number of rolls in a small area such that the cows can be put for about 2 hours per day in order to control the amount of hay that they consume. With this program it is important that all cows have access to the hay, approximately one roll for every ten cows. Obviously, limit feeding hay can be labor intensive.
º If limit feeding: 6 lbs./per head/day X $.03556 = $.213/cow/day
º 135 feeding days X $.213 = $28.80 per cow
35% protein (non-protein nitrogen)
62% dry matter
Recommended at a rate of 1 to 2 lbs/per head/day (We'll average that to 1.5)
• Average of $2.15/gallon
• 10.75 lbs./gallon
•$2.15 ÷ 10.75 lbs./gallon = $.20 per pound
º 1.5 lbs./per head/day X $.20 = $.30/cow/day
º 135 feeding days X $.30/cow/day = $40.50 per cow
28% protein (7% non-protein nitrogen)
94% dry matter
Recommended rate of .5 to 1 lb./per head/day (We'll average that to .75)
• Average of $88.50 tub (225 lbs.)
• $88.50 ÷ 225 = $.39 per pound
º .75 lbs./per head/day X $.39 = $.292/cow/day
º 135 feeding days X $.2925/cow/day = $39.48 per cow
12% protein (natural protein)
Recommended rate of 1% to 3% of body weight (We'll average that to 2% and estimate a 1200 lb. cow)
• Average of $297/ton
• $297 ÷ 2,000 = $.1485/lb
º 24 lbs./per head/day X $.1485 = $3.564/cow/day
º 135 feeding days X $3.564 = $481.14 per cow
NOTE: Actual consumption rates will vary depending on forage type, quality, and availability; weather and facility conditions; and, cow condition and management.