Cattle Performance: The Protein Factor

Protein frequently is the most limiting nutrient for cattle wintered on poor to moderate quality harvested forages as well as for mature cows and growing cattle grazing dormant grass pastures and crop residues. Ample amounts of protein are required in order for cattle to efficiently harvest energy from forage-based feeds. Protein is needed to support a healthy, active population of fiber-digesting microorganisms in the stomach.

Consequently, when dietary protein is limiting, fiber digestion is not optimal.  Poor digestion results in inefficient energy use, and often decreases feed intake too. The combined effect of these factors is a significant decrease in overall energy balance for the animal. This can limit growth rate of young animals or lead to poor body condition scores in reproducing cows and heifers.

Cattle Performance Trial

A study was performed at the Kansas State University Beef Cattle Research Center using 175 crossbred beef heifers averaging 683 pounds. Heifers were fed low quality prairie hay free-choice, or the same hay supplemented with 5 pounds daily of alfalfa hay. Heifers within each forage group had access to two low moisture blocks, one fortified with 12% crude protein, the other with 30% crude protein, or no supplement. Heifers were fed the forage-based diets for 89 days, and had free access to white salt and water at all times.  Daily gains, feed intakes, and efficiencies of heifers are shown in Table 1.

Cattle protein supplement strategy on feed intake.


Heifers fed prairie hay with no alfalfa actually lost weight, indicating that the hay had limited energy content. Performance was improved substantially by feeding blocks. In particular, the higher protein content block improved forage intake and reduced weight loss compared to the un-supplemented controls.  Feeding five pounds of alfalfa daily effectively increased overall energy intake by heifers, allowing for a substantial improvement in gain compared to heifers fed only the prairie hay. Feeding the two low moisture blocks resulted in additional boosts in gain and efficiency, illustrating that low moisture block supplements are effective over a range of forage qualities.

Cattle Digestion Trial

Twelve steers averaging 640 pounds were used in an intake and digestion trial at the Kansas State University Beef Cattle Research Center. Treatments consisted of 1) no supplement, and 2) a low moisture block supplement fortified with 30% crude protein. Steers were kept in individual pens throughout the 18-day experiment. Cattle had free access to coarsely chopped prairie hay and water. All steers were fed approximately 0.7 ounces of plain salt each day. Low moisture blocks were broken into small pieces and fed once daily to the supplemented group at the rate of 0.9 lbs. per head. During the final 6 days of the experiment, total fecal output was measured for each animal. The proportions of dry matter, crude protein, neutral detergent fiber, and organic matter were subsequently determined for hay, blocks and feces. This made it possible to calculate total digestibility for each diet. Results of the digestion experiment are shown in Table 2.

Cattle protein supplement strategy on feed intake and growth performance.


Forage intake increased approximately 13% when the low moisture block fortified with 30% crude protein was fed to the cattle. Likewise, digestibility of the hay and of the total diet increased significantly by feeding low moisture block supplements.

Forage Utilization: The SmartLic Solution

Research has demonstrated that supplementation with SmartLic blocks can effectively improve forage intake and cattle performance. The consistent, economical intake of SmartLic supplements is seemingly small in comparison to the benefits realized by livestock.  The high energy content of SmartLic blocks, combined with increases in forage intake and forage digestion resulted in large improvements in digestible feed intake. Digestible feed intake is a good indicator of total energy intake by the animal, and is a reasonable approximation of total diet TDN. SmartLic NE-30 increased digestible feed intake by more than 33.6%, and increased digestible crude protein intake by over 90%.  Supplementing with SmartLic supplements provides essential nutrients that can improve utilization of low quality forages.