Evaluation of Ryegrass Management on Growth and Performance of Growing Beef Heifers.

Evaluation of Ryegrass Management on Growth and Performance of Growing Beef Heifers

Rocky Lemus, Daniel Rivera, and Billy Johnson

A goal of Mississippi cattle producers is to provide the nutrients their cattle require as economically as possible through grazing during the winter months. Due to rapidly increasing fertilizer prices, there has been a tremendous increase and interest in planting and grazing clovers with winter annuals (ryegrass and small grains).  Forage legumes have the ability to remove or “fix” atmospheric nitrogen in a form that plants can utilize.  There are nearly 248,178 ha of annual ryegrass (planted alone, with legumes or small grains) in Mississippi, representing approximately 40% of the winter feeding.  Annual ryegrass (ARG) pastures are used for grazing stocker cattle, replacement heifers, beef cow/calf pairs and lactating dairy cows.   About 70% of these ryegrass pastures are established by over-seeding into warm-season perennial grasses (bermudagrass, bahiagrass, or mixed pastures) to extend the grazing season.  The objective of the study was to evaluate which ryegrass management strategy would result in the most advantageous system for growing young beef heifers.  Six paddocks, each 0.81 ha were utilized in the study.  The experimental design was a randomized complete design with three treatments replicated twice. The treatments include ryegrass fertilized with ammonium nitrate (RAN), ryegrass + arrowleaf clover (RAC), and ryegrass + berseem clover (RBC).  The RAN treatment was fertilized with a total of 112 kg ha^-1 in a split application of 56 kg ha^-1 in the fall after establishment and 56 kg ha^-1 in the spring after the first grazing period. The other two treatments received a 22.4 kg ha^-1 at time of planting to allow ryegrass and clovers to become established.  Phosphorus and potassium levels in each paddock were adjusted based on soil test recommendations. Glyphosate was applied 3 weeks before planting for weed control and to reduce biomass present.  Treatments were established by broadcasting annual ryegrass, arrowleaf clover and berseem clover at a rate of 56, 11.2 and 16.8 kg ha^-1, respectively. The initial stocking rate was approximately 544 kg of beef per ha (two 272 kg animals) with an estimated 50% utilization rate.  Animal daily gain was measured within each 28-day period, allowing the pasture to rest for approximately 20 days.  Animals were exposed to a uniform hay ration during the rest period.  Biomass subsamples were collected from cages to determine yields and grazing efficiency.  Clover systems showed a slight advantage over nitrogen fertilization, however, it should be noted that grazing period was shortened due to extreme weather conditions during the grazing trial, which may have affected the outcome of the study.