Effects of Interseeding Ladino Clover into Tall Fescue Pastures of Effects of Interseeding Ladino Clover into Tall Fescue Pastures of Varying Endophyte Status on Grazing and Subsequent Finishing Varying Endophyte Status on Grazing and Subsequent Finishing Performance of Stocker Steers Performance of Stocker Steers

Summary Two hundred fifty-six yearling steers grazing tall fescue pastures were used to evaluate the effects of fescue cultivar and interseeding ladino clover on available forage, grazing gains and subsequent finishing performance in 2016, 2017, 2018, and 2019. Fescue cultivars evaluated were high-endophyte ‘Kentucky 31,’ low-endophyte Kentucky 31 ‘HM4,’ and ‘MaxQ.’ In 2016, 2018, and 2019, steers that grazed pastures of low-endo-phyte Kentucky 31, HM4, or MaxQ gained significantly more ( P < 0.05) and produced more ( P < 0.05) gain/a than those that grazed high-endophyte Kentucky 31 pastures. Gains of cattle that grazed low-endophyte Kentucky 31, HM4, or MaxQ were similar ( P > 0.05). In 2017, steer gains were similar ( P > 0.05) among all cultivars. High-endo-phyte Kentucky 31 pastures had more ( P < 0.05) available forage than low-endophyte Kentucky 31, HM4, or MaxQ pastures during both 2016 and 2017. Steer gains and gain/a were similar ( P > 0.05) between pastures fertilized with nitrogen in the spring and those interseeded with ladino clover during all four years. Fescue cultivar or legume treatment had little effect on finishing performance or carcass characteristics of steers grazed in 2016, 2017, or 2018. Steers that grazed high-endophyte Kentucky 31 in 2016 or 2018 had lower ( P < 0.05) final finishing weight and lower ( P < 0.05) carcass weight than those that grazed low-endophyte Kentucky 31, HM4, or MaxQ. In 2017, steers that grazed pastures interseeded with ladino clover had lower ( P < 0.05) finishing gains and greater ( P < 0.


Introduction
Tall fescue, the most widely adapted cool-season perennial grass in the United States, is grown on approximately 66 million acres.Although tall fescue is well adapted in the eastern half of the country between the temperate north and mild south, presence of a fungal endophyte results in poor performance of grazing livestock, especially during the summer.Until recently, producers with high-endophyte tall fescue pastures had two primary options for improving grazing livestock performance.One option was to destroy existing stands and replace them with endophyte-free fescue or other forages.Although it supports greater animal performance than endophyte-infected fescue, endophyte-free fescue has been shown to be less persistent under grazing pressure and more susceptible to stand loss from drought stress.In locations where high-endophyte tall fescue must be grown, the other option was for producers to adopt management strategies that reduce the negative effects of the endophyte on grazing animals, such as diluting the effects of the endophyte by incorporating legumes into existing pastures or providing supplemental feed.In recent years, new tall fescue cultivars have been developed with a non-toxic endophyte that provides vigor to the fescue plant without negatively affecting performance of grazing livestock.Interseeding legumes into tall fescue cultivars with the toxic endophyte should be an effective way of increasing gains of cattle grazing tall fescue.However, these cultivars lack the competitiveness of highendophyte Kentucky 31 and their competitiveness with legumes could be a potential problem.Objectives of this study were to evaluate forage availability, stand persistence, and performance of stocker steers grazing tall fescue cultivars with non-toxic endophyte and high-and low-endophyte Kentucky 31 with and without ladino clover.

Experimental Procedures
Sixty-four mixed black yearling steers were weighed on two consecutive days and allotted to sixteen 5-acre established pastures of high-endophyte Kentucky 31 or low-endophyte Kentucky 31, HM4, or MaxQ tall fescue (4 replications per cultivar) on March 30, 2016 (535 lb); March 28, 2017 (597 lb); April 3, 2018 (581 lb); and April 2, 2019 (563 lb).HM4 and MaxQ are cultivars with a non-toxic endophyte.Two pastures of each cultivar had been interseeded with 5 lb/a of 'Will' ladino clover on February 22, 2016.Four steers were assigned to each pasture.Pastures without clover were fertilized with 80 lb/a nitrogen (N) on February 10, 2016, February 16, 2017, January 31, 2018, and March 6, 2019.All pastures were fertilized with 40 lb/a N and P 2 O 5 and K 2 O (as recommended via results of soil test) on September 13, 2016, September 11, 2017, September 25, 2018, and August 29, 2019.Pasture was the experimental unit and weight gain was the primary measurement.No implants or feed additives were used.Cattle were weighed every 28 days.Forage availability was measured at the same time in 2016 and 2017 with a disk meter calibrated for tall fescue.Cattle were treated for internal and external parasites before being turned out to pasture and later vaccinated for protection from pinkeye.Steers had free access to commercial mineral blocks that contained 12% calcium, 12% phosphorus, and 12% salt.Four steers were removed from the study in 2016 for reasons unrelated to experimental treatment and replaced with grazers to maintain equal stocking rates.Pastures were grazed continuously until November 29, 2016 (244 days); December 6, 2017 (253 days); November 7, 2018 (218 days); and November 14, 2019 (226 days) when steers were weighed on two consecutive days and grazing was terminated.
After the grazing period, cattle were moved to a finishing facility, implanted with Synovex-S (Zoetis, Madison, NJ), and fed a diet of 80% whole-shelled corn, 15% corn silage, and 5% supplement (dry matter basis) to determine the effect of grazing treatment on subsequent finishing performance.Cattle that grazed in 2016, 2017, and 2018 were fed a finishing diet for 98 days, 98 days, and 112 days, respectively.Cattle were then slaughtered in a commercial facility, and carcass data were collected on each individual steer.Cattle that were grazed during 2019 were being finished for slaughter at the time this report was written.

Results and Discussion
Grazing and finishing performance is pooled across legume treatment and presented by tall fescue cultivar for 2016, 2017, and 2018 in Table 1, Table 3, and Table 5, respectively, and pooled across fescue cultivar and presented by legume treatment for 2016, 2017, and 2018 in Table 2, Table 4, and Table 6, respectively.Grazing performance for 2019 is presented by tall fescue cultivar and legume treatment in Table 7 and Table 8, respectively.There were significant interactions (P < 0.05) between fescue cultivar and legume treatment for average available forage DM in 2016 and average daily dry matter intake during the finishing phase in 2017.In 2016In , 2018In , and 2019, steers that grazed low-endophyte Kentucky 31, HM4, or MaxQ were heavier (P < 0.05) at the end of the grazing period, had greater (P < 0.05) grazing gain, greater (P < 0.05) daily gain, and produced greater (P < 0.05) gain/a than steers that grazed high-endophyte Kentucky 31.Average available forage DM of high-endophyte Kentucky 31 pasture was greater (P < 0.05) than that of low-endophyte Kentucky 31, HM4, or MaxQ.In 2016, MaxQ pasture had greater (P < 0.05) available forage DM than low-endophyte Kentucky 31.Average available forage DM of HM4 pasture was similar (P > 0.05) to that of lowendophyte Kentucky 31 and MaxQ pastures.In 2017, average available forage DM of low-endophyte Kentucky 31, HM4, or MaxQ pastures were similar (P > 0.05).Steer gains were similar (P > 0.05) between pastures fertilized with an additional 80 lb/a N and those interseeded with ladino clover in all four years.Pastures with clover had less (P < 0.05) available forage DM than those without clover for all cultivars except highendophyte Kentucky 31 where available forage DM of pastures with and without clover were similar (P > 0.05).
In 2016, fescue cultivar had no effect (P > 0.05) on finishing gain, dry matter intake, or feed:gain ratio.However, steers that had previously grazed high-endophyte Kentucky 31 had lower (P < 0.05) weight at the end of the finishing phase and lower (P < 0.05) hot carcass weight than those that had previously grazed low-endophyte Kentucky 31, HM4, or MaxQ.The weight differential between cattle that grazed high-endophyte Kentucky 31 and those that grazed low-endophyte Kentucky 31, HM4, or MaxQ was similar at the end of the grazing phase (156 lb) and the end of the finishing phase (155 lb).Therefore, the weight advantage of cattle that grazed low-endophyte Kentucky 31, HM4, or MaxQ occurred during the grazing phase and was maintained during the finishing phase.Cattle that grazed high-endophyte Kentucky 31 did not exhibit any compensatory gain during the finishing phase.Backfat thickness of steers that grazed high-endophyte Kentucky 31 or HM4 were similar (P > 0.05) and lower (P < 0.05) than that of steers that grazed low-endophyte Kentucky 31 or MaxQ.Yield grade of steers that grazed high-endophyte Kentucky 31 was numerically lower (P < 0.05) than that of steers that grazed low-endophyte Kentucky 31 or MaxQ and similar (P > 0.05) to that of steers that grazed HM4.Fescue cultivar had no effect (P > 0.05) on ribeye area, marbling score, or percent of carcasses that graded USDA Choice.Overall gain of steers that grazed high-endophyte Kentucky 31 was lower (P < 0.05) than that of steers that grazed low-endophyte Kentucky 31, HM4, or MaxQ, and overall gain of steers that grazed low-endophyte Kentucky 31, HM4, or MaxQ were similar (P > 0.05).Legume treatment had no effect (P > 0.05) on finishing performance or carcass traits.
In 2017, fescue cultivar had no effect (P > 0.05) on finishing performance or overall performance.Steers that grazed pastures interseeded with ladino clover had lower (P < 0.05) finishing gains and greater (P < 0.05) feed:gain than those that grazed pastures with no legume.
In 2018, fescue cultivar had no effect (P > 0.05) on finishing gain.However, steers that had previously grazed low-endophyte Kentucky 31, HM4, or MaxQ maintained their weight advantage from the grazing phase, were heavier (P < 0.05) at the end of the finishing phase, had greater (P < 0.05) hot carcass weight, and greater overall gains than those that had grazed high-endophyte Kentucky 31.Legume treatment had little effect on grazing performance.Steers that grazed pastures interseeded with ladino clover had lower (P < 0.05) feed:gain than those that grazed pastures without clover that were fertilized with additional nitrogen.
Brand names appearing in this publication are for product identification purposes only.No endorsement is intended, nor is criticism implied of similar products not mentioned.Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.Means within a row followed by the same letter do not differ (P < 0.05).Means within a row followed by the same letter do not differ (P < 0.05).

Table 1 .
Research Effects of cultivar on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2016

Table 2 .
Effects of interseeding ladino clover on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2016

Table 3 .
Effects of cultivar on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2017

Table 4 .
Effects of interseeding ladino clover on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2017

Table 5 .
Effects of cultivar on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2018

Table 6 .
Effects of interseeding ladino clover on grazing and subsequent finishing performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2018 Means within a row followed by the same letter do not differ (P < 0.05).

Table 7 .
Effects of cultivar on performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2019

Table 8 .
Effects of interseeding ladino clover on performance of steers grazing tall fescue pastures, Kansas State University Southeast Research and Extension Center, 2019