Intensified cow/calf production in the Southern Great Plains Adam McGee, Jarrod Cole, Corbit Baylif, Miles Redden, Courtney Spencer, David Lalman, Jason Warren, Damona Doye, Ryan Reuter, and Gerald Horn Abstract With the decreased availability of grazing land, enhancing productivity per acre is important to maintain and increase beef production. This multi-year study evaluates whether restricted grazing of small grains and summer annuals (INT) can reduce total land required for cow-calf production compared with an extensive production system using only native range (EXT). The EXT treatment had continuous access to native range stocked at 13.3 acres/cow-calf pair/year. The INT treatment utilized restricted grazing of annual forages in different seasons to reduce total land usage to 8.8 acres/cow-calf pair/year. During the winter, INT had access to wheat pasture for an average of 8 hours per week then had continuous access to native range during early summer and fall; and 4 hours restricted grazing per day on summer annuals. Cattle performance was measured by cow body weight, cow body condition score (BCS), and calf average daily gain (ADG). The INT cow body weight and BCS were greater at all time points (P < 0.01) except late summer in year one (P > 0.06). For year two, body weight and BCS were not different at all time points (P > 0.06) except winter BCS (P = 0.02). The INT calf ADG was greater throughout year one (P < 0.05) and not different in year two (P > 0.08) between groups. Utilizing confinement during strategic periods of the year we increased calf gains and reduced the total land mass required for beef production. Introduction Two of the largest constraints for beef producers, especially those just starting out are; access to capital and grazing land required for the herd. Land resources are being reduced for a variety of reasons including; encroachment from invasive species and urban environments, utilization of grazing land for grain crops; and thus the feasibility for young producers to successfully implement a new livestock production operation is diminishing. As the average age of the American farmer increases (2012 Census of Agriculture), finding ways to promote the opportunity for new producers to enter the industry becomes essential. Wheat pasture has been widely used for growing stocker cattle in the southern Great Plains, but has seen limited use in cow/calf production due to lack of proof of profitability. The objective for this project is to evaluate utilization of semi-confinement and limited winter and summer annual grazing to reduce the land area needed for cow-calf production. Materials and Methods A multi-year study was initiated in the fall of 2013 at the Lake Carl Blackwell Range Beef Cow Center North Range (NR) to evaluate two grazing systems: yearlong continuous grazing (EXT), and semi-confinement utilizing a combination of limited wheat and cover crop grazing and native range (INT). The study was conducted designed as a one way treatment structure with pasture used as replication. All statistical analysis was conducted using SAS (Cary, NC) with pasture within treatment included as a random effect. Each treatment consisted of three replications of fall calving mature Angus and Angus-Hereford commercial mature cows (Table 4). All cows were AI bred the first of December to Angus or Hereford utilizing the 7 day Co- Sync + CIDR timed AI protocol (Stein, 2015) and Charolais cleanup bulls were placed in each
pasture for 45 days. All cows were dewormed in both fall and spring (Safeguard) and fly tags (XP820) were utilized each summer. Mineral was supplied ad lib throughout the year to every pasture. Steer calves were implanted each year in March with zeranol (Ralgro) to coincide with initiation of native warm-season grass green up. Cattle in the EXT treatment were given year round continuous access to 13.34 acres of native range per cow/calf pair, which is considered a conservative stocking rate for this area. They were provided with supplemental protein from October to April, (Lalman, 2015) which was fed 3 days/week and adjusted to provide an average of 2.43 lb/hd/d of 38% CP cubes in year 1 and 3.42 lb of 32% Dried Distillers Grains (DDG) in years 2 and 3. EXT cattle were only supplied hay during periods of snow or ice accumulation when grazing was restricted. Cattle on the INT treatment were transported after breeding each year 17.2 miles from NR to the Wheat Pasture Research Center (WHEAT) located just west of Stillwater, OK. Cows were allowed to graze wheat stocked at 0.99 acres/pair for 12 hours/week during year one and 0.74 acres/pair for 6-9 hours/week in years 2 and 3 (Table 2)(Winter). Calves were allowed unlimited access to wheat through creep gates in the fenced dry lot throughout the restricted grazing period. When not grazing, the cows were kept in a dry lot and given ad lib hay (Native prairie hay, 5.5-6.7% CP) and mineral until approximately first hollow stem (mid-march). After first hollow stem, cattle were allowed unlimited access to the wheat for graze out (Spring Graze-out). Once all the wheat was consumed (May 1), the INT cattle were transported back to the NR and allowed to graze native range stocked at 7.91 acres/pair in year one and 6.42 acres/pair in years 2 and 3 (Early Summer). The stocking rate was increased in year 2 and 3 by adding additional cattle to the study to consume the available forage during the growing season since cattle would not be grazing native range during the winter months. INT cattle remained in their respective pastures until weaning (July 16 year 1, June 18 year 2). Both treatments were comingled on native pasture for approximately 10 days during weaning before the INT cows were transported back to WHEAT (Late Summer) for summer grazing of brown mid rib sorghum and sunhemp in year 1. In year 1 both INT cows and calves were transported back to WHEAT to graze. In year 2 INT calves only were transported back and INT cows were comingled on bermuda-grass pasture. In August, cows were transported back to NR (Fall) and both treatments were comingled prior to and during calving. Cows were placed back into respective pastures after calving where they remained until breeding (Table 1). At each diet change in the INT cattle, all treatment cows and calves were weighed, and body condition scores (BCS) using a 1-9 scale (1=emaciated, 9=obese) were assigned to the cows. A blood test (BioPRyn year 1, PAG Elisa year 2) was used to test for pregnancy in May of year 1 and 2; and pregnancy was determined by rectal palpation by a trained technician (OSU Veterinary Medical School, Stillwater, OK) was used in year 3 to check pregnancy rates in the cattle. All NR pastures were burned each spring, and all cattle were comingled on a bermuda-grass pasture for approximately 1 week during that time to allow grass growth to accumulate. Forage mass estimates were taken monthly using a 1 ft 2 quadrate using GPS marked locations to ensure similar forage production from 4 locations in each pasture/replication at NR and from 8 locations in each pasture/replication at WHEAT to ensure equal forage availability. Wheat DM intake was evaluated utilizing 2 cows/rep/time point. This was accomplished by weighing cattle immediately prior to turning out on wheat, allowing them to graze for the entire grazing allotment while defecation was collected from each cow by observers in each pasture. Calves were kept separated from their mother during this time to prevent any calves from nursing. After
grazing the cow was immediately weighed again. Forage samples were collected and analyzed for DM content. The DM intake was calculated as the difference between the initial and post grazing weight plus fecal divided by the DM content of the wheat sample. Wheat was planted mid-september at 100 lb of live seed/ac and 70 lb/ac of urea nitrogen. Each year after graze-out, wheat was sprayed (glyphosate N-glycine) to kill out any remaining wheat. In year 1 sorghum-sudan, cowpeas, and sunhemp were no-tilled on June 15 th ; in year 2, red river crabgrass was broadcast over wheat on March 13 th at 6 pounds of live seed/acre with 45 pounds of urea nitrogen applied. Results and Discussion Initial body weight and BCS of INT and EXT cows did not differ by design (P = 0.15) in year one. However INT were heavier with greater BCS at all other time points (P < 0.01) with the exception of late summer (P = 0.06 and 0.12 for cow body weight and BCS, respectively). Calf weight followed a similar trend to cow performance with initial weight and weaning (P 0.06) that did not differ but all others were greater (P 0.03) for INT. Calf ADG was different at all time points (P 0.05) where INT calves had a greater ADG for Winter and spring graze-out, but lesser when moved to native range for early summer grazing, at which time EXT calves experienced compensatory gain and gained 0.26 lb/day greater than their INT counterparts. In year 2, cow BW was not different across all time points (P 0.08) with the exception of the initial weight (P = 0.03). Cow BCS was not different for all time points (P 0.06) with the exception of winter (P = 0.02). Since cow BW was different for the initial weight it was decided to increase the wheat pasture restriction in order to keep the INT cows from gaining excess weight during the winter. Similar to year 1, calf weight at the start and weaning of year 2 were not different (P 0.57) but INT were heavier at the remaining time points (P < 0.01). Calf ADG was different for the winter time point only (P < 0.01). All other calf ADG were not different (P 0.09). In Year 3, initial cow BW was not different for both treatments (P = 0.91) but INT cows were heavier for both the winter period and the spring graze-out (P < 0.01). Cow BCS followed the same trend as cow BW, not different at the start of the trial (P = 0.14), but greater for both winter and spring graze-out. INT cow BCS did not differ across the entire wheat grazing period with a change in BCS of 0.3, while the EXT cows lost 1.6 BCS during the winter and spring graze-out periods. In Year 3 calves on treatments did not differ at the start of the trial (P = 0.17), but the INT calves have been heavier at all time points so far (P < 0.01) and had a greater ADG during the winter period (P < 0.01). INT calf ADG was greater for both the winter and spring grazeout periods (P < 0.01). Cow wheat DMI in year 1 averaged 16.3 lb/4 hours of grazing (12 hr/wk) which amounted to 1.8% of their BW. In year 2 when cow DMI was 9.9 lbs for 3 hours (9 hr/wk) which was 0.81% BW. When cows were allowed to graze for 6 hours per week, they consumed 18.3 lbs/ 3 hours grazing or 1.6% of their BW. In year 3 the cows consumed 14.9 and 10.4 lbs of wheat DM during the 3 hour grazing period for January and February, respectively, which amounted to 1.16% and 0.91% percent of body weight for the same two months. Reproductive performance of the cows in year 2 were not different for pregnancy rate, number bred to AI, and calf BW (P
0.09). While there were no statistically significant differences, there seems to be a numerical advantage for EXT with a greater number bred to AI (P = 0.21). This data suggests that by utilizing semi confinement during strategic periods and limit grazing small grain pasture cattle can be maintained and heavier calves produced on fewer acres. While this may not be a viable option for all areas of the country, however with the mild weather and abundant wheat pasture, this system seems to fit the climate of the southern Great Plains. Works Cited U.S. Department of Agriculture National Agriculture Statistics Service. 2012. Census of Agriculture, http://www.agcensus.usda.gov/publications/2012/full_report/volume_1,_chapter_2_ US_State_Level/st99_2_045_045.pdf. Accessed 4/19/16 Cole, Jarrod. Thesis, Intensified Cow-Calf Production in the Southern Great Plains Incorporating Native Rangeland, Wheat Pasture, Semi-Confinement and Cover Crops. Dec. 2015 Lalman, David. 2015 Chapter 21 Supplementing Beef Cows Beef Cattle Manual 7th edition pg 197, Stein, Daniel. 2015 Chapeter 31 Synchronizing Heats in Beef Cows and Heifers Oklahoma Beef Cattle Manual 7 th edition pg 294. Table 1: Intensive Grazing Schedule Date Year 1 Year 2 Year 3 12/4-1/3 12 hours/week 12 hours/week 9 hours/week 1/3-2/24 12 hours/week 9 hours/week 9 hours/week 2/24-4/3 12 hours/week 6 hour/week 9 hours/week
Table 2: Wheat Grazing Times during Winter Period Grazing Year Dates Days Feed/Forage Acres/Cow Period Winter 1 12/9-3/27 109 Dry Lot limit Graze Wheat 0.99 2 12/4-4/3 120 Dry Lot Limit Graze Wheat 0.74 3 12/3-3/15 103 Dry Lot Limit Graze Wheat 0.74 Spring 1 3/27-5/7 41 Ad Libitum Wheat 0.99 Grazeout 2 4/3-5/1 28 Ad Libitum Wheat 0.74 3 3/15-4/7 23 Ad Libitum Wheat 0.74 Early 1 5/7-7-16 69 Native Rangeland 8.40 Summer Late Summer 2 5/1-6/19 49 Native Rangeland 7.90 1 7/22-8/22 30 Sorghum-sudan, Cow peas, 0.49/cow and and Sun hemp 0.74/calf 2 6/22-8- 48 Red River Crabgrass 0.49/cow and 11 0.49/calf Fall 1 8/22-12/4 102 Native Rangeland 8.40 2 8/11-12/3 112 Native Rangeland 7.90 Table 3: Cow Reproductive Performance Year 2 INT EXT P Value Pregnancy 0.27 Bred, hd (%) 48 (91%) 37 (93%) Open hd (%) 4 1 (3%) (8%) Aborted hd (%) 1 (2%) 2 (5%) AI vs Natural Sire 0.21 AI hd (%) 25 (53%) 25 (67%) Natural hd,(%) 22 (47%) 11 (33%) Calf BW 82 85 0.38
Table 4: Cow and Calf Performance Year 1 Year 2 Year 3 Weigh Point INT EXT P Value INT EXT P Value INT EXT P Value Number/Rep, hd 14 14 18 14 18 14 Cow Age 5.6 5.6 0.91 7.1 7.1.97 6.7 6.8 0.80 Cow BW, lb Initial 1177 1146 0.15 1322 1243 0.03 1215 1220 0.91 End of Winter 1126 1027 < 0.01 1157 1093 0.08 1232 1042 < 0.01 End of Graze-out 1258 1117 < 0.01 1287 1223 0.22 1271 1035 < 0.01 Weaning 1439 1329 < 0.01 1364 1309 0.17 End of Late Summer 1514 1437 0.06 1463 1492 0.48 Cow BCS Initial 5.1 5.1 0.60 5.7 5.5 0.65 5.0 5.3 0.14 End of Winter 4.7 3.6 0.01 4.9 3.7 0.02 5.1 3.9 < 0.01 End of Graze-out 6.1 4.8 < 0.01 5.6 5.2 0.06 5.3 3.7 < 0.01 Weaning 7.2 6.5 < 0.01 6.6 6.2 0.27 End of Late Summer 7.5 7.2 0.12 6.7 6.9 0.49 Calf Wt, lb Initial 286 275 0.38 258 252 0.57 255 239 0.22 End of Winter 441 377 0.03 498 395 < 0.01 483 354 < 0.01 End of Graze-out 575 486 0.02 576 500 < 0.01 561 419 < 0.01 Weaning 771 698 0.06 691 633 0.07 Calf ADG lb/d End of Winter 2.22 1.44 < 0.01 2.00 1.21 < 0.01 2.61 1.19 < 0.01 End of Graze-out 3.27 2.66 0.04 3.23 3.84 0.09 3.41 2.00 < 0.01 Weaning 2.76 3.02 0.05 2.36 2.68 0.26