This research was conducted to find the effect of prolonged feeding of sericea lespedeza (SL) leaf meal pellets with or without supplemental molybdenum on changes in body weight, serum and liver concentration of trace minerals (TM), hematology, and serum biochemistry. Thirty weaned ram lambs fed 2 lb. of a control (alfalfa pellets) or SL diet. Within the SL group, half of the lambs were treated with molybdenum to restore reduced serum molybdenum observed previously. Treatment with molybdenum increased serum and liver concentrations to that of control fed lambs; however body weight was similar between molybdenum and no molybdenum lambs. Serum and liver concentrations of trace minerals, mainly molybdenum, zinc copper, selenium, and cobalt were reduced in sericea lespedeza compared with control fed lambs. There were changes in most of the hematological and serum biochemical values between diet groups, but most were small and within a normal range and body condition were similar between diet groups. It appears that there were no detrimental effects in long term feeding of sericea lespedeza pellets, as might be practical for parasite control. It may be best to include a good mineral supplement to lambs fed sericea.
The Southern U.S. has an abundance of pasture for small ruminants, although internal parasites can be challenging. Forage plants rich in condensed tannins like sericea lespedeza (SL; Lespedeza cuneata) may aid in controlling both gastrointestinal nematodes, especially Haemonchus contortus and coccidia species. However, prolonged grazing or feeding of SL leaf meal pellets (> 56 day) decreased weight gain in lambs and kids and serum concentration of trace minerals mainly molybdenum, manganese, zinc and selenium, compared with control diet fed animals. A marked reduction in molybdenum occurred in SL-fed sheep and goats compared with control animals, with as high as 90-fold reduction. Because of the recent popularity of grazing or feeding SL hay or pellets, which are both commercially available, for an aid in the control of parasites, it is important to understand potential limitations to production of small ruminants.
To determine the effect of molybdenum supplementation on changes in body weight and serum and liver concentration of trace minerals in lambs fed SL.
To determine change in body weight, hematology, and serum chemistry in lambs fed condensed tannins rich sericea lespedeza pellets.
Trial was conducted at the USDA-ARS, Dale Bumpers Small Farms Research Center in Booneville, AR (35?N, 94?W); from May 8-August 21, 2013. Average rainfall per month during the trial was 113 millilitres. Average maximum and minimum temperature during the trial was 86ºF and 64ºF, respectively. Thirty Katahdin (n = 14) or ¼ Romanov × ¾ Katahdin (n = 16) ram lambs weaned in May (84 ± 1.5 day of age; 59.9 ± 2.4 lb) were used. Lambs were blocked by body condition score (BCS), body weight (BW), and estimated breeding value for parasite resistance, and assigned randomly to be fed: 2 lb of alfalfa based supplement (CON; n = 10), or a SL based supplement (n = 20). Supplements were balanced for energy and protein and essential minerals and vitamins met or exceeded requirements. Diets were balanced to meet moderate gains according to NRC (2007). Two lots of SL pellets (Sims Brothers, Inc., Union Spring, AL) were mixed and used for the first 5 week, and another lot of SL pellets were used for the last 10 week. Supplements were mixed at the University of Arkansas feed mill (227 lb per mixing which occurred every 14 day). The first day of dietary treatment was considered day 0. Within the SL group, lambs were administered either water alone or 163.3 milligram of sodium molybdate per lamb (mixed with 5 ml of water; sodium molybdate dihydrate, North Metal & chemical Co., York, PA) by syringe on Monday, Wednesday, and Friday (n = 10/drench) and remaining lambs with an equal volume of water. The concentration of molybdenum in sodium molybdate is 39%; thus, the target dose of molybdenum was 27.3 milligram/lamb daily. Lambs grazed one of four 1 acre plots containing predominantly tall fescue (Festuca arundinacea; n = 2 replicate/diet) and rotated among plots every two week to minimize plot effect. About 90% of the feed requirement was met by feed and 10% of the requirement was met through grazing. Water was always available and no trace mineral mix was offered as it was included in the supplement. Lambs were dewormed with a combination of albendazole (15 mg/kg BW; Valbazen, Pfizer Animal Health, Exton, PA) and moxidectin (0.4 mg/kg BW; Cydectin Fort Dodge Animal Health, Fort Dodge, IA) on day 56, which failed to reduce fecal egg counts (44.2% reduction). Hence, lambs were dewormed again on day 70 with levamisole (12 mg/kg BW, AgriLabs, St. Joseph, MO) and fecal egg count reduction was 98.8%. Lambs were treated with sulfamethoxine (55 mg/kg BW; SulfaMed-G, Bimeda, Le Sueur, MN) if signs of coccidiosis were present (watery diarrhea), which occurred in 1 lamb each from SL and SL+MO group. Body weight, and BCS was determined every two weeks. Blood was collected every 2 week to determine hematology and serum biochemistry. Serum was collected for trace mineral analysis on day 28, 56, 84, and 104. Liver biopsy was done for liver mineral level on day 104.
- Even though diets were balanced, serum concentrations of copper, molybdenum, selenium, and zinc were reduced in lambs fed CT rich SL. Supplementation of molybdenum increased liver and serum concentrations of molybdenum in SL lambs similar to control fed lambs, but did not influence in weight gain. Further studies need to focus on increasing copper and selenium in SL fed lambs without feeding too much.
- Based on hematological and serum biochemistry values, means of both groups appeared to be normal, though there were subtle but significant differences between dietary groups.
Educational & Outreach Activities
- Acharya, M. 2014. Thesis. ‘’Improving lamb performance with sericea lespedeza and molybdenum’, was submitted for the partial fulfillment of Masters at University of Arkansas, Fayetteville, AR
- Acharya, M., J. M. Burke, K. P. Coffey, E. B. Kegley, J. E. Miller, G. Huff, E. Smyth, T. H. Terrill, C. Rosenkrans, Jr. 2014. ‘Changes in trace minerals in lambs fed sericea lespedeza and administered sodium molybdate’. Southern Section ASAS, Dallas, TX.
- Acharya, M., J. M. Burke, K. P. Coffey, E. B. Kegley, J. E. Miller, G. Huff, E. Smyth, T. H. Terrill, C. Rosenkrans, Jr. 2014. ‘Hematological and serum chemical profiles in lambs fed sericea lespedeza’. ADSA-ASAS-CSAS Joint Annual Meeting, Kansas City.
- Acharya, M., J. M. Burke, K. P. Coffey, E. B. Kegley, J. E. Miller, G. Huff, E. Smyth, T. H. Terrill, C. Rosenkrans, Jr. 2014. Hematological and serum chemical profiles in lambs fed sericea lespedeza.
- Acharya, M., J. M. Burke, K. P. Coffey, E. B. Kegley, J. E. Miller, G. Huff, E. Smyth, T. H. Terrill, C. Rosenkrans, Jr. 2014. Changes in trace minerals in lambs fed sericea lespedeza and administered sodium molybdate.
- Burke, J. M., M. Acharya, J. E. Miller, T. H. Terrill, E. Smyth, G. Huff, E. B. Kegley, K. P. Coffey, C. F. Rosenkrans Jr. 2014. Influence of sericea lespedeza on relationships between gastrointestinal nematode infection and hematology, serum biochemistry, and trace minerals in lambs.
There is widespread farmer adoption of feeding sericea lespedeza pellets, hay, and grazing pasture to reduce parasites in sheep, goat, and exotic ruminants. Our cooperator, Sims Brothers, Inc., consistently sells out of the pellets and seed every year. In addition, other condensed tannin forages are being explored by farmers to control parasites.
Areas needing additional study
Further studies need to focus on increasing copper and selenium in SL fed lambs and to determine mechanism of action of condensed tannins against Haemonchus contortus and coccidia.