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- Title
Seasonal Effects on Daily Gain and Fecal Egg Counts in Purebred and Crossbred Hair Sheep Lambs on Pasture.
- Authors
Wildeus, S; O'Brien, D; Teutsch, C D
- Abstract
Hair sheep display extended seasonal breeding and lambs can be produced and raised on pasture yearround in the southeastern U.S. This project analyzed data on growth and indicators of gastrointestinal parasitism from grazing trials with pure and crossbred (Dorset-sired) Barbados Blackbelly and St. Croix ram lambs during spring, summer and fall/winter. Project lambs, balanced by breed type, rotationally grazed a 6-paddock pasture system (2.2 ha) with two Bermuda grass and four tall fescue (var. 'Riata') infected with novel endophyte (MaxQ) paddocks as part of larger groups of lambs (receiving supplementation in addition to grazing). Bermuda grass was inter-seeded with annual ryegrass to extend cool season grazing. Portable fencing was used to strip graze, and fences moved at 3 to 6 d intervals based on visual appraisal of forage availability. Fecal parasite egg counts (FEC) were determined at the end of grazing. In spring, lambs (n=12; 7.5 mo old; 26.9 kg BW) grazed fescue (9.0 to 16.7% CP; 41.2 to 58.5% ADF; 46 to 59% TDN) from late March to early June. In summer, lambs (n=12; 5 mo old; 18.8 kg BW) grazed fescue and Bermuda grass (6.2 to 12.4% CP; 39.5 to 50.2% ADF; 52 to 59% TDN) from mid-May to mid-August. In fall/winter, lambs (n=8; 6 mo; 23.2 kg BW) grazed stockpiled fescue (13.3 to 22.3% CP; 34.3 to 43.7% ADF; 57.4 to 65.0% TDN) and annual ryegrass (16.5% CP; 34.3% ADF; 64.9% TDN) from mid-October to mid-December. Data were analyzed with season and breed type as main effects, and starting BW as covariate to account for variation in starting age and breed type effects. FEC was analyzed after log conversion. Daily gain was higher (P<0.01) during spring and fall/winter than during summer grazing (126, 126, and 59 g/d, respectively), and also higher (P<0.001) in crossbred than purebred lambs (122 vs. 84 g/d). There was no season by breed interaction (P>0.1) suggesting that crossbred lambs were able to express their growth potential preferentially during fall and spring grazing. FEC was not affected by grazing season or breed type. There was an indication of fecal counts being higher in crossbred than purebred lambs during summer (3749 vs. 906 eggs/g), but not during spring and fall/winter (season by breed type interaction: P=0.06), suggesting an increased susceptibility to parasitism of crossbred lamb during nutritional stress. Data indicate that supplementation may be needed during summer grazing to improve growth rate of lambs.
- Subjects
HAIR sheep; GASTROINTESTINAL system; PARASITISM
- Publication
Journal of Animal Science, 2018, Vol 96, p72
- ISSN
0021-8812
- Publication type
Abstract
- DOI
10.1093/jas/sky027.136