Gastrointestinal nematode infection and growth of grass based Katahdin lambs

Authors: Wood, Erin; Burke, Joan; DIRK, PHILIPP - UNIVERSITY OF ARKANSAS; ACHARYA, MOHAN - UNIVERSITY OF ARKANSAS; MILLER, JAMES - LOUISIANA STATE UNIVERSITY; COFFEY, KEN - UNIVERSITY OF ARKANSAS

Submitted to: Sheep and Goat Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2018
Publication Date: 4/4/2019
Citation: Wood, E.L., Burke, J.M., Dirk, P., Acharya, M., Miller, J.E., Coffey, K.P. 2019. Gastrointestinal nematode infection and growth of grass based Katahdin lambs. Sheep and Goat Research Journal. Available: https://d1cqrq366w3ike.cloudfront.net/http/DOCUMENT/SheepUSA/SGRJ_V33_1-10_Wood_11-18.pdf. 33(11):1-10.

Interpretive Summary: Grass finishing lambs presents a challenge in the southeastern U.S. due to poor quality perennial grasses much of the year, but is becoming more widespread due to consumer demand. Little is known on optimal grazing and management to take advantage of minimizing off-farm inputs. Scientists from the Agricultural Research Service - Booneville, AR, University of Arkansas, and Louisiana State University determined that modest supplementation can lead to greater gains in fall-born ram lambs and improved tolerance to gastrointestinal parasites when forage quality is limiting, and high quality forage can result in good weight gain without supplementation in these lambs. Winter born lambs were not suitable and ram lambs may be more efficient in a grass-finished system in the southeastern U.S. under these conditions. This information is important to sheep producers, scientists, veterinarians, and extension specialists with an interest in forage finishing in sheep.

Technical Abstract: Grass finishing lambs presents a challenge in the southeastern U.S. due to poor quality perennial grasses much of the year. The objective was to examine the effect of grass-finishing or minimal supplementation on performance of lambs finished to a light BW (rams, = 41 kg; ewes = 36 kg) in Arkansas, U.S.A. Katahdin lambs born in October 2013 and 2014 and February 2014 were weaned in January 2014 and 2015 and May 2014, respectively. Lambs were blocked by sex (fall; winter included only ram lambs) and randomly assigned to receive no (NON) or grain co-product supplement (SUP; 15% CP) at 0.5% of BW/d. Lambs were rotationally grazed on predominantly grass. Body weight, fecal egg counts (FEC), blood packed cell volume (PCV), and body condition score (2014 fall-born lambs only) were determined every 14 d. Winter lambs were removed from the study after 35 d due to declining body condition that compromised animal welfare. Data were analyzed by repeated measures in a mixed model or general linear model. In the 2013 fall-born lambs, ADG between d 0 and 84 was greater for SUP than NON lambs (137 ± 4.9 > 110 ± 5.0 g/d; P = 0.003) in the first year, but similar between treatments the second year (NON, 175 ± 5.3; SUP, 179 ± 5.2 g/d; treatment × year, P = 0.02). The ADG (d 0 to 35) of winter lambs was greater for SUP than NON (33 ± 8 > -6 ± 8 g/d; P = 0.001). The FEC tended to be lower in SUP than NON (P < 0.06) in fall 2013 lambs, but PCV was not different. The FEC were similar between treatments in all seasons, but PCV was increased in SUP compared with NON lambs, particularly at 28 d post-weaning (treatment × yr × day, P < 0.001). Modest supplementation can lead to greater gains in fall-born ram lambs and improved tolerance to gastrointestinal parasites when forage quality is limiting, and high quality forage can result in good weight gain without supplementation in these lambs. Winter born lambs were not suitable and ram lambs may be more efficient in a grass-finished system in the southeastern U.S. under these conditions.