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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #403388
Research Project: Discovery of Novel Traits to Improve Efficiency and Sustainability of Different Sheep Production Systems

Location: Livestock Bio-Systems

Title: Birth season and production system effects on post-weaning growth and gastrointestinal nematode infection of Katahdin lambs

Author
item Murphy, Thomas - Tom
item HESS, ANDREW - University Of Nevada
item MILLER, JAMES - Louisiana State University
item Burke, Joan

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/20/2023
Publication Date: 11/6/2023
Citation: Murphy, T.W., Hess, A.S., Miller, J.E., Burke, J.M. 2023. Birth season and production system effects on post-weaning growth and gastrointestinal nematode infection of Katahdin lambs [abstract]. Journal of Animal Science Supplement. 101(Supplement 3):306-307. https://doi.org/10.1093/jas/skad281.366.
DOI: https://doi.org/10.1093/jas/skad281.366

Interpretive Summary:

Technical Abstract: The objective was to estimate birth season (F = fall, W = winter) and production system (C = conventional, O = organic) effects on Katahdin lamb growth and gastrointestinal nematode (GIN) infection. Lambs were weighed and weaned at ~60 d of age and body weight (BW, n = 5089), fecal egg count (FEC, n = 4772), and packed cell volume (PCV, n = 4962) were recorded at ~90, 120, and 150 d of age. Records were analyzed from 599, 142, 1113, and 126 F-C, F-O, W-C, and W-O lambs, respectively. Lambs weren’t dewormed and FEC was transformed as: LFEC = log10(FEC + 25). Traits were analyzed as repeated measures with fixed effects of time, sex, birth/rear type, and season-system, the linear covariate of actual age at 90 d, and random effects of sire, birth year, and contemporary group. The time x season-system interaction was significant for all traits (P < 0.001). At 90 d, BW was greater for W-C and W-O than F-C and F-O (P = 0.05). By 150 d, W-O lambs had greater BW (P = 0.04) than all other season-systems which weren’t different from each other. Lamb LFEC was greatest for F-C (P < 0.001), intermediate for F-O, and lowest for W-C and W-O at 90 d. All season-systems had similar LFEC at 120 d, but W-C lambs had greater LFEC at 150 d than all others (P < 0.01). At 90 d, PCV was lower for F-C than all others (P = 0.02) except W-O. Both F-C and F-O had greater PCV (P < 0.001) than W-C and W-O at 120 d and, at 150 d, PCV was lower for W-C than all others (P < 0.001). To investigate production impacts of GIN infection in different season-systems, average daily gain from weaning to 90 d (ADG60-90, n = 1842) was analyzed in a similar model with the additional linear covariate of LFEC at 90 d (LFEC90). The season-system x LFEC90 interaction was significant (P < 0.01), indicating differing impacts of GIN infection. A one-unit increase in LFEC90 (e.g., ~500 vs. 5000 eggs/g) had negative impacts on ADG60-90 for W-O, F-C, and W-C (-27.1, -22.4, and -12.5 g/d, respectively) and solutions weren’t different from one another. However, LFEC90 didn’t affect F-O ADG60-90 potentially due to lower performance (158.4 g/d) than other season-systems (171.5 – 204.3 g/d). Overall, BW was lower for F than W lambs and FEC decreased with age for F with the opposite for W lambs. Slight advantages in performance were observed for W-O compared to W-C lambs. Season-system differences could be attributed to varied forage quality and breeding objectives and results utilized in precision sheep management.