|Miller, J -|
Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2010
Publication Date: February 5, 2011
Citation: Burke, J.M., Miller, J.E. 2011. Influence of season of lambing on gastrointestinal nematode infection of lambs. American Society of Animal Science Southern Section Meeting. 89(Suppl.3). Technical Abstract: Gastrointestinal nematodes (GIN) are a major constraint to sheep production, especially during the summer when the conditions for Haemonchus contortus are ideal. GIN infection is minimal during the winter, but there is little known about differences in GIN control between fall born and winter born lambs. The objective was to examine GIN infection and BW gains of lambs born in Oct or Jan. Katahdin ewes lambed in Jan (W) or Oct (F) of 2008 and 2009 (W08, W09, F08, F09). Lambs were weaned at ~120 d of age and supplemented when forage quality was low. BW, FEC and PCV were determined between 90 and 210 d of age. Lambs were dewormed if FAMACHA score was > 3. Data were analyzed using mixed models with a repeated statement for d of age and season was the main effect. GLM were used to analyze dewormings/lamb and ADG. There were 19 single (S) and 79 multiple (M) born lambs in W08, 12 S and 68 M in W09, 10 S and 19 M in F08, and 14 S and 13 M born lambs in F09. ADG between birth and 120 d of age was greater in 2008 (W, 210 ± 6; F, 194 ± 6 g/d) than 2009 (W, 191 ± 5; F, 149 ± 6 g/d) and lowest in F09 lambs (season × year, P < 0.02). After lambs were weaned, ADG was greater in F than W lambs (167 ± 4 > 58 ± 3 g/d) likely because of higher quality of forage at that time. FEC were higher in F than W lambs at 90 d of age, similar at 120 d of age, then decreased in F lambs until 180 d of age. Then, the warmer spring weather led to a slight increase in FEC in F lambs, while the drier summer weather in W lambs led to a decrease in FEC between 180 and 210 d of age (season × age, P < 0.001). The PCV changed little over time in F lambs and dropped to a low at 150 d of age in W lambs (season × age, P < 0.001). The lower PCV in W lambs led to a greater incidence of deworming. There were more W (08, 0.90 ± 0.09; 09, 0.75 ± 0.09 dewormings/lamb) than F (08, 0.07 ± 0.14; 09, 0.67 ± 0.15 dewormings/lamb) lambs dewormed, and more F lambs dewormed in 2009 (season × year, P < 003) because of presence of scours. GIN control was more manageable in F than W lambs.