The effect of forage species on performance and gastrointestinal nematode infection in lambs

An experiment was designed to determine the effect of forage species on growth rate and gastrointestinal nematode infection in lambs. Southdown lambs (n = 20; 26 ± 4.28 kg initial BW) stratified by weight, sex and FAMACHA© score were assigned to graze either bermudagrass [BG; Cynodon dactylon (L.) Pers.] or chicory [CH; Cichorium intybus L.]. Lambs grazed for 80 d from July 7, 2009 to September 25, 2009. Lambs were weighed and FAMACHA© scored every 14 d. Fecal samples were taken on d 14, 42, 56, and 69 for modified McMaster fecal egg counts. Ultrasound measures of subcutaneous fat thickness (FT) over the 12th and 13th rib and longissimus dorsi muscle depth (MD) were taken on d 80. Lambs grazing CH had lower (P < 0.01) FAMACHA© scores by d 69 than lambs grazing BG (2.4 ± 0.43 and 3.1 ± 0.59, respectively). By d 80 FAMACHA© scores were 2.0 ± 0.22 and 3.9 ± 0.64 (P < 0.01) for CH and BG, respectively and fewer (P < 0.01) CH lambs than BG lambs required anthelmintic treatment (0/10 and 7/10, respectively). CH lambs also exhibited lower (P < 0.01) FEC than BG lambs. Average daily gain was greater (P < 0.01) in lambs grazing CH than those grazing BG (0.28 ± 0.04 and 0.08 ± 0.02 kg/d, respectively). At the end of 80 d, weights were 49.2 ± 3.53 and 33.1 ± 3.82 kg (P < 0.01) for CH and BG, respectively. On d 80, FT and MD were greater in CH lambs than those grazing BG (P < 0.01). Lambs grazing CH had increased performance and reduced GIN infection compared to those grazing BG.