The effect of feed restriction and Eimeria maxima infection with or without medication on growth and feed intake in...

Day-old male broiler chicks were raised in floor pens. At 4 days of age, birds in 75% of the pens were inoculated with Eimeria maxima via the feed. There were four dietary treatments: uninoculated, unmedicated control (UUC), infected, unmedicated control (IUC), infected, halofuginone-medicated (3 ppm, HM), or infected, salinomycin-medicated (66 ppm, SM). At 6 days of age, birds in 50% of the pens of each treatment were restricted for 5 days to their maintenance energy intake level. The remainder consumed feed ad libitum. Medication reduced growth from 0 to 6 days of age and feed intake was depressed, irrespective of medication, in infected birds from 0 to 21 days of age. Growth, however, was improved with intake of coccidiostat over IUC from 6 to 11 days of age but did not match UUC until 28 days of age. At 42 and 49 days of age, infected birds were lighter than UUC birds. Dressing percentage for HM and SM birds was greater than that of UUC birds at 49 days of age but HM birds also had a greater percentage of abdominal fat at both 42 and 49 days of age. Feed restriction resulted in some compensatory growth immediately following refeeding. Experimental feed:gain ratio was improved in restricted birds (1.98 versus 2.03 g:g). At 42 and 49 days of age, restricted birds were lighter than birds eating ad libitum and also had a significantly greater percentage abdominal fat. A lower breast yield was observed at 42 days of age in restricted birds.