Dietary Methionine and Lysine Utilization by Chicks as Influenced by Coccidial Infection and Drug Therapy

Abstract

Several chick growth assays were conducted to investigate interactions between ionophorous anticoccidial drugs and dietary factors in both healthy and coccidial-infected chicks. The ionophores studied were monensin and narasin, and the dietary factors were L-lysine$\cdot$HCl, L-arginine, DL-methionine, protein level and source as well as dietary electrolyte balance. Digestibility and bioavailability of crystalline L-lysine$\cdot$HCl were also studied. Coccidial infection was produced via crop intubation of sporulated oocysts of Eimeria acervulina or Eimeria tenella.

Diets containing either monensin, roxarsone, or the combination of the two were fed to chicks for 15 minutes or for 1, 3, 5, or 8 days prior to a E. tenella challenge. Feeding monensin for 15 minutes or roxarsone for 1 day prior to challenge was sufficient to prevent morbidity.

Investigations conducted to assess the effects of monensin supplementation on lysine and arginine utilization in healthy chicks indicated that neither lysine nor arginine utilization is impaired by monensin.

A crystalline amino acid diet severely deficient in lysine was fed to chicks to define the gain and feed efficiency response elicited when chicks are infected with Eimeria acervulina. At day 6 after inoculation commenced, gain and gain/feed of chicks infected with E. acervulina exceeded that of the uninfected control chicks. The growth response due to E. acervulina in lysine-deficient chicks was maintained throughout a 14-day post inoculation period while depressions in growth occurred in lysine-adequate chicks.

The effects of supplemental narasin on nutrient utilization were investigated in chicks infected with E. acervulina. Supplemental narasin improved weight gain and feed efficiency of infected chicks. Based on slope-ratio methodology, L-lysine utilization was the same in both narasin-fed and control chicks. Neither protein level, protein source, nor dietary electrolyte balance had any effect on the narasin response in infected chicks.

L-lysine$\cdot$HCl was observed to be 100% absorbed by cecectomized adult cockerels. Also, L-lysine$\cdot$HCl was found to be 100% bioavailable as established in chick growth trials in which crop intubated lysine was compared to intraperitoneally-injected lysine. (Abstract shortened with permission of author.)