Performance and ruminal changes of early-weaned calves fed lasalocid.
Twenty-two neonatal calves were assigned to a control or lasalocid-fed group and weaned at 3 wk of age. They were fed a prestarter diet from 3 d of age until they consumed 227 g/d and then a mixture of 227 g prestarter daily and starter diet in ad libitum amounts. The lasalocid-fed group received lasalocid in milk at 1 mg/kg body weight daily from 4 to 7 d and at .5 mg/kg body weight daily in milk and medicated prestarter diet (88 mg lasalocid/kg) during the 2nd wk. After 2 wk, lasalocid-fed calves were given medicated prestarter and starter (44 mg lasalocid/kg) diets. Four calves in each group were ruminally cannulated at 3 to 5 d of age, and ruminal contents were obtained at weekly intervals to monitor microbial activity. Rectal fecal samples were collected from all calves and examined for coccidial oocysts. Lasalocid-fed calves had a greater weekly feed intake and weight gain than control calves after 6 wk of age. Total ruminal volatile fatty acid concentrations were higher, but the acetate:propionate ratio was lower in lasalocid-fed calves than in control calves. Total viable anaerobic and amylolytic bacterial counts were higher in lasalocid-fed calves than in control calves. No significant treatment effect was found for ruminal NH3-N concentration or ruminal lasalocid-resistant, lactobacilli, lactate-utilizing, cellulolytic or methanogenic bacterial numbers. No evidence of coccidiosis was detected in either group. In general, lasalocid-fed calves had greater feed intake, weight gain and ruminal microbial activity than the calves fed no lasalocid in the diet.
Anderson
K L
KL
Kansas State University, Manhattan 66506.
Nagaraja
T G
TG
Morrill
J L
JL
Reddy
P G
PG
Avery
T B
TB
Anderson
N V
NV
D000818:Animals; D001835:Body Weight / Q000187:drug effects*; D002417:Cattle / Q000254:growth & development*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000469:parasitology; D005285:Fermentation / Q000187:drug effects; D007832:Lasalocid / Q000494:pharmacology*; D008297:Male; D010270:Parasite Egg Count / Q000662:veterinary; D012417:Rumen / Q000187:drug effects* / Q000382:microbiology; D014886:Weaning
D005232:Fatty Acids, Volatile; D007832:Lasalocid