Effects of Silage Diets on Health, Reproduction, and Blood Metabolites of Dairy Cattle

Abstract

Forty-eight Hostein dairy cows were assigned uniformly by parity and calving date to three forage treatments for three lactations. Forage treatments were corn silage (F-I), corn silage plus Hay-crop silage (-f-II), and corn silage plus hay (F-III). Records of health and reproductive data were kept to evaluate dietary effects. During the third lactation six animals in each treatment were blood-sampled on a 4-day interval from 24 days prepartum to 60 days postpartum to determine metabolites. Reproductive traits were similar among the treatment groups as were occurrences of mastitis. Corn silage and hay-crop silage cows had more ketosis than hay cows. Corn silage cows had more parturient paresis than the other two groups, and abomasal displacement occurred only in the corn silage group. There were differences in concentrations of plasma metabolites among treatments; however, they appeared to be within normal ranges, and no pathological implications were obvious. Blood pH, blood packed cell volume, blood alkaline reserve, and pH values were similar among treatment groups. Histological evaluation of hepatic and endocrine tissues revealed no treatment effects.