Metabolic status and fertility responses of non-lactating cows and heifers following the turn-over from berseem, to concentrates feeding

الملخص EN

Ten non-lactating cows and 12 heifers were used to study the effect of turn-over from berseem feeding (Trifolium alexandrinum) only, ad libitum, to concentrates on both metabolic and fertility statuses.

These animals were acyclic during the whole 6 months of berseem feeding after which they were turned over to concentrates feeding.

Blood samples were collected once monthly during the last 3 months of berseem feeding and once weekly during the first 3 months after turn-over to concentrates feeding.

Serum metabolites (total protein; albumin, cholesterol and urea) and minerals (Ca, P, Zn, Cu, Fe and Mn) were estimated.

The fertility status in terms of resumption of cyclicity, conception rate (CR) and services per conception (SPC) was followed up after turn-over to concentrate feeding.

Regarding the metabolic profile, there was a significant (P < 0.05) decrease in the serum concentration of urea, cholesterol, Zn, Cu, Mn (in cows), and Fe (in heifers) and significant (P < 0.05) increase in the serum concentration of Mn (in heifers) and Fe (in cows) after turn-over from berseem to concentrates feeding.

On the other hand, the serum concentrations of total protein, albumin, Ca and P showed non-significant variations with the turn-over.

All cows (except one) and heifers resumed cyclicity and 70% of cows and 75% of heifers got pregnant within 90 days post turn-over.

It was noted that both the percentage of cows resuming cyclicity and conception rate increased as well as the service per conception decreased with the decrease of serum concentration of both urea and cholesterol post turn-over.

It could be concluded that feeding on berseem only ad libitum is associated with metabolic disturbances mainly in protein metabolism (as has been indicated by increased serum urea concentration) and imbalance in the trace elements profile which are reflected on the fertility status of these animals.

Such adverse effect was more pronounced in cows than in heifer