ENERGY AND CALCIUM BOLUSES AND THEIR INFLUENCE ON PREGNANCY RATE AFTER OVS PROGRAM IN COWS WITH POSTPARTUM ANOESTRUS

Abstract

In many studies, it has been confirmed that the negative energy balance increases the
interval to first ovulation after calving. Vitamin D is involved with Ca and P homeostasis and
immunity. Total confinement of cows that limited exposure to sunlight and increased reliance
on silage may reduce the amount of vitamin D that is synthesized by the cows and consumed
in the basal diet (1,2). It was assumed that an interventional increase in energy, Ca and
vitamin D3 levels could improve the effectiveness of the OVS program in anestrus cows. The
aim of the study was to assess the conception rate in cows receiving the oral energy bolus
and the bolus with the addition of vitamin D3 and Ca. At preliminary stage, 33 cows were
selected on the basis of history, breeding records and per-rectal examination of genitalia. The
cows which did not exhibited an apparent clinical sign of estrum, and had a normal genital
tract with atonic uterus and smooth, small inactive ovaries, even after 90 days postpartum
were selected for further experiment. The study was conducted on 33 cows with postpartum
anestrus, divided into two groups. On the day of the experiment, the first received two
boluses: an energy bolus (to pro animal health) and Calcium bolus (Jfarm) containing high
level of Ca (185 g) and vitamine D3 (group I n = 18); the second (grup II; n=15) served as
control. Boluses were applied to the rumen using a special applicator. At the same time,
animals in both groups were subjected to the OVS program (GnRH (day 0; i.m. inj. 100 μg of
Receptal (Intervet)), PG (day 7., i.m. inj. 500 μg of Estrumate (MSD)), GnRH (day. 9).
Insemination was carried out 24 hours after the administration of the final dose of GnRH.
Blood samples were collected from all cows on day „0” using the Optimum Xido Neo
apparatus (Abbot), equipped with test strips and suitable for field testing. Glucose and β-
hydroxybutyric acid (BHBA) concentrations. The average number of lactations, and days after
delivery before the start of the experiment was 1.16 and 1.66 lactations, and 88,6 and 99.5
days. The mean body condition scoring (BCS) was 2,0 and 2,1. Glucose concentration and β-
hydroxybutyric acid was 2.68 and 2.86 mmol/l, and 0.65 and 0.6 μmol/l in groups I and II
respectively. The conception rate was 50% in group I and 40% in the control group. Based on
preliminary results, it seems that the use of energy boluses may improve the conception rate
in cows with postpartum anesthesia undergoing the OVS program. The research will continue.