EFFECT OF DIETARY SUPPLEMENTATIOM OF ZINC, COPPER AND SELENIM PRE- OR POST-PARTUM ON REPRODUCTIVE PREFORMANCE OF FRIESIAN COWS

The objective of this study was to evaluate the effect of adding zinc (Zn), copper (Cu) and selenium (Se) to the ration on ovarian activity andreproduction performance of Friesian cows. A total of 39 Friesian cows between the 1^st and 3^rd parity  and  average 532.7±23.5 kg LBW was divided into three similar groups (n=13 each). Multiparous cows (n=10 in each group) were divided according to their LBW, parity and milk production of the previous season, while primiparous cows (n=3 in each group) were allotted on their LBW. Cows of the 1^st group (G1) were fed concentrate feed mixture (CFM), rice straw and corn silage (control). Cows of the 2^nd group (G2) were received 60 mg Zn, 20 mg Cu and 0.3 mg Se /kg CFM on day 30 prepartum to calving, while those of the 3^rd group (G3) were received the same diet of (G2) from calving to 60 days postpartum. Throughout the experimental period, oestrus was detected and cows in heat were inseminated. Also, number and length of ovulatery cycles from calving up to conception were recorded. Post-partum 1^st estrus and 1^st service intervals, number of services per conception (NSC), days open (DO) and conception rate were assessed. Pregnancy was diagnosed by rectal palpation on day 60 post-insemination.
Results revealed that Pre- and postpartum supplementationof Zn, Cu and Se (G2 and G3) increased (P<0.05) body weight gain and body condition score as compared to G1. Interval from calving to 1^st oestrus was significantly (P<0.01) shorter in G2 and G3 (23.5 and 27.45 days, respectively) than the G1 (39 days). Post-partum 1^st service interval was significantly (P<0.05) shorter in G2 and G3 (42.5 and 44.15 days) than that in G1 (59.1 days). Supplementation of Zn, Cu and Sein G2 and G3 significantly (P<0.05) reduced NS/C to 1.7 and 1.8 services and DO to 77.6 and 79.8 days as compared to 3.6 services and DO of 128.0 days in the control group, respectively. The Zn, Cu and Setreatment increased conception rate (CR), being significantly (P<0.05) the highest in G3 (84.15%), modest in G2 (76.92%) and the lowest in G1 (53.85%). Supplementation of Zn, Cu and Se in G2 and G3 significantly (P<0.05) decreased average number of total ovulations and ovulatory cycles per cow compared with the control group. Average P4 concentration during the ovulatory cycles and P4 level prior to estrus incidence were significantly (P<0.05) increased in G2 and G3 as compared to G1. Ovulatory cycle length and interval to P4 peak during the ovulatory cycles were not affected by dietary supplementation.