with the aims to assess reproductive performance and prevalence of reproductive problems in crossbred (Holstein Friesian x Zebu) dairy cattle. A questionnaire survey methodology was used. The study sampled 177 randomly selected dairy farms comprising 1013 crossbred dairy cattle (736 cows and 277 heifers). The mean age at first service, age at first calving, first postpartum estrus and calving interval were 24.8 months, 35.3 months, 114.5 days and 401.5 days, respectively. Prevalence rates of reproductive problems recorded in the study area were anestrus (37.8%), repeat-breeding (21.0%), dystocia (11.6%), retained fetal membranes (11.5%), endometritis (6.6%), abortion (6.4%), prolapsed uterus/vagina (2.9%), stillbirth (2.0%) and freemartin (0.2%). Incidence of abortion did not vary with parity and stages of gestation. Breeding and the possible causes of missing insemination/mating while animals were in estrus are problematic. In conclusion, this study has revealed that the reproductive performance of crossbred dairy cattle was not optimal, and anestrus, repeat-breeding, dystocia, retained fetal membranes, endometritis and abortion were the major reproductive problems. More effective breeding and reproductive health management should be considered to improve the fertility of this crossbred cattle herd. Awareness and training should be provided to the farming community to improve the productivity in the region.

Effective breeding management is a crucial tool to enhance the reproductive and productive performance of dairy cattle. To achieve this, regular monitoring of their reproductive status is important. The aims of this study were to monitor the reproductive status of crossbred dairy cattle based on progesterone (P4) concentration in serum, whole milk, saliva and urine, and estradiol in serum using quantitative laboratory ELISA tests, and to document hormonal profiles at different reproductive stages. Three hundred and thirty-six (336) crossbred (Holstein Friesian x Zebu) dairy cattle (232 cows and 104 heifers) from 47 dairy farms owned by smallholder or organized commercial dairy farmers were included in the study. Matched blood, milk and saliva samples were collected twice at 11-day intervals at afternoon milking, while urine was collected just once. Serum was separated within 48 hr of blood collection. All samples were stored at -80 o C until assayed. In both cows and heifers, P4 was higher during pregnancy than in other reproductive conditions. Estradiol was higher during estrus than at other reproductive stages. Estradiol levels were significantly higher (p<0.05) in estrus cows compared with heifers. The mean level of P4 in serum strongly correlated with the value in milk (r = 0.6368, P< 0.0001), however there was no correlation in P4 concentration between serum and saliva or between P4 in serum and in urine. Hence, determination of P4 in serum and milk using an ELISA test is a reliable and precise method to monitor reproductive status in crossbred dairy cattle.

Abstract:Simplifying and improving our understanding of the protocols for inducing or synchronizing estrus is important for improving management of dairy cattle. This study evaluated the estrus response and conception rate of crossbred (Holstein Friesian X Zebu) dairy cows (n=75) and heifers (n=47) assigned to a 10-day controlled internal drug release (CIDR) deviceprostaglandin F2-alpha (PGF2α) -equine chorionic gonadotrophin (eCG) based estrus synchronization protocol. Animals were assigned to three groups (a) anestrus (n=62), (b) repeat-breeders (n=11) and (c) silent estrus (n=46), according to their reproductive history, per rectal palpation, and progesterone concentrations determined by On-Farm enzyme-linked immunosorbent assays (ELISA) in milk (lactating cows) or serum (dry cows and heifers). For each animal, a CIDR device (containing 1.38g progesterone) was inserted into the vagina and allowed to remain in-situ for 10 days. On Day 8 after device insertion, a dose of 500µg of PGF2α was administered intramuscularly (IM). On Day 10 (device removal), 500 IU of eCG was given IM. Animals were inseminated or mated 48 and 72 hrs post device removal. Pregnancy was assessed 20-24 days post insemination by measurement of progesterone in milk/serum and pregnancy was confirmed by per rectal palpation and/or ultrasonography 44-90 days post insemination. Overall estrus response and conception rates were 97.5% and 78.3%, respectively, with no significant differences in parity, pre-treatment reproductive status and farming system (smallholder vs organized commercial farms). Conception rate after induced/synchronized estrus was 82.9% and 72.1% in cows and heifers, respectively, with an overall calving rate of 94.4%. In conclusion, the present study has shown high estrus response and conception rate in crossbred dairy cattle using this CIDR -PGF2α -eCG based estrus synchronization protocol. Application of this protocol is highly recommended to enhance fertility of dairy cattle in the study area, and this could readily be applied to other regions.