Establishment of a Sandwich-ELISA for simultaneous quantification of bovine pregnancy-associated glycoprotein in serum and milk.

Bovine pregnancy-associated glycoproteins (boPAG) are expressed by trophoblast cells in the bovine placenta. The multigene family of boPAG belongs to the group of aspartic proteases. The accumulation and circulation in maternal blood and milk has made boPAG very useful and important for pregnancy diagnosis in cattle. The goal of the present study was to develop and validate a new Sandwich-ELISA which allows the detection of boPAG in maternal serum and whole milk. Therefore, 984 serum and 928 milk samples were collected monthly from 231 Holstein Friesian cows (Bos Taurus) from one week after insemination (p.i.) until six weeks postpartum. The ELISA is able to identify a cow as being pregnant at day 30 p.i. in serum and at day 40 p.i in milk with threshold values of 1.0 ng/ml in serum and 0.0165 ng/ml in milk. The postpartum half-life of boPAG was estimated to be 6.4 days in serum and 7.1 days in milk. The boPAG profile established during pregnancy in serum and milk showed a typical pattern. The amount of boPAG found in milk was 1.5 % of the amount of boPAG present in serum. In conclusion, a Sandwich-ELISA has been developed to quantify boPAG in serum and in whole milk simultaneously with the same test procedure. This is time saving for farmers and more efficient for laboratories.

Across-generation effects of maternal heat stress during late gestation on production, female fertility and longevity traits in dairy cows.

This research paper focuses on time-lagged heat stress (HS) effects from an across-generation perspective. Temperature × humidity indexes (THI) from the last 8 weeks of pregnancy were associated with subsequent female offspring performances. The offspring dataset considered 172 905 Holstein dairy cows from calving years 2002-2013 from 1,968 herds, located in the German federal state of Hesse. Production traits included milk yield (MKG), protein percentage (PRO%), fat percentage (FAT%), somatic cell score (SCS) and milk urea nitrogen (MUN) from the first official test-day in first lactation. Female fertility traits were the non-return-rate after 56 d (NRR56) in heifers and the interval from calving to first insemination (ICFI) in first parity cows. Longevity traits were the length of productive life (LPL), lifetime productivity in milk yield (LTP-MKG) and milk yield per day of life (MKG-DL). The association analyzes for 10 traits combined with meteorological data from 8 single weeks before calving implied in total 80 different runs. THI ≥50 from all single 8 weeks before calving had unfavorably significant effects on FAT%, ICFI and LPL. Heat stress in terms of THI ≥60 from the last 3 weeks before calving impaired MKG. NRR56 decreased with increasing THI, as observed for all 6 weeks before calving. LTP-MKG and MKG-DL decreased due to high THI in the last 4 weeks before calving. Heat stress (THI ≥60) during late pregnancy had no significantly unfavorable impact on PRO% and MUN. Interestingly, SCS in offspring declined with increasing THI during late pregnancy. In conclusion, for most of the primary and functional traits, unfavorable impact of HS from the dry period on time-lagged performances in offspring was identified, even on longevity. From a practical perspective, our data suggest to provide HS abatement to late gestation dams to avoid long-term adverse effects on the offspring.

The effect of dry cow antibiotic with and without an internal teat sealant on udder health during the first 100 d of lactation: a field study with matched pairs.

The objective of this field study was to compare the udder health status as well as the clinical mastitis rate during the first 100 d of lactation in cows that received long-acting dry cow antibiotic alone (group AB) or in combination with an internal teat sealant (group AB + OS). The study was conducted during a 9-month period and included 136 Holstein cows from 12 dairy farms in Hessia, Germany. Between days 1 and 5 after calving a California mastitis test (CMT) was performed. Milk-samples were collected for bacteriological culture before drying off, between days 6 and 14 and days 35 and 56 of lactation. Additionally the cows were monitored for the occurrence of clinical mastitis events until 100 d post partum. Within the 12 herds cow-pairs were formed on the basis of age, milk yield and SCC. A cow-pair consisted of one cow from group AB and one cow from group AB + OS. For statistical analysis within every cow-pair one quarter that has been dried off with internal teat sealant and dry cow antibiotic (group AB + OS) was compared with one quarter that has been dried off with dry cow antibiotic (group AB) alone. As criterion for the matching process of udder quarters the cytobacteriological udder health status before drying off was used. A total of 544 quarters (136 cows) were used in this analysis. In the first 5 d after calving, group AB had significantly more quarters with a positive CMT reaction than group AB + OS (85 vs. 57; P <0·001), and in the first 100 d of lactation, group AB had more quarters with clinical mastitis than group AB + OS (25 vs. 15; P = 0·03). In the time periods 6-14 and 35-56 d of lactation, there were fewer quarters in group AB + OS populated with Corynebacterium spp. (days 6-14, P = 0·05; days 35-56, P = 0·02) and aesculin-positive streptococci (days 35-56, P = 0·02). The internal teat sealant was a promising tool for the prevention of new intramammary infections (IMI) of dry cows with environmental udder pathogens as expressed during early lactation.