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Background: Bovine mastitis causes major economic losses for milk producers by reducing the quantity and the quality of the milk or even leading to the complete loss of the mammary gland secretory capacity. During the transition period, dairy cows are susceptible to infectious diseases; therefore, markers that allow early identification of cows in higher risk of developing diseases are especially useful at this time. Therefore, the aim of this study was to evaluate serum markers in the pre and postpartum of multiparous dairy cows with clinical mastitis and with health condition in the postpartum period in a semi-extensive management system. Materials, Methods & Results: Thirty-Six Holstein cows were monitored daily during milking until 59 days postpartum and were categorized according to the pre-milking strip cup test into clinical mastitis (mastitis group (MG)) and absence of symptoms (control group (CG)) that were negative to the test, representing the health cows. All cows were reared as one group and maintained in a semi-extensive pasture-based system. Blood samples were collected weekly after morning milking via venipuncture of the coccinea vein into tubes without anticoagulant and grouped for prepartum (-21 to 0 days from calving), early postpartum (0 to 30 days from calving), and late postpartum (30 to 59 days from calving) periods. Milk production was recorded daily. The serum markers albumin, aspartate aminotransferase (AST), phosphorus, gammaglutamyltransferase (GGT) and non-esterified fatty acids (NEFA) were measured. Statistical analyses were performed using SAS®. The cases of clinical mastitis occurred on average at 37.2 ± 4.9 days postpartum. Health cows (CG) had higher milk production compared to the mastitis group (MG) only in the late postpartum period (P < 0.05). There was no difference among groups for albumin and NEFA concentrations in all periods evaluated (P > 0.05). In the early postpartum period the AST activity was higher in CG than in MG (P = 0.02). The GGT enzyme tended to be more concentrated in the CG than in the MG during the early (P = 0.06) and late (P = 0.08) postpartum periods. Late postpartum phosphorus concentration was lower for MG than CG (P = 0.04). In the prepartum and early postpartum periods, there was no difference among groups for phosphorus concentration (P > 0.05). Discussion: A decrease in milk production in MG compared to CG observed in late postpartum period was due to the incidence of mastitis observed around 37 days postpartum. Cows that presented clinical mastitis in the postpartum period did not differ in the blood concentration of NEFA in the prepartum period. In the late postpartum period higher concentration of phosphorus was observed in the CG than in MG, indicating that animals affected by mastitis may be in the weakest energy status. Regarding liver health, the concentration of AST was higher in the recent postpartum period for CG, in disagreement with previous studies that related AST to tissue injury caused by mastitis. The GGT enzyme tended to had higher concentrations in CG than MG during the whole postpartum period and may be related to increased hepatic metabolism due to higher production. There were no changes in albumin levels among healthy and mastitis cows, indicating that this marker can not be used to predict clinical mastitis. There were no metabolic alterations in the prepartum period related to the occurrence of postpartum mastitis in multiparous cows in a semi-extensive management system. [ABSTRACT FROM AUTHOR]

Background: The timed artificial insemination (TAI) protocols have been used worldwide as a first service artificial insemination (AI) breed system as well as to resynchronize cows diagnosed as not pregnant. The benefits associated to Heatsynch are the lower cost of the protocol and the increase in the number of cows detected in estrus. Furthermore, it has been suggested that protocols combining AI after estrus detection followed by TAI could increase overall conception rates, as well as increased AI submission rates. The aim of this study was evaluate reproductive responses of dairy cows submitted to a Heatsynch protocol according the estrus behavior and controlled internal device release (CIDR) uses. Material, Methods & Results: Holstein lactating cows (n = 562) were enrolled in protocol using (CIDR) (1.9 g of progesterone) insertion at (day 0) D0 either a new one, a previous used once (7 days - second use) or twice used (14 days - third use). Based on the detection of estrus and the moment of AI after the CIDR removal, cows were divided into 3 groups: cows showing signs of estrus and therefore AI 36 to 60 h after CIDR removal (EPTAI group; n = 241); cows showing estrus and AI 72 h after CIDR removal (ETAI group; n = 207); and cows that did not show any sign of estrus after CIDR removal and were TAI 72 h later (NoETAI group; n = 335). Previous to the first postpartum insemination (47.01 ± 5.43 days in milk) cows were pre-synchronized using one dose of PGF2α (Lutalyse, Pfizer Saúde Animal, Brazil). At 60 ± 3.52 days in milk (DIM), day 0 of the Heatsynch protocol, cows were subjected to gynecological examination by a Veterinarian, where only those animals considered as healthy cows with no signs of uterine disease were kept in the study. In a subset of animals (105/783; 13.4%) an ovary evaluation was performed by ultrasonography (WED-3000, B-mode, linear array, ultrasound scanner equipped with a 5.0-MHz transducer, Welld, Shenzhen, China) at the beginning of synchronization protocol aiming to check the presence of a corpus luteum (CL) and classify the cows as cycling or not cycling. Ovarian structures were examinated aiming to check the CL presence on day zero of the program in a subset of the cows and pregnancy status was also determined by ultrasonography. Higher conception rates were found in EPTAI and ETAI groups than NoETAI, respectivaly 44.8%, 38.2% and 24.8%. Pregnancy losses were calculating considering cows that were not pregnant at 60-65 days re-check and those that showed signs of estrus before the first pregnancy determination. The CIDR reutilization did not affect the estrus behavior, conception rate or pregnancy losses. In conclusion, reproductive responses in dairy cows during a Heatsynch protocol are not affected by CIDR reutilization and are improved in cows showing estrus signs. Discussion: Cows submitted to Heatsynch protocols that demonstrate estrus signs have increased pregnancy rates and lower pregnancy losses. In addition to that, cows exposed to low estradiol concentrations were more likely to experience subsequent premature luteolysis. Thus, coupled with the estradiol cypionate (ECP) action, it can be postulated that cows showing estrus signs during a timed AI protocol could have a higher ovulation rate. This can assume great importance in high producing dairy herds, since in response to ECP becomes possible to overcome the lower concentrations of estradiol due to high hepatic clearance and catabolism o esteroid hormones. [ABSTRACT FROM AUTHOR]