Browsing by Author "Basso Silva, Paula Regina"

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    Effects of Peripartum Recombinant Bovine Somatotropin Treatment and Prepartum Stocking Density on Immune Responses, Metabolism, Health, and Performance of Dairy Cows
    (2016-10) Basso Silva, Paula Regina
    Excessive fatty acids release from the adipose tissue of periparturient cows may result in hyperketonemia and hepatic lipidosis, which are known to compromise liver and damage immune cells. Immunosuppression in transition cows is a result of shortage in energy, nutrients and calcium impairing immune cells’ metabolism. Thereafter, immunosuppressed periparturient cows are at higher risks for developing infectious and non-infectious health disorders. Strategies that improve metabolism and immune function of periparturient dairy cows may reduce incidence of diseases. Six experiments were performed to test two main strategies: the use of recombinant bovine somatotropin (rbST) during the peripartum period and the reduction of prepartum pens’ stocking density (SD) from 100 to 80% of headlocks. The specific objectives of these experiments were to evaluate the effects of treating peripartum dairy cows with rbST on immune, inflammatory, and metabolic responses, incidences of postpartum diseases, performance, and hepatic and leukocyte gene expression; and to evaluate the effects of two prepartum SD (80 vs. 100%) on milk yield, concentration of metabolites, health and reproductive parameters, innate and adaptive leukocyte responses, and serum and hair cortisol concentrations. Results demonstrated that treatment of dairy cows with 125 mg of rbST improved innate immune responses and IgG concentration, with limited effects on metabolism, decreased the incidence of uterine disorders in Holstein and Jersey cows and increased yield of energy corrected milk during the first 30 DIM in Holstein cows. Administration of rbST during the periparturient period may improve liver function and health by increasing hepatic capacity for gluconeogenesis and lipid transport and by reducing inflammation and oxidative stress. Treatment of dairy cows with 125 mg of rbST during the periparturient period may improve leukocyte functions by upregulating mRNA expression of genes involved in glycolysis, pathogen recognition, phagocytosis and oxidative burst, antimicrobial peptides, and antibody production. Finally, in herds with weekly or twice weekly movement of new cows to the prepartum pen and separate housing of nulliparous and parous animals, 100% SD of headlocks on the day of movement does not affect health, metabolic, reproductive, and productive parameters and 80% did not improve leukocyte responses compared with 100% target SD.
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    Effects of prepartum grouping strategy on health, production, and reproduction of dairy cows
    (2013-01) Basso Silva, Paula Regina
    The objectives of the current experiment were to determine the effect of two prepartum grouping strategies on health, metabolic, reproductive, and productive parameters of dairy cows. Jersey cows enrolled in the experiment at 253 ± 3 d of gestation (study d 0 = calving) were balanced for parity and projected 305-d mature equivalent and assigned to one of two treatments. Cows assigned to the traditional (TRD, n = 6) treatment were moved to the study pen as a group of 44 cows and weekly thereafter groups of 2 to 15 cows were moved to the study pen to re-establish stocking density. Cows assigned to the All-In-All-Out (AIAO, n = 6) treatment were moved to the study pen in groups of 44 cows, but no new cows entered the AIAO pen until the end of the replicate. A total of 308 and 259 cows were enrolled in the AIAO and TRD treatments, respectively. At the end of each replicate a new TRD and AIAO group started but pens were switched. Cows were milked thrice daily. Plasma non-esterified fatty acid (NEFA) concentration was measured weekly from study d -18 ± 3 to 24 ± 3 and plasma beta-hydroxy butyrate (BHBA) was measured weekly from study d 3 ± 3 to 24 ± 3. Cows were examined on study d 1, 4 ± 1, 7 ± 1, 10 ± 1 and 13 ± 1 for diagnosis of uterine diseases and had their ovaries scanned by ultrasound on study d 39 ± 3 and 53 ± 3 to determine resumption of ovarian cycles. Binomial data were analyzed by logistic regression using the GLIMMIX procedure and continuous data were analyzed by ANOVA using the MIXED procedure. Average stocking density was reduced for the AIAO (71.9%) treatment compared with the TRD (86.9%) treatment. Treatment did not affect the incidence of uterine diseases (TRD = 19.6, AIAO = 21.9%). Concentrations of NEFA (TRD = 80.4 ± 8.2, AIAO = 62.9 ± 8.5 µmol/L) and BHBA (TRD = 454.4 ± 10.9, AIAO = 446.1 ± 11.1 µmol/L) were not different between treatments. Percentages of cows that resumed ovarian cycles by study d 39 ± 3 (TRD = 70.8, AIAO = 63.1%) and 53 ± 3 (TRD = 90.1, AIAO = 90.2%) were not different between treatments. Similarly, treatment had no effect on rate of removal from the herd {TRD = referent, AIAO [(adjusted hazard ratio (95% confidence interval)] = 0.85 (0.63, 1.45)} or rate of pregnancy establishment [TRD = referent, AIAO = 1.07 (0.88, 1.30)]. Finally, treatment did not affect energy corrected milk yield (TRD = 34.4 ± 0.6, AIAO = 34.3 ± 0.7 kg/d). Considering that no benefits were observed regarding health, metabolic, reproductive and productive parameters the reduced stocking density and consequent increased cost of building prepartum facilities to accommodate an AIAO grouping strategy may not be justified.