Browsing by Subject "Transition period"

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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.
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    Epidemiological assessment of hyperketonemia in dairy herds: implications for disease diagnosis and control
    (2021-06) Rodriguez, Zelmar
    Metabolic disorders are a frequent problem in the transition period of dairy cows. During this period, higher concentrations of circulating ketone bodies, known as hyperketonemia (HYK), indicate that the cow is utilizing body reserves to fulfill the energy requirement of her new physiological state. Hyperketonemia has been associated with other metabolic and infectious diseases during early lactation, decreased milk production, increased likelihood of herd removal, and impaired reproductive performance. However, the influence of the energy balance during the late dry period on the development of HYK has not been fully quantified. Similarly, the role that milk yield in early lactation plays in hyperketonemic cows due to the importance that the lactogenesis process has in the energy balance needs to be explored. In terms of diagnostics, it has been reported a differential effect of HYK in multiple health outcomes and production according to the moment of disease diagnosis. However, these effects have been evaluated only in the short term. Understanding the effect of HYK in the entire lactation according to the moment of disease diagnosis is needed to determine the optimum timeframe for diagnosis. Consequently, the goal of this dissertation is to better understand the epidemiology of HYK to guide the implementation of optimal decisions to control and diagnose the occurrence of the disease. Our results suggest that a) cows with loss of BCS over 0.5 points during the late dry period have the peak of BHB concentration at day 7 of lactation and have a higher risk of HYK than cows without variations in BCS during the late dry period. b) The impact of HYK on health and productivity varied according to the moment of diagnosis. HYK diagnosed on the first week of lactation was associated with lower milk production and pregnancy rate, and with a higher risk of early removal from the herd than non-hyperketonemic cows. c) Furthermore, it was observed that early milk yield plays a role in the association of HYK with reproductive performance. Among low producers, hyperketonemic cows were less likely to become pregnant. Conversely, reproductive performance was similar among mid- and high-yielding cows, independent of HYK status. In conclusion, to prevent HYK in early lactation, management strategies in the prepartum period should focus on preventing loss of BCS over 0.5 points. After calving, the diagnosis of HYK should be performed at the first week of lactation, and especially targeting cows with lower milk yield. Although more studies need to be performed to improve HYK control, this dissertation provides tools to prevent and control the disease in dairies, with straightforward farm-applicable strategies.