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# Factors associated with subclinical hypocalcemia at calving on multiparous Jersey cows

A. Valldecabres, José Pires, N. Silva-Del-Río

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## ► To cite this version:

A. Valldecabres, José Pires, N. Silva-Del-Río. Factors associated with subclinical hypocalcemia at calving on multiparous Jersey cows. Journal of Dairy Science, 100, suppl; 2, pag. 373, 1 p., 2017, Journal of Dairy Science. hal-01608494

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Submitted on 2 Jun 2020

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of Veterinary Medicine, University of Missouri, Columbia, MO,
<sup>2</sup>Department of Animal Sciences, Colorado State University, Foth
Collins, CO, <sup>3</sup>Department of Animal Sciences, University of Missouri,
Columbia, MO.

Fatty liver (FL) is a common condition affecting dairy cows during
the peripartum period, with no diagnostic test that is accurate, fast, and
low cost. FL can be determined by TG extraction, histopathology or
 flotation of liver biopsies from live animals. However, these methods
are invasive, and at higher risk of hemorrhages, infection and adhe-
sions. Cytology for detection of FL in cattle has not been extensively
evaluated. It is feasible in clinical practice, being minimally invasive
and inexpensive, and having a rapid turnaround time compared with
biopsy. The objective was to estimate the sensitivity (Se) and specific-
ity (Sp) of needle aspiration cytology and histopathology for FL using
TG concentrations as the gold standard. Liver samples were harvested
from a slaughterhouse in WI, USA. Livers were visually inspected
for gross evidence of fat accumulation and classified as follow. (1):
Normal—homogeneous maroon color (n = 20), (2): Moderate—moder-
ate yellow-pale color (n = 20) and (3): Severe—more extreme yellow
color (n = 20). Biopsies and needle aspiration were carried out from the
parietal upper portion of the caudate lobe. Two samples of liver tissue
were harvested with a 16 g x 15 cm biopsy needle for histological and
TG concentration assessment. A third sample was harvested for cytology
using an 18 g × 3.81 cm needle. The content of the needle was trans-
ferred to a glass slide, spread and air-dried. TG were assessed by a kit
based on colorimetry/fluorimetry. Concentrations <2% were considered
normal. Histological and cytological evaluation was blind to the visual
classification and conducted by 2 pathologists. Se, Sp, and area under
the receiver-operating curve [ROC] were calculated. For cytology, Se
and Sp were 73% (95% CI 55.9–86.2) and 85% (95% CI 62.1–96.8),
respectively. The area under ROC was 0.79 (95% CI 0.68–0.89). For
histopathology, Se and Sp were 45.9% (95% CI 29.5–63.1) and 100%
(95% CI 83.2–100), respectively. The area under ROC was 0.73 (95%
CI 0.64–0.81). This data suggests that cytology may be a viable less
invasive tool for detecting FL in dairy cattle.

**Key Words:** fatty liver, cytology, histology

**366 Factors associated with subclinical hypocalcemia at calving on multiparous Jersey cows.** A. Valldecabres\*¹, J. A. A. Pires\*², and N. Silva-del-Río\*¹, ¹Veterinary Medicine Teaching and Research Center, University of California Davis, Tulare, CA, ²Unité Mixte de Recherche sur les Herbivores, INRA, VetAgro Sup, Saint-Genes-Champanelle, France.

The objective was to evaluate factors associated with calcemic status at calving on 527 multiparous Jersey cows from 2 commercial dairies. Study variables included: lactation number (Lact; continuous, or 2, 3, ≥ 4); previous lactation 305-d mature equivalent milk production (Pr305ME) and somatic cell count (PrSCC); calving body condition score (BCS; ≤ 2.5, 2.75, ≥ 3) and locomotion score (LS; ≤ 2, 3, ≥ 4); calf number, sex, and stillbirth; and dry period length (dDry). Blood samples for serum Ca analysis were collected from the coccygeal vessels 3 h 14 min (±2 h 04 min) after calving. Previous lactation information and calving outcomes were obtained from DairyComp305 herd records. Based on serum Ca concentration at calving cows were classified as hypocalcemic (SHC; Ca≤8.5 mg/dL; n = 347) and normocalcemic (NC;

Ca >8.5 mg/dL; n = 180). Associations among variables were studied using spearman rank correlations and mixed models for continuous, and chi-squared and exact fisher tests for categorical data (CORR, MIXED, GLIMMIX and FREQ procedures of SAS). A significant positive correlation was observed between Lact and BCS, and both were negatively correlated with serum Ca concentration at calving. Cows with SHC had greater (P < 0.001) Lact (3.6 vs. 2.7), frequency of Lact ≥4 (40.4 vs. 14.4%), dDry (68.8 vs. 64.6 d), and BCS (43.4 vs. 58.2%, 31.2 vs. 27.7% and 25.4 vs. 14.1% for BCS ≤2.5, 2.75 and ≥3, respectively; P = 0.02[N1]) than NC cows. Twinning rate was higher for SHC than NC (5.8 vs.1.1%; P = 0.01). The frequency of male calves (n = 98) was higher for SHC than NC cows (22.4 vs. 14.0%, P = 0.02), however, sexed semen was selectively used on both dairies and these results may derive from herd reproductive management. There was no association of Pr305ME, PrSCC, LS at calving or frequency of stillbirth with calcemic status. These complex associations among SHC, Lact, BCS, dDry, twinning and calf sex, could be used for the decision-making concerning prophylactic SHC treatment at calving.

**Key Words:** Jersey cow, hypocalcemia

**367 Effects of chloride and sulfate-based diets fed to grazing prepartum dairy cows on postpartum plasma calcium.** P. Melendez\*¹, V. Zaror\*², P. Gaul\*², S. Poock\*¹, and J. Goff\*³, ¹College of Veterinary Medicine, University of Missouri, Columbia, MO, ²Tribute Dairy, Benton, MO, ³College of Veterinary Medicine, Iowa State University, Ames, IA.

Hypocalcemia is a common metabolic disorder affecting dairy cows
during the postpartum period. Lowering dietary cation-anion difference
(DCAD) by feeding supplemental chloride or sulfate has been shown
to reduce the incidence of hypocalcemia. Different sources of anions
have not been extensively compared under practical conditions. The
aim of this study was to compare the effect of chloride (Cl) (SoyChlor;
commercial chloride supplement) and sulfate (S) (magnesium sulfate)
fed to grazing prepartum cows on postpartum plasma Ca. The study
was conducted in southeast Missouri, USA in the fall of 2016. Breeds
consisted of 20% Holstein, 20% Jersey and 60% crossbred Jersey ×
Holstein. Cows had been synchronized for breeding such that approxi-
mately 600 cows were due to calve in a short period of time. At 30 d
before expected parturition, 2 groups of 200 cows each were moved into
paddocks where they were fed each day a partial mixed ration (PMR)
containing the anionic supplements. Cows had free access to pasture.
The PMR would constitute half of the daily DMI. Estimated DCAD
for the 2 diets was -25 mEq/kg DM and -26 mEq/kg DM for Cl and
S, respectively. Urine samples were collected each week prepartum and
checked for pH. Average pre-partum urine pH was 7.71 ± 0.12 and 7.81
± 0.10 (P = 0.06) for Cl and S, respectively. At calving, 42 cows per
group were matched by breed and parity (primiparous, multiparous),
and their blood was sampled on d 1, 2, 3, and 7 postpartum. Plasma total
Ca was determined by atomic absorption spectroscopy. Data for blood
Ca concentration were analyzed by developing a mixed model ANOVA
for repeated measures and the best covarinace structure to fit the model.
It is concluded that cows fed a TMR based on chloride had a higher
calcium concentration at d 1 than cows fed sulfur as a source of anions.