Publikationsdatenbank

Diagnosis and prevalence of periparturient hypocalcemia and associated effects on milk production, reproductive performance and health of dairy cows in early lactation (2018)

Art

Hochschulschrift

Autor

Venjakob, Peter Lennart (WE 19)

Quelle

Berlin, 2018 — 96 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/23212

Kontakt

Tierklinik für Fortpflanzung

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Abstract / Zusammenfassung

The overall objectives of this thesis were (1) to evaluate ear skin temperature as a cow-side test to predict serum calcium concentration, (2) to determine the prevalence of clinical and subclinical hypocalcemia in German dairy herds, and (3) to evaluate the impact of hypocalcemia on early lactation milk yield, reproductive performance, and culling risk in early lactation. To evaluate ear skin temperature as a cow-side test, a cross-sectional study was conducted enrolling 251 cows from 7 dairy herds. Skin temperature was scored manually by palpation of the ears and measured by infrared thermography. In addition, skin temperature on the coxal tubers, ambient temperature and rectal temperature were measured. Finally, a blood sample was drawn to determine serum calcium concentration. Cows with a serum calcium concentration below 2.0 mmol/L were considered as hypocalcemic. When clinical symptoms of hypocalcemia (e.g. shivering, recumbency) were apparent, the cow was classified as suffering from milk fever. Hypocalcemia in the absence of clinical symptoms was classified as subclinical hypocalcemia. To evaluate whether serum calcium concentration can be predicted by measuring the ear temperature and other temperature estimates, a multivariate analysis using the GENLINMIXED procedure and a ROC-curve analysis was performed. Hypocalcemia was prevalent in 3.3 %, 27.3 %, 32.8 % and 69.6 % of first, second, third and ≥ fourth lactation cows, respectively. In third and ≥ flourth lactation cows, 6.0 % and 20.3 % were suffering from clinical milk fever. Calcium status affected ear skin temperature. Normocalcemic cows (median 30,3 °C, IQR 26,0 °C – 32,8 °C) had higher ear skin temperature compared with cows affected by subclinical hypocalcemia (median 27.6 °C, IQR 22.1 °C – 30.8 °C) and milk fever (median 21.8 °C; IQR 14.7 °C – 27.0 °C). A decrease of 0.1 mmol/L in serum calcium concentration was associated with a decrease in ear temperature of 0.39 °C (95 % CI 0.25 – 0.54; P = 0.001). Ear skin temperature is not useful as a diagnostic test (sensitivity = 49.3; specificity = 73.8; threshold 2.0 mmol/L) to identify cows with subclinical hypocalcemia because of the great impact of ambient temperature on temperature of the ears. When there was an increase in ambient temperature of 1 °C, temperature of the ears rose by 0.78 °C (95 % CI 0.67 – 0.90; P = 0.001). Although there has been a mild association between serum calcium concentration and ear skin temperature, measurement of ear skin temperature cannot be recommended as a cow-side test to identify cows with subclinical hypocalcemia. The objective of the second study was to evaluate prevalence of clinical and subclinical hypocalcemia in German dairy herds. In a cross-sectional study, blood samples were drawn from periparturient cows 0 to 48 h after calving and analyzed for serum calcium, phosphorus and magnesium concentration. Overall, 1,709 blood samples were taken from 125 farms. Of these 329 blood samples had to be excluded, resulting in 1,380 blood samples from 115 farms (12 animals were tested on each farm). Cows were considered as normocalcemic or hypocalcemic using 2.0 mmol/L as a threshold. Cows with clinical signs (e.g. recumbency) were classified as milk fever. Each of the 115 herds was classified into negative (0 to 2/12), borderline (3 to 5/12), and positive (≥ 6/12) according to the number of animals with hypocalcemia. Preventive strategies against hypocalcemia implemented on the farms were documented. Prevalence of clinical milk fever was 1.4 %, 5.7 % and 16.1 % for second, third, and ≥ fourth parity cows, respectively. None of the cows in first lactation was suffering from clinical milk fever. Subclinical hypocalcemia was present in 5.7 %, 29.0 %, 49.4 % and 60.4 % of cows in first, second, third, and ≥ fourth lactation, respectively. Fourteen, 51, and 50 herds were classified as negative, borderline, and positive, respectively. A positive correlation was observed between serum calcium and serum phosphorus concentration (R2 = 0.335; P < 0.001). Serum calcium and serum magnesium concentration showed a negative correlation (R2 = 0.151; P < 0.001). Of the farms enrolled, 65 had no preventive strategy implemented to control hypocalcemia. Among the farms with an implemented control strategy (n = 50), oral calcium supplementation at parturition was most common (40/50), followed by feeding of anionic salts in the close-up diet (10/50). The results indicate that prevalence of clinical and subclinical hypocalcemia in German dairy herds was high and that the minority of the farms had preventive strategies implemented. The objective of the third study was to evaluate the impact of hypocalcemia on milk yield, reproductive performance, and culling. Herdsmen of the farms that participated in the previous study were asked to provide a backup of their herd management software 150 days after the last cow was sampled. After discarding cows (n = 283) with missing data, a total of 1,426 cows were considered for final analyses. Serum calcium concentration of each cow was related to early lactation milk yield (test day 1 to 3), reproductive performance (DIM at first artificial insemination (AI), pregnancy per AI at first AI, time to pregnancy within 150 DIM) and culling (until 60 DIM) data. Generalized linear mixed models were used to analyze continuous or categorical data. Shared frailty models were used for time to event data. Five different thresholds were used to define hypocalcemia. Thresholds ranged from 1.8 to 2.2 mmol/L using 0.1 mmol/L increments. Milk fever was defined as in the previous studies. Regarding the effect of hypocalcemia on milk yield, the effect was conditional on parity. While primiparous cows suffering from hypocalcemia (threshold: 2.0 mmol/L) tended to produce less milk (2.07 kg/d, P = 0.063) compared with normocalcemic primiparous cows in early lactation, hypocalcemic multiparous cows (threshold 2.1 mmol/L) had a tendency to produce more milk (0.51 kg/d, P = 0.086) compared with normocalcemic multiparous cows. Multiparous cows with clinical hypocalcemia produced 1.90 kg/d (P = 0.002) less milk compared with normocalcemic cows in early lactation. Hypocalcemia did not affect time to first insemination (P = 0.296). Cows suffering from hypocalcemia (threshold 1.9 mmol/L) had decreased odds (OR 0.56; P = 0.001) of pregnancy at first artificial insemination. Calcium status had a significant impact on time to pregnancy (threshold 1.8 mmol/L). Median time to pregnancy was 109 and 134 days for normocalcemic and hypocalcemic animals, respectively. Cows with hypocalcemia (threshold: 2.0 mmol/L) and cows suffering from milk fever had a 1.6 (P = 0.019) and 1.9 (P = 0.029) times greater hazard of being culled within the first 60 DIM compared with normocalcemic animals. Giving the high prevalence of hypocalcemia and the associated negative outcomes, this study re-emphasizes the need to establish control strategies for hypocalcemia. Overall, this thesis shows that there is high prevalence of hypocalcemia on German dairy farms. The results underline that periparturient hypocalciemia has a great impact on early lactation health, reproduction and production. Since measurement of ear skin temperature cannot be used as a diagnostic test, it has to be emphasized that there is an urgent need to develop a reliable cow-side blood calcium test.