Genetic parameters of calcium, phosphorus, magnesium and potassium serum concentrations during the first eight days after calving in Holstein cows

Calcium, Mg, P, and K are of great importance for the health and productivity of dairy cows after calving. So far genetic studies have focused on clinical hypocalcemia, leaving the genetic parameters of these macroelements unstudied. Our objective was to estimate the genetic parameters of Ca, Mg, P, and K serum concentrations and their changes during the first 8d after calving. The study was conducted in 9 herds located in northern Greece, with 1,021 Holstein cows enrolled from November 2010 until November 2012. No herd used any kind of preventive measures for hypocalcemia. Pedigree information for all cows was available. A total of 35 cows were diagnosed and treated for periparturient paresis and, therefore, excluded from the study. The remaining 986 cows were included in genetic analysis. The distribution of cows across parities was 459 (parity 1), 234 (parity 2), 158 (parity 3), and 135 (parity ≥4). A sample of blood was taken from each cow on d1, 2, 4, and 8 after calving and serum concentrations of Ca, P, Mg, and K were measured in each sample. A final data set of 15,390 biochemical records was created consisting of 3,903 Ca, 3,902 P, 3,903Mg, and 3,682K measurements. Moreover, changes of these concentrations between d1 and 4 as well as 1 and 8 after calving were calculated and treated as different traits. Random regression models were used to analyze the data. Results showed that daily heritabilities of Ca, P, and Mg concentrations traits were moderate to high (0.20-0.43), whereas those of K were low to moderate (0.12-0.23). Regarding concentration changes, only Mg change between d1 and 8 after calving had a significant heritability of 0.18. Genetic correlations between Ca, P, Mg, and K concentrations and their concentration changes from d1 to 4 and 1 to 8 after calving were not significantly different from zero. Most phenotypic correlations among Ca, P, Mg, and K concentrations were positive and low (0.09-0.16), whereas the correlation between P and Mg was negative and low (-0.16). Phenotypic correlations among macromineral concentrations on d1 and their changes from d1 to 4 and 1 to 8 after calving varied for each macromineral. This study revealed that genetic selection for normal Ca, P, Mg, and K concentrations in the first week of lactation is possible and could facilitate the management of their deficiencies during the early stages of lactation. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved

Skeletal muscle and adipose tissue reserves and mobilisation in transition Holstein cows: Part 1 Biological variation and affecting factors.

Nutrient deficit during the periparturient period leads to mobilisation of body energy and protein reserves. Research regarding fat reserves and mobilisation is extensive, while, on the contrary, investigation of muscle mobilisation during the periparturient period is limited. The aim of this cohort study was to simultaneously investigate the biological variation of skeletal muscle and subcutaneous fat reserves together with their mobilisation in transition Holstein cows of different herds, using ultrasonography, and to assess potential affecting factors. For this purpose, ultrasound measurements of longissimus dorsi muscle thickness (LDT) and backfat thickness (BFT) from 238 multiparous cows of six dairy farms were obtained at six time points across the transition period (from 21 days pre- to 28 days postpartum). Concentrations of serum creatinine and non-esterified fatty acids were determined in order to confirm the loss of muscle mass and adipose tissue, respectively. Cases of clinical postparturient diseases and subclinical ketosis (scKET) during the first 28 days postcalving were recorded. Cows mobilised on average 32.8% and 37.3% of LDT and BFT reserves, respectively. Large between-cow variation was observed for both the onset and the degree of mobilisation. Time point, initial body condition score and parity were the most important predictors of LDT variation. Cows diagnosed with metritis (MET) had lower LDT postpartum and mobilised more muscle depth compared to cows not diagnosed with MET. Initial BCS, time point, initial BW (estimated by heart girth measurement) and parity were the most important predictors of BFT variation. Cows diagnosed with MET mobilised more backfat between -7d and 7d compared to cows not diagnosed with MET. Cows with scKET mobilised more backfat between 7- and 21 days postpartum compared to healthy ones. Variation of subcutaneous fat and skeletal muscle reserves during the transition period was large and affected by herd and several cow-level factors

Skeletal muscle and adipose tissue reserves and mobilisation in transition Holstein cows: Part 2 association with postpartum health, reproductive performance and milk production.

The aim of this study was, for the first time, to simultaneously assess the association of skeletal muscle and subcutaneous fat reserves and their mobilisation, measured by ultrasonography, with the incidence of specific postparturient health, reproduction, and milk production traits. For this purpose, ultrasound measurements of longissimus dorsi thickness (LDT) and backfat thickness (BFT) from 238 multiparous cows from 6 dairy farms were obtained at 6 time points during the transition period (from 21 days pre- to 28 days postpartum). In each case, LDT and BFT measurements at each time point and LDT and BFT mobilisation variables at each study period were assessed simultaneously. Cases of specific clinical postparturient diseases and subclinical ketosis were recorded. An additional disease trait was used, defined as the presence or absence of at least one clinical condition after calving (CD_1-28). The associated disease odds with LDT/BFT variables were assessed with binary logistic regression models. The associated hazard for 1st artificial insemination (AI) and for pregnancy by 150 days-in-milk (PREG_150DIM) was assessed with Cox proportional hazard models. Moreover, binary logistic models were used to assess the associated odds for pregnancy to 1stAI (PREG_1stAI). Finally, association with 30d, 100d and 305d milk yield was assessed with linear regression models. Increased muscle depth during transition was negatively associated with odds for metritis and CD_1-28, while associations with odds for subclinical ketosis were inconclusive. Moreover, increased LDT reserves were associated with greater hazard for 1st AI by 150 days-in-milk, but results were inconclusive regarding odds for PREG_1stAI. Increased LDT mobilisation was associated with increased odds for metritis. Increased BFT reserves were positively associated with odds for metritis, CD_1-28 and subclinical ketosis and with decreased hazard for PREG_150DIM. Increased BFT mobilisation was associated with increased odds for subclinical ketosis and with decreased odds for PREG_1stAI and decreased hazard for PREG_150DIM. Cows with moderate BFT reserves performed better. Finally, increased BFT mobilisation during -21d to -7d from parturition was associated with less milk by 30d and 100d. On the contrary, increased BFT mobilisation during -7d to 7d was associated with more milk by 305d. Metabolism of muscle and fat tissue during transition period was differently associated with different postparturient health, reproduction and milk production traits. In general, greater muscle mass and moderate fat reserves with limited muscle and fat mobilisation were associated with better performance

Variation in protein metabolism biomarkers during the transition period and associations with health, colostrum quality, reproduction, and milk production traits in Holstein cows

The aims of this study were to assess a) the variation of protein metabolism biomarkers and of factors affecting them during the transition period, b) the association of each biomarker with skeletal muscle reserves and their changes, and c) the association of these biomarkers with postpartum health, colostrum quality, reproduction, and milk production. For this purpose, 238 multiparous Holstein cows from 6 herds were used in a prospective cohort study. Plasma concentrations of 3-methylhistidine (3-MH) and 1-methylhistidine (1-MH) and serum concentrations of total protein (TP), albumin (ALB), urea nitrogen (BUN) and creatinine (SCR) were determined for each cow at -21d; -7d; 7d; 21d and 28d relative to calving. Clinical diseases were recorded during the first 28 d post-calving, and presence of subclinical ketosis (scKET) was investigated at 7d and 21d. Colostrum quality was estimated by Brix refractometry. Reproduction data by 150 d-in-milk (DIM) and milk production records were also available. Linear mixed models including the fixed effects of time point, herd, parity, body condition score (-21d), duration of dry period and post-parturient diseases were fitted to assess the variation in each biomarker's concentration. The association between the biomarkers' concentration during the pre-partum period with the odds for each post-parturient disease and for a combined trait (CD_1-28), defined as the presence of at least one clinical condition during the first 28 d after calving, were assessed with separate binary logistic models for time points -21d and -7d. The relationship of each biomarker's concentration with longissimus dorsi thickness (LDT) and the changes in LDT (ΔLDT) was assessed with pairwise correlations. Separate general linear models were used to assess the association of each biomarker with colostrum Brix values and milk production traits. Finally, the associated hazard for 1st artificial insemination (AI) and for pregnancy by 150 DIM (PREG_150DIM) was assessed with Cox proportional hazard models, while odds for pregnancy to the 1st AI (PREG_1stAI) were assessed with binary logistic models. 3-methylhistidine was affected mainly by herd, time points and their interaction. Higher 3-MH was associated with increased odds for metritis and CD_1-28, increased hazard for PREG_150 DIM and with increased milk production. 1-methylhistidine was affected mainly by herd, scKET and occurrence of displaced abomasum. Higher 1-MH was associated with better colostrum quality, increased odds for scKET, increased hazard for 1st AI by 150 DIM and with decreased milk production. Both 3-MH and 1-MH were weakly to moderately negatively correlated with LDT and moderately to strongly negatively correlated to ΔLDT at the corresponding time-periods. Additionally, higher TP was associated with increased odds for metritis and CD_1-28 and increased milk production, while higher ALB was associated with increased odds for scKET and increased milk production. Moreover, higher BUN was associated with decreased odds for scKET, increased odds for PREG_1stAI and increased milk production. Higher SCR was associated with decreased odds for retained fetal membranes, metritis, and CD_1-28. Peri-parturient protein metabolism is significantly associated with postpartum health, colostrum quality, reproduction, and milk production; mechanisms involved require further investigation

Genetic study of subclinical hypocalcaemia in Holstein dairy cows

The objective of the present thesis was the genetic study of subclinical hypocalcemia in Holstein dairy cows. Nine dairy herds and a total of 1,021 dairy cows were included in the study. All cows were subjected to a detailed clinical examination and blood was sampled on days 1, 2, 4, and 8 after calving, to determine the serum concentrations of calcium (Ca), phosphorus (P), magnesium (Mg) and potassium (K). In blood samples taken on day 8 the concentration of β -hydroxybutyric acid (BHBA) was also determined. Moreover, the average daily milk yields were recorded on a monthly basis for each cow, for one lactation. Pedigree information was recorded for all cows. Based on the determination of the serum concentrations of Ca, P, Mg and K and threshold values provided in relevant literature subclinical hypocalcaemia (SCHCa), hypophosphatemia (HypoP), hyperphosphataemia (HyperP), subclinical hypomagnecaemia (SCHMg) and hypokalemia (HypoK) were expressed as presence or absence of the condition (binary traits). Fixed curves of serum macromineral concentrations and the related subclinical disorders and of all clinical diseases across all lactations during the first 8 d after calving were derived from random regression model analysis. With the use of the same models, phenotypic, genetic and residual variances were estimated for days 1, 2, 4, and 8 after calving. These variances were used for the estimation of heritability for serum concentrations of Ca, P, Mg and K, the corresponding subclinical diseases, and all clinical diseases diagnosed during days 1 to 8 after calving. Relevant genetic and phenotypic correlations between biochemical traits, subclinical and clinical diseases and productive and reproductive characteristics, were estimated, based on co-variance components derived with a series of bivariate analyses based on the aforementioned models. To our knowledge, heritability estimates of macrominerals concentrations and their associated subclinical diseases and the aforementioned phenotypic correlations are reported for the first time in the literature. Results of this study indicate that the serum macromineral concentrations and relevant disorders are heritable traits. Further studies should focus on the identification of specific genomic regions affecting these traits.Ο σκοπός της παρούσας διδακτορικής διατριβής ήταν η γενετική μελέτη της υποκλινικής υπασβεστιαιμίας στις γαλακτοπαραγωγές αγελάδες της φυλής Holstein. Η έρευνα πραγματοποιήθηκε σε εννέα βοοτροφικές επιχειρήσεις και χρησιμοποιήθηκαν συνολικά 1.021 αγελάδες. Για κάθε αγελάδα υπήρχε διαθέσιμη η γενεαλογία της. Έγινε κλινική εξέταση των αγελάδων την 1η, 2η, 4η και 8η ημέρα μετά τον τοκετό και καταγραφή των νοσημάτων που βρέθηκαν κατά την κλινική εξέταση. Κατά τις παραπάνω ημέρες λήφθηκαν δείγματα αίματος από όλες τις αγελάδες για τον προσδιορισμό των συγκεντρώσεων του ορού του ασβεστίου (Ca), του φωσφόρου (P), του μαγνησίου (Mg) και του καλίου (K). Στα δείγματα αίματος που είχαν ληφθεί την 8η ημέρα προσδιορίστηκε και η συγκέντρωση του β-υδροξυβουτυρικού οξέος (ΒΗΒΑ). Επιπλέον, καταγράφηκαν οι μέσες ημερήσιες αποδόσεις γάλατος σε μηνιαία βάση για κάθε αγελάδα, για μία γαλακτική περίοδο. Με βάση τον προσδιορισμό των συγκεντρώσεων του ορού των παραπάνω μακροστοιχείων και τη χρήση των ορίων που αναφέρονται στη βιβλιογραφία έγινε ημερήσια εκτίμηση της προσβολής της κάθε αγελάδας από υποκλινική υπασβεστιαιμία, υποφωσφαταιμία, υποκλινική υπομαγνησιαιμία, υποκαλιαιμία και υπερφωσφαταιμία. Με τη χρήση στατιστικών πρότυπων παλινδρόμησης εκτιμήθηκε η καμπύλη των συγκεντρώσεων ορού του Ca, του P, του Mg και του K και των αντίστοιχων υποκλινικών νοσημάτων κατά τη διάρκεια των οκτώ πρώτων ημερών μετά τον τοκετό. Επίσης, αντίστοιχη εκτίμηση έγινε και για όλα τα κλινικά νοσήματα που διαγνώστηκαν κατά την ίδια περίοδο. Επιπρόσθετα, για τα παραπάνω χαρακτηριστικά εκτιμήθηκε η φαινοτυπική, η γενετική διακύμανση και η υπολειμματική διακύμανση για την 1η, 2η, 4η και 8η ημέρα μετά τον τοκετό. Από αυτούς τους συντελεστές διακύμανσης εκτιμήθηκαν οι συντελεστές κληρονομησιμότητας των συγκεντρώσεων ορού του Ca, του P, του Mg και του K και των αντίστοιχων υποκλινικών νοσημάτων, καθώς και όλων των κλινικών νοσημάτων που διαγνώστηκαν κατά την ίδια περίοδο. Ακόμη, υπολογίστηκαν οι γενετικές και φαινοτυπικές συσχετίσεις των βιοχημικών χαρακτηριστικών, τόσο μεταξύ τους όσο και με τα υποκλινικά και κλινικά νοσήματα, καθώς και με τα παραγωγικά χαρακτηριστικά (γαλακτοπαραγωγή, αναπαραγωγή). Στην παρούσα έρευνα αναφέρονται για πρώτη φορά διεθνώς εκτιμήσεις της κληρονομησιμότητας των συγκεντρώσεων των παραπάνω βιοχημικών χαρακτηριστικών και των αντίστοιχων υποκλινικών νοσημάτων, καθώς και φαινοτυπικές συσχετίσεις μεταξύ των συγκεντρώσεων των μακροστοιχείων με νοσήματα (υποκλινικά και κλινικά) μετά τον τοκετό αλλά και με παραγωγικά και αναπαραγωγικά χαρακτηριστικά. Τα αποτελέσματα της παρούσας έρευνας έδειξαν ότι οι συγκεντρώσεις ορού του Ca, του P, του Mg και του K, καθώς και οι αντίστοιχες υποκλινικές διαταραχές κατά την πρώτη εβδομάδα μετά τον τοκετό είναι κληρονομήσιμα χαρακτηριστικά. Επόμενες μελέτες θα μπορούσαν να εστιάσουν στην εξακρίβωση των γονιδιακών τόπων που ελέγχουν αυτά τα χαρακτηριστικά

Associations among post-partum rumen fill and motility, subclinical ketosis and fertility in Holstein dairy cows

This prospective observational study aimed to investigate the association of rumen fill and motility in post-partum Holstein cows with their future reproductive performance and subclinical ketosis (SCK). The study population consisted of two independent data sets: the first (DS1) included 237 cows from 6 herds and the second one (DS2) 709 cows from 9 herds. Rumen Fill Score (RFS) was transformed into a 3 level-trait, representing very low, low and adequate dry matter intake, respectively. A binary Rumen Contraction Score (RCS) was defined as: 0: &lt;2 contractions/2 min, impaired rumen motility and 1: ≥2 contractions/2 min, normal rumen motility. A combined binary trait based on RFS and RCS (RFCS) was also established, representing unsatisfactory and satisfactory rumen function. Three SCK traits were defined, based on 3 different thresholds, SCK_I: BHB≥1,000 mmol/L, SCK_II: BHB≥1,100 mmol/L and SCK_III: BHB≥1,200 mmol/L. Scores were assessed and blood samples collected on day 7 (DS1) or day 8 (DS2), postpartum. Kaplan-Meier survival analysis, multivariable Cox proportional hazards models and Generalized Linear Mixed Models were performed to evaluate the association of rumen and SCK traits with reproduction. Herd, parity, calving season and several postparturient diseases were also included as potential explanatory variables. Mean days from calving to pregnancy after the 1st artificial insemination (AI) and from calving to pregnancy (all AIs) were shorter for levels of rumen traits representing adequate DMI and normal rumen motility; in most cases these differences were statistically significant in both datasets. Cows with adequate DMI and normal rumen motility (only in DS2) had greater hazard (hazard ratio [HR] = 1.84 and 1.61, for RFS and RFCS, respectively) and odds (odds ratio [OR] = 2.49 and 1.98, for RFS and RFCS, respectively) for pregnancy at 1st AI. Assessment of the association of examined rumen traits with hazard and odds for pregnancy at all AIs yielded statistically significant results in both datasets. For RFS, RCS and RFCS, HRs ranged from 1.57 to 3.31 and ORs from 1.95 to 4.83. No statistically significant associations with hazard and odds for pregnancy at 1st or all AIs were detected, for any of the 3 SCK traits, in either dataset. Overall, the combined RFCS trait constantly identified more than twice the number of cows with future reproductive problems than a positive SCK blood test.</p