Hubert Deluyker - Academia.edu (original) (raw)
Papers by Hubert Deluyker
Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, Jan 12, 1998
PubMed, Sep 1, 1993
Currently somatotropin in being developed for use in several animal species, primarily as a produ... more Currently somatotropin in being developed for use in several animal species, primarily as a productivity enhancer. The objective of this paper was to review direct and indirect effects of somatotropin supplementation on reproduction particularly in the dairy cow. There is substantial evidence that somatotropin plays an important role in the normal ovarian function. This effect is probably mediated via IGF-I. Existing literature indicates that higher milk yields are antagonistic to reproductive performance and require enhanced nutrition and reproductive management. Similarly, studies indicate that reproductive performance may be impaired in diary cattle supplemented with somatotropin. Effects of somatotropin treatment on reproductive performance may depend on the dose and the stage of lactation. Low doses of somatotropin in early lactation may improve reproductive function.
EFSA supporting publications, Sep 1, 2017
EFSA Journal, Nov 1, 2017
EFSA Journal, Jun 1, 2016
An assessment of emerging risk is characterized by the early detection of facts related to that r... more An assessment of emerging risk is characterized by the early detection of facts related to that risk derived either from research and/or from monitoring programs or episodic observations. Assessment of emerging risks must be flexible to accommodate changes in the conditions that affect the risks and also improvements in the methods of detection. Assessment of emerging risks is distinct from the assessment of risks under emergency (or crisis) conditions, as the latter are dealt with through established Commission procedures (*).
The Kenya Veterinarian, 1994
EFSA Journal, Oct 1, 2012
Veterinary Quarterly, Apr 1, 1998
Netherlands milk and dairy journal, 1996
Duplicate samples of mixed milk (n = 13 927) were collected to compare somatic cell counting with... more Duplicate samples of mixed milk (n = 13 927) were collected to compare somatic cell counting with the Somascope and the Fossomatic 360. To estimate sampling and assay variability, somatic cell count (C) was measured with the Fossomatic 360 on 295 duplicate milk samples. The total variance was 1042 x 10 6 . The contribution of the measuring instrument (Fossomatic 360) and the sampling procedure were 12.7 and 87.3%, respectively. The overall variance of the paired differences of the logarithmically transformed numerical value of C (expressed in μL -1 ) (In{C}) of the 295 duplicate milk samples all measured with the Fossomatic 360, was 0.08. Additionally, accuracy of the Somascope was evaluated on 9558 duplicate milk samples. In one of the duplicate milk samples, C was measured with the Fossomatic 360; in the other, with the Somascope. The variance of the paired differences of ln{C} between the Somascope and the Fossomatic 360 was 0.14. Comparison of the ln{C} per class (class width = 1 on the log e scale) showed 77.4, 28.1 and 11.3% overestimation of In{C}, measured with the Somascope, in the classes ≤ 2,2-3 and 3-4, respectively, and 1.4, 2.6 and 4.6% underestimation in the classes 6-7, 7-8 and >8, respectively, indicating a lower accuracy of the Somascope in these classes. The Pearson correlation of In{C} between the Fossomatic 360 and the Somascope was 0.96. The Pearson correlation of In{C} of the duplicate milk samples measured twice with the Fossomatic 360 was 0.97. Simple linear regression (Somascope against Fossomatic) showed a significant intercept, b 0 (±s.e.)= 1.13 (±0.011) and the slope, b 1 (±s.e.) = 0.803 (±0.0022), differed from the ideal value of 1 (P 250 x 10 3 mL -1 using the Somascope as compared to the Fossomatic 360, was 0.89, 0.95 and 0.97, respectively. The Somascope, when correctly calibrated, is an acceptable alternative for measuring C for field trial purposes and for dairy herd improvement programme.
Veterinary Microbiology, Oct 1, 1996
An atypical Staphylococcus aureus (S. aureus) strain, isolated in a dairy herd over an 8 month pe... more An atypical Staphylococcus aureus (S. aureus) strain, isolated in a dairy herd over an 8 month period, was examined. The S. aureus strain was clumping factor negative, weakly heat-resistant deoxyribonuclease positive and produced narrow zones of double haemolysis. In total, 57 quarter infections were observed. Prevalence data per month, calculated as the percentage of quarters infected with this atypical S. aureus strain varied from 7.5% to 17.7% and the new infection rate varied from 0.14 to 0.55. In routine bacteriology, the large number of quarters infected with the atypical S. aureus could easily be misclassified as quarters infected with non-aureus staphylococci.
Journal of Clinical Microbiology, Feb 1, 2005
Animal Reproduction Science, 1996
Journal of Dairy Science, Nov 1, 1993
In a high yielding low SCC herd, changes in milk yield associated with SCC and occurrence of clin... more In a high yielding low SCC herd, changes in milk yield associated with SCC and occurrence of clinical mastitis and differences in SCC with parity, clinical mastitis, and DIM were investigated. Milk yield data were obtained at every milking, and SCC was measured once every 48 h in 117 cows during the first 119 d postpartum. Effects of SCC and clinical mastitis on cumulative milk yield in the first 119 d postpartum were evaluated with least squares linear regression. Repeated measures ANOVA was used to detect changes in SCC. The SCC was highest at lactation onset, and cows with clinical mastitis had significantly higher SCC. During the 10 d prior to onset of clinical mastitis, SCC was higher in affected cows than in matched unaffected controls and surged just prior to diagnosis. During the 10-d period following a mastitis treatment, SCC differences between treated and control cows remained significant but became smaller with time and returned to the premastitis differences. Occurrence of clinical mastitis was associated with 5% milk yield loss. Cows with mean SCC > 245,000 cells/ml over the 119 d showed 6.2% yield loss compared with cows with SCC < or = 90,000 cells/ml. Cows with clinical mastitis had higher SCC prior to and following the end of treatment for mastitis than did controls. Clinical mastitis and SCC were associated with significant yield loss. Milk yield loss attributed to clinical mastitis was greater than that associated with elevated SCC (> 245,000 cells/ml) because a greater percentage of cows (26%) had clinical mastitis than elevated SCC (12.5%).
Journal of Dairy Science, Feb 1, 1991
Changes in milk production associated with occurrence of clinical diseases (dystocia, stillbirth,... more Changes in milk production associated with occurrence of clinical diseases (dystocia, stillbirth, twin births, milk fever, retained placenta, displaced abomasum, limping due to foot lesions, metritis, ketosis, and mastitis) were investigated. Data were collected daily on 388 lactation. Stepwise least squares regression was used to evaluate existence of associations between diseases and six yield measures that characterized milk production in the first 119 d postpartum. Logistic regression was used to investigate whether milk yield 1 to 5 d in milk might be of use to detect cows with early postpartum metritis (less than 21 d after calving). Lower milk production to 5 d postpartum was associated with an increased risk of early postpartum metritis in the logistic regression model. Yield to 5 and to 21 d postpartum was lower in cases of stillbirth, retained placenta, and early postpartum metritis. Yield from 22 to 49 d postpartum remained lower in cows diagnosed with early postpartum metritis. Milk yield losses occurred during diagnosis and treatment of displaced abomasum and mastitis. Ketosis was associated with yield losses prior to and at treatment. Ketosis to 21 d in milk was also associated with lower production after treatment. Limping diagnosed in the first 49 d postpartum coincided with higher yield to 5 d, to 21 d, and after 49 d postpartum.
Veterinary Quarterly, Sep 1, 1996
This article reviews current knowledge concerning enzootic pneumonia. Enzootic pneumonia, caused ... more This article reviews current knowledge concerning enzootic pneumonia. Enzootic pneumonia, caused by Mycoplasma hyopneumoniae and exacerbated by secondary invaders, occurs worldwide and has been known for many years. The organism, with its typical characteristics, invades the respiratory tract in several successive steps. Clinical symptoms and lesion development are the result of the pathogenic capacity of Mycoplasma hyopneumoniae and the defence reactions in the lung. The economic relevance of pneumonia is influenced to a large extent by common secondary infections which follow an initial M. hyopneumoniae infection. Different tests for the diagnosis of pneumonia in individual pigs and in groups are available. Treatment and control is not simple since enzootic pneumonia is a multi-factorial disease. Some epidemiological aspects and the most important measures for prevention of the disease are described.
Journal of Veterinary Medicine Series B-infectious Diseases and Veterinary Public Health, Jan 12, 1998
PubMed, Sep 1, 1993
Currently somatotropin in being developed for use in several animal species, primarily as a produ... more Currently somatotropin in being developed for use in several animal species, primarily as a productivity enhancer. The objective of this paper was to review direct and indirect effects of somatotropin supplementation on reproduction particularly in the dairy cow. There is substantial evidence that somatotropin plays an important role in the normal ovarian function. This effect is probably mediated via IGF-I. Existing literature indicates that higher milk yields are antagonistic to reproductive performance and require enhanced nutrition and reproductive management. Similarly, studies indicate that reproductive performance may be impaired in diary cattle supplemented with somatotropin. Effects of somatotropin treatment on reproductive performance may depend on the dose and the stage of lactation. Low doses of somatotropin in early lactation may improve reproductive function.
EFSA supporting publications, Sep 1, 2017
EFSA Journal, Nov 1, 2017
EFSA Journal, Jun 1, 2016
An assessment of emerging risk is characterized by the early detection of facts related to that r... more An assessment of emerging risk is characterized by the early detection of facts related to that risk derived either from research and/or from monitoring programs or episodic observations. Assessment of emerging risks must be flexible to accommodate changes in the conditions that affect the risks and also improvements in the methods of detection. Assessment of emerging risks is distinct from the assessment of risks under emergency (or crisis) conditions, as the latter are dealt with through established Commission procedures (*).
The Kenya Veterinarian, 1994
EFSA Journal, Oct 1, 2012
Veterinary Quarterly, Apr 1, 1998
Netherlands milk and dairy journal, 1996
Duplicate samples of mixed milk (n = 13 927) were collected to compare somatic cell counting with... more Duplicate samples of mixed milk (n = 13 927) were collected to compare somatic cell counting with the Somascope and the Fossomatic 360. To estimate sampling and assay variability, somatic cell count (C) was measured with the Fossomatic 360 on 295 duplicate milk samples. The total variance was 1042 x 10 6 . The contribution of the measuring instrument (Fossomatic 360) and the sampling procedure were 12.7 and 87.3%, respectively. The overall variance of the paired differences of the logarithmically transformed numerical value of C (expressed in μL -1 ) (In{C}) of the 295 duplicate milk samples all measured with the Fossomatic 360, was 0.08. Additionally, accuracy of the Somascope was evaluated on 9558 duplicate milk samples. In one of the duplicate milk samples, C was measured with the Fossomatic 360; in the other, with the Somascope. The variance of the paired differences of ln{C} between the Somascope and the Fossomatic 360 was 0.14. Comparison of the ln{C} per class (class width = 1 on the log e scale) showed 77.4, 28.1 and 11.3% overestimation of In{C}, measured with the Somascope, in the classes ≤ 2,2-3 and 3-4, respectively, and 1.4, 2.6 and 4.6% underestimation in the classes 6-7, 7-8 and >8, respectively, indicating a lower accuracy of the Somascope in these classes. The Pearson correlation of In{C} between the Fossomatic 360 and the Somascope was 0.96. The Pearson correlation of In{C} of the duplicate milk samples measured twice with the Fossomatic 360 was 0.97. Simple linear regression (Somascope against Fossomatic) showed a significant intercept, b 0 (±s.e.)= 1.13 (±0.011) and the slope, b 1 (±s.e.) = 0.803 (±0.0022), differed from the ideal value of 1 (P 250 x 10 3 mL -1 using the Somascope as compared to the Fossomatic 360, was 0.89, 0.95 and 0.97, respectively. The Somascope, when correctly calibrated, is an acceptable alternative for measuring C for field trial purposes and for dairy herd improvement programme.
Veterinary Microbiology, Oct 1, 1996
An atypical Staphylococcus aureus (S. aureus) strain, isolated in a dairy herd over an 8 month pe... more An atypical Staphylococcus aureus (S. aureus) strain, isolated in a dairy herd over an 8 month period, was examined. The S. aureus strain was clumping factor negative, weakly heat-resistant deoxyribonuclease positive and produced narrow zones of double haemolysis. In total, 57 quarter infections were observed. Prevalence data per month, calculated as the percentage of quarters infected with this atypical S. aureus strain varied from 7.5% to 17.7% and the new infection rate varied from 0.14 to 0.55. In routine bacteriology, the large number of quarters infected with the atypical S. aureus could easily be misclassified as quarters infected with non-aureus staphylococci.
Journal of Clinical Microbiology, Feb 1, 2005
Animal Reproduction Science, 1996
Journal of Dairy Science, Nov 1, 1993
In a high yielding low SCC herd, changes in milk yield associated with SCC and occurrence of clin... more In a high yielding low SCC herd, changes in milk yield associated with SCC and occurrence of clinical mastitis and differences in SCC with parity, clinical mastitis, and DIM were investigated. Milk yield data were obtained at every milking, and SCC was measured once every 48 h in 117 cows during the first 119 d postpartum. Effects of SCC and clinical mastitis on cumulative milk yield in the first 119 d postpartum were evaluated with least squares linear regression. Repeated measures ANOVA was used to detect changes in SCC. The SCC was highest at lactation onset, and cows with clinical mastitis had significantly higher SCC. During the 10 d prior to onset of clinical mastitis, SCC was higher in affected cows than in matched unaffected controls and surged just prior to diagnosis. During the 10-d period following a mastitis treatment, SCC differences between treated and control cows remained significant but became smaller with time and returned to the premastitis differences. Occurrence of clinical mastitis was associated with 5% milk yield loss. Cows with mean SCC > 245,000 cells/ml over the 119 d showed 6.2% yield loss compared with cows with SCC < or = 90,000 cells/ml. Cows with clinical mastitis had higher SCC prior to and following the end of treatment for mastitis than did controls. Clinical mastitis and SCC were associated with significant yield loss. Milk yield loss attributed to clinical mastitis was greater than that associated with elevated SCC (> 245,000 cells/ml) because a greater percentage of cows (26%) had clinical mastitis than elevated SCC (12.5%).
Journal of Dairy Science, Feb 1, 1991
Changes in milk production associated with occurrence of clinical diseases (dystocia, stillbirth,... more Changes in milk production associated with occurrence of clinical diseases (dystocia, stillbirth, twin births, milk fever, retained placenta, displaced abomasum, limping due to foot lesions, metritis, ketosis, and mastitis) were investigated. Data were collected daily on 388 lactation. Stepwise least squares regression was used to evaluate existence of associations between diseases and six yield measures that characterized milk production in the first 119 d postpartum. Logistic regression was used to investigate whether milk yield 1 to 5 d in milk might be of use to detect cows with early postpartum metritis (less than 21 d after calving). Lower milk production to 5 d postpartum was associated with an increased risk of early postpartum metritis in the logistic regression model. Yield to 5 and to 21 d postpartum was lower in cases of stillbirth, retained placenta, and early postpartum metritis. Yield from 22 to 49 d postpartum remained lower in cows diagnosed with early postpartum metritis. Milk yield losses occurred during diagnosis and treatment of displaced abomasum and mastitis. Ketosis was associated with yield losses prior to and at treatment. Ketosis to 21 d in milk was also associated with lower production after treatment. Limping diagnosed in the first 49 d postpartum coincided with higher yield to 5 d, to 21 d, and after 49 d postpartum.
Veterinary Quarterly, Sep 1, 1996
This article reviews current knowledge concerning enzootic pneumonia. Enzootic pneumonia, caused ... more This article reviews current knowledge concerning enzootic pneumonia. Enzootic pneumonia, caused by Mycoplasma hyopneumoniae and exacerbated by secondary invaders, occurs worldwide and has been known for many years. The organism, with its typical characteristics, invades the respiratory tract in several successive steps. Clinical symptoms and lesion development are the result of the pathogenic capacity of Mycoplasma hyopneumoniae and the defence reactions in the lung. The economic relevance of pneumonia is influenced to a large extent by common secondary infections which follow an initial M. hyopneumoniae infection. Different tests for the diagnosis of pneumonia in individual pigs and in groups are available. Treatment and control is not simple since enzootic pneumonia is a multi-factorial disease. Some epidemiological aspects and the most important measures for prevention of the disease are described.